Prepubertal Oocytes

Abstract

Numerous studies of the processes of cell death in newborn to ­prepubertal mammals has been carried out mainly I rodents. In these animals this period was divided in three ranges of age: 1–10 days, 10–15 days and 15–28 days. One day old rats two structural patterns of oocyte dying in the first meiotic prophase can be ­distinguished: one with nuclear elongated parallel structures ­corresponding two synaptonemal complexes of oocytes dying in pachytene stage and the ­second ­pattern corresponding to diakinesis, a pseudo interphase, the last stage of the first meiotic prophase. In ovaries of 10–15 days old rats a large proportion of pre-antral and small antral follicles undergo atresia. Most these oocytes located in these ­follicles are simultaneously positive to active caspase-3, TUNEL markers of apoptosis and also to lamp1 and acid phosphatase markers of autophagy. In ovaries of 15–28 days old rats the simultaneous presence in the same oocyte of the four markers is frequent in atretic follicles. As in the previous groups, a small number of primary follicles are in process of atresia. The most frequent double association of markers is active caspase-3 (apoptotic marker) with lamp1 (autophagic marker). This association is five times more frequent than caspase-3 with TUNEL, both apoptotic markers. These data suggest that very early in the process of cell death, some features of apoptosis and autophagy are simultaneously present. The presence of one or several typical features of apoptosis as DNA fragmentation or caspase-3 are not per se a definitive sign that this cell is dying by an apoptotic pathway, at least until the presence of other processes of cell death as autophagy are determined in this cell. The same is valid for all processes of cell death.