7: Anatomy and Embryology of FM Flashcards
requirements for puberty?
- sexual behavior - receptivity [estrus]
- ovulation
- ability to support pregnancy w/o deleterious effects
age at puberty: canine
12 mos (6-24)
small dogs - puberty younger
age at puberty: feline
8 mos (4-12)
age at puberty: equine
18 mos (12-19)
“second spring of her life” [same for M]
age at puberty: bovine
11 mos (9-24)
age at puberty: ovine
7 mos (4-14)
age at puberty: caprine
7 mos (3-8)
age at puberty: porcine
6 mos (5-7)
age at puberty: llama
6-12 mos
age at puberty: alpaca
1 yr
some factors that affect age of puberty:
- BCS / plane of nutrition
- breed
- external factors: season of birth, photoperiod during onset of pubergy, presence of M during peri pubertal period, housing/stocking density
what is the threshold body weight a FM must reach to achieve puberty?
60-65 % of mature body weight
what effect does presence of boar have on peri pubertal gilt coming into puberty?
exposing gilt to boar brings her into heat/puberty earlier
what effect does housing and stocking density have?
crowd a little bit (esp gilts) -> b/c stress [low levels] helps mediate coming into puberty
importance of surge and tonic centers in FM brain?
to allow for LH surges to occur prior to ovulation
prior to puberty, there is not enough of this hormone to stimulate LH surge
e2 (estradiol)
how/why does growth of animal impact puberty?
b/c slowing of growth allows for inc glucose, fatty acid and leptin in blood -> stimulates higher frequency of GnRH pulses
changes in tonic center at time of puberty?
less sensitive to negative feedback by low e2 levels -> so inc GnRH sec
what does inc GnRH at puberty stimulate? how does this lead to puberty?
inc FSH -> drives follicular growth on ovaries -> inc e2 production by follicles
also inc LH -> ovulation -> puberty achieved
what hormones are produced by developing follicles?
e2
inhibin
what structure produces inhibin? where does it go? and what kind of feedback loop?
follicles produce inhibin
goes to ant pit
negative feedback -> dec LH and FSH sec
e2 is produced by what structure? where does it go? and what type of feedback?
produced by follicle
goes to surge center of hypo
positive feedback -> inc sec of GnRH from hypo
seasonality of canine
NO
seasonality of feline
yes - long day
unless indoor cat - cycles year round when exposed to ambient light
seasonality of equine
yes: long day
winter anestrus
seasonality of bovine
NO
seasonality of ovine
yes: short day
seasonality of caprine
yes: short day
seasonality of porcine
NO
seasonality of alpaca
not in north america…
what hormone mediates seasonality in FM
melatonin
where is melatonin released from
pineal gland
what stimulates melatonin release
darkness
where does melatonin go and what effect does it have?
to hypo
stim GnRH sec for short day breeders
…..GnRH -> inc LH, FSH -> cycle
absence of what factor/hormone allows for dev of FM repro sys
testis determining factor
what duct system develops into FM repro tract?
paramesonephric ducts
mullerian ducts
what tubular structures do the fused paramesonephric/mullerian ducts form?
uterine body,
cervix,
portion of Cr vagina
what structures do the unfused paramesonephric/mullerian ducts form?
uterine tubes
uterine horns
where do the paramesonephric ducts end caudally? (with what structure)
the urogenital sinus
whaat makes up the urogenital sinus?
cd vagina
vestibule
what is the narrowing at the juncture of bud and urogenital sinus proper called?
vestibulo-vaginal junction
is a sphincter in the mare
functions of ovary
gamete production
endocrine gland
what hormones does the ovary produce? and by what structures?
follicles - e2 and inhibin
CL - p4
what outer structure surrounds the ovary?
tunica albuinea
what comprises the ovarian cortex? where is it located? what species is an exception?
