title: Modifications of the structures of the rat lymph nodes by neonatal thymectomy.
abstract: Until recently, the deep cortex of the lymph node was thought to exist as a layer completely underlying the peripheral cortex. It was known, moreover, that through neonatal thymectomy, the lymphocyte population of the deep cortex could be depleted. Through our current research, however, we have demonstrated that the deep cortex actually consists of hemispherical 'units'. Each unit is centered under an opening of an afferent lymphatic and comprises a center and a periphery with different morphological features and functions. In the light of this new knowledge, we felt it appropriate to reexamine the influence of neonatal thymectomy on node histology. Rats were thymectomized 5 h after birth. When they were 8 weeks old, nodes from various anatomical sites were submitted for morphological analysis. The resulting observations were compared to those made with nodes of nude as well as normal rats. It was found that the histological changes induced by neonatal thymectomy were comparable to those resulting from the congenital athymic state, but with marked differences. Differences were also observed in the nodes of thymectomized and semi-thymectomized rats. The discussion deals with these differences and presents new observations.
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D008198:Lymph Nodes / Q000033:anatomy & histology* / Q000276:immunology; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000166:cytology; D051379:Mice; D008819:Mice, Nude; D051381:Rats; D011919:Rats, Inbred Strains; D013934:Thymectomy; D013950:Thymus Gland / Q000502:physiology*