The anatomy, histology and androgen receptor immunohistochemistry of the prostate (P), seminal vesicles (SV), bulbourethral and coagulant gland (CG) were studied in male viscacha, a seasonally reproductive wild rodent. Two histologically well-defined zones, peripheral and central, were identified in the prostate, according to their relationship with the urethra. The epithelial cells were periodic acid-Schiff (PAS)-positive in the central zone and alcian blue negative in the two zones. The SV are a paired gland, tubular, of tortuous aspect and formed by radial layers. The bulbourethral glands were paired, formed by tubuloalveolar acini and surrounded by a thick layer of skeletal muscle. The CG was multilobulated. The large adenomers showed PAS-positive epithelium and were negative to alcian blue. Androgen receptors in the P, SV and coagulating gland showed variations in their distribution with immunohistochemistry heterogeneous pattern. Finally, the reproductive system accessory glands of male viscacha may be considered as a novel and interesting model for the study of seasonal reproduction in photoperiod-dependent animals.

The axons that constitute the ovarian nervous plexus originate mostly in the principal neurons of the superior mesenteric ganglion (SMG) that is part of the sympathetic ganglionic chain and exhibits cholinergic receptors. In order to observe the effect of acetylcholine, the main neurotransmitter in the ganglionic transmission, the purpose of the present work was: first, to standardize an integrated ex vivo superior mesenteric ganglion-ovarian nervous plexus-ovary (SMG-ONP-O) system in oestrus day rats; secondly, to determine if the ganglionic cholinergic stimulus modifies the release of nitric oxide and steroids in the ovary compartment in the absence of humoral factors; and thirdly, to investigate if there are differences in the responses between the left and right ovaries caused by the neural stimulus. The ex vivo experimental left and right systems were developed and standardized. The systems were incubated in Krebs-Ringer phosphate buffer in a Dubnoff metabolic shaker. The progesterone release was determined to standardize the incubation times, obtaining different responses between the left and right systems, which shows that both systems have their own autonomic tone. Non-specific stimulation with KCl in the ganglion compartment provoked different responses in terms of release of progesterone and oestradiol. Progesterone decreased in the left and right systems.However, oestradiol diminished at short times and increased at 60 and 120 min in the left ovary, whereas it increases at 30 and 60 min in the right ovary. These different responses show the sensitivity and viability of both systems. When acetylcholine was used in the ganglion compartment, the release of nitric oxide, progesterone, androstenedione and oestradiol was evaluated. The liberation of nitrite increased at 15, 30 and 60 min in the left system and decreased in the right system at 120 min. Progesterone showed a decrease in its release at 15, 30 and 120 min and androstenedione at 15 min in the left ovary compartment. In the right ovary, only progesterone decreased in relation to the control at 120 min while androstenedione did not show significant changes. Oestradiol showed an increase in the left ovary compartment at all the studied times, while in the right ovary it did not show any changes. These results indicate that the neural stimulus from the superior mesenteric ganglion through the ovarian nervous plexus is one of the factors modulating the secretory activity of the ovarian steroids and nitric oxide. The system is viable and also shows a different sensitivity of the left ovary in relation to the right one at least in this cycle stage, characterized by marked irrigation and profound structural changes in the ovary.

The gonadotropes, LH and FSH cells, were immunohistochemically identified in the pituitary pars distalis of the adult male viscacha (Lagostomus maximus maximus) using specific antibodies against hLH‚ and hFSH‚ with the streptavidinbiotin- peroxidase complex. The distribution, size and percentage immunopositive area of these cells were analyzed by image analysis in viscachas captured during the annual reproductive cycle and after the chronic administration of melatonin. The LH‚ and FSHb cells showed seasonal changes in the distribution, size and percentage immunopositive area. The LHb cells were found widely distributed throughout the pars distalis during the reproductive period, and they were found in the ventro-medial region in the pars distalis during the gonadal regression and gonadal recovery periods. The LHb cells reached the largest size and immunopositive area during the reproductive period and the smallest size and immunopositive area during the gonadal regression period. The FSHb cells were found in the ventro-medial region during reproductive and gonadal regression periods. The FSHb cells were found widely distributed throughout the pars distalis during the gonadal recovery period when they showed the maximum percentage immunopositive area. A decrease in the size of LH‚ and FSHb cells was observed after the chronic administration of melatonin. Moreover, it produces a decrease in the immunopositive area occupied by the LH‚ cells but not in the immunopositive area occupied by the FSHb cells. Our results show great activity of LHb and FSHb cells in different moments of the annual reproductive cycle demonstrating that these cells are not secrete in parallel. Moreover, melatonin acts differentially on the activity of the gonadotrope cells

This research explores the initial assembly of the blood-testis barrier (BTB) during puberty, when a massive physiological apoptosis in the first spermatogenic wave takes place. Fragments of testis from 14-to 20-dayold rats were studied by conventional transmission electron microscopic techniques. Lanthanum hydroxide was used as an intercellular tracer. Light microscopy was used to confirm apoptotic death when paraffin-embedded sections were studied by TUNEL analysis. When the seminiferous cords reached the zygotene-pachytene spermatocyte level, they exhibited abundant apoptotic figures, whereas the remaining segments showed sporadic apoptosis. We found a BTB not yet assembled in the cords with zygotene-pachytene spermatocytes and abundant apoptosis. The observed apoptosis frequency diminished drastically when BTB was organized, as confirmed by the use of the tracer. Our conclusion is that the massive apoptosis found in the zygotene-pachytene spermatocytes between days 14 and 20 coincides with an open BTB. The absence of BTB could be one of the factors causing massive apoptosis of zygotene-pachytene spermatocytes, at least within the time span analyzed. The zygotene-pachytene spermatocytes are left exposed in an open environment instead of being isolated in the adluminal compartment to which they are destined. Anat

Somatotrophs were identified and quantified in pituitary pars distalis of male viscachas (Lagostomus maximus maximus) during the annual reproductive cycle, after the administration of melatonin, after castration and in different growth stages by immunohistochemistry and morphometric analysis. In adult male viscachas, the somatotrophs were distributed throughout the pars distalis during the reproductive cycle. They were oval, pyramidal or round in shape with a large round nucleus. The percentage immunopositive area, the major cellular diameter and the number of cells decreased during the gonadal regression period in relation to the values found in the reproductive period. The administration of melatonin did not provoke any variations of the morphometric parameters studied. On the contrary, a significant decrease in the percentage immunopositive area, in the major cellular diameter and in the number of somatotrophs in castrated viscachas was observed. The study of different growth stages showed that these morphometric parameters increased from immature to adult animals in the reproductive period. The results obtained suggested that the variations of the morphometric parameters of somatotrophs are more related to the gonadal development and activity than to a direct effect of melatonin.