repro Flashcards
kidney topographical anatomy
RIGHT = level of L1-3 w cranial pole @ level 13th rib, in renal fossa of caudate lobe liver
* caudal vena cava medially
LEFT = level L2-4 w cranial pole more caudal than R
* aorta medially
connecting peritoneum bladder
- median lig -> ventral abdom wall
- lateral ligs -> pelvic wall
trigone
area in bladder where ureters enter + urethra exits
* fuller bladder = ureter more closed + harder for urine to enter
topographical anatomy bladder
neck passes -> pelvic canal
empty bladder contracts close to pelvis
full extends cranially into abdom
* ventral to descending colon male/uterus female
gonads
repro gland that prods gametes
* ovaries in female, testes in male
gross anatomy female genital sys
ovaries sat in pocket of tiss (ovarian bursa) then -> uterus via uterine/fallopian tube
uterus = y-shaped w L + R horn (cornu) joining to form bod, sepped from outside world by cervix -> vagina -> vestibule
catheterising dogs
bitch = go in, find urethral opening, then straight
male = hole visible, but then 180deg hairpin loop
ovaries
- paired regular ovals
- inactive = smooth, active = knobbly w follicles
- end = funnel-shaped = infundibulum to catch egg -> uterine tube
peritoneal attachments ovary
- mesovarium = ovarian lig -> lat bod wall @ caudal pole kidney w ovarian artery + vein LIGATE (continuous w mesometrium)
- mesosalpinx -> uterine tube (removed w other bits)
- suspensory lig -> lat bod wall @ caudal pole kidney (not 1 asw!!!)
- proper lig of ovary -> cranial end of uterine horn
all continuous w each other
suspensory lig in bitch
v short + must be broken to allow exteriorisation of ovary for spay
ovarian bursa
pocket of peritoneum encasing ovary
* bitch = lots fat = obscured = complicates
mesovarium cranial, uterine horn caudal
uterine horns attach where
-> ovaries cr., -> uterus bod cd.
uterine attachments
mesometrium (broad lig) -> lat bod wall
* round lig of uterus runs in thru inguinal canal = foetal remnant of gubernaculum (gonad, not needed in females bc ovaries no move) – looks like ureter
vagina
w/in pelvic canal
* external urethral orifice opens on midline ridge (urethral tubercle) w fossa either side = catheterisation awks)
* glans clitoridis in deep fossa under mucous mem fold
hymen
at junction bet vagina + vestibule
vestibule
bounded by labia of vulva caudally
female genitals blood supply
- ovarian artery + vein in arterio-venous complex -> anastomose w uterine art + vein
- vaginal art + vein branch caudally -> supp vag + vestibule
* cranial branch becomes uterine art + vein in mesometrium
need keep vaginal intact bc leaving in animal
where find ovaries
dorsal abdom @ caudal poles kidneys (13th rib)
* level of umbilicus ventrally
topographical anatomy uterus
uterine horns bet intestinal mass + lateral abdom wall w uterine bod mid-line ventral to descending colon, dorsal to bladder
ovario-hysterectomy anatomy
- stretch/tear suspensory lig
- ligate ovarian art + vein in mesovarium
- transect uterine bod @ level of cervix + ligate uterine art/vein
- 50% of time mesometrium vascular enough need ligate
- ureters close to ovaries + cervix - don’t ligate
mammary glands
5 pairs mammae each w papilla (teat)
* 2 thoracic (scant adipose), 2 abdom, 1 inguinal (lots adipose)
blood supply mammary glands
cr. via cranial superficial epigastric
cd. via caudal superficial epigastric
lymph drainage mammary glands
cr. 3 pairs via auxillary
cd. 2 pairs via inguinal
perineum
area under tail round anus
* either side anus = anal glands
perineal muscs
form pelvic diaphragm thru which urino-genital + digestive sys open to outside
1. levator ani lifts anus so poo on floor not down butt
2. coccygeus musc
3. rectococcygeus musc
4. internal anal sphincter = sm musc
5. extenral anal sphincter = sk musc
6. internal obturator musc
weakening = adom contents can protrude = perineal hernia
inguinal canal anatomy
potential space bet abdom wall musc layers - comms w external pouch
1. deep inguinal ring = gap in IAO
2. superficial inguinal ring = slit in EAO
3. vaginal ring = opening of peritoneal cavity into inguinal canal
purpose inguinal canal
allow testes descend from caudal to kidneys -> scrotum
* bc in abdom too hot for sperm to form
development in inguinal canal
peritoneum outpouch (vaginal process) pushes thru -> protrude into scrotum
* females = only bitch has rudimentary vaginal process extending in
abdom structures can pass thru vag ring into ing can = inguinal hernia
who is more at risk of inguinal herniation
pigs, rabbits - deep inguinal ring superimposed over superficial inguinal ring
only female can occur in is bitch
what aids testes descent
