Glial fibrillary acidic (GFA) protein in rat spinal cord. An immunoperoxidase study in semithin sections.

The distribution of glial fibrillary acidic (GFA) protein was examined in cervical spinal cord of adult rat, according to the immunocytochemical peroxidase-antiperoxidase (PAP) method in semithin sections (1-2 microns). We have found astroglial cells in proximal regions of both ventral and dorsal roots. The presence of astrocytic processes reaching the central canal, only in the dorsal region suggest that they are the only radial glia cells which remain attached to the central canal.

Glial fibrillary acidic protein (GFAP) in spinal cord of postnatal rat. An immunoperoxidase study in semithin sections.

The presence and distribution of gliofibrillary acidic protein (GFAP) was studied in the postnatal spinal cord of the rat. On birth GFAP can be seen in astrocytic bodies and their processes of ventral columns; perivascular glial membrane was initially seen within white and gray matter; most of the fibers were transversally oriented. There are many mitotic cells, some of them with GFAP in their cytoplasm, while others lack it, thus providing strong evidence to identify two cellular populations as astrocytes and, possibly, oligodendrocytes and to state that neuroglial cells differentiate to astrocytes before myelination gliosis. The glia limitans membrane is continuous from the 5th day onwards and in 17-day-old animals the astrocytic framework of the spinal cord has reached its adult appearance.

Structure of the piriform cortex of the adult rat. A Golgi study.

The piriform cortex (PC) was studied in the adult rat with anilines, rapid Golgi and Golgi-Colonnier techniques. As in other animals in the PC of the adult rat three layers can be distinguished: layer I or plexiform layer, layer II or superficial cellular layer and layer III or deep cellular layer. Golgi impregnations allowed to describe seven different types of cells. Pyramidal cells, in which it is possible to distinguish three subtypes (superficial, middle and deep pyramidal cells) by virtue of their morphology and location. Bipolar cells, a very little and scarce type of cell restricted to layer I and that has not been previously described. Fusiform cells, similar to those found in other species. Semilunar cells, also like those described in other animals but which are only found in the posterior PC. These cells resemble other type of cell, the ovoid cells that neither have been described in other animals and, on the contrary, are only located in the anterior PC. Stellate cells, which are a very wide population of cells with variable sizes, dendritic patterns and locations. Horizontal cells, similar to pyramidal cells but oriented in horizontal direction and polymorphic cells, whose the most striking feature is their smooth and beaded prolongations. Morphological features of these cells are compared with those described in the cells of the PC of other animals.

Intermediate filament aggregates in mitoses of primary cutaneous neuroendocrine (Merkel cell) carcinoma.

Primary cutaneous neuroendocrine carcinomas express different kinds of intermediate filaments and frequently in a 'paranuclear globular' pattern. We have observed the same pattern not only in interphase but also in mitotic cells, which are very frequent in these tumours. We report a quantitative and morphological study of eight primary cutaneous neuroendocrine carcinomas stained with different antibodies against cytokeratins (CAM 5.2 and anticytokeratin 20), neurofilaments (70 kDa and 200 kDa) and peripherin. We have found a predominance of CAM 5.2 expression in interphase cells and of neurofilament proteins in mitotic cells; 87.02% of the interphase cells were positive with CAM 5.2 whereas only 6.08% were positive for neurofilaments (P < 0.01); 35.41% of the mitotic cells were positive with CAM 5.2, whereas 50% were positive for neurofilaments (P < 0.01). A correlation between a globular pattern of intermediate filament proteins and prognosis has not been found. We describe for the first time the division of neoplastic cells with a globular pattern; the presence of intermediate filament proteins with a globular pattern in all mitotic stages; and the uneven distribution of this formation between the two daughter cells.