Female Reproductive System,
Neonatology
Bovine Reproductive tract
Meso metrium suspends the uterus to
the abdominal roof- in dogs and cats
Uterus anatomy
Perimetrium- outer lining
Myometrium- muscular layer
Endometrium- inner vascular lining
Clitoris- just inside the vagina on the floor
Vaginal Fornix- lateral separation of the distal
vagina that creates difficulty in A.I. of unaware
Canine female
Hymens do occur in dogs and mares
and can increase dystocia if a fibrous
band is maintained
When the vaginal canalization is complete, the
fetal hymen is formed from the proliferation of
the sinovaginal bulbs (where müllerian ducts
meet the urogenital sinus), and becomes
perforate before or shortly after birth
Due to similar reproductive system development,
many mammals, including chimpanzees,
elephants, manatees, whales, and horses, retain
hymens
Factors that affect puberty
• Genetic factors- smaller breeds reach puberty
earlier
• Nutritional factors-poor nutrition delays onset
• Environmental factors- presents of males
enhances puberty, confinement and close
grouping of gilts hastens puberty
Reproductive tract dilates for delivery
Sow Uterus- ovaries with follicles
Mare
Graffian follicle- fully developed which
is producing Estrogen from it fluid
Corpus Hemorrhoragicum- the fill site
after rupture of follicle
Graffian (mature) follicle
A granulosa cell
or follicular cell
is a somatic cell
that is closely
associated with
the developing
female gamete
(called an oocyte
or egg) in the
ovary of
mammals.
• Also FSH stimulates granulosa cells to convert
androgens (coming from the thecal cells) to
estradiol . However, after ovulation the
granulosa cells produce progesterone. The
progesterone may maintain a potential
pregnancy and causes production of a thick
cervical mucus that inhibits sperm entry into
the uterus
• The theca folliculi are responsible for the
production of androstenedione, and indirectly
the production of estradiol by supplying the
neighboring granulosa cells with
androstenedione a substrate for estradiol.
From the Anterior pituitary Gland
• Follicle-stimulating hormone (FSH) is a
hormone. It is synthesized and secreted by
the anterior pituitary gland. FSH regulates the
development, growth, pubertal maturation,
and reproductive processes of the body. FSH
and Luteinizing hormone (LH) act
synergistically in reproduction
From the Anterior Pituitary Gland
 Luteinizing hormone (LH) is a hormone produced by the
anterior pituitary gland.
 In females, an acute rise of LH called the LH surge triggers
ovulation( with Estrogens and Prostaglandin F2 alpha)

 Prostaglandin F2 alpha stimulates breakdown of the Tunica
albiginea at the potential rupture sight on the ovary
 development of the corpus luteum.
 In males, where LH had also been called interstitial cellstimulating hormone (ICSH), it stimulates Leydig cell
production of testosterone.


Corpus Luteumprogesterone
• Progesterone steroid hormone involved in
the female reproductive cycle, pregnancy
(supports gestation) and embryogenesis of
mammals. Progesterone belongs to a class of
hormones called progestogens .
• Progesterone is commonly manufactured from
the yam family, Dioscorea
Corpus Hemorrhoragicum- the fill site
after rupture of follicle- Corpus
Luteum fills – production of
Progesterone to maintain pregnancy
Degeneration of C.l. to Corpus albicans
in the ovary
Here is an ova in ovarian
tissue surrounded by theca
cells and waiting for
appropriate hormonal
stimulation to begin to
develop. FSH, Estrogen,
Prostaglandin, Progesterone
Ova to zygote

 Females are born with all the ova they will ever produce,
ovulating one (moniprrous) or several (pleuriparous) from
puberty until menopause. When it's time for the egg's
great adventure, the ovarian tissue that encases eggs
proliferates and becomes differentiated into granulosa and
theca cells, producing the much larger, cystic Graafian
follicle. When mature, the follicle ruptures, and the egg
explodes from the torn surface of the ovary (occasionally
producing a pain) and is swept up into the nearby fallopian
tube, where, if sperm , fertlize and converted it into a
zygote that begins dividing. This early embryo continues its
way down the tube and into the uterus, where it implants
itself into the uterine wall
• At Ovulation the Fimbria (funnel) gathers the
ova to begin the migration down the fallopian
tube
• Fertilization occurs in the Fallopian
Tube(oviduct)
http://www.newscientist.com/article/dn1415
5-human-ovulation-captured-on-video.html
http://www.metacafe.com/watch/yt-9MnQxiSJZ4Q/3d_sperm_fertilization_project/
Estrouse Cycle (from one heat to the
next)
Proestrus
One or several follicles of the ovary are starting to
grow. Their number is specific for the species.
Typically this phase can last as little as one day or
as long as 3 weeks, depending on the species.
Under the influence of estrogen the lining in the
uterus (endometrium) starts to develop. Some
animals may experience vaginal secretions that
could be bloody. The female is not yet sexually
receptive
 Estrus
 "Estrus" redirects here. For other uses, see Estrus (disambiguation).
 Estrus refers to the phase when the female is sexually receptive ("in
heat," or "on heat"). Under regulation by gonadotropic hormones,
ovarian follicles are maturing and estrogen secretions exert their
biggest influence. She then exhibits a sexually receptive behavior[9],
a situation that may be signaled by visible physiologic changes. A
signal trait of estrus is the lordosis reflex, in which the animal
spontaneously elevates her hindquarters.
 In some species, the labia are reddened. Ovulation may occur
spontaneously in some species (e.g. cow), while in others it is
induced by copulation (e.g. cat). If there is no copulation in an
induced ovulator, estrus may continue for many days, followed by
'interestrus,' and the estrus phase starts again until copulation and
ovulation occur.
