Análise morfológica e funcional do processo espermatogênico em cobaios (Cavia porcellus) da pré-puberdade até a pós-puberdade / Morphological and functional analysis of spermatogenesis in guinea pigs (Cavia porcellus) from pre-puberty to post-puberty

Este estudo descreveu as análises morfológica e funcional do processo espermatogênico em cobaios (Cavia porcellus) de cinco (S5); seis (S6); nove (S9) e onze (S11) semanas de idade (N=5/grupo). Os aspectos analisados incluíram a contagem das populações celulares presentes no estádio 1 do ciclo do epitélio seminífero (CES), eficiência das mitoses espermatogoniais (RMi), produção meiótica (RMe), rendimento geral da espermatogênese (RGE), índice de células de Sertoli (ICS) e capacidade de suporte das células de Sertoli (CSCS). Os resultados mostraram que número médio de espermatogônias A, espermatócitos primários em pré-leptóteno/leptóteno, espermatócitos primários em paquíteno, células espermatogênicas totais e células de Sertoli mostraram variações numéricas em função da idade, entretanto, não detectadas estatisticamente, enquanto espermátides arredondadas aumentaram significativamente na puberdade e depois se estabilizaram. A produção espermatogênica de cobaios de 5 a 11 semanas não atingiu o ponto de estabilização e o RMi, RMe, RGE, ICS e CSCS mostraram variação numérica significativa em função da idade. Os resultados demonstraram que Cavia porcellus na pós-puberdade 2 são um modelo experimental vantajoso para estudos de processos de reconhecimento homólogos, alinhamento, e sinapses durante a prófase meiótica; o rendimento intrínseco da espermatogênese em cobaios é semelhante ao relatado para ratos Wistar, pacas e cutias (Dasyprocta sp.) e menor do que em preás, enquanto que a eficiência funcional das células de Sertoli é superior a de cutias e ratos Wistar e inferior à de pacas, rato espinhoso e catetos. Concluiu-se que em cobaios a espermatogênese está completamente estabelecida na semana 6 de idade, indicando a fase púbere do desenvolvimento sexual, e até a semana 11 eles não atingiram a produção espermática diária máxima e, portanto, a maturidade sexual.

This study describes the morphological and functional analysis of spermatogenesis in guinea pigs (Cavia porcellus) with five (W5), six (W6), nine (W9) and eleven (W11) weeks of age (n=5/group). The aspects analyzed include counts of cell populations present in stage 1 of seminiferous epithelium cycle (SEC), efficiency of spermatogonial mitosis (EMi), meiotic production (EMe), overall yield of spermatogenesis (EOS), Sertoli cell index (SCI) and carrying capacity of Sertoli cells (CCSC). The results showed that the average number of spermatogonia type A, primary spermatocytes in pré-leptóteno/leptóteno, primary spermatocytes in pachytene, total spermatogenic cells and Sertoli cells showed numerical variations according to age; however they were statistically not detected, while round spermatids increased significantly at puberty and then stabilized. The spermatogenic production of 5 to 11-week-old guinea pigs did not reach the stabilization point, and the RMi, RME, EOS, SCI and CCSC showed significant number variation as a function of age. The results demonstrate that Cavia porcellus in post-pubertal stage 2 are an advantageous experimental model to address studies on the processes of homologous recognition, alignment, and synapsis during meiotic prophase; intrinsic yield of spermatogenesis in guinea pigs is similar to Wistar rats, paca and agouti (Dasyprocta sp.) and lower than in cavies, whereas the functional efficiency of Sertoli cells is higher than in agouti and Wistar rats, and lower than in pacas, spiny rat and collared peccaries. We conclude that in guinea pigs the spermatogenesis is fully established at 6 weeks of age, indicating the pubertal stage of sexual development, and until week 11 they do not reach the maximum daily sperm production and therefore sexual maturity.

