Distribution of carbohydrates in the zona pellucida of human oocytes

B. Bar-Shira Maymon, R. Maymon, I. Ben-Nun, Y. Ghetler, R. Shalgi, E. Skutelsky

Research output: Contribution to journalArticlepeer-review

Abstract

The purpose of the present study was to investigate the distribution pattern of carbohydrates in the zona pellucida of human oocytes using lectins and ruthenium red as histochemical probes. For lectin analyses, oocytes that failed to undergo fertilization following in vitro insemination were collected, washed, fixed with glutaraldehyde and embedded in araldite. For ruthenium red labelling, the oocytes were fixed with glutaraldehyde containing ruthenium red, post-fixed with Os4 and embedded in araldite. Araldite sections (1 μm) were de-resined with sodium methoxide, rehydrated, labelled with ten different biotinylated lectins as probes and avidin-biotin-peroxidase complex as visualant, and examined under a light microscrope. The zonae pellucidae of all oocytes studied exhibited a common lectin-binding pattern, expressed in intense binding of lectins from Concanavalia ensiformis (ConA), Lens culinaris (LCA), Ricinus communis (RCA-I), wheat germ agglutinin (WGA), and of succinylated WGA (S-WGA). Peanut lectin (PNA) bound to the zona pellucida only after neuraminidase treatment, whereas the lectins from Griffonia simplisifolia (GS-I), Dolichos biflorus (DBA), Ulex europhaeus (UEA-I) and soybean (SBA) did not bind at all. There was almost no binding of ruthenium red to the matrix of the zona pellucida. The results indicate that the human zona pellucida is characterized by normally exposed mannosyl, N-acetylglucosaminyl and β-galactosyl residues. In addition, it contains masked βGal-(1-3)GalNAc sugar sequences that can be exposed only after removing terminal sialic acid residues. The presence of sialic acid in the human zona pellucida, which is not expressed as an increase in the binding capacity of the polycationic probe (ruthenium red), has not been reported in any of the mammalian zonae pellucidae previously studied.

Original languageEnglish
Pages (from-to)81-86
Number of pages6
JournalJournal of Reproduction and Fertility
Volume102
Issue number1
StatePublished - 1994

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