Practice question

Unlike vertebrates where sperm induces activation, Drosophila oocytes activate during passage through female reproductive tract independent of fertilization. As mature stage-14 oocytes exit ovary into lateral oviduct, mechanical compression and osmotic swelling trigger calcium influx through Trpm channels, initiating a propagating calcium wave throughout ooplasm. This wave drives meiosis resumption from metaphase I, vitelline membrane crosslinking, mRNA polyadenylation via PNG kinase, and translation of stored transcripts. Fertilization occurs later in uterus after activation processes started, demonstrating fertilization-independent activation and explaining capacity for parthenogenesis observed in some insects.