Immunohistochemical Localization of S-100 Protein in the Pig Pituitary Gland

Innervation of the circumvallate papilla of the cat tongue

Immunohistochemically, the distribution of S-100 protein and acetylated tubulin-positive nerve fibres was studied in the circumvallate papilla and its taste buds (TB) in the adult cat. The immunostaining for acetylated tubulin demonstrated an extensive innervation of the circumvallate papilla. Vegetative ganglionic cells were found in the central area of papilla, whereas fine nerve fibres were concentrated under epithelium. Individual positive axons were seen in relation to TB. Nerve fibres enter the TB and branch out among the supporting and sensory cells. Some nerve fibres reach the apical surface of the TB, including the taste pore. Nerve fibres positive for S-100 protein were observed as dense nerve plexus located in the core of the papilla. Satellite cells localized inside the papilla were seen to surround the ganglionic cells. Bands of fine nerve fibres were present under lining epithelium, mainly at the base of the TB. A weak reaction was displayed by taste bud cells and surrounding epithelial cells as well as by the epithelial cells of the papillary side of the moat. A dense network of the nerve fibres was present among the glandular acini and surrounding the ducts of the serous Ebner's glands.

Folliculostellate cells in pituitary pars distalis of male viscacha: immunohistochemical, morphometric and ultrastructural study

Folliculostellate cells (FSC) have been reported in pituitary of several mammalian species. FSC morphology and secreted substances have been instrumental to the understanding of their function. The purpose of this work was to perform an immunohistochemical, morphometric and ultrastructural study of the pituitary pars distalis FSC in adult male viscacha and to analyze their relation with hormone secreting cells. Immunohistoche-mistry and image analysis were carried out in different sectors of the gland, from the middle (sector 1) to the glandular periphery (sector 5). Transmission electron microscopy with lanthanum as electrodense tracer was used. FSC formed follicles with PAS-positive colloid inside. They expressed S-100 protein mainly in both nucleus and cytoplasm. FSC were stellate-like in shape and exhibited short cytoplasmic processes that contacted with blood vessels and endocrine cells. In addition, some follicular colloids were immunostained with anti-S-100 protein. A few FSC were immunostained with anti-glial fibrillary acidic protein (GFAP) and anti-vimentin. The morphometric parameters analyzed (percentages of S-100-positive total, cellular and colloidal areas) increased from sector 1 to sector 3 and then decreased to sector 5. Hormone secreting cells, mainly lactotrophs, gonadotrophs and corticotrophs were associated with FSC and follicles. The ultrastructural study demonstrated that FSC developed junctional complexes and desmosomes between their lateral membranes. Lanthanum freely penetrated the spaces between granulated cells and FSC, but did not penetrate into the follicular lumen.

IN CONCLUSION

1) the differential expression of S-100 protein, GFAP and vimentin may indicate different physiological stages of FSC; 2) the expression of these proteins suggests a neuroectodermic origin of these cells; 3) FSC spatial distribution, association with endocrine cells, and the generation of an intercellular communication network suggest that FSC are involved in the pituitary pars distalis paracrine regulation of the viscacha.

Interaction between chromaffin and sustentacular cells in adrenal medulla of viscacha (Lagostomus maximus maximus)

New evidence provides valuable information about the participation of sustentacular cells in chromaffin cell catecholamine secretion. In this process, calcium ions play an important role. It has been shown that there is an intense ionic traffic between both types of cells. Moreover, sustentacular cells take an active part in calcium metabolism, regulating levels of the ion and indirectly, the synthesis and release of catecholamines. This background information encouraged us to study the sustentacular population of Lagostomus adrenal medulla and its morphologic relationship with the chromaffin population. The animals were captured, transported to the animal facilities, anaesthetized and killed. The adrenal gland was processed by immunohistochemistry using antiserum against S-100 (subunit alpha and beta), a specific marker. Through the morphological and immunohistochemical study, it was found that there are sustentacular cells in deferent regions of adrenal medulla, mainly in the basal zone of chromaffin cells, which constitute the glomerular structure around blood capillaries. Cytoplasmic extentions of sustentacular cells penetrate into chromaffin cells and make contact with the basal membrane of the capillary endothelium. The relationship among chromaffin cells, capillaries and sustentacular cells suggests that they may intervene actively in the adrenal medulla metabolism.