• Metestrus
• During this phase, the signs of estrogen
stimulation subside and the corpus luteum
starts to form. The uterine lining begins to
secrete small amounts of progesterone. This
phase typically is brief and may last 1 to 5
days. In some animals bleeding may be noted
due to declining estrogen levels
• Diestrus
• Diestrus is characterised by the activity of the
corpus luteum that produces progesterone. In
the absence of pregnancy the diestrus phase
(also termed pseudo-pregnancy) terminates
with the regression of the corpus luteum. The
lining in the uterus is not shed, but will be
reorganised for the next cycle
 Anestrus
 Anestrus refers to the phase when the sexual cycle
rests. This is typically a seasonal event and controlled
by light exposure through the pineal gland that
releases melatonin. Melatonin may repress stimulation
of reproduction in long-day breeders and stimulate
reproduction in short-day breeders. Melatonin is
thought to act by regulating hypothalamic pulse
activity of gonadotropin-releasing hormone. Anestrus
is induced by time of year, pregnancy, lactation,
significant illness, chronic energy deficit, and possibly
age
 Frequency
 Some species, such as cats, cows and domestic pigs, are polyestrous and
can go into heat several times a year. Seasonally polyestrous animals or
seasonal breeders have more than one estrous cycle during a specific time
of the year and can be divided into short-day and long-day breeders:
 Short-day breeders, such as sheep, goats, deer, foxes, elk—are sexually
active in fall or winter.
 Long-day breeders, such as horses and hamsters, are sexually active in
spring and summer.
 Species that go into heat twice per year, such as most dogs, are diestrous.
 Monoestrous species, such as bears, foxes, and wolves, have only one
breeding season a year, typically in spring to allow growth of the offspring
during the warm season to survive the next winter.
 A few mammalian species, such as rabbits do not have an estrous cycle
and are able to conceive at almost any arbitrary moment
Cats
The female cat in heat has an estrus of 14–21
days and is an induced ovulator. Without
copulation she may enter interestrus before
reentering estrus. With copulation and in the
absence of pregnancy, cycles occur about
every three weeks. Cats are polyestrous but
experience a seasonal anestrus in autumn and
late winter
 Dogs
 A bitch is diestrous and goes into heat typically twice every
year, although some breeds typically have one or three
cycles a year. The proestrus is relatively long at 5–10 days,
while the estrus may last 5-21 days. With a diestrus of 5-10
days, a typical cycle lasts about 3 weeks followed by about
150 days of anestrus. They bleed during this time, which
will usually last from 7–13 days, depending on the size and
maturity of the dog. Ovulations occur at the end of the
estrus period, therefore this is the best time to begin
breeding. Proestrus bleeding in dogs is common and is
caused by diapedesis of RBCs from the blood vessels due to
sudden withdrawal of estrogen hormone.
 Horses

 A mare may be 4 to 10 days in heat and about 14 days in diestrus. Thus a
cycle may be short, i.e. 3 weeks. Horses mate in spring and summer,
autumn is a transition time, and anestrus in winter.
 A feature of the fertility cycle of horses and other large herd animals is
that it is usually affected by the seasons. The number of hours daily that
light enters the eye of the animal affects the brain, which governs the
release of certain precursors and hormones. When daylight hours are few,
these animals "shut down," become anestrous, and do not become fertile.
As the days grow longer, the longer periods of daylight cause the
hormones from the anterior pituitary (FSH) which activate the breeding
cycle. There is economic advantage, given a gestation period of about
eleven months, it prevents them from having young in winter which
forage, and nutrition is in minimum supply. This is why these animals
reproduce during certain times of the year.
 Rats
 Rats typically have rapid cycle times of 4 to 5 days. Although they ovulate
spontaneously, they do not develop a fully functioning corpus luteum unless they
receive coital stimulation. Fertile mating leads to pregnancy in this way, but
infertile mating leads to a state of pseudopregnancy which lasts about 10 days.
Mice and hamsters have similar behaviour . The events of the cycle are strongly
influenced by lighting periodicity .
 A set of follicles start to develop near the end of proestrus and grow at a nearly
constant rate until the beginning of the subsequent estrus when the growth rates
accelerate eightfold. They then ovulate about 109 hours after starting growth.
Oestrogen peaks at about 11am on the day of proestrus. Between then and
midnight there is a surge in progesterone, LH and FSH, and ovulation occurs at
about 4am on the next, estrus day. The following day, metestrus, is called early
diestrus or diestrus I by some authors. During this day the corpora lutea grow to a
maximal volume, achieved within 24 hours of ovulation. They remain at that size
for 3 days, halve in size before the metestrus of the next cycle and then shrink
abruptly before estrus of the cycle after that. Thus the ovaries of cycling rats
contain three different sets of corpora lutea at different phases of development.
•
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•
•
Estrus frequencies of some other mammals:
Ewe: 17 days
Bovine: 21 days
Goat: 21 days
Sow: 21 days
Elephant: 16 weeks
Estrus in the cow (polyestrous)
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Estrus lasts 16 hrs (Estrous cycle is 21 days)
standing to be mounted
Mounting other cows
Mucous smeared on the buttocks
Nervous
Seeks the bull
Roughening hair at the tailhead
Chin resting on rumps of other ocws, tail raised, urination.
http://www.youtube.com/watch?v=VhIBiZCSs5I&feature=more_r
elated standing heat
 http://www.youtube.com/watch?v=Nmkj5gq1cQU&feature=fvw
 Super cattle
Estrus in the ewe
seasonally polyestrus (17 days cycle)
•
•
•
•
•
•
Standing to be mounted\search out ram
Vulva swells
Nervous
Vibrating, agitating movement of tail
Length of estrus ( 30 hrs)
http://www.youtube.com/watch?v=QbYZatk
EeRw&feature=related
sheep mating
Estrus in the Sow- polyestrus
Estrus 44 hrs (Estrous cycle- 21 days)
Stands to be mounted
Nervous
Tries to mount others
Swollen red vulva/ mucous dischg rarely
http://www.youtube.com/watch?v=4tmmv7M0I
Ak&feature=related mating pigs- note ear

notching for identification
Estrus in the mare- seasonally
polyestrus
Estrus- 6 days ( Estrous cycle 21 days)
Nervous
Interst in stallion
Vaginal winking, and urine excretion
http://www.youtube.com/watch?v=AIWslKz_kL
M
mare winking, in heat
Estrus in the Bitch- diestrus
 Estrus – 6-21 days
 Bleeding begins at proestrus and decreases or stops at
estrus ( Diapedesis because of increasing thickness and
vascularization of the endometrium ( not shedding of
mucosa as in menstration in humans)
 Fertility is highest 48 hrs prior to the end of estrus.
 Many develop pseudocyesis (false pregnancy) during
C.L. production of progesterone.
 Metestrus – regression of the C.L.
