[Ultrastructure of human heterotopic Leydig cells].

It was demonstrated by light and electron microscopical methods that Leydig cells also exist outside of the testis. In the spermatic cord and near the intraabdominal testicular vessels cells were observed with the characteristics of intratubular Leydig cells. Such characteristics were intranuclear precrystalline inclusions, mitochondria with tubular interior structures and lipid droplets, and a well developed smooth and rough endoplasmatic reticulum. The last two items can be regarded as signs of hormonal activity. The extratesticular Leydig cells in the spermatic cord are located within nerves that contain myelinated axons forming monoaxonal Schwann cell units. Possible they are sensory nerves originating in the receptors of the tunica albuginea. Synapses between axons and heterotopic Leydig cells were not found. The degree of the cytological differentiation leads to the conclusion that these cells may serve, for instance after orchidectomy, as substitutes for the Leydig cells inside the testis.