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. Author manuscript; available in PMC: 2015 Jun 4.
Published in final edited form as: J Urol. 2014 Oct 5;193(4):1353–1360. doi: 10.1016/j.juro.2014.09.108

Figure 1.

Figure 1

OPT of male urethral development from 6.5 to 16.5 weeks of gestation. Note progression of urethral meatus (green arrows) from scrotal folds at 6.5 weeks to terminal position on glans at 16.5 weeks. Wide open urethral groove (red arrows) is best seen from 9.5 to 13 weeks, with clear progression of proximal to distal fusion of edges of urethral groove to form tubular urethra (yellow arrows). At 13 weeks urethral groove is within glans penis with tubular urethra completely formed within shaft of penis, consistent with endodermal theory of urethral development. No evidence of ectodermal intrusion is evident in any specimen.