Ultrastructural deficiency in autonomic innervation in cremasteric muscle of boys with undescended testis

Background/Purpose: The cremaster muscles (CM) associated with undescended testis reveal neurogenic alterations that mainly affect type 2 fibers. The ultrastructure of CM has been evaluated to define if further evidence to ex plain the alterations could be identified. Methods: CM of 8 boys with inguinal hernia and 8 boys with undescended test is at similar ages were biopsied. Samples were processed for electron micro scopic evaluations. Semithin and thin sections were examined under an elect ron microscope. Results: The CM associated with inguinal hernia showed normal ultrastructur e. However, some alterations were encountered in CM associated with undesce nded testis. Unmyelinated fibers were diminished in number, and myelinated fibers were outnumbering the unmyelinated fibers. Marked disorientation of myofibers, redundant sarcolemma, empty sleeves of basal lamina, disarray of myofibrils, densely packed myofilaments, Z disk streaming, dilated sarcopl asmic reticulum, and dense-irregularly shaped mitochondria were repeatedly encountered. Satellite cells appeared inactive. Most of the fibers were con tracted. Conclusions: The decrease in number of unmyelinated fibers appears to repre sent a decrease in autonomic nerve fibers. The alterations within muscle fi bers may reflect a deficiency in autonomic innervation. Autonomic nervous s ystem is highly responsive to circulating androgens. Factors decreasing the vulnerability of autonomic nervous system against androgenic effects may r esult in a CM with neurogenic alterations, thus inhibiting testicular desce nt.