 Anestrus-
Ovulation occurs 2 days after LH spike
Are these cornified or non- cornified
epithelial cells- what stage of Estrous
cycle does this most likely represent?
Uterine changes in Estrous Cycle
-Rising Estrogen in prosestrus- edema and
thickening of uterine wall- additional blood
vessels
-Estrogen makes endothelium fragile
-Bleeding may occur in proestrus
-Great media for growing excessive amounts of
bacteria
• Increase in Progesterone at metestrus and diestrusglands develop in the uterine wall and secrete Uterine
Milk which nourishes the embryo until a placenta is
formed
• As the C.L. is killed and stops producing progesterone,
the uterus lining sloughs and is reabsorbed- effects of
• PGF 2alpha
• A. From the uterus at the end of Diestrus
• B. From pregnant uterus a parturition
• C. From drugs (Estrumate, Lutalyse) at post estrus
Prostaglandin F2alpha
destroys the C.L which allows initiation of new cycle
Prostagland stops C.L. and commenses
a new cycle
Female system
Male system
• GnRH (gonadotropin releasing hormone)
• -produced by the pituitary gland (to induce it
to produce FSH and LH
• GnRH is turned off by Progesterone (so that
no new follicles are produced during
pregnancy)
• Factrel and Cystorelin to stimulate follicle
development and create a LH spike
Cystic ovaries-ovulation
Estrogen
• Produced by Graffian follicle/induces sexual
receptivity
• Causes uterine edema, increased vascularity
and blood vessel fragility
• Used in Ear implant growth promotantsinhibits hypothalmus to produce GnRH and
shuts off the pituitary gland production of
FSH/LH, animals stay settled and gain better
Progesterone
• Produced by CH and CL and placenta in some
species
• Uterine wall glandular development for
pregnancy
• Inhibits hypothalamus from producing GnRH,
therefore no FSH and LH
• Megestrol acetate (MGA) to arrest cycle until
it is removed
• Ovaban- for dogs
Double muscling and infertility
Homozygous for myostatin growth differential factor 8
Homozygous for Myostatin (GDF8)
• Animals lacking myostatin do not have the ability
to inhibit muscle growth.
• It is a genetic mutation that inhibits regulation of
differentiation of muscle fibers
• It is closely liked with genes associated with
fertility, thus there can be a combination of these
abnormal genes
• http://www.youtube.com/watch?v=orj6xafX1YY&
feature=related human double muscle or drugs
Some facts as a guide for studying all
species
• Iength of estrous cycle in cows- 21 days
• Length of each of the 4 stages of cycle•
Estrus 14-18 hrs Metestrus- 2-5 days Diestrus 10-14
days Prosestrus 3-5 days
• Ovulation- 12-16 hrs postestrus
• Sexual maturity- 8-14 mo, smaller is earlier
• First bull breeding 14 mo. , mature bull=12 cows
• Bull sperm declines at 7 yrs
• How long does breeding act take- one thrust
• What is the semen volume – 6-10 mls
Study guide for cow reproduction
• What is the trade name of synthetic PGF2alpha
• at what stage of the cow cycle will these preps
Effective- Diestrus- why?
Gestation length- 285 days
Cows should be re-bred by 60 days pp (three heats pp)
Cows should be dry for 60 days prior to delivery
Lochia- discharge of clear fluid a couple of weeks prior
to calving
7% have Retained Placentas
Study guide for cattle reproduction
• Silent heats are unusual and occur most often
at -the first heat after calving (most are
unobserved)
• Why is GnRH sometimes given at estrus of
repeat breeders (pathophysiology of
hormones and cycles)
• Rectal palpation for pregnancy is 3 wks
gestation
Capacitation of sperm and the female
reproductive tract storage
• http://www.youtube.com/watch?v=orj6xafX1YY&feature=rel
ated capaciation- the acrosome of the sperm heat becomes
leaky- releases enzymes which break down the outer coating
of the egg.
• Sperm in the reproductive tract of cows, pigs and sheep travel to
the oviduct isthmus( a sperm reservoir (like the epididymis)
• There is a lower temperature, nutrients that are stimulated by the
ovary and the follicle, and seminal fluid matrix is processed for
nutrients
• Stores sperm for impending ovulation( what is the implication of
this new information?
http://www.youtube.com/watch?v=TDW28qWBhzc&feature=rela
ted to egg with capacitation and “love”
Reproductive pattern Horses
• Anovulatory Phase(seasonally anestrous)
• Induced by lengthening photoperiods
• Resistant to drug manipulation at this time
because Ant. Pit is not receptive to GnRH
unless lengthening photoperiod
• Cycles every 22 days
• Transition Phase Spring increasing FSH but
lacking adequate LH( can use AltrenogestRegu-Mate- progesterone analog daily x 7)
http://www.bing.com/videos/search?q=breeding+on+foal+heat+video&docid=391586055275&mid=1DFED6F945DA01E0D7DA1D
Breeding on “Foal Heat”
6-15 days post partum
-First ovulation cycle
post partum
-Foal Heat diarrhea
-Usually hand bred
because of danger
to the foal and
danger to the stallion
-Mare is often very
anxious around the
foal (diploid)
http://www.bing.com/videos/search?q=horse+breeding+video&mid=BB498DB8684B72507C4BBB498DB8684B72507C4B&FORM
Horse breeding video
Teasing procedure in equine breeding
• Bring the stallion near and watch the mare
response- violent or winking
• Tease daily until mare is standing
• Use breeding hobbles/ twitch
• Encourage stallion until full erection
• Mounting is along side- intromission
• Vigorous pelvic thrust (10-sec)
• 8 seminal jets (70 mls of semen)
• Stallions may hold mare’s withers with teeth
Equine reproduction cycle variations
• May ovulate without showing estrus
• May show estrus without ovulating
• CL may persist up to 2 months
“Split heat” is common ( in heat a few days,
then out, then back in)
Estrus- often multiple follicles (ovary is kidney
shaped), uterus is soft and edematous, not
turgid like a cow, cervix is relaxed and open
Equine reproduction variables
• Late Estrus- LH surges over several days with
20 % multiple ovulations (follicles are 5 cm
diameter),
• One twin is usually absorbed
• Best breeding time- 2 days pre-ovulation(
three days after the beginning of estrus, and
alternate days (sperm survives 2 days in the
uterus
Metestrus in the mare
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•
•
•
- LH fades, estrogen fades, progesterone rises
Corpus hemorrhagicum forms inside the ovary
Uterus is toned
Rejects the Stallion
• Diestrus in the Mare
• Progesterone dominates , C.L. is present
• Can use Lutalyse to shorten the cycle- go to
proestrus
• Cervix tightly closed
Proestrus in the mare
• PGF2alpha kills C.L.
