Drosophila Male Accessory Gland Displays Developmental Ground Plan of a Primitive Prostate

Conservation of developmental genetic toolkits of functionally comparable organs from disparate phyla reveals their deep homology, which may help overcome the challenges of their confounding categorization as either homologous or analogous organs. A male accessory sexual organ in mammals, prostate, for instance, is anatomically disparate from its phylogenetically distant counterpart--the male accessory gland (MAG)--in insects like Drosophila. By examining a select set of toolkit gene expression patterns, here we show that Drosophila MAG displays deep homology with the mammalian prostate. Like mammalian prostate, MAG morphogenesis is marked by recruitment of fibroblast growth factor receptor, FGFR, a tubulogenesis toolkit signaling pathway, starting early during its adepithelial genesis. Specialization of the individual domains of the developing MAG tube on the other hand is marked by expression of a posterior Hox gene transcription factor, Abd-B, while Hh-Dpp signaling marks its growth. Drosophila MAG thus reveals developmental design of unitary bud-derived tube--a ground plan that appears to have been reiteratively co-opted during evolutionary diversification of male accessory sexual organs across distant phylogeny.