Histochemical and ultrastructural studies of mast cells in the intestinal mucosa and skin of the opossumDidelphis albiventris

Summary The mast cells located in the intestinal mucosa of a non-eutherian mammal were studied in comparison with those in the skin of the ear. In the intestinal mucosa, the mast cells exhibited a more variable shape, larger cytoplasmic granules and greater sensitivity to fixatives regarding their staining towards Toluidine Blue. Ultrastructurally, these granules were more heterogeneous but lacked the crystalline content found in granules of skin mast cells; lipid body-like organelles were found only in the mucosa-located mast cells. Histochemically, they differed from skin mast cells by the absence of periodic acid-Schiff (PAS)-positive granules. Unlike the mucosal mast cells of the rat, they fluoresced brilliant yellow after berberine treatment, which is evidence of the presence of heparin.     

Histochemical studies on mast cells in cattle skin

Synopsis Cells in the skin of cattle which gave a green fluorescence after formaldehyde treatment could be stained orange with Acridine Orange and blue with Astrablau. It is concluded that these cells are mast cells containing heparin and a catecholamine, probably dopamine.     

Histochemical and ultrastructural studies on the enterochromaffin-like cell in the gastric mucosa of the opossum Didelphis albiventris (Marsupialia)

Summary An ultrastructural study of enterochromaffin-like (ECL) cells in the gastric mucosa of the white-belly opossum Didelphis albiventris (Marsupialia) was carried out. In parallel, histochemical methods were used at the light-microscopical level to demonstrate argentaffin cells, argyrophilic cells, and serotonin- and histamine-immunoreactive elements. Argentaffin and serotonin-immunoreactive cells were scattered, and argyrophilic cells were numerous, within the full thickness of the mucosa. Argyrophilic cell distribution was similar to that of histamine-immunoreactive elements. At the electron-microscopical level, the oxyntic mucosa of D. albiventris presented endocrine cells with secretory granules morphologically similar to those of the ECL cell of eutherian mammals. However, in this marsupial, the ECL cell exhibited a variable mixture of two distinct types of secretory granules: (1) granules with the morphological appearance of the eutherian ECL cell, and (2) granules morphologically similar to those of the eutherian enterochromaffin (EC) cells. Based on this morphological pattern of the ECL cell granules, it is proposed that in the oxyntic mucosa of the opossum D. albiventris, the EC and ECL cells represent distinct steps in the same line of cell differentiation; the ECL cell should also be a site of histamine storage.     

Histological and ultrastructural studies of the marsupial Didelphis albiventris Peyer's patches

Differing from the studied Eutheria the white belly opossum Peyer's patches do not present a conspicuous dome. M cells are located in the inner layer of bilaminal formed at the bottom of the villi. A great variation in the morphology of M cells was observed. The enterocytes located at the epithelial inner layer may present endocytic vesicles, and the microvilli are shorter than the microvilli of enterocytes lining the small intestine. As these morphological aspects have been described to exist in the enterocytes of the lactent opossum small intestine it was surmised that the opossum Peyer's patches special epithelium could represent the persistence in adult animals of a cellular pattern established before the intestinal maturation had occurred.     

Histochemical,ultrastructural, and three-dimensional observation of smooth muscle cells in human gastric mucosa

The present study was undertaken to clarify the histochemical and ultrastructural properties and the three-dimensional distribution of the smooth muscle cells (SMCs) located in the lamina propria (LP) of the human gastric mucosa. Standard paraffin sections obtained from stomachs surgically resected for gastric cancer were immunostained for alpha-smooth muscle actin (alpha-SMA), vimentin, desmin, laminin, and type IV collagen. In addition, 100-m-thick sections were fluorostained for alpha-SMA and CD34, while three-dimensional images were prepared by confocal laser scanning microscope. Ultrastructural studies were carried out using normal gastric biopsy specimens. The results indicated that SMCs in the LP differed between the upper and lower regions, SMCs in the lower LP being fairly typical SMCs, whereas those in the upper LP had apparently lost reactivity for desmin but gained that for vimentin. The basal lamina became sparser, but a fibronexus was occasionally seen in SMCs in the upper LP. Three-dimensional images revealed bundles of SMCs in the upper LP encircling several foveolae to form acinus-like structures and, in the upper LP, SMCs branching into fine fibrils with a brush-like (corpus) or besom-like (i.e., a twiggy witchs broom) appearance (antrum).     

