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The theca folliculi comprise a layer of the ovarian follicles. They appear as the follicles become secondary follicles. The theca are divided into two layers, the theca interna and the theca externa. [1] Theca cells are a group of endocrine cells in the ovary made up of connective tissue surrounding the follicle.
(a) The maturation of a follicle is shown in a clockwise direction proceeding from the primordial follicles. FSH stimulates the growth of a tertiary follicle, and LH stimulates the production of estrogen by granulosa and theca cells. Once the follicle is mature, it ruptures and releases the oocyte.
The theca of the spinal cord is called the thecal sac, and intrathecal injections are made there or in the subarachnoid space of the skull. In human embryogenesis , the theca cells form a corpus luteum after a Graafian follicle has expelled its secondary oocyte arrested in second meiosis .
Its cells develop from the follicular cells surrounding the ovarian follicle. [5] The follicular theca cells luteinize into small luteal cells (thecal-lutein cells) and follicular granulosa cells luteinize into large luteal cells (granulosal-lutein cells) forming the corpus luteum. Progesterone is synthesized from cholesterol by both the large ...
An ovarian follicle is a roughly spheroid cellular aggregation set found in the ovaries. It secretes hormones that influence stages of the menstrual cycle . At the time of puberty , women have approximately 200,000 to 300,000 follicles, [ 1 ] [ 2 ] each with the potential to release an egg cell (ovum) at ovulation for fertilization . [ 3 ]
The theca externa is the outer layer of the theca folliculi. It is derived from connective tissue, the cells resembling fibroblasts , and contains abundant collagen . [ 1 ] During ovulation, the surge in luteinizing hormone increases cAMP which increases progesterone and PGF2α production.
In the primordial ovarian follicle, and later in follicle development (folliculogenesis), granulosa cells advance to form a multilayered cumulus oophorus surrounding the oocyte in the preovulatory or antral (or Graafian) follicle.
An antral or secondary follicle, also known as Graafian follicle and tertiary follicle, is an ovarian follicle during a certain latter stage of folliculogenesis. Definitions differ in where the shift into an antral follicle occurs in the staging of folliculogenesis, with some stating that it occurs when entering the secondary stage, [ 1 ] and ...