We report the histological, immunohistochemical and ultrastructural findings of an exophytic cutaneous tumor composed of a mixture of typical basal cell carcinoma (BCC) and malignant fibrous histiocytoma. Nine previously reported carcinosarcomas of the skin are reviewed. We prefer the term "sarcomatoid carcinoma" for this rare neoplasm. Only the BCC showed a positive immunoreaction to cytokeratin; the sarcomatous component was negative, but it did express vimentin, and, focally, smooth-muscle-specific actin and KP1 (CD68). Both components showed p53 immunostaining.

In diabetes, the glomerular basement membrane undergoes thickening and structural alterations with loss of glomerular permselectivity properties. However, the onset of the alterations at early phases of diabetes is unclear. Aiming to determine the functional and structural alterations of the glomerular wall in the early stages of diabetes, we have studied the distribution of endogenous circulating albumin and type IV collagen in the glomerular basement membrane, using the immunocytochemical approach. The streptozotocin-injected hyperglycemic rat was our animal model. Renal tissues were examined after 10 days, 2, 4 and 6 months of hyperglycemia. Upon immunogold labelings, changes in the glomerular permeability to endogenous albumin were found altered as early as upon ten days of hyperglycemia. In contrast, no structural modifications were detected at this time point. Indeed, glomerular basement membrane thickening and an altered type IV collagen labeling distribution were only observed after four months of hyperglycemia, suggesting that functional alterations take place early in diabetes prior to any structural modification. In order to evaluate the reversibility of the glomerular alterations, two-month-old diabetic animals were treated with insulin. These animals showed a significant restoring of their glomerular permselectivity. Our results suggest a link between glycemic levels and alteration of glomerular permeability in early stages of diabetes, probably through high levels of glycated serum proteins.

Since their discovery in different human tissues by Zimmermann in 1898, primary cilia have been found in the vast majority of cell types in vertebrates. Primary cilia are considered to be cellular antennae that occupy an ideal cellular location for the interpretation of information both from the environment and from other cells. To date, in mammalian thyroid gland, primary cilia have been found in the thyrocytes of humans and dogs (fetuses and adults) and in rat embryos. The present study investigated whether the existence of this organelle in follicular cells is a general event in the postnatal thyroid gland of different mammals, using both immunolabeling by immunofluorescence and electron microscopy. Furthermore, we aimed to analyse the presence of primary cilia in various thyroid cell lines. According to our results, primary cilia are present in the adult thyroid gland of most mammal species we studied (human, pig, guinea pig and rabbit), usually as a single copy per follicular cell. Strikingly, they were not found in rat or mouse thyroid tissues. Similarly, cilia were also observed in all human thyroid cell lines tested, both normal and neoplastic follicular cells, but not in cultured thyrocytes of rat origin. We hypothesize that primary cilia could be involved in the regulation of normal thyroid function through specific signaling pathways. Nevertheless, further studies are needed to shed light on the permanence of these organelles in the thyroid gland of most species during postnatal life.

The internalization and degradation of glomerular filtered serum proteins by the proximal tubular epithelium has been extensively studied by microperfusion methods. By using a cationic probe that easily traverses the glomerular wall into the urinary space, we have performed a morpho-cytochemical and quantitative study of the in vivo endocytotic activity of the proximal tubular epithelial cell. Bovine serum albumin (BSA) was tagged with dinitrophenol (DNP) and cationized to pI over 8. It was introduced into the circulation of normal mice for 5, 10, and 30 minutes and the distribution of the labeling was determined by protein A-gold immunocytochemistry, using specific antiDNP antibodies on tissue sections of routinely aldehyde-fixed, osmiumpostfixed, and Epon-embedded kidneys. Cationic BSA-DNP was detected at the endothelial and epithelial sides of the glomerular basement membrane, and over capillary and tubular basement membranes. In the proximal tubular epithelial cell, labeling was present over microvilli as well as over endosomal and lysosomal compartments, with labeling intensities varying from one compartment to the other. Morphometric evaluations of the labeling demonstrated a progressive incorporation of the probe from microvilli and endocytic compartments at 5 minutes to endocytic and lysosomal compartments at 10 and then 30 minutes. When considering labeling densities, no significant differences were found on microvilli and basolateral membranes between times of circulation; however, the labeling density over endosomal and lysosomal compartments was very intense at 10 minutes compared with 5 minutes, decreasing at 30 minutes. Results from this study validate the cationic albumin tagged with DNP as a tool in the study of the quantitative aspects of protein endocytosis at the ultrastructural level, in the kidney tubular epithelium.

A study has been carried out to determine the presence of NE cells in the newborn rat lung. The localization of these cell was achieved by an argyrophil method. Both single NE and NEB, were found. Immunoperoxidase techniques were performed to determine NSE, serotonin and calcitonin production in these NE formations.