Studies on the Histogenesis of Autoplastic Thymus Transplantations

Abstract

There are many mooted problems connected with the thymus gland in spite of the numerous studies dealing with the embryology, comparative anatomy, histology, and pathology of this organ. KSlliker (1) in 1879 drew attention to the fact that the thymus has an epithelial anlage from the branchial clefts, and since that time many attempts have been made to explain how from this epithelial germ had arisen the finished structure of the organ, with its important elements--the retieulum, Hassall's corpusdes, and free lymphoid-like ceils. The lack of knowledge and the disagreement as to the origin and biological significance of the small thymic cell have been one of the main stumbling blocks towards a proper understanding of the functions of this organ. These cells have been the subject of contention among those who have worked in the field. Two schools have developed, each of which has during the last 25 years vigorously upheld its views. The Maximow-Hammar (2, 3)" group supported by Rudberg (4),Jonson (5), Pinner (6), Pappenheim (7), and Danchakoff (8) believe in the lymphocytic nature of these cells, while the Maurer-StShr (9, 10) school claims that these cells are epithelial in origin, though they appear like mesodermal lymphocytic cells. In addition they believe that these cells are capable of reverting to their original epithelial state.Since up to the present time no definite solution of the problem has been established, we believed that the method of autoplastic thymus transplantation with a detailed study of the histological changes which occur in the transplants from a few hours after their insertion to their 4O3 on

Intrathymic and Extrathymic T Cell Maturation

“…Although there is good evidence that hemopoietic cells migrate and repopulate the tissues of irradiated hosts , the proportion of migrating cells is much lower when hemopoietic cells are injected into normal hosts (Micklem et al, 1968). On the other hand, the rate of entry of hemopoietic cells into thymus grafts is quite comparable for normal or thymectomized hosts (Leuchars et al, 1967), probably as a consequence af the lymphoid depletion observed after thymus grafting (Gottesman & Jaffe, 1926, Law & Miller, 1950 and the subsequent repopulation of the graft by host cells (Metcalf & Wakonig-Vaartaja, 1964). One advantage of our model is that by using 50-60-daysold NTx hosts, which are also deprived of PTP cells in the periphery (Stutman, 1977), both the traffic of cells to the graft as well as the export of such cells to the periphery appear to be increased, or at least, reach levels where workable numbers of mitoses can be scored.…”

The Thymus and the Cellular Basis of Immunity

“…The thymus graft undergoes a sequence of changes after its implantation. Firstly, many but not all of the lymphocyte-like cells die as evidenced by the large amount of cell debris present (Gottesman & Jaffe 1926, Jolly & Lieure 1932, Dukor et al 1965. Secondly, regeneration commences which is, as adjudged by mitosis, almost entirely due to the residual cells (Metcalf & Wakonig-Vaartaja 1964, Dukor et al 1965, Koller et al 1966a.…”

Studies on Bartonella Muris Anemia of Albino Rats

“…It has been shown in a previous communication (7) that Trypanosoma lewlsi infection in the adult normal albino rat is accompanied at the height of the infection by a moderate anemia and the appearance in the red blood cells of Bartonella muris bodies. Studies on the pathology of this infection indicate that the most significant changes occur in the spleen.…”

“…They were approximately uniform in weight. The methods for preparation of the animals for transplantation have been described in a previous communication (7).…”

“…It is of interest that the transplant though not regenerated, reacted to the infection in the same way as the intact spleen. Marine and Manley (7) observed that in rabbits dying of pneumonia the spleen transplants on section were soft, engorged with blood and microscopically showed an increase in pulp cells. These changes are the same as those found in the intact spleen in the presence of infection.…”