Reproduction 1 - Faculty Web Sites

REPRODUCTION
INTRODUCTION
Efficiency of reproduction is the single most
important trait to consider in the production of
meat and fiber.
 More money is made and lost due to either the
ability to or failure to reproduce.
 It includes an understanding of hormones,
anatomy and physiology and management.
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REPRODUCTION TERMS
Puberty- sexual maturity
 Ovulation- release of ovum (egg) from ovary
 Copulation- the act of mating
 Fertilization- union of male and female sex cells
 Conception- becoming pregnant
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REPRODUCTION TERMS
Estrous Cycle- the interval between two estrus
periods
 Estrus- the time of receptivity to mating during
the estrous cycle; also termed as “heat”
 Gestation- pregnancy
 Parturition- the act of giving birth
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FEMALE ANATOMY
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The ovaries-2 in number-produce ova and hormones.
Infundibulum-captures the ova after ovulation
Oviducts or fallopian tubes-site of fertilization
Uterine horns-leads from oviduct to body of uterus, site
of implantation in many-litter species
Uterine body-site of implantation in non-litter species
Cervix-guards the uterus
Vagina-copulation, parturition
Vulva-external genetalia
FEMALE ANATOMY
FEMALE TRACT
MALE REPRODUCTIVE TRACT
Scrotum- container for the testes, functions in
temperature regulation
 Testes(2)-produce sperm and hormones
 Epididymus-store, transport, mature, conc.
 Vas deferens-ejaculation
 Ampulla-widening of tract
 Seminal vesicles-50% of bulk of semen
 Prostate-nutrition
 Cowpers-flushes tract
 Penis- copulatory organ
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MALE ANATOMY
TESTES
BOAR TRACT
HORMONES
Produced in:
 Hypothalamus-Releasing hormones
 Anterior Pituitary-Tropic hormones
 Gonads-Gonadal hormones
 Uterus-Prostaglandin F2 alpha
 Placenta-Steroids & gonadotropins
 Stored in Posterior Pituitary-oxytocin
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ANTERIOR PIT AND HYPOTHAL.
GLAND LOCATION
HYPOTHALAMUS
Part of lower brain that regulates many
functions of the body including thirst, hunger,
reproduction etc.
 Produces releasing hormones for the release of
tropic hormones from the anterior pituitary
 Anterior pituitary-Small gland in skull that
produces 7 tropic hormones.
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ENDOCRINE GLANDS
Gonads-testes and ovaries produce
reproductive hormones involved in estrus,
ovulation, pregnancy and parturition.
 Uterus-produces prostaglandin F2 alpha which
is lutylase.
 Placenta-produces progesterone, estrogen and
species specific gonadotropins (PMSG & HCG).
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THE HORMONE CYCLE
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Beginning with puberty (age at first estrus or
ejaculation) Gonadotropin Releasing Hormone
(GnRH) from the hypothalamus is secreted from
the hypothalamus through a closed blood
supply directly into the anterior pituitary where
it stimulates the release of Follicle Stimulating
Hormone (FSH).
CYCLE 2
FSH stimulates the follicle to begin the
formation of the phases of follicular
development. The interior lining of the follicle
produces estrogens under FSH influence.
 As estrogens rise in the blood stream, the
reproductive tract is prepared for pregnancy
and the female’s behavior changes (estrus).
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FOLLICULAR DEVELOPMENT
ESTROUS CYCLE
CYCLE 3
When the follicle matures, estrogen is at its
peak of secretion which acts on the anterior
pituitary to inhibit FSH release and allows
GnRH to cause the release of a surge of
luteinizing hormone (LH).
 This surge of LH causes a softening of the
follicle which leads to ovulation.
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HORMONE CYCLE
CYCLE 4
LH continues to act on the ovulation site
(corpus hemorrhagicum) to change it into a
corpus luteum which produces a steroid
hormone progesterone.
 Progesterone has the opposite effects of
estrogens in that estrus is suppressed and the
uterus is maintained in a pregnant state.
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CYCLE 5
If fertilization occurs, LH maintains the corpus
luteum and progesterone is secreted,
maintaining pregnancy for the allotted times.
 Pregnancy lengths: cattle-283 days, sheep and
goats 150 days, swine-114 days and horses330 days.
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CYCLE 6
If fertilization fails, the uterus senses the
absence of an embryo and releases a
pseudohormone, prostaglandin F2 alpha on
day 14 of the cycle.
 PGF2 alpha acts on the CL to destroy it thus
dropping progesterone in the blood which
releases the inhibition of GnRH and the cycle
begins again on day 18 with estrus occurring
on day 21.
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PREGNANCY
Fertilization occurs in the oviduct and the
fertilized egg reaches the uterine horn in 4
days.
 Over the next 45 days, the embryo develops an
attachment to the wall of the uterus by
implanting its placenta which serves the fetus
by transferring oxygen/CO2, nutrients and
waste products from the maternal blood to the
fetal blood streams.
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EMBRYONIC DEVELOPMENT
PARTURITION
When the fetus is fully developed its adrenal
gland secretes adrenal corticosteroids which
stimulates PGF2 alpha to be released by the
uterus.
 This destroys the CL and allows estrogens from
the placenta to begin mild contractions. These
contractions cause a reflex release of oxytocin
from the posterior pituitary which stimulates
increasingly stronger contractions.
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PARTURITION 2
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As the fetus is delivered, (front legs first with
head resting on hooves), contractions continue
until the placenta is loosened from its
attachment to the uterine wall. Once the
placenta is delivered, parturition is complete.
LACTATION
The mammary gland has developed over the
last 1/3 of gestation under the influence of
progesterone, estrogen and luteotropic
hormone (LTH) from the anterior pituitary.
 Oxytocin then causes muscle contractions in
the udder to cause milk letdown and lactation.
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FREEMARTINS
Female born twin to a male
 Female generally has incomplete reproductive
tract; over 90% are infertile
 Fetal membranes anatomose (connect);
compounds from the male fetus inhibit normal
development of female
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RECTROVAGINAL TECHNIQUE
ARTIFICIAL VAGINA
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