Figure 2 in Morphology of the male reproductive tract in the water scavenger beetle Tropisternus collaris Fabricius, 1775 (Coleoptera: Hydrophilidae)

Figure 2 Histology of the male reproductive tract of T. collaris. (A) Longitudinal section of a testis showing the follicles (f); growth (a), maturation (b), and differentiation (c) zones; and vas efferens (ve) opening (arrow) into a vas deferens (vd) with lumen full of spermatozoa (asterisk). (B) Longitudinal section showing detail of the vasa efferentia (ve) in the confluence zone (black arrow) with the vas deferens (vd). The white arrow points to sperm bundles in the vas efferens. The asterisk indicates the lumen of a vas deferens with dissociated bundles. The arrowhead points to the epithelial of the vas deferens. (C and D) Details of the stages of spermatogenesis, showing zones of cell growth (a), maturation (b), and differentiation (c). The arrow points to a sperm bundle. Bars: A and B = 600 µm, C and D = 200 µm.