AGE-RELATED PECULIARITIES OF HISTOLOGICAL STRUCTURE AND CELLULAR COMPOSITION OF CONJUNCTIVA-ASSOCIATED LYMPHOID TISSUE IN PIGS

Objective - to study of the structure and cellular composition of conjunctiva-associated lymphoid tissue (CALT) in pigs in the age aspect. Materials and methods. The conjunctiva of the lower and upper eyelids was studied in 18 piglets and pigs of both sexes aged 5 to 7 days, 2, 6 and 12 months. Histological, histochemical and immunohistochemical methods were used to detect structural changes and to demonstrate T lymphocyte marker (CD3), B-lymphocyte marker (CD79a) and proliferating cell nuclear antigen (PCNA). Results. In 5-7-day-old piglets goblet cells were poorly developed in the conjunctiva, and CALT was represented by single lymphocytes, while lymphoid nodules were absent. In 2 month-old piglets the conjunctival goblet cells were well developed, and CALT contained diffuse accumulations of lymphocytes and plasma cells. In 6 - and 12-month-old pigs CALT contained lymphocytes, plasma cells and lymphoid nodules. In thinned areas of the conjunctiva covering the lymphoid nodules, goblet cells were single or missing. Immunohistochemical studies showed that CALT in 5-7-day-old piglets contained only T-lymphocytes. In other groups it contained both T-and B-lymphocytes. Lymphoid nodules were represented by B-lymphocytes, while T-lymphocytes were mainly located in CALT internodular zones. In the germinal centers of lymphoid nodules proliferation of lymphoblasts was demonstrated. Conclusions. The morphological data obtained indicate the presence in the pig parocular tissue of an immune system in the form of CALT containing lymphoid cells and structures necessary for the induction of the immune response both on the ocular surface and in parocular tissues.

conjunctiva-associated lymphoid tissue, histological structure, immunohistochemistry, pigs