Role of follicle cells in maturation of starfish oocytes

Abstract

The role of the follicles in oocyte maturation was studied with the starfish, Asterina pectinifera. Follicles, obtained from isolated oocytes with follicular envelopes, produced maturation inducing substance (MIS) when incubated in sea water containing gonad stimulating substance (GSS). Isolated oocytes without follicular envelopes had no such capacity to produce MIS even in the presence of GSS. MIS produced by follicles under the influence of GSS was extracted with 95% ethanol and purified on a Sephadex G 15 column. This MIS was identified as 1 methyladenine with thin layer chromatography, showing that the follicles can produce 1 methyladenine under the influence of GSS. MIS was also produced by follicles when they were incubated in sea water containing 1 methyladenosine in the absence of GSS. This indicates that 1 methyladenosine ribohydrolase, which splits 1 methyladenosine to 1 methyladenine and ribose, is present in these follicles. The capacity of follicles to produce MIS under the influence of GSS depended upon the age of oocytes from which the follicles were isolated; follicles taken from young oocytes failed to produce MIS even in the presence of GSS. 1 methyladenosine ribohydrolase was present even in young follicles, although its activity was lower than that of the follicles of full grown oocytes.