Lack of carbachol response indicates the absence of cholinergic receptors in sacs associated with undescended testis

Background/Purpose: The mechanism of testicular descent remains controversi al. The processus vaginalis (PV) contains smooth muscle and should have con tractile activity that may contribute to descent. This study was designed t o evaluate the smooth muscle of PVs associated with incomplete obliteration for spontaneous activities and responses to various stimuli, to determine if differences exist according to sex, diagnostic source, or location of th e testis. Materials: Peritoneal samples (n = 4); sacs from girls (n = 8) and boys wit h inguinal hernia (n = 12); and sacs from boys with hydrocele (n = 3), hydr ocele of the cord (n = 2), or undescended testis (n = 7) were used for the current study. Tissues were attached to the isometric force displacement tr ansducer in an organ bath containing mammalian Ringer's solution at 37 degr ees C, Spontaneous mechanical activity and contractile responses of tissues to the electrical field stimulation, phenylephrine, carbachol, and seroton in were recorded. The values obtained from boys and girls with inguinal her nia and from boys with either undescended or descended testis were compared through Fisher's Exact test. Results: There were no statistically significant differences in patient age between groups. Among the parameters studied, only the carbachol response of the sacs associated with undescended testis showed a significant differe nce compared with the others (P =.001). None of the sacs associated with un descended testis responded to carbachol, whereas all of the sacs from boys and girls with inguinal hernia responded to carbachol. Conclusions: Lack of carbachol response suggests the absence of cholinergic receptors within the sacs associated with undescended testis. The lack of cholinergic receptors may play a role in the failure of the process of test icular descent by hindering either PV elongation into the scrotum or a poss ible propulsive activity of the PV on the testis. J Pediatr Surg 34:1339-13 44. Copyright (C) 1999 by W.B, Saunders Company.