Follicular questions . . . .

Hey guys!!!! So, we had some issues in lab today regarding secondary vs. graafian follicles, so . . . . . I found some really good info on it . . . probably more than you'll ever want to know about ovarian follicles ;)

Primordial follicle

At the time of birth all the surviving primary oocytes are surrounded by thin, single layers of so-called follicular epithelial cells. These are delimited from the rest of the ovarian stroma by a thin basal lamina. Follicular epithelial cells are former coelomic epithelial cells. The primordial follicles always form the majority of the follicles in the ovary.

Primary follicle

In the transition of the primordial follicles into primary follicles the follicular epithelium that surrounds the oocyte becomes iso- to highly prismatic.		Fig. 19 - Primary follicle		Legend
		A B 1 2 Primordial follicle Primary follicle Oocyte Follicular epithelium		Fig. 19 Scheme of the development from primordial follicle to primary follicle.

Secondary follicle

When primary follicles survive, secondary follicles with follicular epitheliums encompassing multiple rows are engendered. This is now called the stratum granulosum. In the secondary follicles a glycoprotein layer, the pellucid zone, between the oocyte and follicular epithelium becomes visible. Cytoplasmic processes of the granulosa cells that lie upon it reach the oocyte through the pellucid zone and thereby assure their maintenance function. Outside the basal lamina the stroma ovarii organizes itself to become theca folliculi cells.		Fig. 20 - Secondary follicle		Legend
		1 2 3 4 Oocyte Pellucid zone Stratum granulosum Theca folliculi cells		Fig. 20 Scheme of a secondary follicle:in the transition from primary to secondary follicle the stratum granulosum is engendered from the cells of the follicular epithelium. The stroma ovarii organizes itself around the secondary follicle to become the theca folliculi (interna and externa). Histology of primordial, primary,and secondary follicles.

Tertiary follicle

If the secondary follicles survive, tertiary follicles are engendered. Their identifying characteristic is a fluid-filled cavity, the antral follicle. The oocyte lies at the edge in a mound made of granulosa epithelial cells, the cumulus oophorus. In the meantime it has grown so large that its cellular nucleus has attained the size of a whole primordial follicle. The connective tissue around the follicle has already clearly differentiated itself into a theca interna, well supplied with capillaries, out of large, lipid-rich cells (hormone production) and a theca externa, which forms a transition to the stroma ovarii and contains larger vessels.

Fig. 21 - Tertiary follicle		Legend
1 2 3 4 5 6 7 8 Oocyte Pellucid zone Stratum granulosum Theca interna Theca externa Antral follicle Cumulus oophorus (Granulosa cells, together with the oocyte) Basal lamina between theca and stratum granulosum		Fig. 21 In a tertiary follicle the theca can be subdivided into an interna (hormone production) and an externa (transition to the ovarian stroma). Histology of tertiary follicles. Histology of cumulus oophorus.

Graafian follicle

This corresponds to an especially large tertiary follicle that can be expected to suffice for ovulation.

So, #8 is pointing to the nucleus of a secondary follicle, #3 is pointing to a primary follicle and #2 is a primordial follicle

So after reading this you're thinking, 'that's nice, but what do I put for the final when it asks for a secondary follicle - antrum or no antrum?' - technically, secondary follicles do not have antrums - it's only when it becomes a tertiary follicle that the antrum begins to form, and a graafian follicle is just a more mature tertiary follicle. Hence, in order to be as accurate as possible and to not mess you up for further classes, SECONDARY FOLLICLES DO NOT HAVE AN ANTRUM!!!!

This will be the standard for the final if any such question arises ;)