The distribution of the androgen receptor (AR) in the adult rat testis was determined by biotin-streptavidin immunoperoxidase, employing tissue embedded in polyester wax which preserves antigenicity without compromising tissue preservation. The antibody probe used, which has been characterized previously, was an affinity purified, rabbit polyclonal antibody raised to the amino terminus peptide of the rat AR. Within the interstitial compartment, AR immunostaining was detected in some Leydig cells and all smooth muscle cells forming the walls of blood vessels, but endothelial cells of blood vessels were negative. Furthermore, in those Leydig cells that were clearly identified as exhibiting AR immunostaining, the intensity of the reaction varied. In the seminiferous tubules AR immunostaining was observed in all peritubular myoid cell nuclei, but not in the distal layer of lymphatic endothelial cells. In Sertoli cells, nuclear AR immunostaining was stage specific. Moderate AR immunostaining first became evident at late stage IV or early stage V of the cycle, reached a robust peak at stages VII-VIII, and then disappeared completely. Specific AR immunostaining was also discerned in the nuclei of stage XI elongated spermatids, the spermatids in which nuclear elongation is apparent but chromatin condensation has not yet begun. Next, with onset of chromatin condensation, nuclear AR immunostaining in elongated spermatids was not discerned concomitant with its detection in the cytoplasm of the germ cells. These results are interpreted in the following manner: 1) The presence of AR in Leydig cells is consistent with the hypothesis that androgens modify Leydig cell activity in an autocrine fashion. Further, that not all Leydig cells exhibited AR immunostaining at steady state suggests a differential, functional activity of these cells within the population. 2) The intense AR immunostaining of smooth muscle cells present in the interstitium indicates that these cells are targets for androgens. 3) AR immunoreactivity in both Sertoli and peritubular myoid cells suggests their involvement in the androgenic control of spermatogenesis. The stage specific AR immunoreactivity in Sertoli cells, however, may be more indicative of a specific androgen response during these stages, whereas peritubular cells may participate in the tonal maintenance of spermatogenesis. 4) The specific presence of AR in step 11 elongated spermatids may suggest that androgens can act directly on germ cells to regulate spermatogenesis.

The distribution of the androgen receptor (AR) in the adult rat testis was determined by biotin-streptavidin immunoperoxidase, employing tissue embedded in polyester wax which preserves antigenicity without compromising tissue preservation. The antibody probe used, which has been characterized previously, was an affinity purified, rabbit polyclonal antibody raised to the amino terminus peptide of the rat AR. Within the interstitial compartment, AR immunostaining was detected in some Leydig cells and all smooth muscle cells forming the walls of blood vessels, but endothelial cells of blood vessels were negative. Furthermore, in those Leydig cells that were clearly identified as exhibiting AR immunostaining, the intensity of the reaction varied. In the seminiferous tubules AR immunostaining was observed in all peritubular myoid cell nuclei, but not in the distal layer of lymphatic endothelial cells. In Sertoli cells, nuclear AR immunostaining was stage specific. Moderate AR immunostaining first became evident at late stage IV or early stage V of the cycle, reached a robust peak at stages VII-VIII, and then disappeared completely. Specific AR immunostaining was also discerned in the nuclei of stage XI elongated spermatids, the spermatids in which nuclear elongation is apparent but chromatin condensation has not yet begun. Next, with onset of chromatin condensation, nuclear AR immunostaining in elongated spermatids was not discerned concomitant with its detection in the cytoplasm of the germ cells. These results are interpreted in the following manner: 1) The presence of AR in Leydig cells is consistent with the hypothesis that androgens modify Leydig cell activity in an autocrine fashion. Further, that not all Leydig cells exhibited AR immunostaining at steady state suggests a differential, functional activity of these cells within the population. 2) The intense AR immunostaining of smooth muscle cells present in the interstitium indicates that these cells are targets for androgens. 3) AR immunoreactivity in both Sertoli and peritubular myoid cells suggests their involvement in the androgenic control of spermatogenesis. The stage specific AR immunoreactivity in Sertoli cells, however, may be more indicative of a specific androgen response during these stages, whereas peritubular cells may participate in the tonal maintenance of spermatogenesis. 4) The specific presence of AR in step 11 elongated spermatids may suggest that androgens can act directly on germ cells to regulate spermatogenesis.

Despite the important role of calcium in the growth and differentiation of a variety of cell types, its exact location and function in the somatic and germ cells of the testis remain to be determined. In the present study, we examined the subcellular distribution of calcium in the immature and adult rat testis. Calcium was localized at the electron microscopic level by ion-capture cytochemistry using combined oxalate and pyroantimonate procedures. Calcium-containing precipitates localized primarily within the nuclei, mitochondria, and cytosol of somatic and germ cells. Differences in the size and quantity of the calcium precipitates were observed among the various cellular compartments. In the somatic cells (Sertoli, Leydig, and myoid), the nuclei exhibited large round-shaped calcium-containing precipitates, whereas the mitochondria in these cell types contained numerous smaller precipitates. The cytoplasmic vesicles possessed single precipitates. These vesicles could be calciosomes, which have been described in other non-muscle cell types. Among germ cells, round spermatids exhibited a large number of vesicular, calsiosome-like structures in the cytoplasm containing single precipitates. The elongating spermatids from adult testis showed calcium localization within the nuclear matrix unassociated with the nuclear envelope, or in a peripheral alignment of precipitates along the nuclear envelope. Calciosome-like structures were also seen in round spermatids. Spermatogonia and spermatocytes exhibited calcium in nuclei, mitochondria, and cytoplasmic vesicles. These results demonstrate a differential distribution of calcium within the various cell types of the testis. The presence of calcium in the nucleus may suggest a role in cell growth and differentiation; calsiosome-like structures may represent the active exchangeable pool of calcium, and the differential type of distribution of calcium in elongating spermatids suggests a role for calcium in spermatid differentiation.

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