gubernaculum guides them = no get lost in abdom (exact process unknown)
female has one but vestigial - looks like ureter (in mesometrium)
scrotum
sac of skin enclosing testes + coverings
* median septum seps testes w/in it
* lots sebaceous + sweat glands = incisions thru scrotal skin no heal well
* blood supply = branch external pudendal art/vein
testis layers
- skin
- tunica dartos - lots sm musc to move to/from bod maintain temp
- spermatic fascia
- parietal peritoneum (vaginal tunic)
- visceral peritoneum
outside to inside
spermatic fascia layers
- external spermatic fascia
- cremasteric fascia cont cremaster musc (sk musc, attaches spermatic sac)
- internal spermatic fascia
extensions of lat abdom wall muscs
testis structures
- epididymis w head, bod, tail (where sperm stored) - ductus deferens = sperm from tail -> urethra
- testis covered visceral peritoneum - gland that prods sperm + male hormones
spermatic cord
cont ductus deferens, testicular vein/art in peritoneal fold (= mesorchium) (continuous w vaginal tunic)
testis blood supply
- test art coveys blood -> testis
- test vein arranged in mesh encasing art = pampiniform plexus = can cool art blood via heat exchange w venous blood
spermatic sac
vaginal tunic + internal spermatic fascia + cremasteric fascia
* attached scrotum via scrotal lig - break to free testis in closed castrate
diff types castration
== orchidectomy
* open/closed depending whether abdom cavity opened or not
* open has potential risk peritonitis (infection back up into abdom) + herniation
open orchidectomy
- scrotum incised to remove testes (break lig of tail of epididymis) + left open to drain bc of glands + inflamm fluid
- haemostasis of art/vein via press => clotting (5 mins)
- herniation unlikely unless superimposition (= suture inguinal canal)
inflammatory fluid passing out prevents contamination peritoneal cavity (usually)
most bc closed needs ligature + hard keep suture mat sterile
which type castration when in dog
> 25kg = open
< 25kg = either
inexperiences surgeon = open
layers incised in open castration
- skin if testes pushed out scrotum -> inguinal area = normal skin cut = can suture (dog so no inflamm fluid in living room)
- all spermatic fascia
- vaginal tunic (= ‘opened perit cav)
remove visceral peritoneum w testes
closed castration
- incise inguinal skin + ESF
- free spermatic sac from scrotum by breaking scrotal lig
- neck of spermatic fascia inc cord ligated
haven’t cut thru vaginal tunic
penis structure
- shaft cont erectile tiss + urethra
- free part lies w/in prepuce (skin protective covering w enlarged tip = glans penis)
root attached ischium
penile erectile tiss
- corpus spongiosum penis
- corpus cavernosum penis
corpus spongiosum penis
encloses urethra from pelvis to penis tip
* expansion near pelvis = bulb of penis/urethral bulb
* expansion at tip = glans penis
how get erection
fill penis w blood + prevent exit
penis arterial blood supply
branch of internal pudendal round ischiatic arch then -> erectile tiss at penis root
* conts along dorsal penis surface outside tunica albuginea
penis venous blood supply
erectile tiss drained at root via internal pudendal
* horse also massive drainage from penis bod -> external pudendal
no vasc connections bet corpus spong + cavern
muscles of penis
- retractor penis
- ischiocavernous
- bulbospongiosus
bulbospongiosus musc
circular, thick, covering bulb (= cd. enlargement corp spong)
prevent venous drain in erec as rhythmic contracts incr press in corp spong
retractor penis musc
- slender musc connected internal/external anal sphincters + cocygeus
- passes ventral to penis midline + attaches 1/2way
- sm musc to retract penis back into sheath
ischiocavernous musc
ischiatic arch -> tunica albuginea of corpus cavernosum
prevent venous drainage in erection + rhythmic contractions incr press in corp cav during erection
covers L + R crura
mitosis
- chromosomes replicate + divide -> 2 new nuclei
- cell division => geneticaly identical daughter cells maintaining no. chromosomes
- prophase, metaphase, anaphase, telophase stages
meiosis
specialised division in germ cells
* 2 rounds division => 4 cells w 1 copy each chromosome
ovarian cycle w hormones etc
follicular phase = before ovulation
luteal phase = after
menstrual cycle of women w hormones etc
compare menstrual + oestrus cycle
menstrual: primates, renewed start follic phase (bleed)
* 2wk follic phase
* 4wk cycle
* day 0 = start follic phase, low oestrogen
oestrus:
* others, no bleed but spot when high oestrog (weak bvs)
* * 1wk follic phase
* 3wk cycle - follicles develop throughout luteal phase
* day 0 = start oestrus, end follic, high oestrog
