Reproductive dynamics of Leporinus obtusidens captured downstream from an important hydropower Station in Brazil / Dinâmica reprodutiva de Leporinus obtusidens capturados a jusante de uma importante usina hidrelétrica no Brasil

This study evaluated the reproductive dynamics and gonadal morphology of piaparas (Leporinus obtusidens) captured downstream from the Funil Hydroelectric Power Station. The 107 piaparas evaluated were captured monthly from Sep 2006 to Aug 2007. The data were stratified among the seasons to evaluate gonad maturation and the reproductive period was determined by assessing the gonadosomatic index, hepatosomatic index, abdominal fat index (AFI), weight:length ratio, condition factor and sexual proportion. The reproductive period lasted from winter to summer (Jul-Mar) in females and from spring to autumn (Sept-Jun) in males. AFI was high during and after the reproductive period in females and only during the reproductive period in males. The highest HIS values for males and females were obtained in spring and summer (Sept-Mar). The females observed did not spawn and showed follicular atresia. These characteristics suggest that L. obtusidens does not use the study area as a reproductive site and probably migrates for this purpose.

Este estudo avaliou a dinâmica reprodutiva e a morfologia gonadal de piaparas (Leporinus obtusidens) capturados a jusante de uma usina hidrelétrica. Os 107 exemplares avaliados foram capturados mensalmente, de setembro de 2006 a agosto de 2007. Os dados foram estratificados entre as estações do ano para se avaliar a maturação gonadal, e o período reprodutivo foi determinado por meio da avaliação do índice gonadossomático, índice hepatossomático, índice de gordura abdominal (AFI), relação peso:comprimento, fator de condição e proporção sexual. O período reprodutivo foi observado do inverno para o verão, julho-março, para as fêmeas, e da primavera para o outono, setembro-junho, para os machos. AFI foi alto durante e após o período reprodutivo em fêmeas e apenas durante o período reprodutivo em machos. Os maiores valores para machos e fêmeas foram obtidos na primavera e no verão. As fêmeas observadas não desovaram e mostraram atresia folicular. Essas características sugerem que L. obtusidens não usa a área de estudo como sítio reprodutivo e, provavelmente, realiza migração.

Histological and immunohistochemical study of apoptosis in granulosa cells of atretic ovarian follicles of adult albino rat

It is well known that during ovarian follicular development, the majority of follicles undergo atresia at various stages of their development. Recent studies have reported that the degenerative changes associated with atresia appear initially in the granulosa cell layer, and follicular atresia occurs by apoptosis, which is an essential physiological process. The present study aimed to examine granulosa cell apoptosis using different, histological, immunohistochemical, and biochemical methods. Fifteen adult female albino rats were used in this study. The rats were sacrificed and bilateral oophorectomy was carried out; the ovaries of rats were processed and paraffin sections were prepared for staining with H and E and also to study immunohistochemistry for apoptotic proteins such as caspase-3 and antiapoptotic proteins such as B-cell lymphoma-2 [Bcl-2]. Some ovarian specimens were processed by electrophoresis for DNA separation. Apoptosis in granulosa cell showed morphological characteristics, including nuclei with marginated chromatin, a single condensed pyknotic nucleus, multiple nuclear fragments, and apoptotic bodies containing variable amounts of chromatin. Moreover, apoptotic changes were detected by immunohistochemical staining in the form of increased staining intensity to caspase-3 [apoptotic protein] and decreased staining intensity to Bcl-2 [antiapoptotic protein], and also increased fragmentation of DNA, which was indicated by a ladder step appearance that was detected using DNA electrophoresis

Occurrence and significance of ovarian and follicular regression in cachara Pseudoplatystoma fasciatum (Linnaeus, 1766): a histology approach

