Female reproductive system Flashcards
What is the female gonad?
The ovaries, producing the egg (oocyte)
what is oogenesis?
This is the synthesis, maturation and production of the egg. At birth, we have 7 million of these follicles, most die before puberty.
What are the three phases of the ovarian cycle (oogenesis)?
The follicular phase, ovulation, the luteal phase
What happens in the follicular phase - pre antral phase?
A group of primordial follicles start to mature and become primary follicles. This is controlled by paracrine factors which limits the amount that matures or all the eggs would mature at the same time. The primary follicles continue to develop and form the pre-antral follicle. The mature pre-antral follicle has a zona pellucida (glycoprotein helping bind the sperm and initiating the acrosome reaction so it can penetrate the egg), zona granulosa (produce sex steroids and growth factors), basal lamina and thecal cells (catalyse androgen production and recruit a single follicle during ovulation).
What happens during ovulation?
This is the inflammatory event that erodes the wall of the ovary and follicle. The oocyte, zona pellucida, corona radiata is released into the peritoneal cavity before being captured by the oviduct. The corona radiata helps the capture of the oocyte. The remnants of the follicle stay in the ovary and form the corpus luteum - hormone secreting gland.
What happens during the luteal phase?
The corpus luteal takes around 14 days to develop. The main hormone produced during this is progesterone. Due to previous LH surge, oestrogen drops but it eventually rebounds. If no pregnancy, the corpus luteum forms scar tissue. If pregnancy occurs, the placenta releases human chronic gonadotrophin, allowing the corpus luteal to continue its function.
What hypothalamic hormones are released?
Gonadotropin releasing hormone (GnRH)
What pituitary hormones are released?
Follicle stimulating hormone (FSH) - stimulates growth of immature follicles. Induces the expression of LH receptors in granulosa cells.
Luteinising hormone (LH) - acts on theca cells to promote androgen production. Its 1-2 day surge triggers ovulation.
What ovarian hormones are released?
Oestrogen - prepares reproductive tract for potential fertilisation and pregnancy.
Progesterone - promotes uterine and uterine tube secretions maintaining the support of potential fertilisation.
Inhibin A and B - secreted by the corpus luteum (granulosa cells) and represses FSH secretion.
What happens in the follicular phase antral phase?
The mature pre-antral follicle continues to mature. the zona layers get thicker, theca interna is more apparent. There is formation of the antrum, a vacuole located in the zona pellucida.
What happens in the follicular phase pre-ovulatory phase?
Forms the graafian follicle in response to a surge of luteinizing hormone, the oocyte completes the first meiotic division and rests in metaphase of meiosis 2. The surge of LH also causes inflammatory cytokines and hydrolytic enzymes that eat away the wall of the ovary and allow the egg and corona radiata to be released.
