Biomedical subjects

J Boya

Publications and source records attributed to J Boya.

At least 37 records · Page 2Linked to original sources

PubMed1992

Postnatal maturation of the parenchymal cell types in the rabbit pineal gland.

An ultrastructural study on the maturation of the parenchymal rabbit pineal cell types from the first postnatal day up to 120 days is presented. Two main cell types are distinguished from the first 24h of postnatal life. Pinealocytes of the types I and II display different developmental degrees. Both immature cell types are arranged in groups. In addition, type II pinealocytes form rosette-like structures. Both cell types progressively become isolated and display cell processes. The nucleus and the cytoplasm of type I pinealocytes are barely electrondense. During the postnatal period, the number of cytoplasmic organelles, cell processes and terminal clubs increase progressively. Terminal clubs are frequently seen near blood vessels. After 30 days, type I pinealocytes show characteristics of adult pinealocytes. However, the maturation of most type I pinealocytes does not complete until the 90th postnatal day. Type II pinealocytes present a fairly electrondense nucleus and cytoplasm. Mature forms can be seen after the 5th postnatal day. During the postnatal period, a close relationship is determined among type II pinealocytes and cell processes and terminal clubs of type I pinealocytes.

Aging↗

PubMed1991

Co-expression of glial fibrillary acidic protein and vimentin in reactive astrocytes following brain injury in rats.

The immunohistochemical expression of glial fibrillary acidic protein (GFAP) and vimentin (VIM) was studied in reactive astrocytes of the rat cerebral cortex 5 days after a brain injury. Seriated Epon semithin sections were immunostained alternatively for GFAP or VIM. Thereafter, both antigens were detected in consecutive sections of the same cell. Bordering the wound, an inner reactive glial layer 300-350 microns thick, showed positive astrocytes with the two immunohistochemical techniques. In this layer, about 60% of the GFAP positive astrocytes were also positive for VIM. Outside the inner layer, only GFAP positive astrocytes could be found.

Animals↗

PubMed1991

Microglial cells in the central nervous system of the rabbit and rat: cytochemical identification using two different lectins.

Microglial cells were selectively demonstrated in the central nervous system of adult rabbits and rats using lectin histochemistry. Biotinylated Ricinus communis agglutinin-120 (RCA-1) and biotinylated Griffonia simplicifolia B4 isolectin (GSA I-B4) were used as histochemical markers on sections of Bouin-fixed paraffin-embedded cerebrum and cerebellum. Results were quite similar using both lectins and both species. GSA I-B4 resulted in a better staining in the rat, while RCA-1 labelling was superior in the rabbit. Neither neurons nor glial cells other than microglia were stained with our technique. Lectin histochemistry applied for the detection of microglial cells appears to be of sufficient selectivity and may be considered as an important tool in the morphological and neurobiological study of these cells.

Animals↗

PubMed1991

Postnatal development of the interstitial cells (palisade cells) of the pars intermedia in the cat pituitary gland. An immunocytochemical and ultrastructural study.

The postnatal development of the interstitial agranulated cells (so-called palisade cells) of the pars intermedia in the cat was investigated immunocytochemically and at the ultrastructural level. Since the first postnatal days, a strong vimentin immunoreactivity and a weaker S-100 protein immunoreactivity were detected in the marginal cells lining the pituitary cleft and in the interstitial bipolar cells located within the pars intermedia. No glial fibrillary acidic protein cells have been found in the pars intermedia of any of the animals studied. This immunocytochemical pattern was maintained throughout the postnatal development. Ultrastructurally these cells showed a vast number of cytoplasmic filaments and well-developed junctional complexes. Secretory granules were never seen. In older animals they lined microcavities and microchannels where they project microvilli and present pinocytotic vesicles on their apical surface. No transitional forms between these cells and granulated secretory cells were found. There is a large number of axons and synaptic endings in contact with the granulated secretory cells. From our findings we guess that palisade cells are not a glial derivative, but they may share a common origin with secretory granulated cells.

Age Factors↗

PubMed1991

Ultrastructural study of the neuroglial and macrophagic reaction in Wallerian degeneration of the adult rat optic nerve.

The Wallerian degeneration of the optic nerve of adult rat has been studied after destroying the retina. Animals were sacrificed between 4 days and 1 year after the lesion. Different cell types of the optic nerve have been studied ultrastructurally. Our results demonstrate the existence of a population of macrophages, probably of microglial origin, responsible for scavenging degenerated myelin. Astrocytes suffer a process of proliferation and hypertrophy, and are massively stuffed by gliofilaments, leading to a glial scar. These cells apparently do not participate in phagocytic phenomena, while some cytoplasmic inclusions (e.g. lipid droplets) suggest some implication in the local metabolization of some tissue degradation products. Oligodendrocytes do not undergo ultrastructural changes, showing a rather quiescent appearance.

Animals↗

PubMed1991

Sex-related differences in the nuclear population of postpubertal rat pineal gland. A quantitative study.