The processes of ovarian regression and follicular atresia which reproduction was not induced by hormone in confined cachara, Pseudoplatystoma fasciatum, were investigated. The macro and microscopic characteristics (oocytes diameter and histology) of the ovaries were described every 20 days, in four stages: initial regression (Rg I = first 20 days), intermediate regression (Rg II = from 21st to 40th day), final regression (Rg III = from 41st to 80th day) and the recovering stage, called resting II (R II = from 81st to 150th day). The experiment was conducted from late January (summer - longer days) to May (autumn - shorter days). In the beginning, A0 samples showed oocyte diameters ranging from 437.5 to 1,187.5mm, suggesting that oocytes were in perinucleolar, at final maturation and atretic phases. After 150 days, the diameters reached the lowest values and a ruptured zona radiata, as well as the nearly complete reabsorption of the yolk could be visualized. At the same time, a sharp decrease in the mean values of the gonadosomatic index (GSI), water temperature, photophase and rainfall was observed. The gradual involution of this long process was dynamic and complex, affecting the spawning success (fertilization, eclosion and larvae survival rates) and, consequently, the whole productive system.

Estudaram-se os processos de regressão ovariana e atresia folicular em cachara, Pseudoplatystoma fasciatum, mantida em cativeiro, na reprodução não induzida por hormônios. As características macro e microscópicas (diâmetro dos ovócitos e histologia) dos ovários foram descritas a cada 20 dias, em quatro estádios: na regressão inicial (Rg I - os primeiros 20 dias), na regressão intermediária (Rg II - do 21° ao 40° dia), na regressão final (Rg III - do 41° ao 80° dia) e na fase de recuperação ou de repouso II (R II - do 81° ao 150° dia). O experimento foi realizado do final de janeiro (verão-dias longos) a maio (outono-dias curtos). No início do experimento, as amostras apresentaram ovócitos com diâmetros que variaram de 437,5 a 1.187,5mm, sugerindo encontrarem-se nas fases perinucleolar, de maturação final e atrésicos. Aos 150 dias, os diâmetros atingiram os menores valores e pôde-se visualizar a zona radiata rompida e o vitelo reabsorvido. Concomitantemente, houve diminuição abrupta dos valores médios do índice gonadossomático, da temperatura da água, das horas de luz e de chuva. A involução gradual do longo processo foi dinâmica e complexa, afetando o êxito da desova (taxas de fertilização, de eclosão e de sobrevivência de larvas) e, conseqüentemente, o sistema produtivo.

Subpopulations of physiological and ovarian follicular fluid peptide induced apoptotic cells.

Ovarian follicular fluid peptide (OFFP) purified from sheep ovaries enhances apoptotic changes in ovarian granulosa cells of mice. To get an insight into the cell subpopulations responding to OFFP, the heterogeneity of granulosa cells was resolved. Subpopulations of granulosa cells were obtained from ovaries of immature mice treated with PMSG alone and autopsied 48 hr (control) and 72 hr after injection (atretic) and from animals injected OFFP 24 hr after PMSG injection and autopsied 24 hr later (OFFP treated) by separation on discontinuous Percoll gradient. Four fractions were collected and studied for their relative distributions and percent apoptotic cells measured by acridine orange staining. FSH binding to granulosa cell (sedimenting as a major) fraction was studied by radio receptor assay. There is a difference in densities in subpopulations of apoptotic cells induced by OFFP and those generated during the physiological process of atresia. This difference may be a reflection of different granulosa cell subpopulations involved in peptide response or differences in phases as the cells transit from normal to apoptotic phenotype. FSH binding to granulosa cells from OFFP treated animals was significantly less than those from control and atretic group.

