Regulation of the ovary (1)

Regulation of the ovary (1)

A follicle in the ovary consists of an oocyte surrounded by granulosa cells; the maturing oocyte makes herself an antrum. Thecal and granulosa cells are separated by a basal membrane. The thecal cells are stimulated by LH, transforming cholesterol into testosterone; granulosa cells are stimulated by FSH, making estradiol from testosterone.

The regulation by the hormones of the hypothalamic-pituitary-ovary axis is shown in the second graphic below. Gonadotropin-releasing hormone (GnRH), which is secreted

from the hypothalamus stimulates the gonadotropic cells in the anterior pituitary to release FSH and LH. Estradiol produced by the granulosa layer has a positive feedback mainly on LH and a negative feedback predominantly on FSH secretion, depending on the time point in the cycle. Progesterone has a negative feedback on GnRH release from the hypothalamus and thus inhibits indirectly the LH secretion.

See also the section on female reproduction in the gynaecology chapter.

1

The hormone that induces ovulation in women and promotes the secretion of progesterone by the ovaries is 

2

I. Steroid hormones can easily pass cellular membranes, because they are hydrophilic structures. II. Cholesterol is required for the biosynthesis of steroid hormones.