Vitamin C and oxidative stress in the seminiferous epithelium

In this article, we focus on the fundamental role of vitamin C transporters for the normal delivery of vitamin C to germ cells in the adluminal compartment of seminiferous tubules. We argue that the redox status within spermatozoa or in semen is partly responsible for the etiology of infertility. In this context, antioxidant defence plays a critical role in male fertility. Vitamin C, a micronutrient required for a wide variety of metabolic functions, has long been associated with male reproduction. Two systems for vitamin C transport have been described in mammals. Facilitative hexose transporters (GLUTs), with 14 known isoforms to date, GLUT1-GLUT14, transport the oxidized form of vitamin C (dehydroascorbic acid) into the cells. Sodium ascorbic acid co-transporters (SVCTs), SVCT1 and SVCT2 transport the reduced form of vitamin C (ascorbic acid). Sertoli cells control germ cell proliferation and differentiation through cell-cell communication and form the blood-testis barrier. Because the blood-testis barrier limits direct access of molecules from the plasma into the adluminal compartment of the seminiferous tubule, one important question is the method by which germ cells obtain vitamin C. Some interesting results have thrown light on this matter. Expression of SVCT2 and some isoforms of GLUT transporters in the testis have previously been described. Our group has demonstrated that Sertoli cells express functionally active vitamin C transporters. Kinetic characteristics were described for both transport systems (SVCT and GLUT systems). Sertoli cells are able to transport both forms of vitamin C. These findings are extremely relevant, because Sertoli cells may control the amount of vitamin C in the adluminal compartment, as well as regulating the availability of this metabolite throughout spermatogenesis.

Inmunorreactividad de enolasa en el epitelio seminífero senil humano / Immunoreactivity to enolase in the human senil seminiferous epithelium

El metabolismo energético intracelular compartimentalizado, activa la enzimo enolasa para formar ácido pirúvico. Este, substrato energético, debe ingresar a la mitocondria para continuar hacia el ciclo de losácidos tricarboxílicos. Sin embargo, durante la proliferación del epitelio seminífero ocurre una distribución y pérdida citoplasmática progresiva y disposición de las mitocondrias a nivel del flagelo inicial. en el presente estudio se describe la inmunoreactividad de la enzimo enolasa en las diferentes poblaciones celulares del epitelio seminífero, en testiculo humano senil. Se trabajo con un paciente de 70 años, sometido a orquiectomía subcapsular terapéutica. El tejido testicular fue fijado inmediatamente en formalina taponada al 10 por ciento y mantenido por 12 horas. Luego se procesó por técnicas histológicas corrientes e incluyo en parafina para obtener secciones de 5 um. Posteriormente se procedió a la reacción inmunohistoquímica para enolasa y revelación con complejo avidina-biotina. Finalmente se cuantificaron las distintas poblaciones celulares del epitelio seminífero con reacción positivo o negativa. Los resultados preliminares se expresan en porcentajes de células positivas respecto del total de células contadas (40x. se observó que la totalidad de las células de Sértoli presentaron reacción negativa a la enolasa. En el epitelio seminífero se encontró que el 76 por ciento de las gonias (gonias tipo A y B) mostraron reacción negativa a la enolasa, mientras que en citos 1 se redujo al 10 por ciento y ausencia total en espermátidas y espermatozoides. Por lo tanto, las célula somáticas (de origen mesodérmico), del epitelio seminífero presentarían isoenzimas enolasas de reactividad diferente en la relación con la línea germinal (espermatogonias). Adicionalmente, en la línea germinal la inmunoreactividad a enolasa disminuye mientras progresa la espermatogénesis

Stereological and ultrastructural study of seminiferous tubules in normal testes and in patients with varicocele

Testicular biopsies from fertile men and patients with varicocele were evaluated and examined by using the recent stereological technique and electron microscope. This study quantitated the seminiferous epithelium using the stereological methods. The numerical density of the germ cells was generally reduced in patients with varicocele when compared with that in the normal fertile men. However such reduction was not associated with a similar change in the supporting Sertoli cells. Moreover, the different ratios between various germ cells and Sertoli cells were statistically reduced in varicocele group. The seminiferous tubules were examined by light and electron microscope. The tissue architecture of the tubules in varicocele patients ranged from mild to severely altered. In affected tubules, spermatid nuclear and acrosomal morpology was abnormal. Sloughing of the individual germ cells as well as the vacuolization and degeneration of the Sertoli cell cytoplasm were evindent. Furthermore, Sertoli-spermatid junctional complexes appeared to be structurally abnormal, whereas Sertoli-Sertoli junctional cornplexes appeared to be structurally intact. On the basis of the results in this work, the Sertoli cell is, in fact, the primary intratubular site of alteration in varicocele patients leading secondarily to sloughing and spermatogenic disruption