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Biomedical subjects

F S Peng

Publications and source records attributed to F S Peng.

At least 37 records · Page 2Linked to original sources
PubMed1985

Lymph nodes of the N:NIH(S)II-nu/nu mouse.

In N:NIH(S)II-nu/nu mice, which express the nu and the Xid genes, T and B lymphocytes are deleted. We studied their lymph nodes in the light of new knowledge of the morphology of the nodes of normal and athymic animals. Histologic preparations of the nodes from various anatomical sites were analyzed in 9-week-old mice. Node sections were also stained for IgM or IgG. The study revealed that, the frameworks of the peripheral cortex, the deep cortex, and the medulla were developed in these nodes, although they were quite devoid of lymphocytes or plasmocytes. However, the outermost (or subsinus) layer of the peripheral cortex of some nodes was populated with lymphocytes. In some cervical nodes, a few follicles, lymphocyte clusters, and a well-developed plasmocyte population were also present. The lymphocytes of the subsinus layer and the clusters were B cells with an increased expression of IgM. The modifications of these nodes are discussed on the basis of recently developed concepts of node functioning.

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PubMed1984

Tridimensional study of the deep cortex of the rat lymph node: VIII. The deep cortex units of the athymic nude rat.

The deep cortex of the lymph node of various species actually consists of hemispherical structures, termed deep cortex "units." Each unit is centered under an opening of an afferent lymphatic and comprises a center and a periphery. In a recent work on the nude mouse, we found that the congenital athymic state inhibits the development of the lymphocyte population in the center of the units as well as in a related area of peripheral cortex, and that it also modifies other nodal components. In the present work, we wanted to compare the effects of the athymic state on the rat nodes. Therefore, nodes from various anatomical locations in 8-week-old nude rats were submitted to a tridimensional analysis. The overall effects of the congenital athymic state were found to be comparable in rats and mice. However, marked differences were noticed in the modifications of the node histology, in both species of nude animals. Their significance is discussed together with new findings.

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PubMed1984

Development of the lymph nodes in the very young, and their evolution in the mature, nude rat.

We recently revised the concepts on the morphology of the lymph nodes of the young adult athymic nude rat. The present work studied the postnatal development of its nodal structures and their evolution with aging. The structural development of the deep cortex "units" was found to progress as usual. However, while the concentration of lymphocytes appeared to develop normally in the periphery of a unit, the center of the unit remained lymphocyte-depleted. Further, the peripheral cortex failed to develop over the middle part of a unit center. With aging, the peripheral cortex over the remainder of a unit center could atrophy and disappear completely. The present findings did not yield information as to whether thymic elements are necessary to trigger the development of a unit, but they revealed that its further development is determined by stimuli. It was concluded that, in the absence of T-cells, stimuli for cellular immune responses provoke the proliferation of the reticular or interdigitating cells of a unit center. On the other hand, an increase of these stimuli was concluded to cause the peripheral cortex to fail to develop over part of a unit center and, later, to atrophy over the remainder of the unit center. The mechanisms of the phenomena are discussed.

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PubMed1984

Modifications of the structures of the rat lymph nodes by neonatal thymectomy.

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.

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PubMed1983

Depopulation of lymphocyte migration sites in the lymph node by irradiation and colloidal carbon.

The purpose of the present investigation was to examine, in the light of recent histological findings, whether irradiation and colloidal carbon can have a lymphocyte depopulating effect on preferentially particular structures of the rat lymph nodes. Normal eight-week-old Sprague-Dawley rats received a 500 R whole body irradiation or a subcutaneous injection of 0.02 ml of India ink. The animals were then sacrificed at various time-intervals. The histological analysis of the irradiated and draining nodes revealed that both treatments almost completely eliminated small lymphocytes from the affected nodal structures, except in the center of the deep cortex units. The affected structures had been predominantly populated by recirculating lymphocytes.Thus, the treatment had a rather preferential depleting effect on a node population of recirculating lymphocytes. This finding provides another possible explanation for the carbon-induced augmentation of a GVH reaction in nodes. This augmentation had previously been attributed to a stimulation by the carbon of host macrophages, which would mediate the proliferation of antigen-reactive donor cells. From our present findings, it appears that carbon, like irradiation, could act by depleting a node of recirculating lymphocytes, thereby weakening its immunological potential against the inoculated lymphocytes.

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PubMed1983

Structural and cell population changes in the lymph nodes of the athymic nude mouse.

A recent tridimensional analysis of the lymph node demonstrated that its deep cortex is composed of grossly hemispherical "units," adjoining a portion of its peripheral cortex. Each deep cortex unit can be distinguished into a center and a periphery. The periphery was concluded to be a site for migration of circulating lymphocytes, the center, a site where T cells would participate in cellular immune responses. The aim of the present work was to determine the influence of the congenital athymic state on the development of the units and of other components in the lymph nodes of the nude mouse. For this, the lymph nodes at various anatomical locations in adult athymic nude mice were analyzed. The present study revealed that the athymic state did not inhibit the development of the units but severely depleted the lymphocyte population of their center only. However, it did inhibit the development of an area of peripheral cortex located over the middle part of a unit. Such an area of peripheral cortex is, thus, concluded to be thymus dependent, as is the center of a deep cortex unit. The athymic state also prevented the development of the cells of the nodules (germinal centers) and of much of the plasmocytes. On the other hand, it yielded to the enlargement of the follicles, the formation of new structures: medullary "lymphocyte clusters" and the transformation of the medullary venules into high endothelial venules. The various modifications of the nodal structures resulting from the congenital athymic state are discussed in relation to some functions of the organ.

