Oogenesis of the German Cockroach: From Morphology to Regulation.

The German cockroach, Blattella germanica, has emerged as an important model organism for studying oogenesis, embryonic and postembryonic development, as well as morphogenesis. As an insect with panoistic ovaries, it provides unique insights into reproductive and developmental processes that differ significantly from those operating in holometabolous insects (including the model species Drosophila melanogaster), characterized by meroistic ovaries, i.e., the presence of specialized germline cells, termed the nurse cells. In panoistic ovaries, the nurse cells are absent; instead, both the oocyte and its nucleus, the germinal vesicle, are metabolically and synthetically active, relying on nutrients obtained directly from the hemolymph. A distinctive feature of B. germanica oogenesis is that during each gonadotrophic cycle, only the basal (terminal) ovarian follicle in each ovariole develops, while the others remain inactive until the basal one is oviposited.B. germanica is particularly advantageous as a model organism due to its relatively short reproductive cycle, ease of laboratory maintenance, and well-studied hormonal regulation. Its sensitivity to RNA interference (RNAi) and the potential for genome editing using DIPA (direct parental)-CRISPR further enhance its value for functional genomics and evo-devo studies.