oogenesis
== development of female gamete (ova) for release from ovary
1. primordial germ cells migrate -> gonadal ridge in early gestation
2. gonad develops medial to embryonic kidney
3. diploid oogonia divide by mitosis in foetal life
4. birth = oogonia stopped in meiotic division (= have all eggs, finite no.) = primary oocytes
5. after puberty: 1st meiotic division at ovulation -> secondary oocyte (haploid) + 1st polar bod
6. 2nd meiotic division after fertilisation
==> 1 large complex female gamete + 3 small polar bods
what happens to primary oocytes
- enter prophase of meiosis 1 in foetal development then nothing until puberty
- 1st meiotic division at ovulation => secondary oocyte (haploid) + 1st polar bod
- 2nd div after fertilisation
==> 1 large female gamete + 3 small polar bods
what drives ovulation
release luteinising hormone (LH) from pituitary gland
primordial follicles
several stimmed each month after puberty to nourish developing oocyte + be endocrine glands driving cycles
1. prim oocyte in prim follicle ->
2. prim oocyte in 2ndary follicle ->
3. 2ndary oocyte in Graafian (tertiary) follicle
first FSH dependent for growth then Graaf = LH dependent for ovulation
follicle types
cells around oocyte grow to form follicle
primordial = single layer squamous granulosa cells
–> cuboidal granulosa cells = primary follicle = prod oestrog
phases graph
oogonia
diploid female gamete mother cells
how is oestrog proded
theca interna cell w LH receptor: cholesterol -> testosterone
-> granulosal cell w FSH receptor: testost -> oestrog
–> blood –> brain/repro tract
effect of oestrog in repro tract
- incr blood flow
- incr oedema of tiss
- incr mucous secr
- incr leukocytes
- incr sm musc motility
- incr growth uterine glands
effect oestrog on brain
- mating posture
- incr phonation
- incr physical activity
when are you fertile
egg lasts 24hrs, sperm 5-6days
== fertile 7days up to + inc day of ovulation
* probability of impregnation incr up to ov
what point to we reference oestrus cycle from
when animal starts showing signs of being on heat = advertising wants to be served (just before ovulation)
21 day cycle
behavioural oestrus
time animal advertises shes fertile
* cow = 18hrs in 21d cycle
* horse = 5d in 21d
* sheep = 30hrs in 17d
* pig = 2d in 21d
pituitary hormones
LH + follicle stimulating hormone (FSH)
reg repro hormones
hypothalamus releases gonadotropin releasing hormone (GnRH), stims release pit hormones (LH + FSH), stims release inhibin + oestrogen from developing follicles in gonad
neg feedback control
what hormones do follicles release
inhibin (inhibits FSH)
oestrogen (inhibits LH + GnRH)
normal neg feedback loop of repro hormones
how does brain reponse to oestrogen change
Changes from neg to pos feedback:
oestrog => surge centre => incr GnRH = incr LH = incr oestrogen… continues until ovulation due LH surge
* ov = Graaf follicle ruptures to release 2ndary oocyte
corpus luteum
mature graafian follicle becomes one = temp. structure to establish + maintain pregnancy = prod progesterone after ovulation
* ~14days w/o fertilise 2ndary oocyte = corpus luteum undergoes luteolysis = stops secr progesterone => corpus albicans (fibrous scar tiss)
what does progesterone do
inhibits release GnRH = inhib LH = inhib oestrogen + ovulation
role of ovary structures overall
- egg release at specific pt in development ready to fertilise
- correct endocrine environ at release
other factors to consider for repro
- seasonal/not
- reflex/spontaneous ovulators
- mono or polyoestrus
who breeds when
mares in spring = long day breeders
ewes in autumn = short day
=> born in spring (12mo vs 5mo gestation)
what controls seasonality in breeding
controlled by effect melatonin on release GnRH from hypothal
* mare = low melatonin incr GnRH, ewe = decr
spring = low melatonin, autumn = high (proded in dark)
reflex ovulators
GnRH pulse generator not enough for LH surge so w/o mating only have follisuclar phase
* brain inputs + vagina stretch inputs + sensory inputs combine to incr GnRH (via signals to hypothal)…..=> ovulation
skips pos feedback loop shenanigans
oestrus cycle of mare
seasonal long day breeders
* 21 day cycle
* oestrus 5day
* ovulate 24-48hrs b4 end oestrus
* 11mo gestation
oestrus cycle sheep
seasonal polyoestrus - short day breeders
* 17day cycle
* oestrus 30hrs
* ovulates 20-25hrs from start oestrus
* 5mo gestation
cow oestrus cycle
not seasonal
* 21day cycle
* oestrus 18hrs
* ovulates 20-30hrs from start oestrus
* 9mo gestation
what causes follicles develop
FSH
only ovulate if progesterone basal bc inhibitory so you get follicular waves:
