Final Reproduction

A lot day 7 increased gnrh and lh release fsh

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Unformatted text preview: port the corpus luteum for about 2 weeks High levels of progesterone coming from the corpus luteum prevent another LH surge from occurring even when estrogen levels get high again from the corpus luteum (high progesterone AND estrogen means the positive feed back cant occur like earlier) (positive feedback can occur Timing of the Menstrual Cycle • Ovary controls timing – There has to be sufficient estrogen levels in the ovary for the positive feedback and LH surge to occur Uterus Lining • Estrogen causes the thickness of the uterus endometrial thickness – – This occurs during the follicular stage, thickness is fully there by ovulation Progesterone and estrogen being secreted from the corpus luteum keep the endometrial layer thick, but once it dies off the layer is shed (bleeding ) • When corpus luteum dies marks the transition back into the follicular stage and layer shedding starts here) Proliferative Phase • • • • Increased estrogen levels from the dominant follicle cause the endometrium and underlying uterine smooth muscle (the myometrium) to grow There’s an increase in blood vessels Increased synthesis of progesterone receptors in endometrial cells Endometrial glands narrow Secretory Phase • • Progesterone produced by the corpus luteum causes the estrogen primed endometrium to convert to endocrine tissue Endometrial glands become coiled (sshaped) and filled with glycogen, more blood vessels, and enzymes – • This is necessary for the embryo to implant for nourishment Progesterone levels need to stay high Period • When the corpus luteum degenerates, causing progesterone and estrogen levels to drop, the endometrium degenerates • Blood vessels constrict • Uterine smooth muscle contracts • • Mediated by prostaglandins produced my the endometrium when the progesterone and estrogen levels decrease After vasoconstriction, vasodilation occurs, Random • • Ovulation can be detected by increased basal body temperature Summary Picture Once the Egg is Released • Cilia and microvilli on the fallopian tube epithelium help capture the released egg and move it down fallopian tube – – • Cilia beat Microvilli secrete moistness It takes egg about 4 days to get to the uterus from the ovary Timing for Fertilization • Sperm can survive in a woman for about 4 to 6 days • • Can fertilize anywhere from 5 days before to 1 day after ovulation Ovulated eggs survives 24 to 48 hours – Females can be sterilized by cutting or tying off the fallopian tubes • • Doesn’t stop gamete production in males or females, just stops fertilization from occuring Sperm travel via their own motility, and Fertilization • A few things have to happen before the sperm can fertilize the egg: – Capacitation: • wave, whip like beats propel sperm forward, this increases the permeability of the sperm membrane to calcium, calcium increases cAMP, which increases motility more (sperm get squiggly) – • Flagellum doesn’t move until...
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This note was uploaded on 09/27/2013 for the course ZOO 305 taught by Professor Schaeffer during the Spring '08 term at Miami University.

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