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Therio - Bovine - Comparative Anatomy & Physio

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drraythe's version from 2017-09-10 03:46

Comparative Anatomy

Question Answer
What is a duplex uterus? (Who has this?)2 cervices (rabbits, marsupials)
What is a bicornuate uterus? (Who has this?)"2 horns" (most domestic sp... cows, mares, bitches, sows, etc)
What is a simplex uterus? (Who has this?)No horn, mainly body (primates, man)
Say the path from the vulva to the ovaryVulva
Vestibule
Vagina
Fornix of vagina
Cervix
Uterine body (usually short)
Uterine horn (intercornual ligament btwn the horns)
Uterine tube (isthmus, ampulla, infundibulum inclduding fimbriae)
Ovary
How does the location of the pelvic organs differ btwn cow & horse?Cow = lie on floor of pelvis
Horse = suspended from dorsal pelvis.
When “AI”ing a cow, what must you be careful of in the vestibule?The suburethral diverticulum, which hosts the urethral opening.
**What type of cervix does a cow have?Fibrous (this steak is tough like fiber! oh wait, that's bc it's the cervix) (4-5 circular folds)
How does the cervix respond to estrogen & progesterone?Estrogen = Open
Progesterone = Closed
What are the 3 layers of the uterus (in to out) (distinct features?)(1) Endometrium - glandular tissue, caruncles present (80-100)
(2) Myometrium - 2 layers of sm mm at right angles (inner circular, outer longitudinal)
(3) Perimetrium - continuous w/peritoneum. Nerves & BVs.
What makes up a Placentome in a cow, & which part comes from who?Mom = Caruncle
Baby = Cotyledon.
***WHERE does fertilization occur in all sp??THE UTERINE TUBE/AMPULLA
What are the 3 components of the uterine tube?Infundibulum w/ fimbriae → ampulla → isthmus (Join uterine horn at utero-tubal Jxn) (isthmus is a small piece of land that connects an island to the main land)
(Said in class) How long does the egg chill in the ampulla after fert. & why?Like 5 days, bc uterus is hostile enviro trying to get rid of the rest of the sperm etc.
List the anatomy of the ovary from out to in (mention Fxn)Surrounded by tunica albuginea (CT protection) → outer cortex (Contains oocytes, follicles, corpus luteum (CL), corpus hemorrhagicum (CH) & corpus albicans (CA) ) → inner medulla (Contains b/v, nerves & lymphatics)
All the action in an ovary is in the...Cortex
Where do follicles ovulate from in the cow, & when they are how big?From anywhere on the ovary surface, follicles ovulate when they reach ± 15-20mm
How might an ovary look (in terms of structures) in... Proestrus?Growing follicle (10-15mm) + regressing CL (<1/2 ovary)
How might an ovary look (in terms of structures) in... Estrus?Large follicle (15-20mm) + small CL (10mm)
How might an ovary look (in terms of structures) in... MetestrusCH – difficult to palpate
How might an ovary look (in terms of structures) in... DiestrusLarge CL w/ distinct “crown”; smaller follicles (10-12mm)
If you look at an ovary, how do the developing follicleSQL appear?CL = yellow & large & raised. Follicles = reddish & not raised
How does the Corpus luteum, follicle, Corpus hemorrhagicum, & Corpus albicans feel when you palpate them?CL: raised crown & 20-30mm diameter
Follicle: fluid filled blister
CH: Soft, mushy area felt shortly after ovulation
CA: Small, hard firm pea sized structure in the ovarian stroma
What do follicles secrete?ESTROGEN (getting ready for preg), predominant 1 also secretes inhibin so it can stay dominant
What do corpus luteum secrete?PROGESTERONE (egg is out, now prepare for maintaining preg) also Oxytocin & relaxin
(For comparison) How does a mare’s ovary differ from a cows?Cortex is in the inside in a horse, so can only ovulate through the ovulation fossa. & can only palpate follicles (not CLs)
What is the Mesometrium?Part of the broad lig that is connected to uterus
What is the mesovarium?Part of broad lig attached to ovary
What is the mesosalpinx?Part of the broad lig connected to uterine tube (salpinx) w/in ovarian bursa
memorize

