all repro

anatomy, endocrinology, species specific

Ovary

• contains thousands of growing follicles

  • Rich supply of blood vessels & nerves

Follicles

• contains ovum (egg)

  • Grows in response to gonadotropins (FSH & LH)

  • Either dies (atretic) or ovulates & releases egg

Corpus Luteum (CL)

• forms from tissue left over after follicle has ovulated

  • Produces progesterone

Corpus Albicans (CA)

• scar tissue on ovary after CL regresses

  • Avascular & non-functional

Oviduct

• Fertilization & early embryonic

• Funnel shaped organ

• Specialized ends (fimbria) picks up ovulated eggs

• Anterior: ampulla

• Interior: isthmus

Uterus

• maintains pregnancy

  • Releases hormones that regress luteal tissue

  • Glandular inner lining surrounded by 2 layers of muscle

  • Longitudinal & circular layers

Cervix

•  isolates uterus from outside during pregnancy

  • Thick, muscular organ

  • Semen deposition in some animals

Vagina

• part of birth canal

  • Protects uterus from bacteria

  • Site for semen deposition for most

Vulva

• external genitalia of vagina

  • Involved w/ recognition of receptivity & pheromones

Testicles

• produces spermatozoa & hormones (testosterone, androgens, etc)

  • Series of seminiferous tubules

Epididymis

• matures & stores the spermatozoa

  • Immature sperm enter epididymis & mature as they pass thru

Vas deferens

• passage for spermatozoa from epididymis to urethra during ejaculation

  • Muscular tube w/ small diameter

Secondary sex glands

•  seminal vesicles, prostate, & bulbourethral glands

  • Produce & secrete most liquid portion of semen

Penis

•  deposits semen into female repro tract

  • Central canal is urethra (common exit for repro & urinary)

Sheath

• pouch that holds penis when not in use

  • Sometimes involved w/ pheromone production

Semen

• suspension

  • 1. Concentrated sperm leaves epididymis

  • 2. Then travels thru vas deferens to urethra

  • 3. Secondary sex glands secrete fluids into urethra that mix w/ sperm (seminal vesicles = largest amount

Estrus (process)

1.  progesterone down, estrogen up

   1. Estrogen cause gonadotropin surge (pituitary)

      1. FSH: follicle stim. Hormone:

         1. Stimulates follicle growth

      2. LH: luteinizing hormone

         1. Cause ovulation

         2. Final follicle growth

         3. Stimulate CL

2. Ovulation: (LH initiated)

   1. Follicle releases egg

   2. Estrogen down, progesterone up, (gonadotropins down)

   3. CL forms & produce progesterone (CL & progesterone maintained for 12-16 d)

3. Prostaglandins cause CL to regress

   1. F2 Alpha = uterine contractions

4. CL regresses

5. CL dies: progesterone down

6. FSH & LH up

7. Estrogen up

8. Repeat

Male endocrinology…

Swine

(ovulate anytime during estrus)

• Gilts bred after 2-4 estrus

• Gest: 114 d (3m, 3w, 3d)

• Farrowing: 4-8 hrs (up to 18)

  • Dystocia: tired sow, stuck babies, meconium staining, umbilical hematomas

• Lactate: 16-21 d

  • Limit piglet growth for ~10 d, for benefit of sow

• Rebred: exhibit estrus 4-7 d after weaning & lactation stops

Beef Cattle

• Puberty: 10-15 m (taurus), 17-27 m (indicus)

  • Must hv min AGE & WT

  • Heifers exhibit a few estrus before breeding

  • Goal is to calf at 2 yrs, bred at 14-15 mo

• Estrous: 21 d

• Estrus: 12-18 hrs (ovulate after estrus)

  • Bred at 14-15 mo

  • Limited to 60-90 d to control calving season

  • Natural service

• Gest: 9 mo 

  • Inc nutrition in 3rd trimester

• Calving: dystocia is large concern

• Lactate: 7 mo long

• Rebred: 60-90 d after calve

  • while still lactating to make sure they calf once a year

  • *Higher conception at first service

  • (9 mo gest + 2 mo recovery means only 1 mo to rebreed)

Dairy cattle

• Puberty: min wt & age

• Estrous: 21 d

• Estrus: 12-18 hrs

  • Ovulate after estrus

  • Bred w/ AI

• Gest: 9 mo

• Calve at 2 yrs

• Wean calves at birth 

  • Fed colostrum 24-48 hrs

  • Calf hutches 7-9 w

  • 1-2 gal milk/day

  • 2nd weaning: put on pasture/ others at 7-9 w

• Lactate: 305 d (for humans)

Equine

• (long day, 15 hrs of light, serotonin)(60-90 d transition period)

  • Puberty: 15-20 mo (MUST be in breeding season!)

  • Estrous: 21 d

    • only cycles w/ ~15 hrs of light (long day breeders)

    • Season is mar/apr → nov/dec

  • estrus : 5-7 d

    • Bred every other day or real time ultrasonography (12-15 mm follicle)

  • Gest: 330-340 d

  • Foaling: 3 steps

    • 1. Cervix relax, myometrial contractions

    • 2. Rupture placental membrane, contractions, expulse foal

    • 3. Expulse fetal membranes (watch for retained placentas!)

  • Foal heat: 5-12 d

  • Weaning age varies

Sheep

• short day/seasonal breeders

  • Puberty: 5-12 mo (must be in breeding season)(aug/sept → dec/feb)

  • Estrous: 16-18 d

  • Estrus: 24-26 hrs

  • Gest: ~150 d

  • Lambing: struggle w/ claiming young, so claiming pen

  • Lactate: 3-5 mo

  • Creep feeding: best 7-10 d old

  • Weaning: 90-120 d, 90-120 lbs

  • 40-70 d until next season

Goat

• short day, less seasonal than sheep

  • Estrous: 21 d

  • Estrus: 24-36 hrs

Cats

•  (induced ovu, male hv spurs on penis, pseudopregnancies)

  • Estrous  duration: 13-15 d avg

Dogs

• (2 cycles/yrs, os penis)

  • Estrous: 183 d (two cycles per yr)

  • Estrus: 9 d avg

Rabbit

•  (induced ovu, no consistent cycle)

  • Pub: 5-8 mo

  • Gest: 30-34 d

Hamster

• (males sterile after 1 yr)

  • Puberty: 30-40 d

  •  Estrous: 4 d

  • Gest: 16 d