from d0 follicles start develop but proges high = no ov = degrade by d10, then start develop again + by time Graaf proges low = oestro incr = LH incr = can ov
in cows (so usually only 1 follicle will ovulate)
why are oestrus cycles shorter than menstrual
follicles develop throughout luteal phase = nearer maturity when progesterone decr at luteolysis
what determines length of oestrus
lifespan of corpus luteum (bc die = no progest = no inhib = can ovulate)
* prostaglandin F(2alpha) from uterus via uterine vein -> ovarian artery = signals luteolysis
luteolysis in rumis
- corpus luteum secr oxytocin + posterior pituitary
- oxytocin receptors appear on endometrium in late luteal phase -> stim release PGF(2α) => luteolysis only at right time
prostaglandin has no known role in cats + dogs
how is penis of dog diff
- L + R corp cav don’t fuse w cr. part ossified (= os penis) - ventral groove conts corp spong
- bulb extra large + glans penis = double structure
- don’t need full erection for intromission - os penis = can get in, then expansion bulbus glandis + extension pars longa glandis extends => fully erect can’t sep until done (+ blood out)
glans penis dog
- bulbus glandis covers proximal half os penis
- pars longa glandis covers distal half os penis
what is tunica albuginea
fibrous envelope covering the corpuses
prepuce gland
tubular cutaneous sheath covering free part non-erect penis
* preputial cavity w external lamina (normal skin) + internal lamina (hairless squamous epithelia)
* cont muscs keep preputial orifice closed + retract prepuce
accessory glands
to lube duct for + nourish sperm
1. ampulla of ductus deferens (covered by prostate)
2. vesicular
3. prostate dorsally on bladder neck w disseminate parts
4. bulbo-urethral gland empties into distal part pelvic urethra
bitch oestrus cycle
monooes w 1-3/yr = prolonged fertile period to make it count
1. prooestrus = 9d, swollen vulva, bloody discharge, v attractive to male, no mate
2. oestrus = 9d, ov d2, accepts male, straw coloured discharge
3. metoestrus/dioestrus = 60d, CL-proges dominant phase
4. anoestrus = ovarian inactivity until next prooestrus (~5mo)
1+2 = follic phase
3 = luteal phase
gestation 9wks
bitch adaptations to max conception
- spontaneous ovulators
- long prooestrus + oestrus
- LH surge late prooestrus/early oestrus
- ov over couple days 48-72hrs after surge
- no luteolytic mech = corp lut lasts 60-70d
oestrus cycle graph bitch
fertilisation in bitch
ova can’t be fertilised for 48hrs after ov + viable 5d
* so fertilisation period = 2-5d after ov
* sperm viability 9-11d = can mate from start oestrus
== get males ready in prooestrus, then accept for all of oestrus
* once chance gone won’t get preg rest of yr so important
label
where does fertilisation occur
- sperm stored in isthmus (narrow oviduct next to utero-tubal junction
- passage oocyte down oviduct => release of sperm
- => fertilisation in ampulla of oviduct (wider part near ovary)
where is semen deposited diff species
- vagina - cows, sheep, dogs, cats
- cervix - pigs
- thru cervical lumen - horse (v projected)
what aids transport w/in female tract
- sm musc contractions
- sperm motility
what do sperm have to do for successful fertilisation
- transverse cervix - select for mobile
- be transported thru uterus -> cd oviduct (isthmus) w/o macrophage phagocytosis or ejection back out vag
what do sperm do once find egg
- bind to zona pellucida (lipid capsule round egg) - specific receptor on sperm for specific prot (ZP3)
- acrosome reaction = release enzs to digest zon pelluc (exocyt)
- fuse w oocyte mem => biochem changes in zon pell/oocyte mem prevent polyspermy (no others can enter)
capacitation is?
sperm mature in epididymis but not fertile
* have reside in repro tract for min length of timt to reveal receptor prot
* can be reversed by putting sperm back in seminal plasma
* can be induced in vitro
why capacitation occur
in epididymis surface mols of sperm coated w seminal plasma prots that mask mem prots
* in female tract seminal plasma coating + some surface mols removed, revealing those that can bind zona pell
complete in oviduct + hyperactive motility pattern develops = facilitate sperm-oocyte contact
acrosomal reaction
- acrosome (membranous organelle) swells
- mem fuses w over-lying p mem = vesicles form
- => exocytosis proteolytic enzs
==> acrosome-reacted sperm can work way thru zon pell
v quick ~15min
biology of preventing polyspermy
- sperm mem fuses oocyte mem
- stims Ca release in oocyte
- => secr cortical granules
- enzs of granules cleave binding site of ZP3 = prevent further attachment/fertilisation
== zona block
sperm journey: what occurs where?
