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FERTILISASI : PERTEMUAN ♀ x ♂
(Prose's penyatuan 2 gamete)
Untuk mencapai inti ovum
spermatozoa hrs melewati
1. sel granulosa
2. Zona pellusida
3. dinding sel ovum
(membran vitellin)
• Kepala sperm menempel pd zone pellucida
(receptor zp)
• Ab antizona: memblok penempelan sperm
• Ikatan ZP dpt dihambat dg Ab antisperm
atau glikoprotein yg diekstrak dr ZP.
•
Glycosyl transferase, proteinase dan glycosidase
pd lapisan membran plasma kepala sperm dpt
menghasilkan ikatan pada ZP3
PENETRASI SPERM
Untuk masuk ke dalam sel ovum, spermatozoa
terlebih dahulu harus menembus:
(a). Massa kumulus (bila masih ada)
(b). Zona pelusida
(c). Membran vitellin
Pertautan kepala sperma dengan permukaan membran vitellus.
aktivasi sel ovum
 Diepididymis (10 – 15 hr)
Maturasi tergt dari sekresi epididymis
dan waktu transport
Motility/hyperactivation
Di Ampula,
Sp aktif bergerak (ampula mengandung zat spt:
bicarbonate, pyruvate, asam amino bebas,oxygen,
karbohidrate, steroid, Co2 dan nucleosides)
produk sel-sel mukosa ampula
Bag kepala sp mengandung enzim hyaluronidase
yg berfungsi mencairkan asam hyhaloronate
diantara sel-sel granulosa
Sp menembus dd zp dan kepala sp bersentuhan
dg membran vitellin dan terjadi reaksi zona (untuk
mencegah sp lain masuk)
Reaksi zona
zat yg dilepaskan oleh granula
kortika yg terdapat diluar membran vitellin
RZ : jelas pada domba, tapi tdk jelas pada babi
(antara m.vitellin dan zp
sering ditemukan
lebih dari 1 ekor sp.) dan kelinci ± 200 sp
Pd hw yg tdk mempunyai RZ,
Vitellin Blok
mempunyai
RZ dan VB sangat penting karena ovum dan sp
adl sel-sel haploid
Haploid + haploid
Diploid
(berkemb normal)
Supplementary sperm
(sperma suplemen):
Pada ruang ZP
lebih dr 1 sp
• Mengetahui lifespans (fertilitas) ovum dan sperm
• Waktu ovulasi (tgt sp.hewanya)
• Kosent sperm ( hanya 1.000 – 10.000 sp mencapai
istmus) dan hanya 10 - 100 sp yg mencapai
ampula setelah 4 sampai 12 jam
Seleksi pada uterotubal junction,
isthmus (babi)
vagina, servik, uterus (ruminansia
Mencegah
polispermi
Setelah Fertilisasi
(Reaksi Acrosoma)
Intracellular calcium oscillations
Cortical reaction
Zona reaction
Block of polyspermy
Istilah:
supernumenary sperm (Sperma Supernumerik) : bila sudah
terjadi RZ dan VB, tapi dlm vitellus didapat lebih dari 1 sp
Polispermia
fertilisasi
gagal fertilisasi (jmlh kromosum > dr normal)
Triploid
kebunt. mati
PENJIWAAN SPERM DAN OVUM
• Kepala sp menyentuh membran vitelin
• Reaksi membran ditandai, adanya tonjolan kecil pd
membran
• Kepala dan seluruh tubuh sp masuk kedlm sitoplasma sel
ovum
• Membran plasma yg menjadi pembungkus sp lebur menjadi
satu dg membran vitellin
• Pengkerutan protein dan pembelahan inti sel ovum yg terakhir
• Hasil pengkerutan: dikeluarkannya cairan kedalam rongga
antara zp dan vitellin
• Hasil pembelahan inti sel ovum menghasilkan polar bodi
