Postnatal T cell development depends on continuous colonization of the thymus by BM-derived T lineage progenitors. Both quantitative parameters and the mechanisms of thymus seeding remain poorly understood. Here, we determined the number of dedicated thymus-seeding progenitor niches (TSPNs) capable of supporting productive T cell development, turnover rates of niche occupancy, and feedback mech...

A vast majority of thymocytes are eliminated during T cell development by apoptosis. However, apoptotic thymocytes are not usually found in the thymus, indicating that apoptotic thymocytes must be eliminated rapidly by scavengers. Although macrophages and dendritic cells are believed to play such role, little is known about scavengers in the thymus. We found that CD4(+)/CD11b(+)/CD11c(-) cells ...

The thymus is required for T cell differentiation; a process that depends on which antigens are encountered by thymocytes, the environment surrounding the differentiating cells, and the thymic architecture. These features are altered by local infection of the thymus and by the inflammatory mediators that accompany systemic infection. Although once believed to be an immune privileged site, it is...

Thymic gland (thymus) represents a huge mystery for biology, medicine (primarily immunology), including pediatric issues. Complexity of the study is determined by multiplicity integral connections thymus with other components immune system, neuroendocrine, hematopoietic systems, connective tissue, different organs and cells which provide appropriate barrier function. Discerning direct thymic fu...

A kinetic procedure, based on differences in affinity of lactate dehydrogenase (LDH) subunits for L(+)-lactate, was employed to measure the M and H subunit activities of this enzyme in a variety of normal and neoplastic tissues of the rat. Total LDH activity was highest in liver (both normal and regenerating) at about 150 units per gm fresh tissue and somewhat lower in heart and femoral muscle ...

In our notice of the first two volumes of this work we commented on its general plan and scope, which limits it entirely to a description of operative technique and disarms criticism of omissions by the statement that only the common operations are dealt with. In our opinion the author would have done better to have given us the benefit of his own personal experience, instead of compiling an en...

Experiments are described in which the thyroid or thymus gland of rabbits was removed prior to inoculation of the animals with Tr. pallidum. The effect of these procedures is described from the standpoint of the manifestations of the disease. After complete thyroidectomy, the disease was considerably more severe than in the controls and very markedly so in certain instances. Partial tyroidectom...

Congenital absence of the parathyroid glands may be associated with congenital absence of the thymus (Lobdell, 1959). This is not surprising as both structures arise together from the 3rd and 4th branchial pouches. In the same way, vascular anomalies of the 3rd and 4th branchial arteries are found to be associated with abnormalities of the thymus, including thymic aplasia (Cameron, 1965). A pat...

Protein-energy malnutrition (PEM) leads to an immune deficiency, which is now well documented. Some investigators have suggested that the associated zinc deficiency is important in thymic involution and changes in cellular immunity. To evaluate the respective roles of nutritional deficiency, infection, and zinc in the alteration of thymic function, we measured the amounts of thymulin (facteur t...

The total tissue nucleic acids (DNA and RNA) have been isolated from normal and neoplastic mouse thymus glands and chromatographically fractionated. Significant differences in the chromatographic distribution of the nucleic acids from normal adult thymus and x-radiation-induced thymic lymphosarcoma were found. Chromatographic patterns intermediate between normal and tumor were found in the thym...