EMBRYOGENESIS/ Puberty/ Anestrus

Question Answer
Primordial germ cells originate from...Inner lining of yolk sac (Germ cells migrate to the genital (/gonadal) ridge & reside in the undifferentiated gonad)
Mesonephric (“Wolffian”) ducts develop into what in who?MALE = WOLF. Will develop into efferent ducts, ductus deferens & epididymis in males (regress in females)
Paramesonephric (“Müllerian) ducts develop into what in who?Will fuse to form the uterus & vagina (regress in males) (girls are stubborn as mules around (para) boys)
How does the Y chromosome cz a boy to be a boy?Y chrom contains TDF (testes determining factor) → czs testes to develop → Sertoli cells secrete anti-müllerian hormone (AMH) → Results in degeneration of paramesonephric ducts + Results in differentiation of Leydig cells w/ testosterone production & development of the male duct system
How does X chromosome cz a girl to be a girl?X chromosome has no TDF therefore, female forms by default
Uterus & vagina are formed from what primordial germ layer? (& structure?)Mesoderm (from paramesonephric ducts)
Vestibulum & vagina are formed from what primordial germ layer? (& structure?)Ectoderm (urogenital sinus)
How does the hymen form?Point where mesoderm (vag+uterus) & ectoderm (vag+vestibule) meet
What is 2 uteri called?Uterus didelphys
Paramesonephric ducts fail to fuse → what are some things that can happen?2 uteri, 2 cervices, vaginal septum, persistent hymen
Who gets Segmental aplasia of paramesonephric ducts, & why does it happen? What problems does this cz?"White Heifer Dz" of shorthorn cattle Recessive gene linked to white hair coat, Often results in uterus unicornis (often persistent hymen too, horn fills w/ mucus)
What is freemartinism?Male & female twins, Common blood supply therefore female twin is exposed to testosterone & AMH, Results in incomplete development of the paramesonephric ducts & incomplete ovarian growth. Female acts bullish
How is a heifer physically affected by freemartinism?Sm ovaries, lg clit, no uterine body or cervix
Infantile external genitalia
Increased ano-vulva distance
Prominent hair on ventral commissure of vulva
When does a heifer reach puberty? How can you guess this?Attained when heifer reaches 65% of adult body mass- this can be predicted bc it is heritable, & related to large scrotal circumference of sire
What are some Factors affecting puberty?Genotype (Bos taurus > indicus)
Season of birth
BW/nutrition
Which reaches puberty faster, Bos taurus or bos indicus?B. indicus is faster, B. taurus takes longer
What is post-partum anestrus/why does it occur? (How long?)Time taken for involution of the uterus to occur+ resume cycling (4wk)
How does suckling affect the cow's cycle? Who is more prone?Suckling or even the sight of a calf can cz an anestrus. obv a prob w/ beef cattle (dairy calves are removed at birth)
Which type of cow is highest risk for anestrus, why?1st time calfers (growing & trying to feed a calf-- must feed them properly!)
*What time of yr is there dec fertility, & why?Summer bc HEAT STRESS dec fertility
Why might you tell your farmer to change the floors of their barn?If slippery, cows might feel too unstable to perform mating BH
memorize

