Distribution and morphometry of fiber types in cremaster muscles of boys with inguinal hernia or undescended testis

In the present study, we determined and compared the distribution and mean diameters of fiber in the cremaster muscles (CM) of boys with either inguin al hernia (IH) or undescended testis (UT). Samples of CM were obtained from 20 patients (10 boys with IH, and 10 boys with UT) of similar age. The CM muscles of two boys each, without inguinal pathology, were sampled during autopsy. Sections were stained for oxidative and glycolytic enzymes, as well as for ATP-ase reactions after acid (pH: 4 .6) and alkaline (pH: 10.6) preincubations. Specimens were also analyzed mo rphometrically using a KONTRON 400 computerized image analysis system. The Mann- Whitney U test was applied to compare the percentages of fiber types and mean diameters of fibers according to the types of the CM of boys with IH or UT. In boys, the CM is mainly composed of type 1 fibers. The CMs of patients wi th UT reveal alterations of neurogenic origin. Although both type 1 and typ e 2 fibers reveal alterations, type 2 fibers appear to be affected more pro foundly and characterized by significantly decreased mean diameters. Signif icantly decreased mean diameters of type 2 fibers in CM may support disuse, lack of sensitivity to the hormonal influences, or an alteration in the co rticospinal tracts of boys with UT.