Male genital system of Pholcus phalangioides in subadult stage 1 (about four weeks before final molt). (a-b): Drawings of the palpal organ from medial (a) and lateral (b) view to characterize the age of the observed males. (c): Longitudinal section of the male genital system (anterior = left). The vas deferens and large part of the testis are bordered ventrally by silk glands. The proximal part of the lumen of the vas deferens is very voluminous and filled with some spermatozoa and dense secretion. (d): Longitudinal section in the region of the genital opening (arrow). In this part, the vas deferens has a very narrow lumen without recognizable content. (e): Transition between testis and vas deferens. The connection between these two parts has a valve-like appearance. The vas deferens possesses a thick epithelium and is filled with dense secretion and some spermatozoa. (f): Section of the testis. Note germ cells at different stages of spermatogenesis in cysts. The branched lumen is very narrow and a secretion is not yet recognizable. Mg, midgut gland; Sg, silk gland; Sp, spermatids; Te, testis; Vd, vas deferens.