Kepala sperma terlepas dg bagian lainnya dan menggembung
Period of Cleavage
• zygote
• blastomeres
• morula
• Fertlisasi
Zygote (gamet)
2 cell, 4 cell, 8 cell, 16 cell dan 32 cell
(Dlm Zona Pelluucida)
32 cell (stadium morulla)
– Cairan terlihat terkumpul diantara cel morulla
Balstocoele
– Tubuh embrio terlihat terbagi 2, karena ada bag sel yg tumbuh
membentuk lapisan tipis dibag permukaan
– Bag luar disebut
Trophoblast
Plasenta
– Bag dalam
inner cell mass
Mahluk baru
32 cell (stadium morulla)
• Cairan terlihat terkumpul diantara cel morulla
Balstocoele
• Tubuh embrio terlihat terbagi 2, karena ada bag
sel yg tumbuh membentuk lapisan tipis dibag
permukaan
• Bag luar disebut
Trophoblast
Plasenta
• Bag dalam
inner cell mass Mahluk baru
• Morolla masuk uterus
Blastocyst yg mempunyai
trophoblast
• Fungsi trophoblast : menyerap cairan yg mengandung nutrisi
bagi embrio
• Pada beberapa mamalia zp pecah setelah Blastocyst
menyentuh endometrium
Implantasi
• Cairan uterus memp. peran sangat penting dalam
menunjang kehidupan embrio menjelang implantasi (spt;
Glysin, alanine, taurine dan glutamine)
Time of Events in Early Embryonic Development
spesies
Gamet Longevity (Hours)
• Sperm
• Ovum
Cattle
Horse
Sheep
Swine
30-40
20-24
72-120
6-8
30-48
16-24
34-72
5-10
Ebryonic Development (days)
• 2- cell
• 4-cell
• 8-cell
• Blastocyst
• Hatching
1
1,5
3
7-8
9-11
Blastocyst Transport to Uterus
Hours
Cell stage
72-84
8-16
Blastocyst Elongation (days)
13-21
1
1,5
3
6
8
140-144
Blastocyst
-
1
1,3
1,5
6-7
7-8
66-72
8-16
11-16
0,6-0,8
1
2,5
5-6
6
46-48
4
11-15
Initial Placentation (days)
Birt (days)
22
17
278-290
335-345
15
145-155
13
112-115
AWAL PERKEMBANGAN ENBRIO
IMPLANTASI
Proses implantasi adl proses yg berlangs scr bertahap
1.
2.
3.
4.
Persentuhan embrio dengan endometrium
Terlepasnya Zona pellusida
Pergeseran atau pembagian tempat (polytocous)
Pertautan trophoblast dengan epitel endometrium
Pecahnya Zp: - ada sebelum menyentuh endometrium (beberapa mammalia)
- setelah menyentuh endometrium (marmot)
akibat
adanya juluran-juluran protein yg berasal dr trophpbalst (akibat
reaksi dr embrio)
Hewan Polytocous: mekanisme penyebaran embrio disebut dingan
mekanisme kontraksi uterus
Pecahnya Zp:
• ada sebelum menyentuh endomet (bbrp mammalia)
• setelah menyentuh endometrium (marmot), akibat
adanya juluran protein yg berasal dr trophpbalst (akibat
reaksi dr embrio)
Hewan Polytocous: mekanisme penyebaran embrio
disebut
mekanisme kontraksi uterus
(Spacing embrio)
Implantasi terjadi: bila embrio telah bertautan dengan
endometrium dan tempatnya tdk berubah
SIFAT IMPLANTASI
• Embrionya terbenam dalam kripta endomet (seluruh
trophoblast berhub. sangat erat dng dinding kelenjar
endomet)
hewan pengerat (rodentia)
• Emb. hanya bersentuhan dng epithel endomet (pertautan
terjadi karena penjuluran protein trophoblast ke endomet
sehingga seluruh tubuh embrio masih berada dlm lumen