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PubMed1982

Tridimensional study of the deep cortex of the rat lymph node. VI. The deep cortex units of the germ-free rat.

The deep cortex of the normal rat lymph node consists of semirounded lymphocytic structures, termed deep cortex "units," each being centered on the opening of an afferent lymphatic. The aim of the present work was to investigate the morphologic features of the units in germ-free animals, in an attempt to evaluate the influence on natural exogenous antigenic stimulation on the development of the units. For this, the lymph nodes from various anatomic locations from 8-week-old Sprague-Dawley germ-free rats were analysed tridimensionally. The observations revealed that, in comparison with the lymph nodes of normal rats, the units of the cervical and mesenteric lymph nodes of the germ-free animals were underdeveloped, while those of the brachial, inguinal, and popliteal lymph nodes were unchanged. Moreover, the germ-free state modified the units of the mesenteric lymph nodes in a manner not encountered in the remaining lymph nodes. Other morphologic features of the peripheral cortex of the lymph nodes of germ-free rats also differed from those of normal ones. The significance of these differences is discussed with respect to immune responses and the process of lymphocyte recirculation. They are of interest because they support previous proposals regarding some aspects of the functioning of the normal lymph node, accounting for the features of the structures and overall architecture of the organ.

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PubMed1982

[Distribution of a diffusible tracer in the subcapsular sinus and the cortex of lymph nodes in the rat].

The observations of a previous work on the architecture of the rat node suggested that the organ is divided into "physiological compartments". Each compartment corresponds to a node portion stimulated by the immunogenic content poured by an opening of an afferent lymphatic or a branch of it. The same study also investigated the lymph flow in the organ sinuses by analysing the distribution, in draining nodes, of a locally injected small dose of China ink. It was found that the ink, pouring into a node from a lymphatic opening, had spread in a restricted portion of its subcapsular sinus corresponding to that of a compartment. The finding thus supported the proposal on the physiological compartmentation of the organ. However, the question arose as to whether such restricted ink distribution in the sinus did not result from the non-diffusible and unphysiological nature of the ink. We, therefore, repeated the latter analysis with a diffusible and physiological tracer: uridine-3H. The similarity of the results of the latter analysis, with those of the preceeding one, indicate that the observations witness the physiological modalities of the pattern of lymph flow in the organ sinuses. It, therefore, confirms that the node is divided into physiological compartments. Additional observations of present work, further demonstrate that small sized lymph substances diffuse from the subcapsular sinus into the cortex. The process is maximal under a lymphatic opening and decreases along the sinus with distance from the opening.

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PubMed1981

Tridimensional study of the deep cortex of the rat lymph node. IV. Differential labelling of the deep cortex units with 3H-uridine.

Using tridimensional reconstruction, it was recently found that the deep cortex of rat lymph nodes comprises one to several basic "units." Each unit is a semi-rounded structure contiguous to the peripheral cortex and bulging into the medulla of a node. Other investigators reported that transfused lymphocytes, heavily labelled in vitro by 3H-uridine, became concentrated in an ill-defined region of nodes, referred to as the mid and deep cortex. This suggested to us that the in vivo labelling of nodes with 3H-uridine might allow to further characterize the units on a physiological basis. Therefore, rats were injected intravenously with a dose of 1--20 muCi of 3H-uridine/gm body weight and sacrificed 1 hour to 3 days later. The radioautographs of their nodes were exposed up to 535 days. The observations revealed that a large dose of 3H-uridine combined with a long exposure of the radioautographs yielded a differential labelling of the cell population of the units, characterized by a much more intense reaction than that of the surrounding structures. This demonstrated that the physiology of the lymphocyte population of the deep cortex units differs from the morphologically similar lymphocyte population of the extrafollicular zone of the peripheral cortex. The possible reason(s) for the differential labelling of the units is discussed.

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PubMed1975

Migration into pseudo-follicles of draining lymph nodes of medullary small thymocytes injected in the mediastinal cavity.

After an intramediastinal injection of labelled thymic cells, few cells were found in the pseudo-follicles of the draining nodes while the extrafollicular zone of their cortex contained abundant labelled cells (Sainte-Marie and Peng, in press). We proposed that the cells having migrated into the pseudo-follicles were small lymphocytes of the thymic medulla, or medullary small thymocytes, which accounts for about 5% of the thymocyte population. The purpose of the present study was to test the validity of the proposal. Rats received corticosterone injections to destroy, their cortical thymocytes and, thereafter, a dose of 3H-cytidine in order to label the surviving medullary small thymocytes. One hour later, these cells were suspended and injected in the mediastinal cavity of recipients which were killed 3 and 24 hours after the injection. The radio-autographs of the draining, and of the remaining, nodes revealed that most labelled cells, present in the nodes at the 24-hour interval, were situated mostly in the pseudo-follicles. The finding indicates, that, unlike the cortical small thymocytes, the medullary small thymocytes can migrate into pseudo-follicles. This is probably due to the greater motility of the medullary small thymocytes and possibly, to their involvement in the function(s) carried out in the pseudo-follicles.

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