Ultrastructural localization of lectin binding sites in the developing brain microvasculature

Beatrice Nico, Fabio Quondamatteo, Domenico Ribatti, Mirella Bertossi, Giangiuseppe Russo, Rainer Herken, Luisa Roncali

Research output: Contribution to journalArticlepeer-review

Abstract

The temporo-spatial patterning of lectin-binding sites was examined by lectin histochemistry and quantitative methods in the microvasculature of the optic tectum of 9-, 14-, 20-day-old embryos and 30-day-old chickens. Horseradish peroxidase and colloidal-gold-labelled lectins were used for detection of β-D-galactose (RCA-I, Ricinus communis agglutinin-I) and of N-acetylglucosamine and sialic residues (WGA, Wheat germ agglutinin) at light and electron microscopical levels. At the light microscopical level, RCA-I and WGA binding sites were detectable in the early embryonic capillaries in a diffuse staining pattern; in later embryonic stages and in adult animals, RCA-I labelling became located on the abluminal surface of the vessels, while WGA staining was detected on the luminal surface. Ultrastructurally, gold labelling for RCA-I was seen intracytoplasmically in endothelial cells in 9-day-old embryos. In 14- to 20-day-old embryos and in chickens, binding sites for RCA I were detected in endothelial tight junctions and basement membranes. In contrast, labelling of the gold-coupled WGA lectin was distributed almost exclusively on the luminal endothelial surface already in early embryos. The results indicate that the endothelial cells of the optic tectum acquire functional polarity early in their development and that glycoconjugates containing β-D-galactose residues are involved in the biochemical composition of the tight junctions and basement membrane, which are considered to be key structures in blood-brain barrier (BBB) differentiation.

Original languageEnglish
Pages (from-to)305-315
Number of pages11
JournalAnatomy and Embryology
Volume197
Issue number4
DOIs
Publication statusPublished - 1998

Keywords

  • Blood-brain barrier
  • Chick embryo
  • Endothelium
  • RCA-I
  • WGA

ASJC Scopus subject areas

  • Anatomy
  • Developmental Biology
  • Cell Biology
  • Embryology

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