Cortical granule

Cortical granule (CG) distribution within cortex of human oocyte at metaphase II
Cortical granule (CG) distribution within cortex of human oocyte at metaphase II

Cortical granules are regulatory secretory organelles (ranging from 0.2 um to 0.6 um in diameter) found within oocytes and are most associated with polyspermy prevention after the event of fertilization.[1] Cortical granules are found among all mammals, many vertebrates, and some invertebrates.[2] Within the oocyte, cortical granules are located along the cortex, the region furthest from the cell's center. Following fertilization, a signaling pathway induces the cortical granules to fuse with the oocyte's cell membrane and release their contents into the oocyte's extracellular matrix. This exocytosis of cortical granules is known as the cortical reaction. In mammals, the oocyte's extracellular matrix includes a surrounding layer of perivitelline space, zona pellucida, and finally cumulus cells. Experimental evidence has demonstrated that the released contents of the cortical granules modify the oocyte's extracellular matrix, particularly the zona pellucida. This alteration of the zona pellucida components is known as the zona reaction. The cortical reaction does not occur in all mammals, suggesting the likelihood of other functional purposes for cortical granules.[1] In addition to modifying the oocyte's extracellular matrix and establishing a block to polyspermy, the exocytosis of cortical granules may also contribute towards protection and support of the developing embryo during preimplantation.[3] Once the cortical granules complete their functions, the oocyte does not replenish them.[1]

  1. ^ a b c Liu, Min (17 November 2011). "The biology and dynamics of mammalian cortical granules". Reproductive Biology and Endocrinology. 9 (1): 149. doi:10.1186/1477-7827-9-149. PMC 3228701. PMID 22088197.
  2. ^ Wessel, Gary M.; Brooks, Jacqueline M.; Green, Emma; Haley, Sheila; Voronina, Ekaterina; Wong, Julian; Zaydfudim, Victor; Conner, Sean (2001). The Biology of Cortical Granules. Vol. 209. pp. 117–206. doi:10.1016/s0074-7696(01)09012-x. ISBN 9780123646132. PMID 11580200. {{cite book}}: |journal= ignored (help)
  3. ^ Hoodbhoy, Tanya; Talbot, P. (December 1994). "Mammalian Cortical Granules: Contents, Fate, and Function" (PDF). Molecular Reproduction and Development. 39 (4): 439–448. doi:10.1002/mrd.1080390413. PMID 7893493. S2CID 640323. Retrieved 13 May 2015.