uterus
sifat implantasi mengambang (sulit ditentuka
Domba: implantasi ± hr ke 10-22 setelah IB
Sapi: hr ke 11 – 40
Model implantasi kedua sp ini adl sangat rawan
Implantasi pd babi
•
•
•
•
•
Setelah 1,5 – 2 hr di tuba : embrio masuk utereus
Spacing embrio (pengaturan tempat embrio)
10-15 hr
Terlepasnya zp (sebelum implantasi)
Stl Implantasi: trophpblast tumbuh cepat
Nutrisi untuk embrio berasal dr uterus
Histotrophe
(susu uterus)
• Terjadi hubungan yg erat antara trophoblast dengan
endometrium
terbentuk plasenta
Domba
• 3hr post ovulasi
morulla dan memasuki lumen uterus
• Morulla
blastula
• Blastula melayang-layang dlm histotrophe (17 hr post
ovulasi)
Masih dapat di flushing
• Db. Mempunyai karunkula dan tersebar diseluruh
•
•
•
•
•
permukaan endomet
Jumlah karunkula terbanyak adl pada curvatura mayor dr
cornua uteri dan mempunyai demensi lebih besar drpd di
bagian apex cornua uteri
Karunkula berbtk mangkok (cotyledonaria) jml ± 90 buah
Terjadi persentuhan antara trophoblast dg epitel karunkula
Sel-sel trophoblast masuk dalm cell vili pada karunkula
pertautan yg sangat erat
Hr ke 30 implantasi selesai
Sapi
• Hampir sama dg db (karunkula)
• Jumlah embrio hampir sama 1-2 buah
Bedanya: faktor waktu dan kemungkinan terjadinya
anastomosa bila kembar (tidak pd domba)
• Anastomosa (kembar ♂♀)
Freemartin (majir)
• Implantasi lebih lambat yi. ± 33 hr
• Karunkula berbtk spt bunga kol (cotyledonaria) jml 100 -110
KOTILEDON / CHORION
Endometrium
Endometrium
KARUNKULA
Membran Slip
Plasentoma
PADA KUDA
• Blastocyst dapat hidup dlm susu uterus sampai 60 hr
• Ukuran embrio tdk mengalami perkemb yg cepat (± 5 cm)
• > 60 hr, trophoblas tumbuh vili-vili
• Umur 14 mgg (3,5 bln)
terjadi pertautan
implantasi terjadi
PLACENTATION
Tenunan tubuh embrio dan induknya, yg terjalin waktu pertumb. embrio
untuk keperluan penyaluran makanan dr induk ke anak dan zat buangan
dr anak ke induk.
Kebuntingan muda: jr tubuh embrio paling luar menjadi
Amnion, allantois, chorion dan kantong kuning telur
(yolk sac)
Amnion: bag yg menyelubungi fetus dibagian paling dalam
Khorion: bag yg menyelubungi fetus dibagian paling luar
Allantois: bag yg terdapat diantara amnion dan khorion
• Lapis sel allantois dibag dalam menjadi satu atau berhimpitan dg
sel-sel membrana amnion
• Lapis luar berfusi atau berhimpitan dng sel-sel membrana khorion
• Arteri dan vena dr plasenta ke tubuh embrio berada pd lapisan
membrana allantois dan khorion
• Adanya ruang amnion yg berisi cairan yg konsistensinya agak kental
Fungsi cairan amnion: mengurangi getaran atau goncangan dr luar
tubuh induk dan sbg tempat penampungan
zat buangan dr embrio mll urethra.
• Cairan allantois konsistensinya lebih encer
fetus mengikuti perubahan posisi induk
memungkinkan bagi
Fungsi : sebagai tempat pembuangan urin melalui urachus (sal urin
yg menghubungkan kantong urin dan kantong allantois melalui tali
pusar.
