fertilization (or not...)

             Oogenesis

zona pellucida: (vitelline membrane) glycoprotein layer that surrounds the oocyte and is secreted by both the oocyte and the follicle cells. It binds with proteins on the sperm membrane and  induces the acrosome of the sperm to release its enzymes so it can fuse with the egg's membrane. This fusion triggers the
cortical reaction = exocytosis of cortical granules forming a hard barrier which prevents polyspermy.
  
corona radiata: granulosa cells that surround and protect the 2ndary oocyte when it is released during ovulation.

                                     pathology

    Spermatogenesis

Sperm capacitation permits the acrosome to penetrate the zona pellucida and chemically alters the tail so that mobility is increased. 

oxytocin is released by the posterior pituitary

Reproductive System Lecture

                parturition

overview of meiosis

Estrogen stimulates parturition by upregulating the expression of genes in uterine cells that code for oxytocin receptors.

                the placenta

The corpus luteum secretes progesterone which helps develop and maintain the
endometrium. It also produces relaxin which is a hormone that makes the pubic symphysis more pliable (think child birth). If fertilization does not occur, the corpus luteum degenerates into scar tissue called the corpus albicans. If fertilization does occur and the embryo implants, cells of the blastocyst secrete
human chorionic gonadotropin (hCG)
which maintains the corpus luteum and its progesterone secretion. The placenta eventually starts to produce progesterone causing the corpus luteum to degrade into a corpus albicans. 

The theca folliculi are a layer of endocrine cells (interna /externa) in ovarian follicles that first appear with secondary follicles. 
Theca cells produce androstenedione and provide support to the maturing follicle. Androstenedione is used by the granulosa cells
to synthesize estradiol (E2). FSH triggers the granulosa cells to produce aromatase, the enzyme that is necessary for the conversion of the androgen to estradiol.

Granulosa cells convert androgens (from the thecal cells) to estradiol using aromatase. After ovulation, these
granulosa cells remain as part of the corpus luteum and start to
produce progesterone which maintains the endometrium and also causes the secretion of cervical mucus which prevents sperm from entering the uterus.

The trophoblast (syncytium) infiltrates the endometrium by triggering apoptosis (it secretes hyaluronidase) in the uterine cells creating cavities which allows the blastocyst to penetrate further into the endometrium.