Male and female parenchymal pineal cell types have been studied throughout postpubertal development to determine the existence of sex-related differences on a time basis. Six age groups (2, 3, 4, 8, 15 and 24 months) of eight rats (4 males and 4 females) were used in this study. Nuclei of both parenchymal pineal cell types were counted in 5 areas of 26.377 microns 2 per pineal gland on semithin sections. Nonparametric statistics of our results (Mann-Whitney U-test and Kruskal-Wallis H-test) demonstrated significant differences between male and female pinealocytes through the stages studied. In all age groups, the number of nuclei per unit area was larger in female rats. Pineoglial cells did not show significant sex-related differences.

Animals↗

PubMed1991

A lectin histochemistry study on the development of rat microglial cells.

A lectin-histochemical study on microglial development has been performed on the rat central nervous system. Isolectin B4 from the Griffonia simplicifolia (GSA I-B4) and Ricinus communis agglutinin-120 (RCA-1) were used as labelling lectins. Our results demonstrate the existence of microglial elements in the nervous parenchyma at E18, derived from the meningeal connective tissue layer. Later, another microglial source became evident, namely the cavum septum pellucidum, which serves for entrance of microglia pervading the supraventricular corpus callosum and the subependyma of the lateral ventricles. From P12 onwards, the microglial sources became inactive.

Animals↗

PubMed1990

Coexpression of vimentin and glial fibrillary acidic protein in astrocytes of the adult rat optic nerve.

The localization of vimentin (VIM) and glial fibrillary acidic protein (GFAP) was studied immunohistochemically in adult rat optic nerve. Consecutive Epon semithin tissue sections were immunostained respectively for VIM or GFAP. With this method, both antigens were detected in consecutive sections of the same cell. According to our results, most astrocytes in the adult rat optic nerve showed coexpression of VIM and GFAP.

Animals↗

PubMed1990

Postnatal development of the dog pineal gland: electron microscopy.

The ultrastructure of the dog pineal gland from the first postnatal day to the seventh month is described. In the first postnatal stages, pineal parenchyma only shows immature proliferative cells with abundant cytoplasmic glycogen. Nerve fibers are seen in the pineal connective tissue spaces. The differentiation of the dog pineal cell types begins in the first postnatal week. Both pinealocytes and pigmented cells are first seen on the fourth postnatal day. The pineal astrocytes are observed on the tenth day. Immature cells are still found in the pineal gland of 1 mo-old dogs. The differentiation of the dog pineal cell types is completed by the second postnatal month.

Animals↗

PubMed1990

Postnatal development of the dog pineal gland. Light microscopy.

The light microscopical morphology of the dog pineal gland from the first postnatal day to maturity is described. In the first postnatal week, the pineal parenchyma shows immature cells and many mitotic figures. In this week, pigmented cells are observed for the first time, both in the pineal gland and in extrapineal nodules. Throughout the second week, the pineal parenchyma shows a cordonal pattern that disappears progressively in the following stages. From the 20-30th day onward, it is feasible to discern the cell types characteristic for the adult pineal gland. In the adult animals, the length of the pineal gland axes almost quadruplies that of the pineal gland in neonatal stages. The light microscopical features of the adult dog pineal gland are also described.

Age Factors↗

PubMed1990

Ultrastructural changes in the rat pineal gland after sympathetic denervation. Quantitative study.

Ultrastructural changes in the rat pineal gland were studied quantitatively 7 and 60 days after the sympathetic denervation by bilateral excission or decentralization of superior cervical ganglia. The surface occupied by pineal parenchymal cells decreased in rats of experimental groups with respect to the control group. Furthermore, profile areas of the cytoplasm, nucleus and nucleolus of the pinealocytes were also diminished. Cytoplasmic lipid droplets in the pinealocytes were markedly decreased in number and size in experimental rats. As demonstrated by the Kruskal-Wallis H test, statistically significant differences were found between rats of the control and operated groups. Rats treated by superior cervical ganglionectomy or decentralization showed morphological changes indicating a hypofunctional pineal gland, although differences were found between both groups.

Animals↗

PubMed1989

Immunocytochemical localization of vimentin in stellate cells (folliculo-stellate cells) of the rat, cat and rabbit pituitary pars distalis.

The occurrence of vimentin, a specific intermediate filament protein, has been studied by an indirect immunoperoxidase method in the anterior pituitary gland of adult rats, cats and rabbits of both sexes. In the three species studied, the immunoreaction product was detected in the cytoplasm of stellate-shaped cells scattered throughout the pars distalis. These stellate cells showed long cytoplasmic processes which could be seen between the secretory cells, and occasionally, encircling them. These processes sometimes reach the vasculo-connective septa. The marginal cells lining the anterior layer of the hypophyseal cleft of the rat and the cat pituitary glands also showed a positive immunoreaction. Finally, cyst or follicle-like structures lined by immunostained cells with basal processes could be observed in the anterior lobe of the rat, but not in that of the rabbit or the cat. These findings support the previously held view that folliculo-stellate cells and marginal cells of the anterior pituitary gland have a common nature and suggest that these cell types might be derived from glial neuroectodermic cells.