• Kantong kuning telur tehenti tummbuh setelah kantong amniom dan
allantois terbentuk seutuhnya
Placentation
Reptilian Chorioallantoic Placenta
Chorioallantoic placenta
of the lizard Mabuya
Mammalian Placentation
• Transitory placentae exist in most species
– Yolk sac
– Chorionic
– Chorioamniotic
• Chorioallantoic – formed by chorion,
• Chorioallantoamniotic – final placenta
Chorionic Connective Tissue
• Embryo travels down tube and enters uterus
• Embryo interacts with wall of uterus
– Implantation
– Maternal recognition of pregnanc
Trophoblast
• expands and forms placental
tissues
• 2 types
•Cytotrophoblast
•Syncytiotrophoblast
• Cyto - main region of the placenta
• Syncytio- invasive tissue
Uterine Response
•Decidualization
•Inflammation response
endometrium overgrowsembryo
Inflammation response
• endometrium
overgrows embryo
• decidualization
Placental Shapes
• Diffuse
– Horses, camels, pigs, dolphins
• Zonary
– Carnivores (raccoon, dog, cat)
• Cotyledonary (placentomes)
– Cows, sheep
• Discoid
– Primates, rodents, rabbits, insectivores
Discoid
Cotyledonary
Zonary
Diffuse
• Zonary
– Dog, Cat
Chorion
Paraplacenta
(pigmented)
STRUKTUR HISTOLIOGIS
FETUS
INDUK
Kapiler
Endothel
Endothel
Jar. Ikat
Epitel
Chorion
Epitel
Endometrium
Jar Ikat
STRUKTUR HISTOLIOGIS
• Macamnya dibedakan berdasarkan jumlah lapisan
tenunan sel yg memisahkan aliran darah induk dan anak
• Ada 5 struktur scr histologis
1. epiheliochoreale
2. syndesmochoreale
3. endotheliochoreale
4. hemochreale
5. hemoendothelia
Ephiteliochoreale: tdp pd tipe P difusa (kd)
darah induk dan anak dipisahkan oleh 2 lapis epitel, 2 lapis
endotel, dan 2 lapis tenunan pengikat yg masin-masing berasal
dr endo dan trophoblast
syndesmochoreale: tdp pd tipe P. cotyledonaria (sp,kb,db)
darah anak dan induk dipisahkan oleh 3 lap. Tenunan sel yi.
Endotel, tenunan pengikat dan tenunan epitel trophoblast (dr
anak). Dari induk hanya endothel
endotheliochoreale : tdp pd tipe P. zonaria (aj, kc)
Hemochreale : tdp pd tpe plasenta diskoidales (man, mencit,
tikus, marmot dan kelinci)
mempunyai lapisan pemisah darah anak dan induk lebih tipis
dan dipisahkan oleh 3 tenunan lap sel yg berasal dr
trophoblast (endotel, t.pengikat dan ep. trophoblast)
Hemoendothelia : (hemo = darah, endothel = epithel p.darah)
darah induk dan anak hanya dipisahkan oleh 1 lapis
tenunan sel yi endothel dr p.darah anak (tdp pd kelinci dg
tipe P.diskoidale)
Placental Classification
• Based on number of layers separating fetal and maternal
blood
Syndesmochorial (Epitheliolchorial)
(Ruminants)
Binucleate giant cells (unique)
• Transfer placental lactogen
• Secrete pregnancy
specific protein B
• Steroidogenesis
Endotheliochorial (bitch, queen)
 Complete erosion of endometrial epithelium and
interstitium; maternal capillaries exposed to
chorionic epithelium
