The three-dimensional structure of the Sertoli cell in the Korean native bull was investigated by scanning electron microscopy. Morphologically, four types of Sertoli cell processes were evident: 1) sheet-like processes, 2) sleeve-like processes, 3) bough-like processes and 4) finger-like processes. The sheet-like processes rested upon more than half of the surface of each spermatogonia, spermatocyte and spermatid. Sleeve-like processes, bough-like processes and finger-like processes are observed in the middle and apical portion of seminiferous tubule. All Sertoli cell processes are originated from Sertoli cell column. Just before spermiation, the apical sheet-like processes are shifted from their position at the spermatid head, and bough-like processes covered the disengaged residual body, after which the residual body was no longer evident in the tubule. Though the mechanism for this elimination is not known, the process suggests a reciprocity between the Sertoli and germ cells.