histo/phys final

What’s the difference between musculovascular (musculocavernous) + fibroelastic penises?

What is the urethral process, its fxn, and why can it be problematic?

What are the corpus cavernosum + spongiosum?

Describe the biochemical and vascular basis for tumescence + detumescence

Describe the autonomic components of tumescence, detumescence, and ejaculation

Name the hypothalamic peptide that is the central regulator of male repro physiology

What are the 2 major anterior pituitary hormones that regulate male repro physiology + what are their fxns?

What is the negative regulator of male repro physiologic hormones, where does it come from, and how does it work?

Why does testosterone interact w/ an intracellular receptor while the other hormones (LH, FSH, GnRH, prolactin, and inhibin) interact w/ receptors that extend outside of the cell?

What is the os penis + bulbus glandis?

Why is cancer a side effect of anabolic steroids that mimic testosterone?

What is the major barrier for sperm in the female repro tract? What is the privileged pathway thru this barrier?

What is the major barrier for sperm in the female repro tract? What is the privileged pathway thru this barrier?

3 mechanisms by which sperm are inactivated/lost

3 mechanisms by which sperm are inactivated/lost

What is bidirectional myometrial contractility?

What is bidirectional myometrial contractility?

What is sperm capacitation?

What is sperm capacitation?

Describe the fertilization process (zygotogenesis) from attachment to syngamy

Describe the blastogenesis process

Describe the 4 steps of embryonic preparation b/t syngamy + implantation

For post-hatching embryogenesis, which pole of the embryo is the amnion formed on? Which pole is the chorioallantoic membrane formed on?

What are the different signals rmt + swine embryos send to the uterus that implantation is imminent? How does this signaling influence the ovary?

What is the role of CG in maintaining early preg?

What is the importance of accessory CL in the maintenance of early to mid-preg?

What is the importance of the placenta in the maintenance of mid-pregnancy to beyond?

What is the fxn of eCG in the mare? What about eCG in other species?

What is placental lactogen + its fxn?

What are the hormonal changes at parturition? How is fetal cortisol involved?

What is the major feedback mechanism of parturition + the post-partum period?

What are the 5 general endocrine fxns of the placenta?

What are the classifications of placentas w/ examples?

Which types of molecules can cross the B-P-B?

• B-P-B = blood-placental barrier

What does aromatase do?

convert testosterone into estrogen

What is the general structure + layout of most species ovary vs the mare’s ovary?

• most species

  • ovarian cortex houses follicles

  • ovarian medulla houses vasculature, old CLs, stroma, etc

What is the utero-ovarian vascular countercurrent exchange system? Which species truly possess it?

• ovarian a. twists around uterine v.

• allows PGF2a to circulate locally instead of systemically

  • uterus releases PGF2a → PGF2a goes dir. to ovary to lyse CL

    • very efficient

• truly present in ruminants only

  • other species may have smn similar

big comparative repro table but just cow column

Briefly, what do FSH + LH do in females?

• FSH → make follicle grow

• LH → make CL grow

Describe the 2-cell-2-gonadotropin theory in females

• 2 cells w/i follicle

  • theca cell stim. by LH to turn cholesterol into androstenedione

  • granulosa cell stim. by FSH to turn androstenedione into estrogen

    • dominant follicles have more granulosa cells to make more E2

Day 0 of the estrous cycle = ______. Then, the ______ ___________ forms, develops into a full ___, and produces the hormone ___. This hormone has _____ feedback on the HPG axis causing E2 levels to _____. In the absence of conception, the uterus will produce _____ which will cause _____ of the CL. The development of a _____ follicle in the background of this combined w/ the absence of the hormone _____ results in an ____ surge which causes _______.

• Day 0 of the estrous cycle = ovulation.

• Then, the corpus hemorrhagicum forms, develops into a full CL, and produces the hormone P4.

• This hormone has negative feedback on the HPG axis causing E2 levels to decrease.

• In the absence of conception, the uterus will produce PGF2a which will cause luteolysis of the CL.