- immediate transport = entrance to cervix/uterus - lose to retrograde + phagocytosis
- cervix = removal non-motile sperm + abnormalities
- uterus = capacitation initiated - loss to phagocytosis
- isthmus = capacitation completed, hyperactive motility
- ampulla = acrosome reaction, penetration, male + female pronuclei form (fert)
syngamy
fusion pronuclei to form zygote (after oocyte 2nd meiotic division)
fertile period defn
period time over which mating might result in preg
* around same length as behavioural oestrus
cleavage
rapid mitotic division of zygote => blastomeres (pregressively smaller cells proded)
* eventually forms morula = grp lots blastomeres
in embryonic period
forming blastocyst
granulation as blastomeres of morula line edges zygote =>
* eventually ruptures = hatches => hatched blastocyst
attachment
extra-embryonic mems (placenta) develop + attach to hatched blastocyst
* allow comm w mum + get nutrients etc
* no attachment for 1st 7 days
= implantation in menstruators
progesterone for pregnancy
essential + secr by placenta but takes while for it develop enough to secr
=> proges from CL can provide whilst forming if luteolysis prevented
how block luteolysis
block luteolytic signal (prostaglandin) = maternal recog of preg (MRP)
* bitches no need bc no luteolytic signal = incr chance maintain preg
proges usually determines length cycle
zygote
fertilised egg
stages gestation
- embryonic period = 20-30% gestation
- foetal period = 20/30%-> parturition
maternal recog of preg (MRP)
process by which early conceptus signals presence to maternal sys preventing luteolysis
* ensures maternal milieu supportive of preg continuation
species mechs of MRP
- inhibit luteolytic factor - pigs, cows, sheep
- secretion luteotrophic factor - humans
- mechanical - horses
- none - dogs + cats
inhibition of luteolytic factor
block PGF2alpha to inhibit normal regression CL
* cows + sheep = embryo prods interferon to block synth oxytocin receptors = prevent release PGF from endometrium
* pigs = embryo prods oestradiol = PGF released rerouted -> uterine lumen = exocrine secr - no worj w/in lumen uterus (need at least 2 conceptuses per horn to work)
secr luteotrophic factor
developing blastocyst prods - similar struct to LH = acts LH receptors in CL to prolong life + maintain proges levels
e.g. hCG (human chorionic gonadotropin) b4 attaches myometrium
MRP in horses
conceptus prods MRP signal but not understood
* mechanical? as equine conceptus migrates over endometrial surface to initiate + complete
* 12-14 times/day on days 12,13,14 to inhibit PGF
hatched blastocyst no spread out like others, stays globular
embryonic mems + what form
- endoderm -> dig sys, lungs, endo sys
- mesoderm -> musc, skeleton, CV + repro
- ectoderm -> NS, skin, hair
foetal mems
derived from foetal cells (discarded as stuff see lambing)
== extraembryonic mems that must form b4 attachment to endometrium can occur
structures of hatched blastocyst
trophoblast = outer ectoderm
development from hatched blastocyst
- primitive endoderm grows downward form lining on inner surface trophoblast
- mesoderm begins develop bet primitive endoderm + embryo
- primitive endoderm completes growth forming cavity = yolk sac
- mesoderm forms sac round yolk sac push against trophectoderm => fold up form amniotic folds round embryo
- mesoderm surrounds yolk sac + allantois
- mesoderm fuses w trophectoderm form chorion
- amniotic folds grow round embryo + fuse => amniotic sac
- yolk sac decr, allantois incr
allantois
diverticulum from primitive gut
parts of developing embryo
inner sac = trophectoderm + mesoderm => amnion + amniotic cavity (continuous w GI tract)
outer sac = chorion fused w alliontois => allantochorion/chorioallantois = allantoic cavity (continuous w bladder)
- allantois conts expand + fill cavity
yolk sac conts regress
allantochorion
foetal contrib to placenta = surface for attachment endometrium
* functional part = chorionic villi = exchange apparatus = small protrusions incr SA for exchange
micro anatomy least invasive placenta type
6 layers:
1. chorionic caps
2. chorionic interstitium
3. chorionic epithelium
4. endometrial epithelium
5. endometrial interstitium
6. endometrial caps
horses, pigs, rumis
carnivore placenta
5 layers:
1. chorionic caps
2. chorionic interstitium
3. chorionic epithelium
4. endometrial interstitium
5. endometrial caps
bit more invasive
primate placenta
3 layers (just chorionic ones) as foetus breaks down basement mem + implants self so just pool maternal bood => periods + bleeding out childbirth (v few layers bet foetus + maternal blood
cotyledonary placenta
numerous cotyledons attached at 1 point (= discrete) - button-like structures of chorionic villi
* attach to maternal caruncles in endometrium (maternal part)
rumis
diffuse placenta
uniform distribution chorionic villi = pigs
horses = appear same but acc lots tiny ones
zonary placenta
band-like zone chorionic villi
dog + cat
placenta
- interface for metabolic exchange bet dam + foetus
- endocrine gland prod horms maintain preg, stim mammary gland, promote foetal growth
transient organ = no last
