Two Distinct Types of Reticular Cells in the Pig Sheathed Artery

Abstract

The morphology of reticular cells of the sheathed arteries, in the red pulp of pig spleen, was studied by using transmission electron microscopy; and their histochemical reactivity with periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP). The phagocytic ability was evaluated by injecting colloidal carbon into the splenic artery. Reticular cells of the sheathed arteries were classified as type I and type II cells. Type I cells have a nucleus with scanty chromatin, and the cytoplasm reacts positively to PA-TCH-SP. The PA-TCH-SP-positive granules are considered to be subunits of β-glycogen particles based on their morphological features. Type II cells have a nucleus with abundant chromatin and are not stained by PA-TCH-SP. Both types of reticular cells are connected with reticular fibers. Results of the colloidal carbon injection showed that type I reticular cells did not ingest carbon particles during the time frame of the experiment, whereas type II reticular cells are phagocytic and ingested carbon.

Peripheral blood fibrocytes contribute to the formation of the avian spleen

“…The cells of the sheath are those first exposed to the intravenously injected extracellular tracers or antigens, because these tracers leave the circulation through the stomata of the penicillar capillaries (White et al, 1975; Oláh et al, 1984, 1990; Jeurissen, 1993; Miyata et al, 1994). In the avian species, endocytosis triggers the macrophages to detach from the sheath and migrate to the T‐dependent areas.…”