Spawning Female‐Specific Egg Envelope Glycoprotein‐Like Substances in Oryzias latipes

In addition to the spawning female‐specific (SF) substance (3, 6), a group of new higher molecular weight proteins cross‐reacting with anti‐egg envelope (chorion) glycoprotein (F1) antibody (original antibody) were found in the liver, blood plasma and the ovary of spawning female fish and in the ascites of the estrogenized fish of Oryzias latipes. Exploiting the antibodies specific for the SF substance and the new proteins, which were made of the original antibody by absorbing with the new proteins or the SF substance, the new proteins were found to behave very similarly to the SF substance concerning their localization in the inner layer of the oocyte envelope, intrahepatic formation in response to estrogen etc. They include the protein bands corresponding to Zl‐1 and ‐2, two major constituent glycoproteins of the oocyte envelope, while the SF substance corresponds to ZI‐3, the third major constituent of the envelope. Thus the three major constituent proteins of the inner layer of oocyte envelope are probably formed in the liver under the influence of estrogen in this fish.