• Gestation Period- 340 days (11 months)
• Light horse have longer gestation than heavy
horse breeds
• Male fetuses have a slightly longer gestation
Caprine reproduction
• Puberty 6-8 mo, bucks- 3 mo
• Does need the scent emitted from the buck to
stimulate her to cycle (scent glands are medial
and caudal to the horns)
• Female bleats, flags, vulva swollen
• Increase in milk production
• Breed as soon as estrus occurs
• Gestation 145 days (5 months)
Ovine Reproduction
• Estrus- tail twitch
• Often use teaser rams (vasectomized) with a
marking harness
• “Flushing”- increasing plane of nutrition prior
to breeding season
• Breed ASAP when estrus occurs
• 1 ram= 30 ewes (synchronized using
progesterone tampons (14 days then remove)
Pregnancy toxemia in
ewes and does
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•
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When a pregnant ewe takes ill, a likely cause is pregnancy toxemia. Pregnancy
toxemia goes by several other names including pregnancy disease, twin lamb
disease, lambing paralysis, and ketosis.
Pregnancy toxemia is a metabolic disorder caused by low glucose
concentrations in the blood and excessive breakdown of body fat to
compensate. "Ketones" are the toxic by-product produced during this rapid
breakdown of fat, and it is possible to test for their presence in the ewe's
urine.
Inadequate nutrition during the last one-third of pregnancy is the primary
cause of low blood sugar/pregnancy toxemia, as ewes cannot consume
enough feed (energy) to meet the demands of their growing fetus(es).
Pregnancy toxemia in ewes and does
• Successful treatment of pregnancy toxemia
requires early detection and steps to quickly
meet the energy (glucose) needs of the
affected ewe. The most common treatment is
to drench ewes with 2 to 3 ounces of
propylene glycol 2 to 3 times daily. Yogurt
mixed with water will also provide energy and
bacteria to stimulate the rumen. Intravenous
glucose is another possibility, but harder for
producers to do on the farm.
Porcine reproduction-population
Breeding
Originally were seasonally polyestrous
Gilts mature at 5-8 month of age (170220 lbs)
Hastens puberty if they visit the boar each day at 150 days
-Estrus- 2.5 day
-Estrous cycle- 21 days
-Stands for mounting which
Can be tested by hand
-Pressure on their back or
Riding them
-Estrus occurs 5days after
Weaning and is fertile
_Batch breeding of sow all
Weaned at the same timeGestation- 3mo, 3wks,3days
(115 days)
Boars can’t smell females in EStrus
Females respond to Saliva of Boars champing which contains pheromones
Boar ejaculation- 5-15 min
150-1000 mls
1st fraction-clear prostatic fluid
2nd fraction- sperm rich
3rd fraction- thick gel from
bulbourethral gland
Estrus Synchronization in Animals
Cattle- cycle 21 days practised most often in dairy cattle-
batch breeding in pigs-
shorten the
Calving interval in for beef cattle can be shortened. 2/3 of cows will be in diestrus
PGf2alpha lyses CL only works in Diestrus (Estrumate), can repeat in 11 days
Sheep- Cycle 14-19 days Estrumate as in cows or use Veramix
sponges- prevents
Ovulation and no new cycles can begin.
CL present will mature and be eliminated
Goats- Cycle 21 days- Estrumate
Horses- Cycle 21 days- Lutalyse
Sow - Cycle 21 days Estrumate has no
effect until 12 days post partum and they
cycle 2-5 days post weaning- use weanas the synchronization method.
progesterone
Disturbances of Estrus in Large animals
• cow- Retained C.L. and pyometra- anestrus
after parturition (15-60 days) C.L. normally
dies at 17 days pp. Cervix is open and uterine
manipulation reveals large amount of
purulent material from vagina
• Ttt – Estrumate kills C.L.
•
Pyometra bovine
Follicular cysts cattle
• Enlarged follicular structure greater than 25 mm persisting for 10 days
or more in the absence of a corpus luteum. Follicular cysts are thin
walled, fluid filled, and anovulatory. These cows can have anestrus type
behavior or have nymphomania behavior (always standing to
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be mounted). The uterus is
generally flaccid, and they
may have a constant clear
discharge from the vulva.
Most of the time there are
multiple follicular cysts.
Progesterone concentrations are low.
Relative size of C.L. and Follicular cyst
Follicular cysts- horses
• Most common reason for anestrus during the
breeding season
• Purulent material does not accumulate
because the cervix is NOT partially open like in
the cow
• Treat with Lutalyse (Estrumate is not for
horses)
Corpus luteal cysts - cattle
Canine Reproductive patterns
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Onset of Puberty- great variation
Silent heat- no outward signs of estrus
Ideal breeding age: after 2 year of age
After genetic screening for defects
Estrus- every 7 mo. ( Shepherds every 4-4.5 mo)
- once per year- Basenji
http://www.vetmed.lsu.edu/eiltslotus/theriogen
ology-5361/the_normal_canine.htm
Non-cornified epithelial cells in vagina
• Non-cornified
• Parabasal cells have a large stippled nucleus
and a rounded cytoplasm The nucleus is large
compared to the cytoplasm.
Non-Cornified epithelial cells of the
vagina
• Intermediate cells have a have a stippled
nucleus and more cytoplasm than parabasal
cells. The cytoplasm may even become
angular.
Cornified epithelial cells of the vagina
• Superficial cells have a pyknotic nucleus and
angular cytoplasm. There is no stipling in the
nucleus.
Cornified epithelial cells of the vagina
• Anuclear cells have no visible nucleus and
angular cytoplasm.
Interestrus
• Interestrus consists of diestrus (60 days) plus anestrus (a
variable time).
• Average duration is 7 months.
• G. Shepherd dogs average about 6.5 months interestrus.
• Dachshunds average about 8.3 months interestrus.
• Basenjis average about 12 months interestrus.
