A.C. Assis Neto

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 Spixs 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 Spixs yellow-toothed cavy.

Spermatogenesis in goats with and without scrotum bipartition

The objective of the present research was to quantify the seminiferous epithelium cells, spermatogenesis efficiency and characterize the ultrastrucure of Sertoli cells in goats. Eighteen goats were used and divided into three groups: Group I - goats without bipartition of the scrotum; Group II - animals with bipartition of the scrotum in up to 50% of the testicular length; Group III - goats with bipartition of the scrotum in more than 50% of the testicular length. The goat testes in Group III had a greater number of primary spermatocytes (25.37 ± 4.55 cells per cross sections), spermatids (112 ± 15.12 cells per cross sections), and Sertoli cells (9.46 ± 1.74 cells per cross sections) than the animals in Groups I and II (P<0.05). The spermatogenic mitotic, meiotic, and general efficiency were greater in animals in Group III (1.25 ± 0.28; 5.12 ± 1.63; 6.44 ± 1.96) when compared to those in Groups I and II. Sheet-like processes originated from the Sertoli cell body as simple and smooth structures which involved almost all the surface of germ cells. Slender cord-like processes originated from Sertoli cells and also from the sheet-like processes. The relative frequency of the cycle stages showed differences among the groups of goats studied, and the highest frequency was in Stage 3 (20.68% for goats in Group I, 21.15% for those in Group II, and 16.89% for the animals in Group III). In conclusion, goats with bipartition of the scrotum have a greater number of germ and Sertoli cells per cross section of seminiferous tubule, that indicated a greater sperm production when compared to the other groups, and the ultrastructure of the Sertoli cell process did not present any relationship with bipartition of the scrotum.

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.

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.

Ultrastructure of the epididymis and vas deferens of agoutis at different stages of sexual development

The agouti (Dasyprocta spp.) is a rodent found predominantly in the Brazilian Caatinga and has importance as an alternative source of protein. In this study, the objective was to describe the ultrastructure of components of sperm pathways, especially the epididymis and vas deferens, during sexual development of agoutis kept in captivity. Segments of the vas deferens and epididymis of 8 agouti males at different stages of sexual development (prepubescent, prepubertal, pubescent, and adult) were fixed in glutaraldehyde. The following laboratory procedures were performed: histology following the standard protocol for semithin cut (toluidine blue), and transmission electron microscopy. This was a pioneer study in which it was observed that the epididymis of agoutis is composed of principal, basal, halogen, apical, and clean cells. During prepubescent and prepubertal stages, clean cells were observed in addition to principal, basal, and halogen cells. Once puberty was reached, apical cells were also present, and clean cells were no longer visible. This epithelial change during sexual development is possibly due to physiological functions. The interaction between these cells supports this, and age probably influenced the change. With regard to the vas deferens, this study was also a pioneer to note that before pubescence there were two muscle layers, differing from older animals, which had three muscle layers. This may be due to lack of sperm transit in younger animals. We concluded that the pseudostratified stereociliated epithelium of the epididymis and vas deferens of agoutis kept in captivity undergo morphological and functional changes during sexual development.

Steroidogenesis during postnatal testicular development of Galea spixii

The androgen/estrogen balance is essential for normal sexual development and reproduction in mammals. Studies performed herein investigated the potential for estrogen synthesis in cells of the testes of a hystricomorph rodent, Galea spixii The study characterized the expression of the key enzymes responsible for estrogen and androgen synthesis, cytochromes P450 aromatase (P450arom), 17α-hydroxylase/17,20-lyase (P450c17) respectively, as well as the redox partner NADPH cytochrome P450 oxido-reductase (CPR) required to support electron transfer and catalysis of these P450s, by immunohistochemistry (IHC) and quantitative polymerase chain reaction (qPCR) analysis, throughout postnatal sexual development. Testes (immature, pre-pubertal, pubertal and post-pubertal) were collected, fixed for IHC (CYP19, CYP17 and CPR) and stored frozen for qPCR for the relevant gene transcripts (Cyp19a1 and Cyp17a1). Expression of P450c17 was significantly elevated at the pre-pubertal and pubertal stages. Based on IHC, P450c17 was expressed only in Leydig cell clusters. The expression of P450arom was detectable at all stages of sexual development of Galea spixii IHC data suggest that estrogen synthesis was not restricted to somatic cells (Leydig cells/Sertoli cells), but that germ cells may also be capable of converting androgens into estrogens, important for testicular function and spermatogenesis.

Bovine conceptus of Bos indicus produced by somatic cell nuclear transfer and parthenogenesis present morphological variations since the blastocyst stage

In cattle, embryo development is characterized by the appearance of two distinct cell layers, the trophectoderm and the inner cell mass. The latter will undergo differentiation to form the embryonic disc consisting of the epiblast and hypoblast. The aim of this study was to ultrastructurally characterize the bovine embryo from different in vitro production techniques, with emphasis on trophectoderm and inner cell mass cells. Bovine embryos on day 7 (conception = D1) of pregnancy, derived via in vitro production techniques, were fixed for light and transmission electron microscopy processing. Results suggested that embryos produced by nuclear transfer of somatic cells and parthenogenesis showed significant changes in macroscopic and microscopic structure. Size was reduced, and the inner cell mass had no defined shape. Furthermore, organelles responsible for the absorption processes, communication, growth, and cellular metabolism were fewer and had changes in shape, when compared to results in embryos produced by in vitrofertilization. We concluded that embryos produced by parthenogenesis and SCNT exhibit morphological differences when compared with IVF embryos, such as undeveloped blastocoel, poorly defined distribution of ICM, and morphological differences in organelles.