Investigation of Nectin-2 Expression in the Rat Thymus During Organogenesis in the Embryo

Objective: The thymus is a primary lymphoid organ which provides the essential microenvironment for T lymphocyte development and matures through epithelial-mesenchymal interactions. Nectins are Ca2+-independent Ig-like cell adhesion molecules. The purpose of this study was to investigate nectin-2 expression in the thymus at different stages of development in the rat foetus. Material and Method: In this study, 24 pregnant adult female Wistar-albino rats were used. The rats were decapitated under ketamine anaesthesia and their foetuses were removed at 14, 16, 18, and 20 days of gestation (GD). Foetuses were embedded in paraffin blocks. In order to determine the general histological structure, sections were stained with hematoxylin-eosin. Nectin-2 was detected in the foetal thymus by immunohistochemistry using the avidin-biotin-peroxidase technique. Results: The thymic primordium was surrounded by a connective tissue capsule at GD14 and GD16. At GD18, the connective tissue capsule formed septa that subdivided the tissue into incomplete lobules. Lobulation was more evident at GD20. Nectin-2 immunoreactivity was observed at medium density at GD14 and GD20 and weakly at GD16 and GD18. Conclusion: It is thought that nectin-2 contributes to cell-to-cell interactions during thymopoiesis.