Ultrastructure of spermatogenesis and spermatozoa in agoutis during sexual development.

The aim was to study the ultrastructure of testicular parenchyma and define the morphological ultrastructure of spermatozoa of agoutis kept in captivity. Segments of testes from eight agouti males at prepubescence, prepuberty, pubescence and sexual maturity were fixed in glutaraldehyde. Laboratory procedures were performed for transmission electron microscopy. Spermatogonial cells of Type A - pale, Type A - dark, intermediate and Type B were found. Spermatocytes in the pachytene phase were abundant among primary spermatocytes. From the prepubertal phase, Sertoli cells exhibited invaginations in the nuclear membrane and lipid inclusions in the cytoplasm due to their phagocytic function. Leydig cells displayed higher metabolic activity during puberty as evidenced by the presence of lipid droplets. Spermatozoa were fully formed morphologically at prepuberty. The centriolar complex had partially degenerated and featured a centriolar space as in rodents. Sperm heads were tapered, without prominence of the acrosome or evidence of the perforatorium, differing from cavies, rats and mice. This is the first study to describe the ultrastructure of agouti spermatozoa. This research may assist as a basis for future work related to fertility and other biotechnologies applied to reproductive biology in agoutis.

Development of spermatogenesis in captive-bred Spix's yellow-toothed cavy (Galea spixii).

The aim of this study was to evaluate the phases of sexual development and spermatogenesis of Spix's yellow-toothed cavy (Galea spixii) based on analyses of the structural components of the testes. The testes of animals from 0 to 150 days of age were collected by orchiectomy, weighed, and processed for analysis by light microscopy. At 45 days of age, spermatozoa were seen in the tubular lumen. Spermatogenesis was not established in animals from 45 to 150 days of age. The stages of sexual development may be classified into the following phases: from birth to the age of 15 days (immature); 30 days of age (prepubertal); 45-105 days of age (pubertal); and 120 and 150 days of age (postpubertal). This is the first study to address the male reproductive biology of Spix's yellow-toothed cavy.

Daily sperm production and testicular morphometry in goats according to external scrotal conformation.

The present study aimed to compare testicular histology and the testicular cell population as well as spermatogenic efficiency in goats with different scrotal conformations. Eighteen goats were divided into 3 groups: Group I - goats without bipartition of the scrotum, Group II - animals with bipartition of the scrotum up to 50% of the testicular length, Group III - goats with scrotal bipartition more than 50% of the testicular length. In goats in Groups I, II and III, the values for the volume density of seminiferous epithelium were 68.9 ± 0.6%, 71.5 ± 2.8% and 73.4 ± 4.7% (P<0.05), the height of the seminiferous epithelium were 60.2 ± 4.9 µm, 61.0 ± 5.0 µm and 73.1 ± 6.6 µm (P<0.05), total length of seminiferous tubules found for Groups I, II and III were 2091.9 ± 27 m, 2172.5 ± 24.1 m, and 2340.1 ± 14 m (P<0.05), number of Sertoli and Leydig cells were 1.8 ± 0.4×10(9) and 1.4 ± 0.1×10(9), 2.2 ± 0.4 and 2.2 ± 0.7×10(9), and 2.5 ± 0.1 10(9) and 2.3 ± 0.5 10(9) (P<0.05) and daily sperm production observed were 2.1 ± 0.3×10(9), 2.8 ± 0.4×10(9), and 3.1 ± 0.7×10(9) (P<0.05). In conclusion, goats with greater scrotal bipartition have a greater capacity to produce reproductive cells that is reflected in a greater reproductive potential.

Cellular localization of androgen synthesis in equine granulosa-theca cell tumors: immunohistochemical expression of 17alpha-hydroxylase/17,20-lyase cytochrome P450.

Elevated blood testosterone concentrations, often accompanied by male-typical behaviors, is a common signalment of mares with granulosa-theca cell tumors (GCTCs), but no definitive information exists regarding the cellular differentiation of tumors associated with androgen secretion. This study was conducted to localize and thereby define the cellular expression of 17alpha-hydroxylase/17,20-lyase cytochrome P450 (P450c17), the enzyme most directly responsible for androgen synthesis, in 30 GTCTs and control tissues (gonads and adrenal glands) using immuno-histochemistry (IHC). Immuno-reactivity for P450c17 was evident in approximately half of 30 specimens examined, was most consistent in the interstitial cells surrounding existing or developing cysts, and was less intense in cells within cysts in the smaller proportion of specimens where this was observed. In control tissues, the expression of P450c17 was localized primarily in theca interna of normal ovarian follicles, in theca-lutein cells of some corpora lutea, but not in granulosa-lutein cells. Testicular interstitial cells and islands of adreno-cortical cells located in the adrenal medulla of the adrenal cortex further established the specificity of the antisera used. These data provided the first substantive evidence that polyhedral cells identified previously in GTCTs by histopathology have the potential to synthesize and secrete androgens, similar to theca interna and theca lutein cells in normal equine ovaries.