Histologia

Flamini, M.A., Barbeito, C.G., Gimeno, E.J. and Portiansky, E.L. 2009. Histology, histochemistry and morphometry of the ovary of the adult plains viscacha (Lagostomus maximus) in different reproductive stages. -Acta Zoologica (Stockholm) 90: 390-400

Flamini, M.A., Barbeito, C.G. and Portiansky, E.L. 2014. A morphological, morphometric and histochemical study of the oviduct in pregnant and nonpregnant females of the plains viscacha (Lagostomus maximus). -Acta Zoologica (Stockholm) 95: 186-195.

Thymulin is a thymic hormone exclusively produced by the thymic epithelial cells. It consists of a nonapeptide component coupled to the ion zinc, which confers biological activity to the molecule. After its discovery in the early 1970s, thymulin was characterized as a thymic hormone involved in several aspects of intrathymic and extrathymic T cell differentiation. Subsequently, it was demonstrated that thymulin production and secretion is strongly influenced by the neuroendocrine system. Conversely, a growing core of information, to be reviewed here, points to thymulin as a hypophysotropic peptide. In recent years, interest has arisen in the potential use of thymulin as a therapeutic agent. Thymulin was shown to possess anti-inflammatory and analgesic properties in the brain. Furthermore, an adenoviral vector harboring a synthetic gene for thymulin, stereotaxically injected in the rat brain, achieved a much longer expression than the adenovirally mediated expression in the brain of other genes, thus suggesting that an anti-inflammatory activity of thymulin prevents the immune system from destroying virus-transduced brain cells. Other studies suggest that thymulin gene therapy may also be a suitable therapeutic strategy to prevent some of the endocrine and metabolic alterations that typically appear in thymus-deficient animal models. The present article briefly reviews the literature on the physiology, molecular biology, and therapeutic potential of thymulin.

We have investigated the effects of EA21a and EA34 mammary carcinomas on daily PI cell proliferation in mice. Animals were divided into groups grafted with either EA34 or EA21a carcinomas (and a non-grafted control group). They were all injected intraperitoneally with 2 mg colchicine per g of body weight 4 h before sacrifice and the number of mitoses per 1000 nuclei was calculated. The mitotic index (MI) of pars-intermedia epithelial cells in control animals showed significant temporal variations. However, the MI from mice grafted with EA34 or EA21a carcinomas showed no such variation. There was no difference between the daily MIs of controls and tumor grafted groups. The absence of a 24 h mitotic activity curve in both EA21a and EA34 tumorbearing animals demonstrates a lower level of synchronization of cells entering mitosis. Ó

Tongue keratinocytes have high S-phase and mitotic indices with evident circadian variation. Transplanted tumors modify the intensity and temporal structure of the S-phase index in cell populations in tumor-bearing animals; also, partial hepatectomy changes the concentrations of substances involved in cellular proliferation, leading to compensatory liver hyperplasia. The aim of our study was to analyze the interaction between tumor growth and the liver regeneration that follows partial hepatectomy, and the effects of both these processes on lingual keratinocytes. We used 380 adult male mice divided into six groups: tumor-free and tumor-bearing mice without surgery, with sham hepatectomy, and with partial hepatectomy. Each group was divided into six subgroups, which were killed at 4-h intervals until a circadian cycle was completed (from 26 until 50 h post-surgery in the operated animals). Each animal was injected with 5-bromodeoxyuridine (50 mg/kg) 1 h before it was killed, and tongue samples were obtained and processed for histology. The sections were placed on silanized slides and incubated with the primary antibody Bu 20a (1/100 dilution). The reaction was developed using diaminobenzidine and staining was detected visually. SIs were measured as the number of labeled nuclei per thousand cells. The mean AE S.E. of each group was calculated. Differences among experimental groups were analyzed by ANOVA and the StudenteNewmaneKeuls Multiple Comparisons Test. The results show that the presence of a tumor alters the normal circadian curve of SI in lingual keratinocytes, irrespective of whether the mice underwent surgery. This finding has to be considered in drug treatments for neoplasms and in experiments related to growth. Ó

In the brain, specific signaling pathways localized in highly organized regions called niches allow the persistence of a pool of stem and progenitor cells that generate new neurons in adulthood. Much less is known about the spinal cord where a sustained adult neurogenesis is not observed. Moreover, there is scarce information concerning cell proliferation in the adult mammalian spinal cord and virtually none in aging animals or humans. We performed a comparative morphometric and immunofluorescence study of the entire cervical region (C1-C8) in young (5 mo.) and aged (30 mo.) female rats. Serum prolactin (PRL), a neurogenic hormone, was also measured. Gross anatomy showed a significant age-related increase in size of all of the cervical segments. Morphometric analysis of cresyl violet stained segments also showed a significant increase in the area occupied by the gray matter of some cervical segments of aged rats. The most interesting finding was that both the total area occupied by ...

Aging is a process associated with both anatomical changes and loss of expression of some cell markers. Intermediate filaments are known to impart mechanical stability to cells and tissues. Some of them are present in different cell populations of the central nervous system. In order to explore the impact of extreme age we immunohistochemically characterized the changes in intermediate filaments and other cellular markers present in cells populating the gray matter cervical spinal cord of very old rats (28 months) taking young (5 months) counterparts as a reference. The spinal cord weight of the senile animals (12.6 ± 1.1 g) was significantly higher (P < 0.001) than that of the young animals (8.4 ± 1.1 g). Spinal cord length also increased significantly (P < 0.05) with age (7.9 ± 0.3 cm vs. 8.28 ± 0.1 cm for young and senile, respectively). An increase in both neurofilament staining area and density was observed in senile rats in comparison to young animals. A significant (P < 0.05) age-related increment in the mean area of the cervical segments was observed. Vimentin expression in the ependymal zone decreased in area and intensity during aging. Our data show that there are some significant changes in the morphological and histochemical patterns of the cervical spinal cord in senile rats. However, they do not necessarily represent a pathologic situation and may rather reflect plastic reorganization.