Hemochorial (primates, rodents)
 Maternal blood in contact with chorionic
epithelium
Hemoendothelial (rabbit, rat, guinea pig)
 Maternal blood in contact with chorionic capillaries
Placental Transfer
• Simple diffusion
– Water, gases
• Facilitated diffusion
– Glucose, amino acids
• Active transport
– Na, K, Ca
• Not transferred:
– Immunoglobulins (species dependent)
– Proteins
– Lipids
• Transferred
– Steroid hormones
– Toxic substances (pharmaceuticals, heavy
metals)
– Microorganisms (viruses, bacteria)
Placental Hormone Production
 Maintenance of pregnancy
 Stimulation of ovarian function
 Stimulation of mammary gland
 Promotion of fetal growth and maturity
Assist in parturition
Placental Hormones:
Chorionic Gonadotropins
• Equine (eCG)
– LH like activity in
horses
– FSH activity in others
– Produced by
endometrial cups
Placental Hormones:
Chorionic Gonadotropins
• eCG
– LH-like
– Secondary CL’s
– Accessory CL’s
Placental Hormones:
Chorionic Gonadotropins
• Human (hCG)
–LH like activity
– Present in urine of pregnant women
–Used to induce ovulation,
luteinization
Human Hemochorial
Maternal Recognition of Pregnancy
• Prevention of luteolysis
– Anti-luteolytic
– Luteotrophic
• Maintenance of elevated progesterone
Cow, Ewe
 Trophoblastic protein
- Interferon tau
Cow: bIFN-τ (btp-1)
Ewe: oIFN-τ (otp-1)
- Produced by trophoblast, d 13-21
post ovulation
Inhibits oxytocin
receptor synthesis by
endometrium
Also promotes protein synthesis
by endometrial glands for
embryo survival
Sow
• Estradiol
– Produced d 11-12 post ovulation
– Increases prolactin receptors
– Promotes exocrine secretion of PGF
– Stimulates uterine contractions to distribute
fetuses
– Minimum 2 conceptuses per horn required
Mare
• Embryonic mobility
• Embryo doesn’t
•
elongate
Day 12-14 post
ovulation
“Implantation”
Initial
attachment (d)
Attachment
complete (d)
Cow
25
40
Ewe
16
30
Sow
12
18-20
Mare
45-50
100-120
Placenta
• Metabolic exchange between dam and
conceptus
– Chorion (villi)
– Endometrium
• Transient endocrine organ
– Maintenance of pregnancy
– Preparation for parturition, lactation
– Initiation of parturition
BENTUK MAKROSKOPIS PLASENTA
BENTUK MAKROSKOPIK PLASENTA
• Khorion adl bagian lap terluar dr trophoblast
• Trophoblast tumbuh menjalar menyelimuti seluruh
•
•
•
•
•
•
•
permukaan endo
Terbentuknya jar plasenta karena penjalaran
trophoblat (tgt dr spesies)
Sapi dan domba: lap luar trophoblast bersentuhan
langs dg endo.
Kuda dan babi: plasenta terbentuk dr hub.
Superfisial dr sel epitel endo dan epitel khorion
Tipe plasenta pd sp,db dan kb: Cotyledonaria
Tipe pada babi dan kuda: difusa
Tipe pd anjing: zonaria
Tipe pd kera: diskoidalis
Periode dr mulai fertilisasi sampai kelahiran normal
3 periode kebuntingan
1. Periode ovum : mulai fertilisasi sampai implantasi)
2. Periode embrio : implantasi sampai pembentukan
3.