Mecanismos do consumo folicular ovariano / Mechanisms of ovarian follicle depletion

Este estudo resume o conhecimento atual dos mecanismos envolvidos no consumo folicular no ovário humano. Após o desenvolvimento da gônada e início dos processos de mitose e meiose das oogônias e oócitos, o número de oócitos alcança cerca de 6 a 7 milhöes ao redor da 22ª semana de gravidez. No momento do nascimento o número de oócitos fica reduzido a 1-2 milhöes, refletindo consumo folicular na vida intra-uterina. No início da puberdade o número total de folículos foi reduzido a 400.000. A partir daí, mais de 99,9 por cento dos folículos sofrem degeneraçäo ao longo da vida e apenas 0,1 por cento destes conseguem alcançar um desenvolvimento completo e serem ovulados. Este processo de consumo folicular é um evento complexo. Na vida intra-uterina a mulher perde a maioria dos folículos formados, como resultado de uma taxa de consumo muito rápida. Enquanto gonadotrofinas e certos peptídeos intra-ovarianos atuam como fatores favoráveis à sobrevida dos oócitos nesta fase, os androgênios, um peptídio semelhante ao GnRH e a interleucina-6 säo importantes indutores da atresia. Após o nascimento há diminuiçäo na taxa de consumo folicular e durante o menacme cerca de 1000 folículos säo consumidos a cada mês. Este número é aumentado após os 38 anos de idade, parecendo resultar da aceleraçäo na taxa de crescimento folicular ou de excessiva atresia dos folículos que se encontram em estágios iniciais de desenvolvimento. A apoptose parece ser o mecanismo básico celular de degeneraçäo ou atresia folicular.

Changes in catalase activity during follicular growth, atresia and luteinization in rat ovary.

Quantitative changes have been observed in the catalase activity during follicular growth, induced atresia and in corpora lutea of cycle and pregnancy. Large growing and preovulatory follicles showed higher enzyme activity as compared to the smaller follicles; the activity was mainly present in the thecal layer of the preovulatory follicle. After the blockade of ovulation with barbiturate, the activity increases significantly in the whole follicle and also in the thecal layers till third day of ovulation and afterward it declines on 5th day, suggesting that rise in catalase activity may exert a protective function against lytic actions of peroxide which is known to be produced in the ovary during several metabolic and steroidogenic events. The corpora lutea of the cycle showed significantly less enzyme activity than the corpora lutea of pregnancy. The significance of catalase activity during follicular and corpus luteum degeneration is discussed.

Chemotactic detection of incipient ovarian follicular atresia.

Chemotactic activity was measured in the follicular fluid collected from normal and atretic Graafian follicles isolated from the rat ovaries. The atresia of Graafian follicles was induced by pentobarbitone injections for 3 days beginning the day of proestrous. The chemotactic activity, as measured by direct morphological evaluation of cellular locomotion of individual cells and Boyden leading front assay, was significantly higher in follicular fluid from atretic follicles and it showed a progressive increase from day 1 to day 3 of blockade of ovulation. In vitro exposure of blocked follicles to PMSG and hCG on day 1, 2 and 3 failed to alter the chemotactic response of leukocytes towards follicular fluid of atretic follicles. Increased chemotaxis in the follicular fluid after 24 hr of blockade of ovulation appears to form an important criterion to identify atretic follicles well in advance, before the morphological symptoms of degeneration become apparent and the incipient change once induced in follicles is not reversed by gonadotropins.

Comparison of glucose-6-phosphate dehydrogenase activity in healthy and atretic follicles in rat ovary.

Changes in the glucose-6-phosphate dehydrogenase activity have been determined in relation to atresia of Graafian follicles in the rat ovary. Induction of atresia in follicles either due to absence of hCG in the hormonally stimulated immature ovaries or by repeated injections of pentobarbitone sodium to proestrous rats caused significant rise in the enzyme activity. Measurement of enzyme activity in isolated follicular compartments of healthy and atretic follicles revealed that it is significantly higher in the thecal tissue than the granulosa. Increase in enzyme activity in the atretic follicles than the healthy ones occurs due to its rise both in theca and granulosa cells. The significance of these changes in the enzyme activity in healthy and atretic follicles are discussed in relation to the precocious luteinization of cells in the follicular envelope with the onset of atresia.