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Histology of the preovulatory follicle

A granulosa cell is a somatic cell found closely associated with the developing female gamete (called an oocyte or egg) in the ovary of mammals.

Granulosa cells form a single flattened layer around the mammalian oocyte in the primary ovarian follicle and later in follicle development (folliculogenesis) they advance to form a multilayered cumulus oophorus surrounding the oocyte in the preovulatory or Graafian follicle.

The major functions of granulosa cells include the production of steroids, as well as a myriad of growth factors thought to interact with the oocyte during its development.

Also FSH stimulates granulosa cells to convert androgens (coming from the thecal cells) to estradiol by aromatase. However, after ovulation the granulosa cells produce progesterone that may maintain a potential pregnancy and produce a thick cervical mucus which inhibits sperm entry into the uterus

In the development of the urinary and reproductive organs, the oogonia become invaginated in the gonadal ridge.

In the 1970’s, evidence emerged that the first cells to make contact with the oogonia were of mesonephric origin. It was suggested that mesonephric cells already closely associated with the oogonia proliferated throughout development to form the granulosa cell layer.^[1][2][3]

Recently this hypothesis has been challenged with some thorough histology. Sawyer et al. hypothesised that in sheep most of the granulosa cells develop from cells of the mesothelium (i.e., epithelial cells from the presumptive surface epithelium of the ovary). ^[4]

The embryological origin of granulosa cells remains controversial.

Oocyte granulosa cells

1. ^ Satoh M. "Histogenesis and organogenesis of the gonad in human embryos.". J Anat 177: 85-107. PMID 1769902. 
2. ^ Upadhyay S, Zamboni L (1982). "Preliminary observations on the role of the mesonephros in the development of the adrenal cortex.". Anat Rec 202 (1): 105-111. PMID 7059014. 
3. ^ Zamboni, L., Bezard, J., and Mauleon, P. (1979). The role of the mesonephros in the development of the sheep fetal ovary. Annales de Biologie Animal Biochimie et Biophysique 19, 1153-78.
4. ^ Sawyer H, Smith P, Heath D, Juengel J, Wakefield S, McNatty K (2002). "Formation of ovarian follicles during fetal development in sheep.". Biol Reprod 66 (4): 1134-50. PMID 11906935. 

• Granulosa cell tumour
• Ovulation
• Membrana granulosa

• Histology at BU 18404loa - "Female Reproductive System: ovary, cumulus oophorus"
• Histology at BU 14808loa - "Female Reproductive System: ovary, membrana granulosa"
• MeSH Granulosa+Cells

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