Granulosa cells
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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.
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[edit] Anatomy and function
Granulosa cells form a single flattened layer around the mammalian oocyte in the primordial 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.
[edit] Embryology of ovarian granulosa cells
During early embryonic development, cells from the dorsal endoderm of the yolk sac migrate along the hindgut to the gonadal ridge. These primordial germ cells (PGCs) multiply by mitosis and once they have reached the gonadal ridge they are called oogonia (diploid stem cells of the ovary).
The gonadal ridge consists mainly of mesenchyme and cells of underlying mesonephric origin (presumptive kidney cells). Once oogonia enter this area they attempt to associate with these somatic cells.
Development proceeds and the oogonia become fully surrounded by a layer of cells (pre-granulosa cells).
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.
[edit] Additional images
 Oocyte granulosa cells |
[edit] References
- ^ Satoh M. "Histogenesis and organogenesis of the gonad in human embryos.". J Anat 177: 85-107. PMID 1769902.
- ^ 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.
- ^ 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.
- ^ 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.
[edit] See also
[edit] External links
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