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Differentiation and development of the external genitalia occurs during weeks 8-15 of gestation.  In females, the urethral (urogenital) folds do not fuse and ultimately form the labia minora and the vestibule of the vagina.  In males, the urethral folds fuse to form the ventral aspect of the penis and the penile raphe, which serve as the anterior wall of the urethra.

Incomplete fusion of these folds in a male would result in an abnormal opening of the urethra at a location proximal to the distal tip of the glans penis.  Depending on the degree of nonunion, the urethral opening can be anywhere from the perineum to just proximal to the glans penis.  This condition is known as hypospadias and can generally be repaired surgically to allow normal urination and sexual activity.

(Choice A)  A bifid scrotum (two separate sacs) results from malunion of the labioscrotal folds.  In females, the labioscrotal swellings form the labia majora.

(Choice B)  Cryptorchidism is failure of a fetal testis to descend into the scrotum.  Most undescended testes will descend spontaneously by the time the infant is 4 months old.

(Choice C)  The genital tubercle becomes the glans penis in males and the clitoris in females.  Epispadias is an abnormal opening of the urethra on the dorsal surface of the penile shaft that results from faulty positioning of the genital tubercle in the fifth week of gestation.

(Choice D)  The processus vaginalis is a projection of the peritoneal cavity that accompanies the descending testis into the scrotum and ultimately forms the tunica vaginalis of the testis.  Hydrocele is development of a fluid-filled peritoneal sac within the scrotum that results from incomplete obliteration of the processus vaginalis.

Educational objective:
In males, incomplete fusion of the urethral (urogenital) folds results in hypospadias, an abnormal opening of the urethra proximal to the glans penis along the ventral shaft of the penis.