timing placental attachment species
- cow = 18-22d post ov
- sheep = 15-18d post ov
- mare = 36-38d post ov (migrates = takes longer)
- sow = 11-12d post ov
occasions for pregnancy loss
- ov = 2% lost (1d)
- fert = 15% lost (2d)
- hatching + elongation = 30% lost (8-13d)
- MRP = 45% lost (2wk)
- uterus distension = 50% lost (5wk)
most lost by 5/6 wks
% = total lost at the pt (cumulative)
development gonads
in foetus
primordial cells migrate yolk sac -> gonadal/genital ridge
* primitive germ cells induce local tiss diff into sex cords (gonads bi-potential)
sexual differentiation
flow chart
sex chroms w/on spermatozoa determines
* * gene on Y chromosome => SRY prot => reg
all w/in 1st trimester
bovine twins
- placentae (chorion) fuse = share common blood supply
- testes of male develop b4 ovaries of female
- AMH + testosterone secreted reaches both foetuses
- = repro tract female no develop = canalisation no complete = ovaries no continue grow = sterile = ‘freemartin’
tract no continue to cervix
vagina + vestibule of freemartin
derive from ectoderm = still develop as not sensitive effect AMH
* cr. vagina + uterus from mesoderm = sensitive effect
major components male repro sys
- testis = prod sperm + synth, release, store horms
- excurrent ducts
- accessory sex glands
- penis = deliver sperm -> female
histology testis
sperm prded seminiferous tubules in testis
* total length 500-1000m
seminiferous epithelium
complex stratified cont:
1. spermatogenic cells = stem cells replicate + diff into mature sperm as migrate -> lumen
2. sertoli = sustentacular = physical + nutritional support + release androgen-binding horms
3. CT w leydig cells to prod + release testost
spermatogenesis
born w un-diffed diploid sperm cells = spermatogonia at basal lamina seminif tubs
starts at puberty:
* develop w/in sertoli cells from basal aspect -> lumen of seminiferous tubule
meiosis:
-> diploid spermatogonia (prim spermatocytes)
-> haploid 2ndary spermatocytes (spermatids = mature sperm)
sperm testis barrier
physical barrier bet bvs + tubules
== basal + adluminal compartments tubule bc tight juncts bet sertoli cells
* sep haploid cells bc not ‘self’ = foreign = provoke immune reaction
diff bet oogonia + spermatogenesis
- s = cont prod, o = cyclic release finite no.
- concurrent prod sperm + sex steroids but cyclic prod ova + sex steroids
- lots sperm, few oocytes
- male = mitosis activated puberty, female = completed by birth -> prim oocytes
- male = stem cell renewal, infinite no. gametes, fem = no self-renewal, finite no.
- 1 prim spermatocyte -> 4 secondary, 1 prim oocyte -> 1 mature ovum
- spermatogenesis cont thruout life, gametogenesis in humans ends at menopause
route sperm take
seminiferous tubules -> rete testis -> efferent ducts -> head, bod, tail epididymis -> ductus deferens -> pelvic urethra
epididymus
30-60m tube surrounded sm musc
* sperm mature as pass thru duct + concd in tail
* no. fertile breedings male can perform limited by sperm stored tail
ductus deferens
connects tail epididymis -> pelvic urethra
maturisation of sperm
leave sertoli = non-motile + DNA in head no condensed = non-fertile
* takes 8-15d to mature whilst passing thru epididymis
spermatogensis general
- 5-9wks depend species
- no. sperm proded each day independent amount ejaculated
- released continually from seminiferous tubules
- requires testosterone
leydig cell
respond LH to secr testosterone
* equiv theca interna cells
in seminiferous tubules
sertoli cell
respond FSH
-> secr inhibin
-> convert testosterone -> dihydrotestosterone + oestrodiol
male equiv follicular granulosa cells
in seminiferous tubule
reg LH + FSH + effects
release controlled GnRH hypothal
* GnRH on leydig stims testost = stim sertoli = initiate spermatogensis
* FSH on sertoli stim prot synth, testost receptor expression, testicular fluid prod, inhib secr
neg feedback
testosterone actions
- stim growth internal + external genitalia
- stim 2ndary sex characteristics - behaviour + sex drive
- enhance growth sk musc + bone
what is required for testis function
- pulsatile GnRH secr (every3-6hrs)
- adequate LH receptors in leydig cells
- high concs testost in seminiferous tubules
- correct temp
homeostatic control scrotal temp
rams
thermosens neurons in scrotum -> spinal cord -> hypothal -> motor neurons -> pant, sweat glands on scrotum
specific scrotum temp control
- lots sweat glands
- tunica dartos = sm musc under sndrogen control contract -> body wall for warm/opp
- cremaster musc = sk musc draw testis -> bod fast for protect or pull in to warm short period
- testi arts + veins close contact = counter-current heat exchange = cool art blood
what do accessory glands secr
- fructose as E source
- horms + enzs
struct + funct dependent on testost
non-cellular = seminal plasma
copulation
- mounting
- intromission + friction movements
- emission = seminal fluids acc glands -> pelvic urethra = mix w sperm
- ejaculation - symp NS due sensory (temp, press) stim penis head - sperm + seminal plasma out repro tract
erection
- elevated art blood flow
- dilation corporal sinusoids
- restrict venous outflow
- incr intra-penile press
