21.6 Pathology – Embryology

From an embryologic point of view, hypospadias of the penis and scrotum arise from a closure disorder of the urethral groove (spongy part of the urethra) by the urethral folds or the genital swellings, going out from the urethral plate, which has an endodermal origin. The urethral groove closes in the posterior part through fusion of the genital swellings and anteriorly progressively through the closure of the urethral folds up to the glans. The urethra within the glans has an ectodermal origin. So hypospadia glandis can be traced back to a closure disorder of the epithelial lamella on the penile tip and can extend up to the navicular fossa.

The cause for this disorder is multi-factorial: besides genetic factors the damaging effects of a hormone therapy with progesterone during the first month of pregnancy also plays a role. An altered synthesis of testosterone (or its derivative) and/or an anomaly of the receptors for this hormone can also be blamed.

Under the most frequent abnormalities associated with a hypospadia are penile deviations, a stenosis of the urinary meatus and a deviation of the raphe mediana. Finally, a hypoplasia of the cavernous body, leading to a micropenis, is also not rare.

Hormone therapy (in the case of a micropenis) for stimulating growth is often combined with a surgical reconstruction of the urethra.

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21.6 Pathology - Embryology