Animals↗

PubMed1989

Immunocytochemical localization of vimentin in the posterior lobe of the cat, rabbit and rat pituitary glands.

The presence and distribution of vimentin, a subunit of intermediate filaments, in the neural lobe and in the pars intermedia of the cat, rabbit and rat pituitary glands were investigated immunocytochemically. In the pars intermedia, our study revealed the presence of vimentin in glial-like cells located between glandular secretory cells of the three species and in the cells of the marginal layer of the cat and rat hypophyseal cleft. In the neural lobe of the cat and rabbit pituitary glands, there was a large amount of cell processes and immunoreactive pituicytes. In contrast, in the rat neural lobe, few pituicytes exhibited immunoreactivity, and these were located principally in the posterior region near the pituitary stalk. The significance of immunoreactive vimentin in these cells is discussed.

Animals↗

PubMed1989

Immunohistochemical localization of intermediate filament and S-100 proteins in several non-endocrine cells of the human pituitary gland.

The presence and distribution of glial fibrillary acidic protein, vimentin, neurofilament protein, cytokeratins No. 8 (52 Kd), No. 18 (45 Kd) and No. 19 (40 Kd) and S-100 protein in pituicytes, folliculo-stellate cells, the epithelium of the Rathke's cysts and squamous cell nests of the pars tuberalis were investigated immunohistochemically by the peroxidase-antiperoxidase (PAP) method in eleven normal human pituitary glands. An identical immunostaining pattern was expressed by both folliculo-stellate cells and pituicytes. In both cell types the immunostaining for glial fibrillary acidic protein (GFAP), S-100 protein and vimentin was strongly positive. These results indicate the probable glial origin of the folliculo-stellate cell, and enlarge the group of glial cell types expressing vimentin. The co-expression of cytokeratins No. 8 and 19, both characteristic for simple epithelia, and S-100 protein was evident in the epithelial cells lining the Rathke's cysts and the squamous cell nests of the pars tuberalis. Furthermore, some epithelial cells of the Rathke's cysts co-expressed cytokeratins, S-100 protein and GFAP, a fact seldom reported and only in relation to rare neoplasms. The cytokeratin No. 18, characteristic for glandular epithelia, was not clearly demonstrated. Finally, the neurofilament protein was detected only in axons of the neurohypophysis; no immunopositive cells could be found throughout the adenohypophysis. Similarities in the antigenic patterns of these cell populations and the possible relation with their origin and nature are discussed.

Adult↗

PubMed1988

Ultrastructural study on meningeal regeneration and meningo-glial relationships after cerebral stab wound in the adult rat.

Meningeal regeneration and meninges-glial relationships during the reparation of an experimental brain stab wound, are studied with the electron microscope. At 14 days after the wound, a continuous newly formed basal lamina separates both nervous and meningeal tissues. Later, the astroglial processes of regenerated glia limitans showed very infolded surfaces and numerous filaments inside of them. Across the cavity left by the wound, filament-rich astroglial processes, forming bundles or glial cords of variable diameter, were seen. Each glial cord was surrounded by a basal lamina covered on the outside by a discontinuous sheet of meningocytic processes. Although regenerated meningocytes displayed interlacing processes forming a loose reticular network, large cellular meningocyte masses were also found.

Animals↗

PubMed1988

Presence of glial cells in the rat pineal gland: a light and electron microscopic immunohistochemical study.

Immunoperoxidase methods for the demonstration of three glial antigens, vimentin, glial fibrillary acidic protein, and S-100 protein, were applied to routine-fixed paraffin sections of rat pineal gland. A pre-embedding electron microscope immunoperoxidase method was also used to study the ultrastructural localization of S-100 protein in pineal cells. Light and electron microscopic results showed the presence of these antigenic glial markers in the second pineal cell type. The term glial cell is proposed for the second of parenchymatous cell in rat pineal gland.

Animals↗

PubMed1988

Ultrastructure of the pineal gland in the adult dog.

The adult dog pineal gland was studied with the electron microscope. Pineal connective tissue spaces were poorly developed and showed capillaries with nonfenestrated endothelial cells. Two cell types, pinealocytes and astrocytes, could be identified in pineal parenchyma. Dog pinealocytes showed microtubules, centrioles, occasional cilia, and well-developed Golgi complexes. These cells showed thin processes with bulbous endings packed with vesicles. Astrocytes were characterized by the presence of numerous filaments. Their processes finished forming a glial layer bordering connective tissue spaces. The presence of myelinated and unmyelinated nerve fibers was also described.

Actin Cytoskeleton↗

PubMed1988

Myofibroblasts in human palatal mucosa.

Myofibroblasts in human osseous palatal mucosa are described. They appear as fusiform or ramified cells, rich in homogeneous 60- to 70-Angström-thick microfilaments, rough endoplasmic reticulum cisternae, and abundant pinocytotic vesicles in relation with the plasma membrane. On the surface of these cells there are small areas covered by basal lamina. Contacts between myofibroblast processes and other tissue elements are described. Small clusters of oxytalan fibers appear in the vicinity of these cells.

Female↗