- relax retractor penis musc
non-adrenergic non-cholinergic (NANC) parasymp neurons dominate
how ejaculate
symp NS due sensory stim = ischiocavernous, bulbospongiosus + urethralis musc contract together to squeeze semen out
cryptorchid horses
== rigs
== 1/both testis retained in ingional canal/abdom
* don’t just test testost bc if retained may not prod much
* inject LH + test blood b4 + after + if testicular tiss will get incr in testost
general progest pattern during preg
remains high thruout gestation, rapidly decr just b4 parturition
species variation in specifics
horse progest in preg
embryo prods pregnant mare serum gonadotropin (PMSG)
=> stims FSH + LH receptors on ovarian follicles to initiate ov 2nd oocyte
=> prod accessory corp lut
=> augment progest prod
progest obligatory to maintain preg - luteolysis early = abortion
progest sources diff species
- horse = PMSG
- cow = 6-80mo using corp lut
- bitch = progest from corp lut thru whole preg
luteal phase preg vs not bitch
prolactin in preg luteotrophic = plateau progest prolonged then sidden decline for parturition
not preg = more gradual decline
pretty similar
terminating preg
give exogenous prostaglandin whilst relying on progest from CL = induce luteolysis = terminate preg
also to induce cow just b4 parturition
what does placenta prod
progest + then oestrogen peaking HIGH just before partur (as progest declines)
why does progest decline before partur
removes block to oestrog + promotes myometrial contractions
what initiates partur
- end gestation = foetal mass approaching space limitation uterus + exchange limitation of placenta
- = foetus stressed = secr stress hormones cortisol from adrenal, ACTH from ant pit
majority foetal growth in last 1/3 gestation
remove/add stress hormones = prevent/induce partur
result of foetal cortisol
- progesterone convert -> oestrogen = contractions can begin
- placenta synth prostaglandin = luteolysis
relaxin
synth in CL/placenta stimmed prostaglandin
=> softening soft tiss of cervix + incr elasticity pelvic ligs
oestradiol effects
- incr secr mucous -> wash out cervical seal + lube vaginal + cervical canal
- incr myometrial contractions
stages partur
- initiation myometrial contractions + cervical dilation
- expulsion foetus
- expulsion foetal mems
expelling foetus
uterine contraction push foetus + allantois into vagina =>
1. neuroendocrine reflex to release oxytocin
2. spinal reflex to stim abdom straining
when do sacs rupture
- allantois ruptures in vagina
- amnion can burst at vulva or can cover head of offspring (mares + bitches partic)
amnion = water bag
stim + role of oxytocin
stretch sensitive cells in cervix activated by descending foetus => neuroendo reflex => secr oxytocin from post pit
== incr strength + frequency uterine contractions
doesn’t initiate partur, but later big pos feedback loop until delivery
mammary gland is
modified sweat gland - ectoderm
* arises from lat lines on ventral surface developing conceptus = mammary ridges
* vary in no, location + teat no.
mammary tiss development
terminal alveoli (prod milk) grow into lobules = grape-like structures empty common duct
* 90% mass mammary gland
growth mammary gland post puberty
induced cyclical ovarian activity
1. oestrogen = ducts branch + incr in diameter
2. progest = terminal portions branch form alveoli
prolactin + GH incr during puberty + needed complete + rapid development ducts
faster than normal body growth, development only so far if not preg
mammary alveoli epithelial cells
metab active on basement mem surrounded collagenous ECM
* incr rough ER for prot synth
* incr smooth ER for phospholipid + triglyceride synth
* milk synthed across apical surface
* tight junctions bet cells = impermeable barrier
composition milk
prot, fat, lactose
Na+, K+, Cl-, Ca2+ prot-bound (lots more than plasma)
similar osmolarity to ECF
formation colostrum
gland plasma cells prod immunoglobulins = passive immunity (animals w/o passive placental transfer)
* high in fats, prots, vit A, low lactose
lactogenesis
onset milk secr
1. acquisition secretory capability pre-partum
2. onset copious secr at partur (horms ensure right time)
hormonal control lactogenesis
- low progest at end preg allows synth prolactin receptors
- prolactin binds receptor + upregs α-lactalbumin + enzs involved synth lactose
incr cortisol, prolactin, oestrogen, placental lactogen in late preg
galactopoesis
== maintenance milk secr, requiring:
1. horms
2. removal of milk as alveolar cells secr prot Feedback Inhibitor of Lactation (FIL) - builds up + inhibits secr unless removed
horms for galactopoesis
- prolactin maintains alveolar cell metabl + secr α-lactalbumin
- oxytocin stims myoepithelial cells to help remove milk
- rumis = GH helps uphold secr
- GH, insulin, thyroid + cortisol required indirectly
factors affecting milk yield
- no. secretory cells in mammary gland
- blood supply to mammary gland
- water intake (milk mostly water)
- incr blood gluc = decr lactose = decr vol (most important factor)
- milk removal - sucking frequency to remove FIL
where is milk secreted
- mammary epithelial cells of alveoli secr milk -> alveolar lumen