oocytes/follicles
CL
corpora albicantia
loc outer area of ovary
mare - loc inside
what is the ovarian medulla? where located? exception?
connective tissue (CT)
vasculature
Nn (nerves)
loc on inside area of ovary
mare is exception - loc outside
what unique structure on the mare allows ovulation to occur despite the cortex w the follicles being located on the inside?
ovulation fossa
why CL is not palpable - can palpate the follicle protruding and note when it leaves to determine when she ovulates - but cannot palpate the CL itself/directly
what are 4 barriers along the tubular tract
- vulva
- vestibulo vaginal sphincter
- cervix
- utero tubular junction
what is the infundibulum?
Cr/ovarian end
- fimbriae
- forms ovarian bursa in some species
what is the ampulla?
site of fertilization
mare: unfertilized oocytes remain there
3 parts to uterine tube?
infundibulum
ampulla
isthmus
what structure forms the ovarian bursa?
infundibulum (species dependent)
in what species is ovarian remnant syndrome more common (dog/cat)? why?
canine - b/c bitch has ovary encased in substantial bursa (infundibulum) whereas the queen has more exposed ovary
what effect does e2 have on the utero tubal junction conformation?
UTJ kinks under influence of e2 and “unkinks” with dec e2 -> straightens and allows embryo to enter uterine horn
during this time: greater chance for salpingitis, phosalpinx - b/c of loose sphincter
shape of uterus in most domestic animals?
bi cornuate uteri
2 uterine horns and a uterine body
what determines the length of the uterine body relative to the length of the horns?
the degree of fusion btwn the paramesonephric ducts
which species have highly developed uterine horns?
bitch
queen
sow
which species have shorter horns relative to body length of uterus?
mare, cow
what is the uterine serosa called?
perimetrium
what is the myometrium?
muscular layer of tissue in cervis
how many layers are there to the myometrium?
2 - outer longitidunal and inner circular
what type of muscle is the myometrium?
smooth muscle
why are myometrial contractions important?
facilitate sperm transport, evacuation post breeding and fetal delivery
what type of contraction draws semen to promote pregnancy?
retrograde
what is superficial lining of uterus called?
endometrium
what are the layers of the endometrium?
sub mucosa and mucosa
function of endometrium?
nourishment of pre attachment embryo
maternal contribution to placenta
PGF2a secretion
what is function of uterine milk glands?
where are they loc?
nourishment of pre attachment embryo
loc in endometrium
what is general role of PGF2a in FM?
control cyclicity
unique feature of cow uterus
caruncles
unique appearance of mare uterus
about 7 longitudinal endometrial folds
what is the broad ligament?
extension of peritoneum - surrounds repro organs and suspends them from dorso lateral body wall
what covers the ovary?
mesovarium
what covers the uterine tube?
mesosalpinx
what covers the mesometrium
uterus
due to the nature of attachment of the broad ligament, what kind of mobility does the bovine and equine have?
bovine - high
equine - low
2 types of cervices?
fibrous and muscular
what animals have a fibrous cervix?
ruminants
sow
what animals have a muscular cervix?
mare
camelid
what is the orientation of tissue impinging upon the canal in ruminants and sows?
transverse rings
what is the orientation of tissue impinging upon the canal in mare?
longitudinal rings
what are the functions of the cervix?
mucus production - lubrication during copulation, flushing of foreign material
conduit - barrier to sperm transport in some species
isolation of uterus from external environment during pregnancy
anatomy of cow cervix?
3 annular folds
anatomy of ewe cervix?
5 eccentrically positioned cervical rings
anatomy of sow cervix?
multiple inter digitating rings forming a spiral
anatomy of mare cervix?
longitudinal cervical folds
anatomy of bitch cervix?
smooth, w/o rings or folds
prominent vaginal portion
large fornix area with small hole located ventrally (hard to find)
vagina functions
copulatory organ
birth canal
vaginal fornix anatomy
which species have one?
formed by protrusion of Cd portion of cervix, into cranial vagina
cow, mare, dog
anatomy of bitch vagina
paracervix and paracervical tunnel
vagina narrows (2/3) b/c dorso median ridge impinges on canal opens into fornix cranially
vestibulo vaginal junction in mare - function?
