The primary urethral groove or urethral groove is a temporary linear indentation on the underside (ventral side) of the male penis during embryonic development.
In humans, it typically appears around 8 weeks of gestation and becomes closed into a normal male urethra by the 12th week.
Famous quotes containing the word primary:
“Parental attitudes have greater correlation with pupil achievement than material home circumstances or variations in school and classroom organization, instructional materials, and particular teaching practices.”
—Children and Their Primary Schools, vol. 1, ch. 3, Central Advisory Council for Education, London (1967)