Effect of dietary crude fibre level on intake, digestibility and productivity of slow-growing indigenous Venda chickens aged one to 91 days

Abstract

Histological studies were conducted on the palatine tonsil of six male crossbred goats of six months of age. The tonsils were lined by a stratified squamous non-keratinized surface epithelium which continued into the crypts forming the non-reticular epithelium. At some areas in the crypts, the non-reticular epithelium associated with lymphoid follicles showed a great reduction in height with only one to two intact cell layers and were called reticular epithelium or lymphoepithelium. Propria-submucosa of the palatine tonsil was characterized by dense irregular connective, lymphoid, glandular, adipose and muscular tissues. Lymphoid tissue constituted majority of the palatine tonsil and was organized into primary and secondary lymphoid nodules and dense diffuse lymphatic tissue. Average diameter of lymphoid nodules was 684.17±6.88µm while the lymphocyte count in the nodules was 28826.54±236.25. The average number of lymphatic nodules counted per field under low power magnification of microscope was 2.67±0.42 and the internodular distance was 34.67±1.41. Glandular tissue was present in the deeper areas of propria-submucosa. A well developed connective tissue capsule separated the lymphoid and glandular tissues of the palatine tonsil. In the immunohistochemical staining technique strong positive reaction for cytoplasmic IgG bearing B- lymphocytes was noticed within the germinal centre of lymphoid nodules, towards the base of the FAE and some cells even infiltrated the crypt epithelium. In the mantle zone and internodular area, reaction was very mild indicating that T- lymphocytes predominated in these areas. It was concluded that the palatine tonsils were histologically mature as a local defence mechanism against the harmful substances to be encountered from the environment after birth.