• Therefore, larger dogs tend to have shorter interestrus
intervals than small dogs (contrary to popular opinion)
• The variation of the interestrus interval within a bitch was
actually found to be greater than that between bitches in a
research study done by Dr. Guy Bouchard.
• Interestrus tends to become longer as bitches are greater
than 8 yrs
•
Anestrus
• Anestrus is not the same as interestrus. Anestrus
is a variable time after diestrus. Interestrus
(diestrus + anestrus) averages 5 - 7 months.
• Anestrus lasts 90 - 150 days (anestrus does not
include diestrus).
• Anestrus is a time of mandatory endometrial
repair that has been documented in Beagles
• The endometrium is being 'repaired' after the
progesterone effects during diestrus for the
preceding 60 days
Anestrus
Intermediate and parabasal cells predominate in smears
taken during anestrus. Superficial cells are absent or
found in very small numbers. Neutrophils may also be
present or absent.
Anestrus
• Progesterone is at baseline concentrations (<1
ng/ml). Even spayed bitches run basal levels of
progesterone. This baseline progesterone is
probably of adrenal origin.
• Prolactin secretion by the pituitary may
promote anestrus, because prolactin
inhibitors can be used to terminate anestrus
(i.e. induce estrus).
Proestrus
• Serum concentrations of estrogen rise during
proestrus, leading to capillary breakage and leakage
of red blood cells through uterine epithelium, as
well as proliferation of the vaginal epithelium.
• Examination of vaginal smears from early to late
proestrus will reveal a gradual shift from
intermediate and parabasal cells to superficial cells.
Typically, red blood cells are present in large
numbers and neutrophils are commonly observed.
Large numbers of bacteria are also often present.
proestrus
• In some bitches, proestrus can persist for two
to three weeks. In such cases, prolonged lack
of receptivity may suggest the need to
artificially inseminate or force-breed the
animal. Examining vaginal smears in such
cases will alleviate such concerns - certainly, if
more than a very small percentage of cells are
parabasals and small intermediates, breeding
is a waste of time.
Estrus
•
• The defining characteristic of cytologic estrus
is the predominance of superficial cells. Most,
but not all, bitches will undergo full
cornification, and the smear will reveal a
monotonous pattern composed almost
exclusively of anucleate superficial cells.
Estrus
• If the bitch has been bred within a day of
preparing a vaginal smear, it is quite likely
that sperm will be observed among the
epithelial cells. Indeed, careful examination
for sperm in a smear taken within a few
hours of an alleged breeding is a fairly
reliable means of confirming or denying
such an incident.
• In the image below, an intact sperm (left
panel) and a sperm head (right panel) are
present next to superficial cells.
• Diestrus
• The onset of diestrus is marked by a precipitous
decline in the number of superficial cells and
reappearance of intermediate and parabasal
cells. Most commonly, the cellular profile changes
within a single day from essentially 100%
superficial cells to less than 20% superficial cells.
However, it is best to confirm the onset of
diestrus by examining a smear prepared on
diestrus day 2.
Diestrus
The significance of identifying the onset of diestrus is
that it is a considerably more accurate predictor of the
time of ovulation, and hence gestation length, than
sexual behavior.
• Dogs ovulate 5-7 days prior to the onset of
diestrus (7-9 days after the preovulatory LH
surge), and hence, gestation length is usually
57 + 1 day from the onset of diestrus day
. The period of behavioral estrus is variable, and
often extends up to several days before and/or after
cytologic estrus. Gestation lengths calculated from
the onset or cessation of receptivity are
correspondingly inaccurate. The onset of diestrus
also correlates well with loss of fertility, and
breedings after the diestrus shift are rarely fertile.
• Normally, LH is present in the bitch's blood in very
small amounts. Just prior to ovulation there is a
significant increase in the serum LH value. LH will
then return to the baseline level within a 24- hour
time period.
• It is this surge of LH that triggers ovulation and
therefore determines the fertile period of the bitch.
The LH surge may occur any time from 3-28 days
after the first signs of heat (swelling of and bleeding
from the vulva). The average is 8-12 days. Ovulation
will occur approximately 2 days after the LH surge.
The eggs will require an additional 2-3 days to
mature so that fertilization may take place. The eggs
are viable from 48 to 72 hours after maturity.
Therefore the fertile period of the bitch averages 4-7
When do you progesterone test?
Typical
morphological
features of the
vaginal mucosa
and endometrium
in anestrus (A),
proestrus (P),
estrus (E), and
early diestrus (D).
H&E. Original
magnification
200X.
• · Nipples
• Nipples on Pregnant dog
• Frequently the first change noticed in a pregnant dog is
in the breast. Before pregnancy takes place, a dog goes
through a cycle called Estrus. This is the period of time
in which a dog can conceive. If the female becomes
pregnant hormones cause the breast to enlarge. More
specifically, the nipples become swollen soon after the
pregnancy occurs. These growth and swelling changes
will continue throughout the pregnancy in preparation
of feeding the puppies when they arrive.
• Appetite
• Feed More Often
• Many dogs lose their appetite during very early
pregnancy. They may eat less or sometimes not
at all. After approximately 2 weeks their hunger
comes back to the point that the dog may seem
to want to eat all the time. Their bodies are using
the food at a much faster rate to support
themselves and however many puppies that are
developing. Dogs should be fed almost double
the amount of their usual food before pregnancy
• Morning Sickness
• Sick Dog
• Like humans, pregnant dogs can suffer from
morning sickness early in the pregnancy. Some
dogs won't experience it at all and others will
vomit intermittently. It rarely lasts longer than
2 weeks or causes problems as long as the dog
does not become dehydrated from vomiting.
• Stomach
• Pregnant Stomach
• Besides the nipple changes, a pregnant dog will
experience other changes in the stomach as the
puppies grow. The stomach becomes visibly extended
mid-pregnancy. As the process continues the puppy's
movements can be seen under the belly. The mother
gains body weight as well as the weight of the puppies
and placenta. A very pregnant dog with a large litter
will look like she's about to pop. Dogs with short legs
may actually have trouble walking during the last week
or so of pregnancy.
• Nesting
• Nesting
• As the pregnancy draws to a close the dog will start seeking
a place to give birth away from everything else. This is
called nesting. They may start crunching rugs together with
their paws or start resting in a particular corner that's out
of the way. Some dogs may choose something familiar that
represents security to them, like your bed. For that reason,
it is best to arrange an out of the way place for her with an
old blanket, familiar toys and extra food and water bowls.
