Ultrastructural study of the gubernacular‐scrotal interface during testicular descent in the newborn rat

Abstract

AbstractThe gubernaculum has been described as the “rudder” that guides the testis into the scrotum. Prior to inguinoscrotal testicular descent, the gubernaculum rests in the groin and does not attach to the scrotum. Subsequently, it migrates and attaches to the scrotum under control of the genitofemoral nerve. This study evaluates, with electron microscopy, the relationship of the gubernaculum with the developing scrotum during normal testicular descent.Male rats were sacrificed at 0, 2, 4, 7, 10, 14, and 18 days (n = 2 for each group) and sagittal sections through the gubernacular‐scrotal interface evaluated with transmission electron microscopy. We observed the following with increasing animal age: (1) gubernacular cremaster muscle matured and nuclei shifted to the periphery of cells as connective tissue surrounding myofibers decreased, (2) scrotal fibroblasts initially showed high activity with dilated endoplasmic reticulum, but activity and number subsequently decreased, (3) scrotal collagen increased and organized into defined fibers and bundles, (4) a well‐delineated band of collagen developed along the gubernaculum and advanced towards the inferior scrotum, and (5) nerve fibers appeared between the layers of cremaster muscle, increased in number with increasing age, and became myelinated at age 14 days. Gubernacular migration is intimately associated with scrotal development and testicular descent. Knowledge of cellular and intracellular differentiation during migration in the normal animal can further understanding of abnormal development and lead to improvements in treatment for common surgical problems such as cryptorchidism. © 1993 Wiley‐Liss, Inc.