- milk in alveoli + fine ducts = small diameter = big resistance = hard suck
milk ejection
milk pushed out mammary gland -> larger ducts + cisterns as myoepithelial cells contract
* stimuli = tactile stim teat, smell, vision, sound
* = oxytocin secr = contraction reflex
milk pushed not sucked out - eject reflex easily conditioned for parlour
tunica albuginea
thick CT capsule around testis w CT septa sepping testis into lobules cont seminiferous tubule + interstitial tiss
where is urethra in penis
extending down centre corpus spongiosa
Uterus layers
- Endometrium lining = simple columnar w uterine glands + bvs
- Myometrium = layers sm musc (inner circ, outer longi) w large bvs bet - responsive horms esp oxytocin
- perimetrium = loose ct w lymphatic vessels
cervix struct
fibromuscular plug at opening uterus
* lining = simple columnar
* secr mucous
function cervix
- seal off uterus during preg
- maintain sterile stable internal environ for embryonic development
vagina histo
- non-keratinised stratified squamous epithelium
- secr prod acidic environ
- then lamina propria
- then double layer sm musc (inner circ, outer longi)
label
testis
label
ductus deferens
label
prostate gland = tubulo-alveolar gland
label
seminal vesicle = coiled tubular gland that enters ductus deferens
label
penis
label
ovary w follicles in diff stages development
glands in uterine horn
acinar glands lined cuboidal epithelium
label
epididymis
journey sperm
seminiferous tubules -> rete testis (channs in mediastinum testis) -> efferent ducts -> epididymis -> ductus deference -> urethra lumen
umbilical cord vessels
- 2 umbilical arts from internal iliac art
- 1 umbilical vein
- urachus = allantoic duct -> allantoic art (drains bladder)
art + vein oxygenation wrong way round
what do umbilical arts connect
L + R internal iliac art -> foetal-maternal blood exchange at chorionic villi
what do umbilical vein connect
foetal-maternal blood exchange at chorionic villi -> ductus venosus
what happens at birth
- amniotic mem of cord broken
- umbilical arts retract
- umbilical vein + urachus close (temporarily remain outside bod)
what does umbilical art become
round/lateral ligaments of bladder
what does umbilical vein become
round lig of liver = falciform lig
what does urachus become
median lig of bladder
what happens in postpartum period
- myometrial contraction to return uterus to size + expel lochia (normal remnants)
- endometrial repair
- resumption ovarian function
- elimination bac contamination from repro tract
uterine involution
== return pre-preg status so myometrium conts contract after birth so decr in size
2. = sm musc cells decr in size
3. glands in endometrium degraded
4. granulocytes invade lumen + decomp tiss remnants + kill microorgs
lochia
normal remnants foetal tiss expelled out vagina (brown discharge)
species variation in uterine involution
rapid in animals w diffuse placenta
* mare oestrus + ov can occur 1-2wks after foaling (= foal heat)
effect of suckling on uterine involution
suckling = oxytocin for milk let down but uterus still has oxytocin receptors for few days after parturition so also incr speed uterine involution
GnRH pulse generator
drives repro function bc incr frequency pulses of GnRH drives LH + FSH which drive gonadal function
too low frequency = no repro function
what controls GnRH release
- sex-steroids (feedback)
- inflamm
- stress
- drugs
- metabolism
synth of GnRH
peptide neuro-hormone made neural cell in preoptic area of hypothal + released at terminal end
puberty =
acquisition of repro competence
what controls puberty
hypothal
* GnRH v low in young animals
* sexual maturity signalled by incr in GnRH pulsatility
GnRH hard to measure so LH often used as marker
factors in onset puberty
- size + fatness (more in female) due effects metabolic hormones on GnRH pulsatility, e.g. leptin
- season of birth + photoperiod - depends E supply, seasonality
- social cues - large grps + presence of male
- age
- metabolic status
all affects GnRH release
defn puberty in males
age when ejaculate contains sufficient sperm to fert
also:
* when behavioural traits expressed
* at first ejaculation
* when sperm 1st appear in ejaculate
defn puberty in females
age when female can support preg w/o deleterious effects
also:
* at 1st oestrus
* at 1st ov
normal reasons supress GnRH pulsatility + ovarian cycles stop
- lactation
- preg
- photoperiod
- starvation
lactation + preg
lactation amennhorea (LAM) = avoid preg based natural postpart infertility associated fully breastfeeding
* suckling reduces = ov returns
lactation on GnRH
- lactation = lots inhib GnRH pulse generator
- plasma FSH insufficient for follicle development but GnRH too low for ov
suckling frequency incr inhib
what controls seasonality in breeding
effect melatonin on GnRH pulse generator
who goes back into oestrus faster dairy or beef
beef bc calf suckling more times a day than milked = more oxytocin = more contraction uterus = returns back faster = oestrus starts sooner
newly calved dairy heifer + cycle
2yrs old = still growing + new calf + bred for loads milk + stress of bullying = inhib GnRH pulse generator