• The development of a dominant follicle in the background of this combined w/ the absence of the hormone P4 results in an LH surge which causes ovulation.

Describe what is happening during recruitment, selection, and dominance in the follicular waves of cattle

• recruitment phase

  • small follicles produce smol amt of E2

  • E2 stim. GnRH release in surge center of hypothalamus

• selection phase

  • medium follicles produce medium amt of E2 + inhibin

  • inhibin inhibits FSH release from the anterior pituitary → comparatively more LH release

• dominance phase

  • dominant follicle emerges and produces a LOT of E2 + inhibin → stim. surge center to release a LOT of GnRH → stim. anterior pituitary to release a LOT of LH + little FSH → LH surge → ovulation

What are the feedback mechanisms of the hormones produced by the CL + follicles during the luteal phase compared to the follicular phase?

• luteal phase → developing CL (metestrus + diestrus)

  • CL release P4 → DEC. hypothalamus GnRH release + anterior pituitary LH and FSH release

  • follicle release E2 → DEC. hypothalamus GnRH release + anterior pituitary LH and FSH release

  • follicle release inhibin → DEC. anterior pituitary FSH release

• follicular phase → developing follicles (proestrus + estrus)

  • follicle release E2 → INC. hypothalamus GnRH release + anterior pituitary LH and FSH release

  • follicle release inhibin → DEC. anterior pituitary FSH release

What is happening in the follicular phase?

• growth of follicles

• proestrus

  • period from CL regression to estrus

  • increasing E2 + decreasing P4

• estrus

  • period of sexual receptivity at the end of follicular phase

  • highest E2 + LH surge

What is happening in the luteal phase?

• development of CL

• metestrus

  • period b/t ovulation + formation of fxnal CL

  • low but increasing P4 + low E2

  • luteinization occurs

    • granulosa cells become large luteal cells

    • theca cells become small luteal cells

• diestrus

  • period from formation of fxnal CL to luteolysis or termination of pregnancy (abortion/parturition)

  • highest P4

  • PGF2a released at end of diestrus to induce luteolysis if no preg.

What can cause anestrus in cattle?

• delayed puberty

• negative energy balance

• not enough time since calving

  • cows start cycling again ~45d post-partum

• disease

• lactational anestrus

  • prolactin + presence of calf will suppress GnRH → suppress LH surge → no ovulation

Approximately how many days is gestation in cattle? What maintains pregnancy?

When must + how does MRP occur in cows?

What type of placenta do cattle have? When does attachment of the embryo occur? What is the gross appearance? What are the fetal membrane layers?

3 ways pregnancy is diagnosed in cows

• transrectal palpation → by ~25d

• transrectal/transabdominal US

• blood test for pregnancy specific protein B (PSPB) from placental cells

big comparative female anatomy table but just the cow parturition stages part

male comparative repro table but just bulls

What part of the hypothalamus do males lack compared to females?

• males only have tonic center + lack surge center

• don’t need LH surge bc males don’t ovulate

What hormones are produced by a growing ovarian follicle that can affect the HPG axis?

• E2 → inhib GnRH

• inhibin → inhib FSH

What type of penis does the bull have?

fibroelastic

What type of cervix does the cow have?

cartilaginous

comparative female repro table but small rmt columns only

In short-day breeders like small rmts, what stimulates cyclicity?

• dec light → inc melatonin → sustained, high melatonin stim HPG → inc GnRH → cyclicity

  • inc GnRH → inc LH pulse freq → inc testosterone in males + follicular wave development in females

• E2 has negative feedback on LH pulse freq when melatonin is absent

Describe the transition periods in small rmts when going from breeding to anestrus and anestrus to breeding.

• transition from breeding to anestrus (2-3 wks)

  • dec LH pulse frequency

  • no E2 rise or LH surge

• transition from anestrus to breeding (1-4 wks)

  • E2 loses negative feedback on LH → increases in LH become possible

  • high LH in late anestrus

  • inc LH pulse frequency w/i 1 wk prior to P4 increase (1st ovulation)

How is estrus detected in small rmts?

