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Mammalian Reproduction II Estrous cycles, Gestation, & Lactation

Mammalian Reproduction II Estrous cycles, Gestation, & Lactation

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Mammalian Reproduction II Estrous cycles, Gestation, & Lactation

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  1. Mammalian ReproductionIIEstrous cycles, Gestation, & Lactation EEOB 625 6 February 2004

  2. Questions in Mammalian Reproduction II • Estrous cycle and menstrual cycle: Is the difference in the name? • Are the physiological, morphological, or behavioral changes different in the two types? • Induced vs. Spontaneous ovulation: What is same and what is different about LH?

  3. The Estrous Cycle and Gestation in Mammals 1 Estrous cycle is a series of recurring physiological, morphological, and behavioral changes in the female, marked by estrus and ovulation. • A matrix of glands, hormones, and time 1) Hypothalamus – GnRH, 2) Anterior pituitary - FSH & LH, 3) Ovary – estrogen & progesterone, 4) uterus Cascade of hormonal effects: GnRH FSH & LH estrogen & progesterone uterine tissues

  4. Hypothalamus Pituitary Ovary Uterus H-P-G Axis Fig. 9.6, Feldhamer

  5. The Estrous Cycle and Gestation in Mammals: 2 • Ovary: follicular phase, ovulation, luteal phase • Uterus: proliferative phase and secretory phase • Hormonal control of follicular development, estrus, ovulation, and secretion of progesterone • Signals for estrous & ovulation: 1, 2, 3, 4, 5 Positive feedback of estradiol on LH releaseLH surge • LH surge stimulates ovulation. Meiosis I in the oocyte is completed at this time • The process of ovulation: rupture of the follicle wall • Spontaneous & Induced (e.g. cats)ovulators compared

  6. Questions in Mammalian Reproduction II • Estrous cycle and menstrual cycle: Is the difference in the name? • Are the physiological, morphological, or behavioral changes different in the two types? • Induced vs. Spontaneous ovulation: What is same and what is different about LH?

  7. The Estrous Cycle and Gestation in Mammals 3 Corpusluteum from granulosa cells of ruptured follicle Conception: Union of pronuclei (gametes) in oviduct Implantation of the blastocyst & development of placenta • Four extraembryonic membranes of amniotes - Function of each in oviparous species - Vitelline (yolk sac) membrane and allantois in metatherians and eutherians

  8. The Placenta and Gestation - 4 • Ovulation, Fertilization, and Oviductal transport of the embryo • Hormonal (E, LH, & P) control of events • Eutherian Implantation: Chorioallantoic placenta and uterine epithelium (Figs 9.11, 9.12) • Placenta • Choriovitelline placenta of metatherians • Delayed fertilization & delayed implantation?

  9. The Placenta and Gestation • Ovulation, Fertilization, and Oviductal transport of the embryo • Hormonal (E, LH, & P) control of events • Eutherian Implantation: Chorioallantoic placenta and uterine epithelium (Figs 9.11, 9.12) • Placenta

  10. Austin & Short 1973

  11. Austin & Short (1973)

  12. Harder & Kirkpatrick (1996)

  13. Harder et. Al 1993

  14. Questions in Mammalian Reproduction III • Origin of the mammary gland: What’s a brood patch (or sweat) got to do with it? • Why is lactation dependent upon suckling? • Milk is milk: How different can it be?

  15. Mammary Gland & Lactation • Origin & evolution: derived sweat glands? • Nutritive secretions in other taxa: ___, ____ • Original (pre-mammary) function ? • Origin of the mammary gland: What’s a brood patch (or sweat) got to do with it? • Epidermal secrections: first source of 1) moisture for the neonate? 2) source of nutrition? 3) or something else? __________________

  16. Mammary Gland & Lactation • Origin & evolution: derived sweat glands? • Nutritive secretions in other taxa: ___, ____ • Original (pre-mammary) function ? • Epidermal secrections: first source of 1) moisture for the neonate? 2) source of nutrition? 3) or something else? __________________ • Histology, internal anatomy, & hormones

  17. Mammary Gland & Lactation • Origin & evolution: derived sweat glands? • Nutritive secretions in other taxa: ___, ____ • Original function: water, nutrition, or _____ • Location & Morphology: udder, teat, & nipple • Histology & internal anatomy (handout) • Hormones ‑ Somatotropin, P, & E during development

  18. Physiology of Lactation and the Nature of Milk • Prolactin: a hormone of maternal care • Synthesis of milk: Prolactin & lactiferous cells Secondary effect on ovarian activity (anestrus) • Delivery of milk: oxytocin & myoepithelial cell

  19. Physiology of Lactation and the Nature of Milk • Prolactin: a hormone of maternal care • Synthesis of milk: Prolactin & lactiferous cells Secondary effect on ovarian activity (anestrus) • Delivery of milk: oxytocin & myoepithelial cell • Components of milk: Casein, lactose & lipids • Taxonomic variation in fat content of milk • Change of content during the period of lactation

  20. Reproduction II END