anat31.txt

Developing germ cells which divide by mitosis.

Larger germ cells that are ready to undergo meiosis

Cells with form a barrier around an oocyte, protecting and feeding it

An ooctye surrounded by a layer of follicular cells

400 000

Process of degrading and dying primordial follicles

• 40 000 remaining primordial follicles
• beginning of sexual maturity

0 eggs remaining

• Peptide hormones: follicle-stimulating hormone, luteinizing hormone
• Steroid hormones: estrogen and progesterone

Ovarian cycle and uterine cycle

• Surface- simple cuboidal epithelium continuous with lining of the peritoneal cavity
• Tunica albuginea- white appearing ECM devoid of blood vessels and cells
• Cortex- outer layer of ovary containing ovarian follicles
• Medulla- inner layer in which blood vessels enter and leave

• Follicular phase (development of follicle under the influence of FSH)
• Primordial follicle to primary follicle- cells change from squamous to cuboidal epithelium
• Zona pellucida forms between the oocyte and the follicular cells
• Granulosa cells divide into several layers and begin to produce estrogen
• Surrounding CT differentiates into 2 layers; theca interna and theca externa
• With increasing FSH levels, the primary follicle becomes a secondary follicle and then a Graafian follicle

• ECM between granulosa cells and oocytes
• contains extensions from both the oocyte and granulosa cells- holds them together

• differentiated fibroblasts
• produce androstenediaone, a precursor to estrogen

• differentiated fibroblasts
• have contractile functions which aid in the expulsion of the egg

The granulosa cells pick up the androstendione produced by the theca interna cells and convert it into estrogen.  They then secrete it in large amounts.

Follicle containing 'lakes' full of estrogen

Intracellular spaces merge to form one large space aka the antrum.  The antrum contains estrogen and hyaluronic acid. Formation of the antrum pushes the oocyte off to one side where it sits on a group of granulosa cells calles the cumulus oophorus.

A group of granulosa cells supporting the oocyte in a Graafian follicle.

The layers of granulosa cells actually surrounding the oocyte in a Graafian follicle.  No different from the cumulus oophorus.

• Exists in the antrum of a Graafian follicle
• It is viscous and helps to protect the oocyte.

• The high estrogen level has negative feedback on FSH and positive feedback on LH produced the LH surge.
• The LH surge influences the follicle to finish the 1st meiotic division and enter the 2nd division, stopping at metaphase (primary oocyte to secondary oocyte).
• The secondary oocyte doesn't progress any further unless fertilization occurs.
• Ovulation occurs under the influence of LH and the contractile function of the theca externa.

• Luteal phase
• High levels of LH influence the production of the corpus luteum which is made up of theca lutein cells (produve mainly estrogen) and granulosa lutein cells (produce mainly progesterone) as well as an external corpus luteum.
• It eventually degrades into the corpus albicans (remaining ECM).
• If fertilization doesn't occur, LH turns off and FSH is produced again.

The egg will produce human chorionic gonadotrophin (HCG) which takes over the function of LH, continuing the stimulation of production of estrogen and progesterone.  It continues this role for about 3 months until the placenta has formed.