The cytochemistry of glycoconjugates in the zona pellucida of murine ovarian oocytes and two-cell embryos

Summary Changes in glycoconjugates of the zona pellucida induced by maturation, ovulation and fertilization of mouse oocytes have been studied by means of light microscopic methods of cytochemistry. These methods consisted of periodic acid-Schiff (PAS), Alcian Blue pH 1.0 and pH 2.5, and peroxidase-labelled lectin diaminobenzidine (PO—LT—DAB) procedures in combination with the digestion technique with neuraminidase. According to the results obtained, glycoconjugates of the zona pellucida of fertilized eggs contained a smaller amount of sulphate groupings than that in ovarian oocytes, whereas their reactions for sialic acid and fucose residues were significantly stronger in intensity in the former, as compared with those in the latter. The cytophysiological significance of such cytochemical changes in glycoconjugates of the zona pellucida has been discussed with special reference to its functional alterations following maturation, ovulation and fertilization.