Meiosis activating sterols (MAS) and fertility in mammals and man.
In mammals two meiosis activating sterols (MAS) have been found to activate meiotic resumption in mouse oocytes, in vitro. FF-MAS (4, 4-dimethyl-5alpha-cholesta-8,14,24-triene-3beta-ol) was extracted from human preovulatory follicular fluid and T-MAS (4, 4-dimethyl-5alpha-cholest-8,24-diene-3beta-ol) from bull testicular tissue. Quite unexpected, these two sterols, which introduce the cholesterol biosynthetic pathway from lanosterol, may be locally acting substances with important physiological function for reproduction. FF-MAS and T-MAS are present in the preovulatory follicular fluid of different mammalian species and have the capacity to initiate resumption of meiosis in mouse oocyte cultured in the presence of hypoxanthine, a natural meiosis maturation inhibitor. FF-MAS is produced by the cumulus cells of intact oocyte-cumulus complexes upon FSH-stimulation and provides the oocyte with a go-signal for the resumption of meiosis. T-MAS constitutes the vast majority of MAS found in the mammalian testis and in the human ejaculate; in particular a high concentration is found in the spermatozoa. T-MAS may be produced by the spermatids and the presence of T-MAS in spermatozoa may suggest that T-MAS plays a role in fertilization by affecting the second meiotic division.J. Exp. Zool. (Mol. Dev. Evol.) 285:237-242, 1999.
Byskov
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AG
Laboratory of Reproductive Biology, Juliane Marie Center for Children, Women and Reproduction, University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark. agb.lrb@notes.rh.dk
Andersen
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CY
Leonardsen
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L
Baltsen
M
M
D000818:Animals; D002478:Cells, Cultured; D002775:Cholestadienols / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D005298:Fertility / Q000502:physiology*; D015571:Follicular Fluid / Q000378:metabolism; D006801:Humans; D008297:Male; D008540:Meiosis / Q000502:physiology*; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D015398:Signal Transduction; D013091:Spermatogenesis / Q000502:physiology; D013737:Testis / Q000378:metabolism
C114832:4,4-dimethyl-5alpha-cholest-8,14,24-trien-3-ol; C114833:4,4-dimethyl-5alpha-cholest-8,24-dien-3-ol; D002775:Cholestadienols