Optical projection tomography demonstrating male urethral embryonic development

Optical projection tomography demonstrating male urethral development from 6.5 to 16.5 weeks of gestation. Note the progression of the urethral meatus from scrotal folds at 6.5 weeks gestation to a terminal position on the glans at 16.5 weeks gestation. Wide open urethral groove is best seen from 9.5 to 13 weeks gestation, with progression of proximal to distal fusion of the edges of the urethral groove to form the tubular urethra. At 13 weeks gestation, the urethral groove is within the glans penis and the tubular urethra is completely formed within the shaft of the penis.