Postnatal growth of the ventral prostate in Wistar rats: A stereological and morphometrical study

Dynamics of the epithelium during canalization of the rat ventral prostate

Outgrowth and branching of solid cords are the initial events in postnatal prostatic morphogenesis. These processes involve cell proliferation and their projection into the stroma and precede epithelial canalization. The purpose of the present study was to examine the dynamics of the prostate epithelium during canalization of the rat ventral prostate in the first week of postnatal development using histological, stereological, and ultrastructural analyses. The terminal deoxynucleotidyltransferase [TdT]-mediated deoxy-UTP nick end labeling assay was used to investigate the occurrence of DNA fragmentation. Our results demonstrate that canalization of the prostate epithelium starts as early as on day 1 (24 hr after birth) and progresses thereafter. By the end of the first week (day 6), luminal volume density reached approximately 3% (P < 0.05) of the organ. Canalization was the result of epithelial cell differentiation and apoptosis. The former involved organization of the epithelial cells into a single layer sitting on the basement membrane, polarization, enlargement of secretory organelles and accumulation of secretory vesicles, microvilli formation, and establishment of the adult pattern of cell junctions. The latter was observed to occur mostly to epithelial cells not in contact with the basement membrane. Structures of variable electron density were observed in the developing lumen. In conclusion, different phenomena seem to be involved in the canalization of the rat ventral prostate. However, it was evident from the present results that complex epithelial cell fate decisions take place during this process.

Lobe Identity in the Mongolian Gerbil Prostatic Complex: A New Rodent Model for Prostate Study

Knowledge of structural and physiological differences among the prostatic lobes (PL) is the basis for development of experimental studies in traditional laboratory rodents. Although Mongolian gerbil reproductive organs have been increasingly investigated, its prostate structure is far from being properly known, and investigations of this organ focused on the ventral lobe (VL). Thus, the present study provides a thorough morphological description of prostatic complex in the male adult gerbil on the basis of topographic, histological, and ultrastructural analysis and ductal branching. Like other rodents, four pairs of PL were observed. However, in contrast to the rat and mouse, the VL is the least voluminous component and the dorsolateral lobe (DLL) is the most prominent and spatially isolated from remaining PL. The occurrence of a dorsal lobe (DL), hidden between bladder and insertion of seminal vesicles, has not been mentioned in previous reports with Mongolian gerbil. Collagenase digestion followed by microdissection revealed that, except for DL, which has a tubular-acinar organization, all PL exhibit tubular organization and variable ductal branching. Distinct histological and ultrastructural features such as secretory epithelium, aspect of luminal secretion and stromal organization are reported for each PL and are confirmed by morphometric and stereological methods. Histological sections showed at least three intralobar segments in VL and DL. Ultrastructural analysis evidenced that, although luminal epithelial cells of PL share typical features of exocrine secretory cells, there are striking lobe phenotypical variations. Both merocrine and apocrine pathways are observed in variable rates in all PL, with the predominance of the former in the DLL and the latter in the CG. The morphological observations presented herein point to distinct structural identities for each PL, which probably reflects specific functional compromise of seminal fluid secretion. These data also point to the gerbil as a good model for investigations concerning the regulation of prostate development and homeostasis, mainly with regard to the dorsal and dorsolateral PL.

Melanocytes in the Testes ofEupemphix nattereri (Anura, Leiuperidae): Histological, Stereological, and Ultrastructural Aspects

Ectothermic vertebrates have a well-developed system of melanin-containing cells, which localize in several organs and tissues and compose an extracutaneous pigmentary system. This research aimed at characterizing histological and ultrastructural patterns of pigmented cells in the testes of the anura Eupemphix nattereri (Steindachner, 1963), including the stereological and quantitative evaluation of this cell type in the gonads. Ten adult males were collected in Nova Itapirema, São Paulo, Brazil, and submitted to morphological studies with light and transmission electron microscopy. The testis presents a great number of large cells with many brown granules and long cytoplasmic processes. The pigmented cells found in the testis are structurally similar to melanocytes, characterized by large amounts of melanosomes. The cells may be in intimate contact with the same cell type, with myoid cells surrounded by a large amount of collagen fibers, Leydig cells, and next to fibroblasts. The distribution and amount of extracutaneous melanocytes is variable when other organs and membranes are analyzed, allowing the establishment of species-specific patterns for the extracutaneous pigmentary system.

Tissue evidence of the testosterone role on the abnormal growth and aging effects reversion in the gerbil (Meriones unguiculatus) prostate

Prostate differentiation during embryogenesis and its further homeostatic state maintenance during adult life depend on androgens. Abundant biological data suggest that androgens play an important role in the development of the prostate cancer and other prostatic diseases. The objective of this work was to evaluate the effects of the testosterone supplementation in gerbil (a new experimental model) at different ages. Tissues from experimental animals were studied by histological and histochemistry procedures, androgen receptor immunohistochemistry assay, morphometric-stereological analysis, and transmission electron microscopy (TEM). After the treatment were observed increase of prostate weight and epithelium height in all ages studied. In some adult and aged treated animals, hyperplasic and dysplastic process were observed, including prostatic intraepithelial neoplasias and adenocarcinomas. Increase of the thickness of the smooth muscle cell (SMC) layer was observed in pubescent and adult animals and TEM revealed apparent SMC hypertrophy. An apparent increase in the frequency of blood vessels distributed by the subepithelial stroma in the treated animals was noticed. Reversion of the natural effects of aging on the prostate was observed in the aged treated animals in some acini of the gland. These data demonstrate that the gerbil prostate is susceptible to androgenic action at the studied ages and it can serve, for example, as experimental model to studies of prostate neoplastic process induction and hormonal therapy in aged animals.