Differences in the morphology of the Processus vaginalis with sex and underlying disease condition

The structures of sacs from boys and girls with inguinal hernia, and from b oys with undescended testis or hydrocele were evaluated and compared. Parti cular attention was directed to determine if a clue helpful in describing t he mechanism of obliteration of processus vaginalis (PV) exists. Sacs from boys (n: 8) and girls (n: 11) with inguinal hernia, and sacs from boys with undescended testis (n: 11) and hydrocele (n: 10) were obtained a nd stained with hematoxylin-eosin, trichrome and elastic van Gieson. The hi stologic structures of each group of samples were determined and compared. Smooth muscle was presented as a layer within the sacs of girls and bays wi th inguinal hernia. However, smooth muscle bundles were sparsely presented in sacs associated with undescended testis and hydrocele. Myofibroblasts we re commonly encountered in sacs associated with inguinal hernia. The smooth muscle was invariably presented in sacs that contained myofibroblasts. Whi le sacs from boys only had smooth muscle, sacs from girls also had striated muscle. Since the muscle components of sacs vary, PV is sexually dimorphic. Persist ence of PV seems to be associated with the presence of smooth muscle and my ofibroblasts within the sac wall. Myofibroblasts may have originated from t he smooth muscle, and reflect the attempts at obliteration of PV.