Mammalian Reproduction II Estrous cycles, Gestation, & Lactation - PowerPoint PPT Presentation

Mammalian ReproductionIIEstrous cycles, Gestation, & Lactation

EEOB 625

6 February 2004

• 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?

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

Hypothalamus

Pituitary

Ovary

Uterus

H-P-G Axis

Fig. 9.6, Feldhamer

• 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

• 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?

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

• 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?

• 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

Austin & Short 1973

Austin & Short (1973)

Harder & Kirkpatrick (1996)

Harder et. Al 1993

• 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?

• 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? __________________

• 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

• 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

• Prolactin: a hormone of maternal care
• Synthesis of milk: Prolactin & lactiferous cells

Secondary effect on ovarian activity (anestrus)

• Delivery of milk: oxytocin & myoepithelial cell

• 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