alat2 tubuh bag. dalam)
Periode fetus : periode terakhir dari terbentuknya
alat tubuh bag dalam, extremitas sampai lahir
Lama kebuntingan: masing-masing sp berbeda
Perbedaan individu dalam spesies disebabkan oleh:
. Faktor genetik
. Faktor sosial dan lingkungan
SIRKULASI PLASENTA
• 2 sirkulasi yg paralel yaitu sirkulasi fetus dan maternal
•
•
•
•
•
(induk)
Pada plasenta epithelichoreale, darah ini tidak tercampur
Darah yg mensuplai plasenta adalah darah arteri dan
vena uterina
Arteri umbilicus membawa darah dr fetus ke plasenta
Darah kembali ke vena umbilicus dr plasenta ke fetus
Aliran darah fetus dan maternal bisa countercurrent,
concurrent dan crosscurrent (aliran yg berbeda)
SIRKULASI DARAH FETUS
• Pada prinsipnya sama dg hewan dewasa, kecuali oxygenation
terjadi pada plasenta bukan pada paru-paru
• Sirkulasi fetus juga diperkirakan mempunyai aliran darah oksigen
langsung kejaringan
1. Ductus venosus
liver ke
darah terbesar vena umbilicalis dr dalam
Parturition
Initiation of Parturition
•
•
•
•
Fetal maturity
Stage 1: Initiation of myometrial contractions
Stage 2: Expulsion of fetus
Stage 3: Expulsion of fetal membranes
• Fetal pituitary-adrenal axis
– Fetal stress
– Release of fetal ACTH
– Stimulates fetal adrenals to produce corticoids
Fetal corticoids
Promotes synthesis of:
•17a hydroxylase
•17-20 desmolase
•Aromatase
Increased E2
Decreased P4
Removal of ‘P4 block’
Increased secretions of
reproductive tract
Hormonal Changes that Control Parturition
Hypothalamus
Steps
Fetal ACTH causes -
Fetal anterior
pituitary gland
Corticotropic Releasing
Hormone CR
Time of parturition is
F
controlled by maturation
of the hypothalamuspituitary-adrenal axis
Adrenalcorticotropic
Fetal Corticosteroids
Hormone (ACTH)
causes Removal Blocks Parturition
Progesterone levels
Infusion
Stimulates
placental production induces
oxytocin receptor
or CL regression) parturition
Fetal
in myometrium
Adrenal
Production of Estrogens
Estrogen
by placenta Corticosteroid
(Increase)
PGF2a production by
uterus -
Pine-needle abortion in
cattle - cause by a
corticosteroid-like product
Glucocorticoid
Redrawn from Liggins, G.C.
1969. In Foetal Autonomy
Progesterone
(Decrease)
Prostaglandin
F2a
(Increase)
Significance of initial hormonal changes
Progesterone - removes block on uterine contractions.
Allows myometrial muscle fibers to work together in bundles
Estrogen - makes uterus more responsive to induction of
contractions i.e., more irritable and smooth
muscle tissue stimulation. Induction of
oxytocin receptors
Events just Prior to Parturition:
1. Pelvic ligaments soften - Tail head sinks due to estrogens
and relaxin.
2. Cervix softens and begins secreting stringy mucus - estrogens
and relaxin.
Increased water content in cervical tissue and
cervical plug is removed
3. Swelling of vulva.
Collagenase breaks down collagen which also widens
the pelvis
4. Udder swells - fills with first milk and due to edema:
Prolactin, Estrogens and glucocorticoids
5. Fetus moves into proper position - resting on thorax, front feet
and head facing the cervix
Stages of Parturition:
I. Dilation of Cervix. (2-6 hours, cow) Heifers 12 hours
Uterine contractions become coordinated and regular Synchronized
Estrogen & PGF2a induced
This occurs because progesterone has declined
Fetus pushed against cervix - amnion dilates cervix
Stimulates oxytocin release
Chorioallantoic membrane may break
1st Water Bag
Pressure of fetus in cervix stimulates oxytocin release and reflex
Ferguson
contractions of abdominal muscles.
Reflex
Contractions force the calf legs and head to
spread cervix
II. Expulsion of Fetus (.5-2 hours, cow)
Longer than 2 hours considered to have dystocia
Strong uterine contractions due to synergistic actions of high
estrogen, PGF2a and oxytocin
Strong abdominal muscle contractions
Amnion ruptures - mucin lubricates vagina - vestibule
2nd Water Bag
Fetus passes through vagina - vestibule.
