Pheromone: chemical messenger secreted into the environment
Flehmen reaction: an investigative mating behavior of some ungulates and carnivores toward potentially estrous females; receptivity is determined by olfaction (sniffing the urine/perineum) and physical contact (nudging)
Vomeronasal organ: a sensory structure near the nasal septum that detects pheromones (signals are relayed to the hypothalamus)
Lordosis: a mating posture of estrous females of some species (eg., rodents and pigs) characterized by arching of the back and elevation of the rump in response to investigation by a male (or other contrived tactile stimulation)
Whitten effect: estrus-synchronizing effect of the male (mice)
Coolidge effect: increased libido of males when exposed to novel females
Capacitation: final maturation of sperm cells within the female reproductive tract (removal of seminal decapacitation factors from the acrosomal surface)
Acrosomal reaction: release of fertilizing enzymes upon contact of the sperm head with the ovum
Corona-penetrating enzyme: a hyaluronidase that digests the extracellular matrix that adjoins cells of the corona radiata
Acrosin: enzyme that degrades the zona pellucida
Zona block: a reaction of the ovum to sperm fusion with the vitelline membrane; cortical granules release acrosin inhibitors into the perivitelline space that prevent further sperm cell penetration
Polyspermy: fertilization of the ovum by more than one sperm cell; is normally prevented by the zona block
Foley catheter: a two-way catheter with retaining balloon used to collect embryos
Histotrophe: uterine milk; secretions from the endometrium that nourish the embryo before implantation (especially important in superficial implanters)
Diapause: delayed implantation; a unique strategy to allow birth under favorable conditions (eg., lactating kangaroo, rat; hibernating bats, bear; seals; skunk); length dictated by metabolic/environmental factors
Zygote: fertilized ovum
Morula: early cleavage-stage embryo (not yet hatched from the zona pellucida)
Blastula: cavity-containing (blastocoel) embryo (blastocyst) formed by the rearrangement of blastomeres of the morula; rapid expansion leads to hatching
Gastrula: embryo exhibiting definitive germinal layers (organogenesis)
Trophoblast: outer layer of cells of the blastula that differentiate into the chorion
Inner cell mass: embryonic cells of the blastula that give rise to the amnion and fetus
Turner's syndrome: nondisjunctional disorder of sexual differentiation characterized by X chromosome defects or deletions (45,XO) represented by sterile (streak gonad) females of short stature
Klinefelter's syndrome: nondisjunctional disorder of sexual differentiation in males attributed to the presence of an extra X chromosome (47,XXY); manifestations include testicular atrophy, mental retardation, and gynecomastia
Pseudohermaphroditism: an individual whom is XY (has testes) or XX (has ovaries), but otherwise exhibits phenotypes of both sexes
Freemartin: a virilized female calf born co-twin to a male; due to placental fusion
SRY: sex-determining region of the Y chromosome; codes for a DNA-binding protein that causes testicular differentiation
Embryonic gene transfer: injection of DNA into a fertilized ovum (with the objective of producing a recombinant animal)
Cloning: production of identical siblings by embryonic manipulation (cutting) or from a pluripotent adult cell transferred into an enucleated ovum
Thalidomide: an embryopathic drug formerly used to control nausea and vomiting during early pregnancy
DES: diethylstilbesterol; a potent nonsteroidal estrogen receptor agonist that was once used to prevent spontaneous abortions; treatment predisposed individuals to reproductive structural defects and cancer
Placentome: endometrial (caruncle)-chorionic (cotyledon) exchange unit of the ruminant
Rh incompatibility: release of Rh+ erythrocyte antigens from the fetus into the circulation of an Rh- mother (scant/hemochorial placental barrier) can induce a maternal immune response that threatens future Rh+ pregnancies
Decidual response: proliferation/edema of endometrial stroma around the site of (intrusive) implantation (maternal placenta)
Accessory CL: supplemental luteal structures formed during pregnancy in some species (eg., in response to choriogonadotropin in mares)
Pseudopregnancy: false pregnancy (extended luteal function) induced by infertile mating (eg., rat = 12 days) and sometimes after spontaneous ovulation (eg., dog = 60 days)
Stages of labor: I (uterine contractions, relaxation of pelvic ligaments, cervical dilation); II (membrane rupture, fetal expulsion); III (placental delivery)
Dystocia: difficult birth
Colostrum: antibody-rich fraction of milk; consumption by the neonate (passive immunity) is important in species (eg., farm animals) with diffusion-limiting placental barriers
Puberty: ability to produce gametes
Sexual maturity: capacity to mate, carry a fetus to term, and provide adequate care for the offspring
Steroidogenic control of mating behaviors: estradiol plays a central inductive role in mating behaviors of both males (CNS aromatization) and females (gender-specific/dimorphic responses are entrained during sexual differentiation); progesterone primes the estrous response to estradiol in females that exhibit long cycles
Average lengths (days) of gestation: pig (115); sheep (150); cattle (280); horse (335)
Adaptive significance of seasonal breeding: young are born during a time of the year when chances of survival are most advantageous (relative warmth and plentiful food supply)