ESTROUS CYCLE

Question Answer
*WHAT IS THE TYPE OF CYCLE COWS HAVE?NON-SEASONAL POLYESTROUS
What’s polyestrous?Can go into heat several times a yr
Estrous vs EstrusOUS = the WHOLE cycle
US = The period of sexual receptivity (just the 2 of US~)
What is the length of a cow's cycle?21d
List cycle in order starting w/ proestrusPro → Es → Met → Di
When does ovulation occur??Ovulation occurs 12h after the end of estrus
What does FSH do? Secreted by?Stimulates the follicles to mature & develop → secreted by pituitary
What does estrogen do?Czs the pre-ovulatory GnRH surge, which czs a surge in LH secretion & ovulation
What does LH do? Secreted from?Triggers ovulation & development of the corpus luteum, secreted by pituitary
What does progesterone do? Secreted from?Made by CL to maintain preg
What does GnRH do? Secreted from?From hypothalamus → stimulates pituitary to secrete FSH & LH
What do follicles secrete?Estrogen (encourages release of GnRH → pituitary → LH → get a CL) , & if dominant, inhibin (stop LH from pituitary)
What does the CL secrete?Progesterone (inhibits GnRH & LH from hypo & pit)
What does prostaglandin do? What is it secreted by?If no signal is received from the uterus to indicate pregnancy, endometrium secretes prostaglandin, leading to luteolysis (kills CL which is producing progesterone, so that goes down, which stops the inhibition of estrogen → heat cycle)
What are follicular waves?Progesterone doesn’t inhibit FSH (inhibits GnRH & LH) so during high levels of progesterone small waves of FSH are produced (2-3 per cycle), recruiting cohorts of follicles, which start to mature & produce estrogen at low levels, which cant stim the LH bc it's being inhibited so no LH, therefore regression of the maturing follicles
Explain the follicular phase vs the luteal phase--, which parts of the cycle are in these categories?(1) Follicular: inclds proestrus & estrus. The cow is in heat & follicles are dominant. estrogen is dominant hormone
(2) Luteal: inclds metestrus & diestrus. The CL is the dominant structure on the ovary & the main hormone is progesterone
**What are some of the effects of estrogen on the repro system?Open cervix
Inc mucus production
Inc uterine defenses
Inc tone of uterus
*Mounting other cows vs standing to be mounted means the cow is in what part of the cycle?Mounting = Proestrus
Standing = Estrus
What is a bull string?Clear vaginal discharge found during the follicular phase (esp heat) (other signs of heat/follicular phase incld: Bellowing, Moving around a lot, Soliciting attention from other cows, Resting chin on other cows, Saliva or mud on flanks/around tail head)
What time of day is it best to look for if cows are in heat (heat detection)?Watch for 30 minutes in the cool of the day ie. Early morning & late afternoon
*What is the most common cz of poor fertility in dairy herds?Poor heat detection (lack of observation/tools)
What is a Kamar heat detector?Snaps & fills w/ red paint when cow mounted (place on butt)
What’s Estrotect heat detector?Scratchy lotto ticket thing to see if they’ve been mounted (place on butt) (can also use tail paint or pedometers ← walking more to find males)
Explain what an inc or dec in milk progesterone levels indicates?INC = diestrus or preg
DEC = proestrus/estrus, anestrus, follicular cysts
What day is estrus?D0
When you palpate the ovary in estrus, how does it feel?There is a dominant, large, mature follicle & maybe a small CL
When does metestrus happen? (Days & position in cycle)Immediately after estrus, days 1-4 (so 4 days long).
A farmer fails to impregnate his cow on the right day, & now she has blood coming from her vagina. What happened?Metestral bleeding, it is NORMAL
When you palpate an ovary in metestrus, how does it feel?Corpus hemorrhagicum at the site of ovulation (feels soft)
What happens if you give PGF2α during metestrus?NO EFFECT- prostaglandins are for rupturing the CL, at this point there is only a CH/developing CL & they are resistant
When does diestrus happen? (Days & position in cycle)Majority of cycle, happens after metestrus. Days 5-16 (12 days)
What would you palpate on the ovary during diestrus?Large CL (rosette or crown of CL easily palpable)
**How does progesterone affect the repro system?Closes cervix, suppresses uterine defenses, low uterine tone (setting up for baby)
When is the CL sensitive to the PGF2α?During diestrus (when the CL is large & mature)
If you feel a big cavity in the CL, how concerned are you?Not very, this is normal
So, cow is in diestrus, & there is no baby. What happens?Endometrium has not received any signals to say that the cow is pregnant (Interferon tau), so the endometrium secretes PGF2α which czs luteolysis & cycle resumes
Where is PGF2α (prostaglandin) secreted from?Uterine wall
Which signal tells the uterus that it's preg? Where does it come from?Interferon tau, secreted by the fetus itself
How does luteolysis occur in the cow?From uterus comes the PGF2α, & w/ Countercurrent exchange btwn uterine vein/ovarian artery (to affect ipsi ovary) the PGF goes to the ovary (see pic slide 83)
How does the body get rid of all the PGF2α now?Large amt of PG dehydrogenase in the lungs
Why must you use a much lower dose of PGF2α in horses than in cattle?They have no countercurrent exchange (PGF goes from uterine VEIN to ovarian ARTERY) & they have No PG dehydrogenase in the lungs
Side effects of too much prostaglandin?SM MM CONTRACTION → colic in GI! Also uterine contractions (CAUTION: ABORTOGENIC IN PPL)
What signal is used for maternal recognition of pregnancy? (2)(1) Rapid outgrowth of the trophoblast to come into contact w/ the entire endometrium
(2) Conceptus secretes interferon-tau (τ)
*(NAVLE?) On any given day, approximately how many heifers in a group of 100 normally cycling cows are in heat?Cycle is 21 days. A cow has a 24hr estrus, so 1 day out of 21 is (1/21) = 0.05 aka 5% of the herd
About how many days is pro, es, met, & die?21 day cycle
Pro = 3d
Es = 1d
Met = 4d
Di = 12d
How do management systems vary btwn dairy & beef?Dairy is visual heat observation+aids, & AI. Beef is natural will bull present
What is the Am-pm rule?If cow seen in heat in the morning, then she is inseminated in the afternoon. If cow seen in heat in the afternoon, she’s inseminated the following morning
Es or Di? → BullstringEs
Es or Di? → Saliva, mud on flanksEs
Es or Di? → High tone uterus thats curled upEs
Es or Di? → Dry vulva, uterus soft & saggyDi
Es or Di? → Feel CLDi
Es or Di? → Feel follicleEs
What will the uterus look like on ultrasound during estrus?Small amt of intraluminal fluid
What will the uterus look like on ultrasound during diestrus?No fluid in lumen of uterus, CL appears as soft tissue opacity on the ovary. Remember may have central fluid-filled cavity = normal
memorize