Cause of death in 6.4% of calf losses on average
Three Barriers in Delivery of a Calf
1. Head
2. Shoulders
3. Hips
Sow Delivery of Piglets
Length of Stage II in sow is 2 to 4 hours
Delivery of piglets is usually between 8 to 45 minutes
between each one.
Delivery will alternate piglets between horns
Last 1/4 of horn in large litters increases the chance
of stillborn Length of umbilical cord
Uterine horn contracts to shorten distance after delivery
of each piglet
III. Expulsion of the Placenta (4-5 hours, cow)
Uterine contractions continue
Blood forced from cotyledon villi - shrinkage separates
cotyledon and caruncle
Prolapsed uterus cow tired need to give
Contractions push placenta out
oxytocin
Causes of retained Placentas:
-Infections caused adhesions between cotyledon and
caruncle
-Calving stress - twins or calving difficulty - edema of
cotyledon - won't separate from caruncle
-Weak uterine contractions - villi won't shrink Oxytocin
Milk fever - Calcium low
Parturition: Stage I
• Increased myometrial activity
• Fetal positioning
• Cervical relaxation/dilation
• Oxytocin release
• Rupture of chorioallantois
Parturition: Stage II
• Estrogen stimulates secretory activity
• Fetal activity (response to hypoxia)
stimulates myometrial activity
• Cervical stretching (pressure) causes
oxytocin release
• Eventually fetus is delivered
Parturition: Stage III
• Release of fetal membranes
Care of retained placentas:
Do not manually remove from uterus; uterine damage greater
than infection of retained placenta
Do not pull placenta out even in Mare!
Check to see placenta is fully intact in Mare or you need a
Veterinarian to clean her out.
Don’t breed on foal heat if there is a problem
Infuse Bovine uterus with tetracycline and systemic injections of
penicillin until placenta passes ~ 2-4 days.
Don’t give mare tetracycline as this will cause inflammation!!
Can treat cow with either PGF2a or oxytocin (ergonovine)
to expel the infection
Hormonal changes cause:
1. Final maturation of fetus
Cortisol - stimulates lung surfactant
2. Expansion of birth canal
Initiates parturition
and lung development
3. Maternal behavior
4. Synthesis and ejection of
milk
5. Initiation of uterine
contractions
6. Termination of pregnancy
Fescue toxicity problems:
Ergot causes inhibition of
prolactin release and thus
milk production
Prolactin completes final
mammary development
and milk secretion
Fetal Corticoids
• Stimulate PGF synthesis
– Stimulates myometrial activity
– Causes luteolysis
Puerperium
• ‘Reproductive repair’
– Uterine involution
• Myometrial contractions
• Expulsion of lochia
• Endometrial repair
– Resumption of ovarian activity
– Elimination of bacterial contamination
Myometrial Contractions
• Stimulated by oxytocin
• Removal of debris and fluid from uterus
• Compress uterine vasculature, minimize
hemorrhage
• Reduce size of uterus
Lochia
• Normal discharge
• Duration varies with species
Lactation
• Mammary Gland
– Isometric growth until puberty
– Allometric growth post-puberty
• Hormonal influence
Mammary Gland Development
• Repeated estrous cycles result in
development of mammary glands
• Alveoli
– Secretory tissue
– Develop under progesterone
• Ducts
– Estrogen
– Prolactin
– Somatotropin
Mammary Gland Development
• Last trimester
– Lobules develop in alveoli
– Milk secretion dependent on
• Prolactin
• Adrenal cortical hormones
• Placental lactogen
Mammary Gland Secretions
• Colostrum
– Immunoglobulins
– Growth factors
– Temporary secretion
• Milk
– Composition differs among species
Mammary Gland Involution
• Decreased suckling
– Pressure atrophy
• Capable of rapid cessation
• Critical for milk production after
subsequent pregnancy
Milk Ejection
• Secretion vs. Ejection
– Secretion into alveoli
– If not secreted, pressure atrophy occurs
• Ejection
– Neuroendocrine reflex
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