Muscles and innervation of the genital and postgenital abdominal segments of the female american cockroach Periplaneta Americana (L.) (Dictyoptera : Blattidae)

Abstract

The locations of skeletal muscles in abdominal segments 7–10 of female Periplaneta americana (Dictyoptera : Blattidae) are described, and the action of some of those attached to the gonapophyses is hypothesized. The muscles are innervated from a terminal synganglion, a composite formed by fusion of embryonic neuromeres of abdominal segments 7–11. Pathways of the 5 pairs of segmental nerves and 3 pairs of transverse nerves that issue from the synganglion are documented. In addition to supplying skeletal muscles, certain of the nerves can be traced to the oviducts, spermatheca, colleterial glands, ventral glands, hindgut, and apparently, to sensilla of the cerci, gonapophyses, paraprocts, tergum, pleura, and sternum. Homologous relationships of the nerves are proposed, and the observations are compared to those reported by others who have, for the most part, examined males only. Putative neurosecretory somata occur in abdominal segments 7 and 8, at the junction of the transverse and segmental nerves. The association may be comparable to the “link nerve” complex described by others.