CHARACTERIZATION OF THE COMPLEX CARBOHYDRATES IN THE ZONA-PELLUCIDA OF MAMMALIAN OOCYTES USING LECTIN HISTOCHEMISTRY

The objective of this study was to characterize the glycoconjugates pr esent in the zona pellucida of the follicular oocytes in sheep, goats and pigs. The zona pellucida was stained with periodic acid-Schiff, lo w iron diamine, high iron diamine, and nine different lectin horseradi sh conjugates: Con-A, SBA, DBA, PNA, RCA-I, GSA-II, WGA, LTA and UEA-I . Staining with DBA, PNA, SBA and RCA-I was performed with and without saponification with KOH and sialidase digestion. The results showed t he presence of neutral and acidic glycoconjugates with different termi nal sugars and also sialic acid radicals in the zona pellucida of all the animals studied. In particular, the positive staining with WGA, SB A, PNA and RCA-I suggests the presence of oligosaccharides with N-acet yl-D-glucosamine and sialic acid linked to the penultimate beta-N-acet yl-D-galactosamine and to the disaccharide galactosyl-(beta 1-3)-N-ace tyl-D-galactosamine. The terminal trisaccharide sialic acid galactosyl -(beta 1-4)-N-acetyl-D-glucosamine was identified only in the zona pel lucida of ovine and porcine oocytes. Thus, the zona pellucida exhibite d species-specific variations in the content and distribution of lecti n-binding patterns that may reflect the species specificity of gamete interaction.