Parvalbumin in cortical epithelial cells of the pigeon thymus

Abstract

We examined the distribution of parvalbumin in the pigeon thymus by light and electron microscopic immunohistochemistry. Tissues were also examined by conventional electron microscopy to determine the ultrastructure of immunoreactive cells. Parvalbumin immunoreaction was located in epithelial cells of the cortex, which formed dense mesh-like structures. Parvalbumin-positive epithelial cells were classified into 2 types. The first comprised elongated cells. In these, the nucleus was spindle-shaped, oval, or triangular, with a slightly irregular contour and contained rich heterochromatin peripherally. The cytoplasm was pale and processes extended laterally or ramified among the surrounding thymocytes. This type of cell formed the majority of immunoreactive cells. The other cell type consisted of polygonal epithelial cells. The nucleus was oval with deep indentations. Euchromatin occupied a large part of the nucleus. The cytoplasm contained numerous cell organelles compared with the elongated type, in particular, electron-dense vacuoles of various sizes and often bundles of tonofilaments. Both types of epithelial cell were interconnected by desmosomes. No secretory granules were found in the cytoplasm of elongated or polygonal cells. These results indicate the presence of heterogeneous group of parvalbumin-immunoreactive epithelial cells and suggest the likelihood of different functional roles for parvalbumin in the pigeon thymus.

Partial loss of parvalbumin-containing hippocampal interneurons in dementia with Lewy bodies

“…48 And last but not least, parv might leak from compromised/injured neurons and reach the CSF by diffusion, where elevated levels of the protein have been measured in patients suffering dementia with Lewy bodies. 18,19 Since a stimulus-induced, active secretion of parv is only known from non-neural tissues, 49 an increase of parv in the CSF is most probably the result of neuronal injury, which finally may lead to the loss of cells as observed. Remarkably, elevated CSF parv concentrations in DLB are regarded to be of diagnostic value, since no such changes were measured in AD or Parkinson disease.…”