• buck does it best

  • use teaser = infertile male that still has testicular hormones that helps tell you if female in heat or not

• cervical discharge

  • clear → too early

  • cloudy → just right

  • clumpy, cottage cheese → too late

What is the earliest you can induce a doe and have viable kids? Lambs?

• viable kids: 143d

• viable lambs: 138d

3 general ways to diagnose preg in sm rmts

• behavior

  • observe signs of estrus after known breeding date → she prob not preg

• imaging

  • radiographs → can’t detect babies until 75d when bones ossify

  • transrectal US → can’t detect until 28-30d

  • transabdominal US → can’t detect until 45d

• biochemical tests

  • preg specific protein B blood test

male repro comparative table but just sm rmt columns

female comparative repro table but just mare

What is the first barrier of the female repro tract? What does good conformation of this structure on a mare look like?

• vulva

• ideally straight + commissures close tgt

Where do you collect samples from a mare for contagious equine metritis?

• collect samples at clitoral sinuses + fossa

What does high + dry vs loosy goosy mean when evaluating a mare’s cervix to determine heat? What cervical structure are you specifically looking for?

• high + dry

  • not in estrus

  • influence of high P4

• loosy goosy

  • in estrus

  • influence of high E2

• specifically looking at dorsal frenulum to observe high + dry vs loosy goosy

What’s different about how embryos get into the uterus of a mare compared to other species? Where are unfertilized embryos retained in the mare?

• embryos must secrete PGE2 to relax oviductal sphincter and be allowed entry into the uterus

• unfertilized embryos are retained in the oviduct

Does the mare have the utero-ovarian vascular countercurrent exchange system?

nno

How is cyclicity initiated in long-day breeders such as the horse?

• inc light → dec melatonin → low melatonin stim HPG → inc GnRH → cyclicity

  • inc GnRH → inc LH pulse freq → inc testosterone in males + follicular wave development in females

• melatonin inhib GnRH in horses

What are the 4 “seasons” for broodmares in a year?

• breeding season (spring-early fall)

  • long days

  • cycling

• autumnal transition (1-2 mo in fall)

  • decreasing day length

  • transition period from cycling to anestrus

• winter anestrus (short days)

  • short days

  • anestrus

• vernal transition (55-60d in spring)

  • increasing day length

  • transition period from anestrus to cycling

What 2 drugs can you give to a mare to induce ovulation?

• GnRH analogs

• hCG = human-chorionic gonadotropin

  • has LH-like activity in mare → causes LH surge

3 ways to stage where a mare is at in her estrous cycle

• palpation of repro tract

• US

• behavior

When must + how does MRP occur in horses?

• must occur by d 14 of estrous cycle to prevent luteolysis

• MRP done by embryo moving along entire endometrial surf. to prevent uterus from producing PGF2a

At how many days is a foal considered non-viable, premature, and dysmature?

• <300d =non-viable

• <320d =premature

• >320d + signs of prematurity = dysmature

How is pregnancy maintained in the mare? What will happen if preg loss occurs before vs after day 35?

4 ways preg is diagnosed in mares

• behavior

  • not accurate

  • look for signs of estrus

• serum progesterone assay

  • also not super accurate

  • blood sampled at 18-20d post-ovulation, high P4 indicates CL persistence indicating preg.

• repro tract palpation

  • can feel embryo by ~20d

• transrectal US

  • most accurate

  • 14d post-ovulation

How do mammary secretions change in a mare in the days leading up to parturition?

• dec. Na+ and inc K+

• pH changes

• inc Ca2+

• waxing = serous crusts turn into waxy substance over teats

• secretions go from having a cloudy appearance to a milky one

What is foal heat? When would a mare be a candidate for foal heat breeding?

• foal heat = mare’s 1st estrus following parturition

• mare returns to cycling 5-12d post-partum → ovulates 20d pp

• if mare ovulated >10d pp → candidate for breeding

• if mare ovulated <10d pp → uterus not ready yet for embryo