The role of Glycoconjugates in development of floor plate during early morphogenesis in mouse embryo

The floor plate is a small group of cells located at the ventral midline of neural tube. During early neurogenesis the floor plate plays critical role(s) in differentiation of ventral portion of neural tube. The purpose of this study was to determine the distribution of glycoconjugates in floor plate as well as underlying mesoderm (Notochord) and their inductive activities in mouse embryo. Formalin fixed sections embedded in paraffin from 10 to 14 days old Balb/c mouse embryos were processed for histochemical studies by using 5 different horseradish peroxidase (HRP) labeled lectins including: Glycin max (SBA) specific for Gal and GalNac terminal sugar, Vicia Villosa (VVA) and Arachis hypogaea (Peanut) for GalNac, Ulex europeus (UEA-1) and Lotus tetragonolobus (LTA) for ?-L-fucose. Our results showed that SBA sensitive glycoconjugates react and change in floor plate, notochordal cells and surrounding extracellular matrix and these changes were significant (P<0.05). Extensive differences between GalNac sensitive lectins were observed during motoneuron differentiation. There was no reaction with other tested GalNac lectins. Furthermore we observed significant changes (P<0.05) in fucose glycoconjugates during notochordal development. The results suggest that the timing and distribution of SBA sensitive glycoconjugates may play a key role(s) in interactions and subsequent formation of adjacent tissues such as floor plate and notochord during critical period of morphogenesis. Our finding also showed that glycoconjugates with fucose terminal sugar may play a role(s) in notochordal development but probably have no function on floor plate development. Keywords: Glycoconjugate, Notochord, Floor plate, Interaction, Embryogenesi

Distribution of Glycoconjugates terminal sugars during neurohypophysis development in Rat

Background and Objective: The neurohypophysis originates from the floor of diencephalon. Its development controles by several cellular interactions that mediated by some molecules such as cell surface and extra cellular matrix Glycoconjugates terminal sugars. In this study we used lectin histochemichal technique to evaluate distribution of the Glycoconjugates and their changes during development of neurohypophysis. Materials and Methods: This experimental study carried on 40 female and 20 male adult Rats. After mating and appointment day zero of pregnancy, pregnant Rats were sacrificed from days 10-20 of gestation and their embryos were collected for histochemical study. The serial section of head specimens were fixed and incubated with different HRP-lectins from Orange fungus (OFA) Vicica villosa (VVA), Glycine max (SBA), Wistaria floribunda (WFA), peanut (PNA), Griffonia simplicfolia (GSA1-B4), Lotus tetragonolobus (LTA) and Ulex Europeus (UEA-1). OFA, LTA and UEA-1 lectins are specific for terminal sugars α-L–Fucose and WFA, SBA, VVA and PNA are specific for D-GalNAc, α, ß-D-GalNAc and GalNAc, D-Gal-(ß-1-3)- D-GalNAc of complex glycoconjugates respectively. Results: Our findings demonstrated that the reaction of neurohypophysis cells with OFA initiated from gestational GD10 and increased to GD15 (P<0.05) and then increased to GD17 (P<0.05). A few cells of neurohypophysis reacted with PNA from GD13 to GD16 and decreased afterward (P<0.05). Some cells of neurohypophysis reacted with SBA from GD14 to GD18 and decreased afterward (P<0.05). Reacting of many cells of neurohypophysis with WFA started on GD13 and increased to GD15 (P<0.05) and then decreased afterward (P<0.05). Neurohypophysis cells showed no reaction with the UEA-1, LTA, VVA and GSA1-B4 lectins. Conclusion: The expression of Glycoconjugates with terminal sugars α-L–Fucose, α, ß-D-GalNAc and D- Gal– (ß-1-3)- D-GalNAc have importanct role and special spatiotemporal situation in neurohypophysis development