Breeding season is resolved by length of gestation: species with intermediate gestations (eg., sheep) breed during the short days of fall/winter (and give birth in the spring); species with long (eg., horse) or short (eg., hamster) gestations breed during days of increasing length (and give birth during the spring/summer)
Relay of photoperiodic information: retinal photoreceptors > optic nerves > suprachiasmatic nucleus > paraventricular nucleus > superior cervical ganglion > pineal gland
Melatonin synthesis: increases during the dark period (NAT and HIOMT are induced)
Transitional alterations in hypothalamic sensitivity: melatonin increases sensitivity to negative steroid feedback in long-day breeders - therefore, the suppression in gonadotropin output negates fertility during short days … until the "gonadostat" is reset (decreased sensitivity) the consequent spring; in contrast, melatonin blunts the negative feedback effect of steroid hormones (during the breeding season) in short-day breeders
Sperm life span within the female reproductive tract: ~ 48 hours
Unfertilized ovum: ~ 24 hours
Barriers to sperm transport: acidic vagina; cervical mucus; uterine inflammatory cells; utero-tubal constriction
Semen extender: sodium citrate (buffer); egg yolk or milk (protection against cooling shock); glucose or fructose (energy); glycerol (protection against freeze-thaw damage); antibiotics
Contraceptive mechanisms of IUD action: decreased sperm transport; enhanced uterine inflammatory response; altered endometrium (implantation failure)
IUD side-effects: pain (dysmenorrhea); uterine perforation; intermenstrual bleeding; prolonged menses; pelvic inflammatory disease
ET procedure in cattle: treat donor with FSH on Days 10 and 13 of the estrous cycle; treat donor and recipient with PGF2a on Day 12; AI donor 12 hours after estrus > collect embryos on Day 7 and transfer to (synchronized) recipient
IVF-ET procedure in women: induce growth of multiple follicles (clomiphene/hMG) during the follicular phase > (if positive response) on Day 13 treat with hCG > follicular oocyte aspiration (before ovulation - 24 hours after hCG) > IVF/culture for four days > transcervical uterine transplantation > progesterone supplementation
Intrusive implantation: the embryo actively invades the endometrium by proteolytic enzyme secretion (interstitial, human) or becomes lodged in a uterine crypt (eccentric, rodents)
Superficial/central: the embryo remains free-floating in the uterine lumen for an extended period (farm animals; eg., ~ 40 days in the mare) before making contact with the endometrium by placental outgrowth
Primordial germ cells: originate in the yolk sac endoderm and migrate into the genital ridges by ameboid movement along the dorsal mesentery
Wolffian ducts: differentiate into the epididymis, vas deferens, and seminal vesicles
Mullerian ducts: differentiate into the oviducts, uterus, cervix, and cranial vagina
Hormonal control of phenotypic differentiation: testosterone and MIH stimulate Wolffian development and Mullerian regression respectively in the XY genotype (testicular differentiation); Wolffian ducts regress and Mullerian ducts development in the relative absence of hormones in the XX genotype (ovarian differentiation); exposure of the hypothalamus to androgen (XY) inactivates the GnRH surge center
[chromosomal sex > gonadal sex > phenotypic sex]
Placental layers: amnion (surrounds fetus); allantois (contains blood vessels continuous with the umbilicus); chorion (contacts endometrium)
Gross anatomical placental classifications: diffuse (horse, pig); zonary (dog, cat); discoid (primate, rodent); multiplex (ruminants)
Microscopic placental classifications: epitheliochorial (horse, pig); syndesmochorial (ruminants); endotheliochorial (dog, cat); hemochorial (primate, rabbit, rodent)
Maternal tolerance of fetal allograft: placenta nonimmunogenic; placenta neutralizes maternal antibodies; DCR; local immunosuppression
Progestational roles of progesterone: secretory endometrium; myometrial quiescence; cervical plug
CL rescue: primate (choriogonadotropin); pig (estrogen); ruminants (interferon-t); rat (prolactin)
Pregnancy detection by palpation in cattle: ~ one month
Pregnancy detection by ultrasound in women: ~ five weeks
Neuroendocrinology of labor/parturition in sheep: fetal CRH > ACTH > cortisol > placenta progesterone fall/estradiol rise > prostaglandin, relaxin production; estradiol/prostaglandins > myometrial contraction > increased oxytocin > (stronger) myometrial contractions > increased oxytocin … (neural positive feedback loop); estradiol > liquefaction of cervical plug; PGF2a > luteolysis; relaxin > relaxation of pelvic ligaments, cervical dilation, coordination of uterine contractions
Hormonal effects on maternal behaviors: increase (prolactin, lactogens, oxytocin, estradiol)/decrease (progesterone, opiates) qualities
Mammary alveolus: blind sac lined by epithelium surrounded by smooth muscle-like cells (myoepithelium)
Hormonal control of milk synthesis: growth and functional development of the mammary gland is stimulated by ovarian/placental steroids; lactogenesis is induced by prolactin (or GH); other hormones (placental lactogen, insulin, cortisol, thyroxine) contribute to production
Milk-ejection reflex: suckling (conditioning) > oxytocin > myoepithelial contraction (alveolar pressure) > milk displacement into duct system
Comparative roles of lactation and uterine involution in resumption of fertility postpartum: women (lactation/prolactin is rate-limiting); beef cattle (lactation is rate-limiting [but prolactin is not the mediator]); dairy cattle, horses, rodents (lactation has a weak effect - uterine involution is rate-limiting)