2nd barrier to contamination
incompetence following foaling injury may contribute to pneumovaina [wind sucking]
what are borders of vestibule?
from vestibule vaginal jxn (just Cr to external urethral orifice) to vulva
functions of vestibule?
copulaltory organ (constrictor vastibuli muscles) opening of urethra
what are vestibular (Bartholin’s) glands?
pathology? in what species?
mucus like secretions during estrus
may become cystic in cattle
what is the perineum?
covering of pelvic outlet
area around anus and vulva
vulva function?
- Cd most barrier to repro tract contamination
- physical barrier comprised by labia and constrictor vulvae muscles
in what species is vulva responsive to hormonal stimulation?
bitch and sow
what do constrictor vulvae muscles do?
contract around the penis after intromission to promote ejaculation
perineum/vulva of mare conformation?
normal: 1/3-1/2 of cleft length dorsal to ischiatic arch
vertical orientation
why is poor perineal conformation in mare problematic?
predisposes to pneumovagina -> bacT contamination of the Cd repro tract -> endometritis
recessed vulva/perineum conformation of bitch?
- congenital or overweight bitches
- moist environment favors growth of bacT and yeast -> perivulvar dermatitis -> UTIs
why is ventrally positioned orientation of bitch problematic?
predisposes to problems with natural mating
common problem with vulva/perineum of alpaca? also common with dogs
hypoplastic vulva
alpaca orifice may be like a pin point
anatomy and function of clitoris
FM homologue of penis
fxn not known
significance of clitoris when breeding bitch and cow?
stimulate for cow and dog during AI to inc preg rate
in dog, called feathering
in the mare, loc and fxn of clitoral fossa?
loc ventral to glans clitoris
houses glans clitoris
clitoral sinus loc and fxn?
loc dorsal to glans clitoris
may harbor pathogenic bacT
what is segmental aplasia?
- absence of portions of tubular repro tract
- mucoid fluid accumulates proximal to occlusion
- imperforate hymen
what species is segmental aplasia most common?
cattle
white heifer dz - assoc w white coat color
what is freemartinism?
heifer calves born co-twin to bull calves
vascular anastomosis of chorioallantoic membranes so that AMH, TDF and testosterone from M reach FM fetus during organogenesis of repro sys
why does free martinism affect the FM development?
b/c testicles develop first
what is the sex chromosome chimera that occurs with freemartinism?
XX/XY - exchange of hematopoietic blood and germ cells btwn feti via common blood supply
what developmental defects occur with freemartinism?
segmental aplasia
gonad development range from ovaries with no oocytes to testes like organs
clinical signs of freemartinism?
fail to become pregnant [sterile]
small vulva with long hairs
FM act “bullish” and appear more masculine or bull like
dx freemartinism?
vaginal length measurement - test tube measurement
palpate
u/s
genetic testing
MC congenital anatomic abnormalities in vagina and vulva of bitch at vestibulo vaginal junction?
vertical trans luminal band [when 2 paramesonephric ducts come together and the common wall where they oppose each other does not break down and remains as septum]
and
circumferential stricture [due to excessive tissue]
what is the persistent hymen at the vestibulo vaginal jxn of the mare?
embryologic remnant of jxn btwn paramesonephric ducts and urogenital sinus bud
appears like “laying an egg”
Tx of persistent hymen in mare?
manual rupture under sedation
fertility fine
what is cause of intersex conditions of FM clitoris?
masculinization of FM feti due to altrenogest administration during preg - canine
what is effect of post natal exposure to steroids?
androgens in race fillies and bitches - hyperadrenocorticism in bitches
intersex condition in offspring
