Formation of the chorion (zona pellucida) in the teleost, Oryzias latipes. II. Polysaccharide cytochemistry of early oogenesis.

It has been proposed that the mechanism of formation of the chorion of Oryzias latipes involves the transfer of precursor material from the Golgi bodies of the oocyte to the chorion by means of a population of dense cored vesicles. Thin sectioned ovarian material was investigated by means of several techniques available for the resolution of periodate reactive material at the ultrastructural level. The techniques employed were modifications of the thiocarbohydrazide, thiosemicarbazide, alkaline bismuth subnitrate and silver methenamine reactions. These all demonstrated a positive reaction in the material of the chorion and that of the dense cored vesicles. This finding is in accord with the hypothesis that the dense cored vesicles are transporting material from the Golgi to the growing chorion.