Doing this early in the pregnancy helps the dog become
familiar enough with that spot so she will feel safe giving
birth there.
• Behavioral
• One sign of pregnancy, through the pregnancy and birth,
are behavioral changes. A friendly dog may suddenly
exhibit a need to stay away from people, even those she
knows. On the other hand, a dog that has never been that
friendly may suddenly love to be petted and be playful.
While giving birth, some dogs will want to be left alone and
some will need a reassuring voice or hand. It all depends on
the dog. Be aware that dogs and animals in general are very
protective of their young, so the new mother should be
allowed to get to know her new family without anyone
handling the puppies or making unnecessary visits until
they are older.
Diestrus
Intermediate cells
and a few
neutrophils
Sheets of cells are
often
Seen on the first
day of
Diestrus
Nucleated and anucleated
superficial vaginal cells
Feline reproductive cycle
Domestic cat reproductive cycle
• 2-4 estrous periods every year, each lasting
15-22 days. If she is bred, estrus seldom lasts
more than 4 days. If successful mating does
not occur, a heat cycle may last for 7-10 days
and recur at 15-21 day intervals. It is possible
for an unmated female to cycle every 3-4
weeks indefinitely. Cats also have an estrous
period 1-6 weeks after giving birth, so a
female may be nursing one litter while
pregnant with another.
Domestic cat Estrous Cycle
• Females will not ovulate unless her cervix is
stimulated by copulation or by artificial
means(moist Q-tip)
• Rabbits, ferrets are the same
• If not stimulation
•
in heat 10 days, follicles regress, then
•
again in 10 days
• Estus 3-40 hrs post ovulation, metestrus 2
days, then diestrus 30 to 50 days.
• start howling and this can go on for several
minutes at a time.
• Some females can even spray urine in the
same manner that is usually associated with
tomcats - lifting the tail and squirting urine on
a vertical surface.
• The female cat may adopt postures suggestive
of a desire to mate - tail raised, rear end held
high
Seasonally polyestrous- induced by
lengthening daylight
Inducted ovulators- gestation 58-63 days
• queens kept under a minimum of 10 hours (12
to 14 hours is better) of artificial light per day
may cycle all year round. Cats kept in eight
hours of daylight (and 16 hours of dark) will
virtually stop cycling
• queens are described as induced ovulators
Margay
• Reproduction and life cycle
• Female margays are in estrus for four to ten days over
a cycle of 32 to 36 days, during which they attract males with
a long, moaning call. The male responds by yelping or
making trilling sounds, and also by rapidly shaking his head
from side to side, a behavior not seen in any other cat
species. Copulation lasts up to sixty seconds, and is similar
to that in domestic cats; it takes place primarily in the
trees, and occurs several times while the female is in
heat.[4]
• Gestation lasts about 80 days, and results in the birth of
only a single kitten (or, very rarely, two), usually between
March and June. The kittens weigh 85 to 170 grams (3.0 to
6.0 oz) at birth. This is relatively large for a small cat, and is
probably related to the long gestation period. The kittens
open their eyes at around two weeks of age, and begin to
take solid food at seven to eight weeks.[4]
• Gamete Transport
• Fertilization depends upon the two gametes
bumping into one another. In species with
internal fertilization, which includes all
mammals and birds, both sperm and egg must
be transported into the oviduct, which serves
as the site of fertilization.
• Sperm survive up to 6 days in the uterine
horn
• Placentation in Dogs and Cats
• Dogs and cats are well-known members of the
group of species that have zonary placentae.
Other examples of animals with this type of
placentation include mustelids (ferrets,
skunks), bears, seals and elephants
• Implantation
• Dogs and cats are litterbearing species, and
prior to fixation and implantation, the
blastocysts become evenly spaced throughout
the uterine horns. In both species, there
appears to be efficient transuterine migration
• Gestation- 58-63 days
• In dogs, implantation occurs roughly 18 to 20
days after the preovulatory LH surge (about
diestrus day 8 to 10). In cats, implantation has
been reported to occur 12 to 14 days after
mating.
• Gross Structure of the Placenta
• The zonary placenta takes the form of a band
that encircles the fetus. In dogs and cats, it is
complete, while in species like ferrets and
raccoons, it is incomplete (i.e. two half bands).
• Cats typically have 3 to 8
fetuses. It is not unusual
for one or more to die in
utero and the others
survive to be born. This
image shows the end of
one uterine horn. The
zonary placentae of two
fetuses are clearly visible
through the uterine wall.
• Dissecting the uterus
away from the
conceptuses reveals
the chorioallantois
as an ovoid structure
modified
circumferentially to
form the zonary
placenta.
• In this image,
the
chorioallantois
has been
dissected away
to show the
fetus, encased
in its amnion
• When the placenta
is opened up, its
rich vasculature and
the umbilical
vessels of the fetus
are evident. (Note:
the amniotic fluid is
crystal clear, but
looks dark due to
the background.)
• The canine placenta looks very similar to that
of cats. A feature usually seen in the placentae
of both species is marginal hematomas
(hematophagus zones). These are bands of
maternal hemorrhage at the margins of the
zonary placenta. The products of hemoglobin
breakdown give them a distinctly green
coloration in dogs, whereas in cats they are
brownish and usually less obvious
Microscopic Structure of the
Placenta
• Dogs and cats have an endotheliochorial type
of placenta. In this type of placenta, the
endometrial epithelium under the placenta
does not survive implantation, and fetal
chorionic epithelial cells come to be in contact
with maternal endothelial cells
• surrounding the central third of the
chorioallantois proliferate to form a syncytium
• erodes through the endometrial epithelium
and flows around maternal capillaries. Initially,
the invading fetal cells are in the form of villi
Placental Endocrinology
• significant gaps remain in our understanding
of the source of these hormones, that is,
precisely what contribution is made the the
corpora lutea versus the fetoplacental unit.
• corpora lutea appear to be the exclusive
source of progesterone in the bitch. Luteal
secretion of progesterone is, in turn,
dependent on secretion of luteinizing
hormone and probably prolactin from the
anterior pituitary.
