External genitalia 1) Male differentiation It results in the formation of the penis and scrotum: ✪ The penis results from a significant elongation of the tubercle genitalia occurring in the 3rd month which leads to a stretching of the urogenital slit and a rapprochement of the genitalfolds forming an open groove on the underside of the penis. ✪ The closure of this gutter is the origin of the penile urethra in continuity through its proximal end with the membranous urethra. This conduit is however blind at its enddistal because this process does not involve the glans derived from the end of the genitaltubercle. ✪ The formation of the terminal segment of the male urethra, the urethra balanic, comes from a fold of the epidermis covering the glans which invaginates towards the end of thepenile urethra then deepens by a process of cleavage. ✪ The epidermis also gives rise at the base of the glans has a fold, the foreskin, which circumscribes the glans and gradually covers it. ✪ The labio-scrotal folds merge on the midline with formation of a raphe which extends to the base of the penis. This is how the scrotum is formed, a pleated covering which coversthe two bursae. 2) Malformations They result from anomalies in different stages of development and can occur in all theconstituents of the urogenital system: Incomplete migration of the testicles results in their maintenance in ectopic position afterbirth in the abdominal region or along the path of the inguinal canal: this anomaly requiresmedical or surgical treatment. The absence of closure of the peritoneovaginal canal leads to the maintenance ofcommunication between the vaginal cavity and the abdominal cavity and can be the cause ofthe accumulation of serosities in the vaginal cavity around the testicle (hydrocele) and/or thebreak-in of an intestinal loop into the inguinal canal up to 'to the scrotal region (inguinalhernia).
At the level of the male external genitalia, the anomaly the most common is a defect in thefusion of the penile urethra (hypospadias) over a variable length with lack of continuitybetween the penile urethra and the balanic urethra (urine flows to the underside of the penisand not to the urinary meatus at the end of the glans). The opening of the penile urethra to the upper surface of the penis (epispadias) is muchrarer, it can be associated with another rare anomaly, bladder extrophy.