Female Reproductive System Functions: Oocyte Production Receive Sperm Develop Offspring Deliver Offspring

Oocyte Production Ovaries: Visceral Peritoneum Germinal Epithelium Cortex - (dense C.T.) - Contain follicles, Each with a single ovum Medulla -(loose C.T.) - contains blood vessels, Lymph vessels and nerves - Continuous with ovarian ligament

Egg Production – Oogenesis Begins before birth 2 million in ovaries At puberty, meiosis restarts Oogonia – divide by mitosis during fetal period Primary Oocytes (stall after prophase I of meiosis until puberty) Secondary oocyte (continues meiosis but stalls after metaphase II until fertilization) First Polar Body (disfunctional) Second Polar Body Second Polar Body Second Polar Body Fertilized ovum If fertilization doesn’t occur, these never form and secondary oocyte deteriorates

Egg Production – Follicle Development Primordial Follicles (1): -Single layer - flattened cells At puberty: cells enlarge = Primary Follicle mitosis creates multiple layers (2,3,4) - Antrum forms - cavity between oocyte and granulosa cells - filled with fluid Secondary Follicle (5) - Continues to enlargen - Estrogen secretion begins - Glycoproteins are secreted - form membrane = Zona Pellucida - Expands until oocyte is isolated on a stalk and surrounding capsule of granulosa cells = Corona Radiata Eruption = Ovulation (7) - Ruptured follicle collapses (8&9) - Graafian Follicle bulges from ovarian wall (6)

Luteal Phase Antrum fills with clotted blood = corpus hemorrhagicum Corpus Luteum (8) - forms from remaining granulosa cells - degenerates if no pregnancy occurs scar = corpus albicans (9) - if pregnancy does occur, corpus luteum remains as an endocrine gland for about 3 months

Hormonal Regulation Hypothalamus - GnRH (gonadotropin releasing hormone) - targets anterior pituitary gland Anterior Pituitary Gland - Gonadotropins: Follows an approximately 28 day cycle Day 1 LH (luteinizing hormone) - targets thecal cells outside follicle Thecal cells secrete androgens FSH (follicle stimulating hormone) - targets follicle cells Follicle cells convert androgens to estrogens Estrogens - target endometrial cells

Hormonal Regulation Day 14 Estrogens Negative feedback on hypothalamus Positive feedback on follicle cells Estrogens reach critical threshold Positive feedback on hypothalamus LH and FSH spike – triggers ovulation - damages follicle Estrogen levels decline Corpus luteum forms Progesterone and estrogen are produced - Supports endometrium Negative feedback on hypothalamus - inhibits new follicle development LH declines as corpus luteum degenerates estrogen and progesterone drop sharply Cycle restarts! Day 28

FSH Estrogen LH Progesterone

Hormonal Regulation In the event of fertilization: Embryo secretes hCG (human chorionic gonadotropin) - acts like LH - maintains corpus luteum for continued production of estrogen and progesterone