Maintenance of Pregnancy in
cats
• elevation of progesterone in pregnancy
reflects placental synthesis or enhanced luteal
synthesis. Apparently, the ovaries can be
removed after about day 45 in cats without
interupting the pregnancy, which might
suggest that the placenta can indeed
synthesize progesterone.
• Both dogs and cats
produce the hormone
relaxin during pregnancy.
In pregnant bitches,
relaxin is first detected in
serum about 4 weeks into
gestation, and increases
substantially during the
remainder of gestation.
The placenta is known to
be the primary site of
secretion of relaxin in dog
Fertilization and Early Embryonic
Development
• The union of two haploid
gametes
• the one-cell embryo rapidly
cleaves into 2, 4, 8 and more
• develop a discrete inside and
an outside
• start to secrete hormones
that ensure their survival - a
process called maternal
recognition of pregnancy
• sperm must overcome a series of barriers,
each of which eliminates a substantial
proportion of the original population of sperm
• The cervix connects the vagina to the uterus.
The cervical canal follows an irregular,
tortuous route, and the epithelium contains
many deep crypts
• endowed with mucus-secreting cells, and, as a
consequence, the lumen is filled with mucus
The consistency and viscosity of
cervical mucus is under endocrine
control
• When estrogen levels are high and
progesterone levels low, as occurs prior to
ovulation, cervical mucus becomes watery and
its mucin strands assume a parallel
orientation. This state apparently greatly
facilitates passage of sperm through the
cervical canal
• Studies in several species have shown that
sperm are able to get from the distal uterus to
the oviducts in times as short as a few
minutes while eggs remain for three days
• sperm transport in the uterus is largely a
result of uterine contractions
• sperm transport in the uterus is largely a
result of uterine contractions
• In other cases, sperm can remain viable in the
uterus for several days
• The uterotubal junction is the region
joining the tip of the uterine horn to the
oviduct. The morphology of this region varies
considerably among species, and and this
structure appears to be a significant barrier to
sperm especially in animals like rodents and
pigs where huge numbers of sperm are
deposited directly in the lumen of the uterus.
Egg Transport
• The oviduct provides the
appropriate environment not
only for fertilization, but for
early embryonic development
• The embryo remain there for
a period of about three days
• The highest probability of
becoming pregnant was seen
when breeding occurred
during the two days
preceeding
Cleavage and Blastocyst
Formation
• The product of fertilization is a one-cell
embryo with a diploid complement of
chromosomes
• formation of a hollow sphere of cells known as
a blastocyst
• the embryo moves out of the oviduct, into the
lumen of the uterus.
• Unfertilized oocytes
• four cell embryo is shown here. The cells in
cleavage stage embryos are known as
blastomeres
•
•
•
•
signals formation of the
blastocyst
the blastocyst then undergoes
implantation in the uterine wall
Implantation= Nidation
Embryo wanders
freely before nidation
• , the image to the left
shows an expanded
blastocyst from a dog.
This embryo was
stained to accentuate
the trophoblast
and inner cell mass.
Trophoblast
Maternal Recognition of
Pregnancy
• it is a process in which some type of signal prevents
luteal regression, allowing the corpus luteum to persist
and continue to secrete progesterone. This concept can
be illustrated by looking at blood progesterone
concentrations over time in a cycling sheep that
becomes pregnant.
Early Embryonic Death
•
•
•
•
10% EED in mares
15-30% EED in cattle and sows
Occurs in the first 30 days
Clients see it as a “return to heat” assuming
that that female did not conceive
• Genetic abnormalities account for a majority
of EED
• Although the end result is the same, several
different mechanisms for maternal recognition
of pregnancy have evolved in different groups
of mammals. Some of this diversity can be
appreciated by looking at humans, cows and
dogs
Blastocysts of humans and other primates
secrete large quantities of a protein
hormone called chorionic gonadotropin
(CG), which is very similar to luteinizing
hormone. CG binds to luteinizing hormone
receptors in the corpus luteum and
stimulates continued secretion of
progesterone. It may also block signals in
the corpus luteum that cause luteal
regression.
• In cattle and other ruminants, the
corpus luteum regresses at the
end of the non-pregnant cycle as
a result of secretion by the
endometrium of prostaglandin F2alpha (PGF). The early ruminant
embryo secretes copious
quantities of a protein called
interferon tau. Exposure of the
endometrium to this hormone
dampens the secretion of PGF,
thereby blocking the signal for
luteolysis. As a result, the corpus
luteum survives and
progesterone levels are
maintained.
• Dogs do not have multiple,
sequential cycles like women
or cows. Rather, they have a
single cycle roughly every 4 to
6 months. Following ovulation,
the pattern of progesterone
secretion is essentially the
same regardless of whether
the bitch is pregnant or not.
Consequently, dogs do not
have a need for maternal
recognition of pregnancy and
apparently no mechanism for
Last updated on December 16, 2000
this process.
Author: R. Bowen
Colorado State University
Adhesion/ attachment
• Implantation is the first stage in development of the
placenta. In most cases, implantation is preceeded by a
close interaction of embryonic trophoblast and
endometrial epithelial cells that is known as adhesion or
attachment.
Nidation occurs at 7 days
• attachment involves a tight intertwining of microvilli on
the maternal and embryonic cells. Following
attachment, the blastocyst is no longer easily flushed
from the lumen of the uterus. In species that carry
multiple offspring, attachment is preceeded by a
remarkably even spacing of embryos through the uterus
• effect of implantation in all cases is to obtain
very close apposition between embryonic and
maternal tissues
• however, substantial differences among
species in the process of implantation,
particularly with regard to "invasiveness," or
how much the embryo erodes into maternal
tissue
• implantation in humans involves the embryo
eroding deeply into the substance of the
uterus
• Horses and Pigs have a similar attachment
Centric: the embryo expands to a large size before
implantation, then remains in the center of the
uterus. Examples include carnivores, ruminants,
horses, and pigs
Eccentric: The blastocyst is small and implants within
the endometrium on the side of the uterus
Examples include rats and mice.
Interstitial: The blastocyst is small and erodes through
endometrial epithelium into subepithelial connective
tissue. Examples include primates, including
humans, and guinea pigs.
In some species Estrogen and Progesterone are required for Implanation,
species having highly invasive embryos have
systems for prenatal transfer of antibodies from
the mother to the fetus.
