Oocyte Maturation and Ovulation Induced in Hypophysectomized Winter Flounder (Pseudopleuronectes americanus) by Preparations from Pituitary Glands of American Plaice (Hippoglossoides platessoides)

Abstract

Hypophysectomized winter flounder (Pseudopleuronectes americanus) did not undergo spontaneous oocyte maturation, but the glycoprotein fraction of extracts of American plaice (Hippoglossoides platessoides) pituitaries induced maturation and ovulation. The nonglycoprotein fractions, previously shown to contain a vitellogenic factor, were less efficient than the glycoprotein fractions in the induction of maturation and ovulation. The activity of the nonglycoprotein fraction was further reduced by rechromatography on Con-A Sepharose, suggesting that its action on oocyte maturation and ovulation was due to contamination by the glycoprotein gonadotropin. Key words: hypophysectomy, gonadotropin, oocyte, maturation, ovulation, vitellogenesis, flounder, plaice, Pseudopleuronectes, Hippoglossoides