Structural and ultrastructural aspects of folliculogenesis in Didelphis albiventris, the South-American opossum / Aspectos estructurales y ultraestructurales de la foliculogénesis de Didelphis albiventris, la zarigüeña sudamericana

The ovarian histology, the structural and the ultrastructural characteristics of the folliculogenesis in Didelphis albiventris were described in detail. Recent studies suggest that methatherian mammals have unusual reproductive cycle but there are few informations regarding the marsupials reproductive life. Despite of the opossum folliculogenesis pattern resembles methatherian and eutherian pattern in many aspects, the analysis shows some peculiar features of the oocyte structure and ultrastructure that make available new data on the reproductive biology of marsupials.

Fueron descritas con detalles la histología ovárica, las características estructurales y ultra-estructurales de la foliculogénesis del Didelphys albiventris. Estudios recientes sugieren que mamíferos metaterios tienen un ciclo reproductivo inusual, pero existen pocas informaciones en relación a la vida reproductiva de los marsupiales. A pesar de que el modelo de foliculogénesis de la zarigüeya se parece al modelo metaterio y euterio en muchos aspectos, el análisis muestra algunos rasgos peculiares de las estructura y ultra-estructura del oocito, que colocan a disposición nuevos datos en la biología reproductiva de los marsupiales.

Canine corpus luteum regression: apoptosis and caspase-3 activity.

The present study evaluated the occurrence of apoptosis and caspase-3 activity in the canine corpus luteum during the period of luteal regression in eight pregnant and nine nonpregnant diestrus bitches. Intact luteal cells were obtained from corpora lutea in both peripartum pregnant bitches and nonpregnant diestrus bitches at approximately 65 d (range 63-68) after estrus, but not at days 75 and 85 in nonpregnant bitches. In all bitches, apoptotic cells were rarely detected and when present, those cells were more easily detected using the hematoxylin and eosin technique than using the critical electrolyte concentration technique. The luteal structures at 75 and 85 d of diestrus had histological characteristics similar to a corpus albicans. Caspase-3 activity was detected in morphologically normal corpora lutea from both pregnant and diestrus bitches around day 65, and also in the later structures considered corpus albicans tissue. These results suggested that apoptosis may not be the major mechanism involved in canine functional luteal regression, and that caspase-3 participated in both functional and morphological luteolysis and in the tissue reorganization involved in corpus albicans formation.

Follicular diameter range based on morphological features in Synbranchus marmoratus (Bloch, 1795) (Teleostei, Synbranchiformes, Synbranchidae) from the South-central region of Brazil.

The morphological characteristics of Synbranchus marmoratus female germ cells in various development stages were described in details; then measurements of ovarian follicle diameters were taken from primary and secondary growth as during these development stages the oocyte size varied considerably along the fish growth. The results were correlated to total fish length, using the individuals division in six size classes. It was possible to group oocytes by stages according to histological characteristics but not according to morphometric diameter, as there was a wide variation in diameter in each stage and overlap between different maturation stages. These data make available new information on the reproductive biology of Synbranchidae.