Monotremes and marsupials
• In some species, progesterone alone appears
to be adequate, while in others, estrogen and
progesterone are required for implantation.
All mammals except monotremes and
marsupials which unlike monotremes are
born only about one month after
mating. They emerge from the womb
no larger than the size of a cherry and
immediately climb into the mother's
pouch to nurse
Echidna
Kangaroo
Platypus
Opossum
Placental Structure and
Classification
• The gross shape of the placenta and the
distribution of contact sites between fetal
membranes and endometrium.
• The number of layers of tissue between
maternal and fetal vascular systems.
• Diffuse: Almost the entire surface of the
allantochorion is involved in formation of the
placenta. Seen in horses and pigs.
• Cotyledonary: Multiple, discrete areas of
attachment called cotyledons are formed by
interaction of patches of allantochorion with
endometrium. The fetal portions of this type
of placenta are called cotyledons, the
maternal contact sites (caruncles), and the
cotyledon-caruncle complex a placentome.
This type of placentation is observed in
ruminants.
• Discoid: A single placenta is formed and is
discoid in shape. Seen in primates and
rodents.
• Zonary: The placenta takes the form of a
complete or incomplete band of tissue
surrounding the fetus. Seen in carnivores like
dogs and cats, seals, bears and elephants
Summary of Species Differences in
Placental Architecture
Common Examples
• Type of Placenta
• Diffuse,
Horses and pigs
epitheliochorial
Ruminants (cattle, sheep, goats,
• Cotyledonary,
deer)
epitheliochorial
• Zonary,
Carnivores (dog, cat, ferret)
endotheliochorial
Humans, apes, monkeys and
• Discoid, hemochorial rodents
Equine pregnancy and associated
hormones
• Beginning on days 36 to 38 of gestation ,
blastocyst cells begin to destroy underlying
endometrium. In this process they denude
surface endometrial epithelial cells and
migrate down into endometrial glands,
eventually breaking through the basement
membrane and invading into the underlying
tissue. Within 2 to 3 days after entering the
uterine tissue, they round up and differentiate
into mature eCG-secreting endometrial cup
cells.
• Endometrial cups
• At about 36-38 days, fetal tissue along the chorionic
girdle begin to invade the endometrium and form
the endometrial cups.
• Endometrial cups secrete eCG ...Equine Chorionic
Gonadotrophin (formerly PMSG...Pregnant Mare
Serum Gonadotrophin). This acts to luteinize the
normal follicular waves that are occurring and results
in formation of the secondary corpora lutea.
• The cups remain, even if the pregnancy is lost, and
are then sloughed at the normal time (120 days).
Equine endometrial cups
The images below show endometrial cups (EC) at
three stages of gestation. In the rightmost image,
umbilical vessels are seen at the bottom.
•
•
•
•
•
•
•
•
This response is initially seen
as A. accumulation of T
lymphocytes at the periphery
of the cups, and progresses to
a massive accumulation of
T cells, B cells, macrophages
surrounding the cups.
B. After day 70 to 80, these leukocytes begin to
invade / destroy the cup (the time of this event
varies significantly among mares, but usually occurs
between days 100 and 140).
• It turns out that eCG is actually equine
luteinizing hormone, and is encoded by the
same gene responsible for pituitary LH. In
contrast to LH from most other species,
equine LH/eCG possesses considerable follicle
stimulating hormone-like bioactivity.
•
Hormones from the Equine
Placenta
• The high blood levels of eCG during this time
stimulate development of ovarian follicles.
These follicles ovulate or luteinize, resulting in
development of so-called secondary and
accessory corpora lutea. In concert with the
primary corpus luteum, these structures
secrete sufficient progesterone to maintain
pregnancy until placental progerone synthesis
is adequate.
Hormones produced by the Equine
Placenta
• Progestins: The equine placenta maintains
pregnancy.
• Toward the end of gestation, blood levels of
these progestins are typically 100 times the
maximal level of progesterone.
• The placenta maintains pregnancy without
any ovarian input of hormones
Hormones from the Equine
placenta
• Estrogens: In has been known for many
decades that mare urine contains high
concentrations of estrogens during the second
and third trimesters of pregnancy. Indeed, a
large industry has developed for collection of
pregnant mare urine, which is used to
produce Premarin, an estrogen replacement
therapy used widely by post-menopausal
women.
• Estrogen levels in the serum and
urine of pregnant mares begins to
rise around day 60 of gestation,
peaks at about day 200 then
declines during the remainder of
gestation.
• Estrogens are synthesized in the
equine placenta from androgens
that are produced by the fetal
gonads.
Hormones from the Equine
Placenta
• Relaxin: a hormone that, in various species,
is thought to act synergistically with
progesterone to maintain pregnancy and to
promote loosening of pelvic ligaments at the
time of parturition. In horses, relaxin appears
to be produced by the fetoplacental unit
rather than the corpus luteum. It is detected
in mare serum starting at about day 80 of
pregnancy, and remains at high levels until
term
• http://www.vetmed.lsu.edu/eiltslotus/theriog
enology-5361/equine%20pregnancy_2.htm
• Reproduction in equine
• Secondary CLs
• The secondary CLs result in progesterone rise
about day 60-120. The endometrial cups
regress (they are sloughed from the uterus by
an immunologic response).
• ovulatory or anovulatory follicles produce
C.L.,s
• The second rise is associated with the
formation of accessory and secondary CL.
• Progesterones rise from mid gestation to
term.
• The fetal placenta produces sufficient
progesterone, that ovariectomy can be
performed after 120-150 d
• progestins rises (last month of pregnancy)
• From fetal adrenal glands
• The Early Embryo
• At about 24 hours post ovulation the embyro is
at 2 cell stage
• 4-5 days forming a hollow ball
• 5-6 days blastocyst
• 5-6 days enters uterus
• Capsule forms around the blastocyst
– Protective covering
– Origin not clearly known - may be embryonic, may
have endometrial contribution
– Lost at 21 days
Embryo development of neurotube
• http://www.bing.com/videos/search?q=embr
yo+development&qpvt=embryo+development
&mid=CAEFBE0D58A9FA7D9B84CAEFBE0D58
A9FA7D9B84&F
• ORM=LKVR6#mon
• Chicken embryo dev
• http://www.youtube.com/watch?v=aw5v6_5
GaLQ
• Embryo development
Fetal Circulation and umbilicus