Exam #3: Repro Pt. 1 Flashcards
Structure and tubular tract of mare repro tract
- Two ovaries: bean shaped
- Tubular tract = paired oviducts, paired uterine horns, single uterine body, cervix (external os and fornix), vagina, vestibule, and vagina
What’s special about the equine ovary?
Inverted compared to other ovaries = inner cortex, outer medulla, ovulation fossa is internal (where ovulation occurs, includes surface germinal epithelium)
Where do we interrupt oocyte migration for oocyte transfer?
Infundibulum, before it enters the oviduct
Where does fertilization occur?
Ampulla of the oviduct
Where, in the female repro tract, is the sperm reservoir and deep insemination site?
Oviductal papilla, at the utero-tubal junction
Where is the more superficial and common insemination site?
Just past the cervix? - Go dorsal in the vagina (otherwise you’ll inseminate the bladder)
Extent of the vagina and vestibule, anatomically
Vagina = from external os of cervix to vestibulovaginal junction (up to the transverse fold, covering the urethral opening)
Vestibule = vestibulovaginal junction to vulva (includes urethral opening)
Clinical importance of clitoral sinuses and clitoral fossa
Sinuses = dorsal to clitoris Fossa = ventral to clitoris
*Places that can potentially harbor venereal pathogens
Three physical barriers protecting the uterus
1) Vulva
2) Vestibulovaginal junction
3) Cervix
Position of epididymal tail and testes in the stallion
Testes = inguinal position
Epid. tail = should be caudal (not caudal? May indicate torsion)
What tissue surrounds the urethra and forms the glans penis/corona glandis?
Corpus spongiosum penis
Accessory sex glands in the stallion
> Have all three = vesicular glands, prostate, and bulbourethral (difficult to palpate) glands
- Ductus deferens become the ampulla
What important structures are on the tip of the stallion penis?
- Urethral process = ventral
- Fossa glandis and urethral sinus = dorsal (where smegma can be impacting, harbor veneral disease)
Definition and clinical signs of puberty
> First achievement of the capability of successfully sexually reproduce
+ Maturation of genital organs
+ Development of secondary sex characteristics
+ Psychosocial interaction
Age of puberty of fillies and stallions
- Filly = 15 months (range 8-37)
- Stallions = 2.5-4.5 years (start producing sperm at 19 months)
Things that influence puberty (6)
- Breed = light weight horses come into puberty sooner than heavy draft breeds
- Season of birth (born late in year, have to wait another year to come into heat)
- Nutrition
- Management
- Systemic disease
- Parasites
When do we start breeding fillies?
2-3 years (ideal) time, depending on breed and purpose
Any earlier (< 2 yrs) = irregular cycles, higher abortion rates
Seasonality and cyclicity of mares? Four phases?
Long day seasonal breeders (majority have winter anestrus) - POLYESTROUS
1) Spring transition
2) Ovulatory seasons
3) Fall transition
4) Anestrus
What hormones play a role in the seasonality of the mare’s cycle?
Increasing light/photoperiod = seen by retina, decreased secretion of melatonin from pineal gland = signals hypothalamus to secrete GnRH and pituitary gland to secrete LH, FSH = follicular growth, and increasing estrogen
Main events of the spring transition
> After winters solstice
- Late winter = increasing FSH but inadequate LH to ovulate
- Increasing steroidogenesis (estradiol) and follicle development, secrete LH
- End of transition = sufficient LH to ovulate (first ovulation of the year)
Official birthday date program, and operational/physiologic breeding seasons
- Birthday date (official) = all born on Jan 1st
- Operational breeding = Feb 15th-July 15th
- Physiologic = May to October
Use of artificial lighting in the spring transition
> > 14-16 hours
- Minimum - 14.5 hours, 16 hrs is more common
- Increase light in 30 min increments
- Exposure in the evening»_space; more important than morning
- Start on Dec 1st, to ensure she’s cycling by Feb 15th (8-10 wks to first ovulation)
- GOAL = make the spring transition earlier
OTHER = 1-hr pulse of light, 18.5 hrs after onset of daylight or 9.5 hrs after onset of darkness
Role of P4 in manipulating the spring transition
> Suppress LH = increase LH reserve available
- 10-15 days of P4, then PGF –> estrus in 3-7 days
+/- Addition of estradiol = stronger gonadotropin suppression (suppresses FSH)
Role of GnRH in manipulating the spring transition
Increase FSH/LH ==> IMPRACTICAL to administer frequently enough
Role of dopamine (D2) receptor antagonists
Increase in prolactin = increase of estradiol production from follicles = advances first ovulation (works better with artificial lighting)
Estrous cycle length of mares
21 days (19-24 days)
Estrus duration
7 days
Diestrus duration
14 days
Hormonal indication of estrus
< 1 ng/mL of progesterone
Clinical signs of estrus in the mare
> Receptive to the stallion \+ Stands calmly \+ Squats \+ Winks vulva \+ Urinates \+ Flags tail
Soft uterus and cervix, edematous endometrial folds, open/moist/pink cervix, follicles on ovary, no CL