Published online by Cambridge University Press: 26 September 2008
In each oestrous cycle only a limited number of follicles are selected for ovulation whereas the remaining majority undergo atresia. The earliest and most prominent feature of atresia is the death of granulosa cells. Recent biochemical evidence has demonstrated that granulosa cell death during follicular atresia in swine (Tilly et al., 1992), bovine (Jolly et al., 1994) and rodent (Tilly et al., 1991) ovaries occurs by apoptosis, a process whereby cells die in a controlled manner. A biochemical event considered to be characteristic of apoptotic cell death is the intranucleosomal cleavage of genomic DNA into fragments 180–200 bp in size, which separate into a distinctive ladder-like pattern on agarose gel electrophoresis. Detection of this pattern of oligonucleosomes in DNA provides a marker of apoptotic cell death.