Figure 3. Male reproductive system of Salmoneus carvachoi* A, B, detail of the PVD showing the lumen of anterior part completely filled with spermatozoa immersed in the basophilic secretion type I* In the posterior part of the PVD the spermatozoa are packed at the opposition side of the typhlosole, which is salient to the PVD tube* The typhlosole epithelium is columnar and different of the rest the posterior part epithelium, which is smooth* The typhlosole produces a secretion type II (black arrow) more basophilic and an unstained material (white arrow) promoting the sperm mass formation* A, haematoxylin and eosin; B, xylinine ponceau stain* C–F, the secretion type I is reactive to proteins, weak positive to neutral polysaccharides and negative to acid ones* On the other hand, the secretion type two depicts two compounds a globular (white arrow), positive to proteins and neutral polysaccharides without acid ones while a homogeneous compound (black arrow) in contact to secretion type I is reactive to both polysaccharides neutral and acids* C, Xylidine ponceau stain; D, PAS stain; E, F, Alcian blue stain* G, ultrastructure of medium vas deferens (MVD) showing the typhlosole salient but more discrete than found in proximal region of vas deferens* H* Under light microscopy, the MVD exhibits a typhlosole formed by a columnar epithelium on a well-developed musculature sheet* Secretion type I is proteinaceous and occupies a significant portion of the lumen* Secretion type II also displays a protein reaction* The globular components (white arrow) appear to fuse together (black arrow) to form a thin layer* The globular secretion seems to fuse and form the external layer of the spermatophore at the opposite side of the typhlosole* Xylidine ponceau stain* EP, epithelium; L, testes lobule; M, musculature; MVD, medium vas deferens region; N, nucleus; PVDa, anterior part of proximal vas deferens; PVDp, posterior part of proximal vas deferens; SI, secretion type I; SII, secretion type II; T, typhlosole*