Document Type : Original Article
ANATOMY DEPARTMENT, MASHHAD MEDICAL SCIENCES UNIVERSITY, MASHHAD, IRAN
Introduction: During early neural tube formation, the notochord is essential for the induction of ectoderm and for the subsequent differentiation of the neuroepithelium forming diverse cell types in the neural tube. Due to the key role of the glycoconjugates in many developmental events, the early distribution of these molecules in early notochordal interaction with adjacent tissues were studied.
Material and Methods: Paraffin fixed 5µm sections of days 10 to 14 of mouse embryo were processed for histochemical studies by using horse radish peroxidase labelled DBA, VVA-B4, WFA, UEA-1 and OFA lectins.These lectins have binding specificity for D-GalNac and a-fucose sidechains of the glycoconjugates.
Results: Histochemical analysis revealed that notochord and its intermediate extracellular fluid show extensive reaction with the floor plate of neural tube on 10th day, using OFA. This reaction was absent in the next day but a sever reaction was observed in the floor plate region. The results revealed a reaction in venteral portion of notochord with VVA-B4 and it expanded in to gut tube. Furthermore, a WFA-reaction was observed in the notochord and some of adjacent mesenchymal cells, but UEA-1 and DBA, don,t showed any reaction.
Conclusion: The expression of the GalNac and also fucosilated glycoconjugates is stage-dependent and thus probably genetically regulated. The timing and distribution of lectin reactions suggest that these molecules (GalNac and fucose) may play a role(s) in notochordal interactions and subsequent formation of the adjacent tissues.