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Biomedical subjects

G T Simon

Publications and source records attributed to G T Simon.

At least 55 records · Page 3Linked to original sources
PubMed1971

Ultrastructure of the normal lymph node.

The "normal" lymph node has been studied by electron microscopy. The lymphoid tissue can be divided into three distinct zones. Zone 1 consists of loosely arranged cells surrounding the lymphatic sinuses and blood vessels. This is the only zone in which plasma cells are present. Zone 2 is surrounded by zone 1 and consists of compactly arranged cells in which lymphocytes predominate. Zone 3 (germinal center) appears only after antigenic stimulation. It is characterized by large, ribosome-rich cells and macrophages containing phagocytosed lymphocytes. These zones are arranged with their longest diameters pointing towards the hilus. Zone 1 is the longest and extends across the cortex, paracortex and medulla. Zone 2 spans across cortex and paracortex. Zone 3 usually is confined to the cortex. Our preliminary studies indicate that zone 1 is mainly bursal dependent, zone 2 is mainly thymic dependent and zone 3 is bursal dependent.

Animals↗
PubMed1971

Phagocytosis of colloidal carbon in a lymph node.

Colloidal carbon, injected intramuscularly, migrates rapidly and selectively to a corresponding lymph node by lymphatics, in which the carbon travels as free particles. In the lymph node, carbon particles are mainly phagocytosed and stored by macrophages, which exhibit morphologic changes in the plasma membrane and the tubules of endoplasmic reticulum. The subsequent migration of these cells results in wide distribution of carbon in the lymph node. Cytoplasmic changes also occur in sinusoidal macrophages, in which no carbon is seen. A possible relation of these macrophages to macrophage migration in lymph node is postulated. The lymphatic endothelial cells, like endothelial cells in any other organ, phagocytose only a small amount of carbon and only after functional overload of the macrophages.

Animals↗