Histochemical comparison of vertebrate mast cells

Synopsis Mast cells from representative species of each of the five vertebrate classes have been studied histochemically. Histamine was found in reptilian, avian and mammalian species. An N-sulfated mucopolysaccharide was present in all species but the carp. A chymotrypsin-like or a trypsin-like esterase or both was found in the turtle and the several mammalian species examined. The mast cell thus appears to have developed the biological armamentarium associated with the mammalian cells in discrete steps during vertebrate evolution.     

Histochemical and ultrastructural identification of neurotensin cells in the dog ileum

Summary In the dog ileum, neurotensin cells stained with immunofluorescence or immunoperoxidase proved distinct from argentaffin (EC) cells, glucagon immunoreactive (GLI) cells and pancreatic peptide immunoreactive (PP) cells. Neurotensin cells showed various degrees of reactivity with Grimelius'silver. With electron microscopy, besides EC cells, large granule cells with a thin peripheral rim of Grimelius-reactivity (L cells) and large granule cells with variable Grimelius-reactivity of the core (N cells) were found. On distributive grounds, L cells were identified with GLI cells and N cells were interpreted as neurotensin cells.     

Thymosin beta 4 expression in normal skin,colon mucosa and in tumor infiltrating mast cells

Mast cells (MCs) are metachromatic cells that originate from multipotential hemopoietic stem cells in the bone marrow. Two distinct populations of MCs have been characterized: mucosal MCs are tryptase-positive while mast cells in skin contain tryptase and chymase. We now show that a sub-population of MCs is highly immunoreactive for thymosin β₄, as revealed by immunohistochemical analyses of normal skin, normal colon mucosa and salivary gland tumors. Four consecutive serial sections from each case were immunostained for thymosin β₄ (Tβ₄), chymase, tryptase and stained for toluidine blue. In skin biopsies, MCs showed a comparable immunoreactivity for Tβ₄, chymase and tryptase. In normal colon mucosa the vast majority of mucosal MCs expressed a strong cytoplasmic immunoreactivity for tryptase and for Tβ₄, in the absence of chymase reactivity. A robust expression of Tβ₄ was detected in tumor-infiltrating and peritumoral mast cells in salivary gland tumors and breast ductal infiltrating carcinomas. Tumorinfiltrating MCs also showed a strong immunoreactivity for chymase and tryptase. In this paper, we first demonstrate that normal dermal and mucosal mast cells exhibit strong expression of thymosin β₄, which could be considered a new marker for the identification of mast cells in skin biopsies as well as in human tumors. The possible relationship between the degree of Tβ₄ expression in tumor-infiltrating mast cells and tumor behaviour warrants further consideration in future investigations.Key words: mast cells, thymosin β₄, tryptase, chymase.     

Histochemical and ultrastructural identification of neurotensin cells in the dog ileum.

In the dog ileum, neurotensin cells stained with immunofluorescence or immunoperoxidase proved distinct from argentaffin (EC) cells, glucagon immunoreactive (GLI) cells and pancreatic peptide immunoreactive (PP) cells. Neurotensin cells showed various degrees of reactivity with Grimelius' silver. With electron microscopy, besides EC cells, large granule cells with a thin peripheral rim of Grimelius-reactivity (L cells) and large granule cells with variable Grimelius-reactivity of the core (N cells) were found. On distributive grounds, L cells were identified with GLI cells and N cells were interpreted as neurotensin cells.