Cytokeratin staining of serial sections through an 8-week human fetal penis grown for 14 days in a DHT-treated host. Top, A–C, approximate section levels: Distal (A), mid-shaft (B) and proximal (C) transverse sections stained for K6 and K7. K6 is expressed in the urethral plate (A), in basal cells of the surface epidermis, the urethral groove (B) and proximal tubularized urethra (C) of the graft. K7 is present in apical layers of the urethral groove (B) and the tubularized urethra (C) as in non-grafted penile specimens (Fig. 4). Bottom, D–F, approximate section levels: Distal (D), mid-shaft (E) and proximal (F) sections through the same xenograft stained for K6 and K10. K6 is expressed as above. K10 is present in apical layers of the surface epidermis but is absent in urethral structures, indicating that these are true urethral structures and not invaginations of surface epithelium.
Gross 9.5-week human fetal penile specimen showing approximate levels of post-grafting histologic sections.