External Genitalia
Ass. Prof. Dr. Malak A. Al-yawerExternal Genitalia Indifferent Stage
External Genitalia Indifferent Stage
External Genitalia in the Male (phallus)
Development of the external genitalia in the male is under the influence of androgens secreted by the fetal testes and is characterized by rapid elongation of the genital tubercle, which is now called the phallus.
External Genitalia in the Male (urethral plate)
External Genitalia in the Male (penile urethra)
At the end of the third month, the two urethral folds close over the urethral plate, forming the penile urethra. This canal does not extend to the tip of the phallus.
External Genitalia in the Male (external urethral meatus)
The most distal portion of the urethra is formed during the 4th month Ectodermal cells from the tip of the glans penetrate inward and form a short epithelial cord. This cord later obtains a lumen, thus forming the external urethral meatus.
External Genitalia in the Male (Scrotal swellings)
The genital swellings, known in the male as the scrotal swellings, arise in the inguinal region. They move caudally, and each swelling then makes up half of the scrotum. The two are separated by the scrotal septum.
Defects in the Male Genitalia (Hypospadias)
Defects in the Male Genitalia (Epispadias)
Defects in the Male Genitalia
Micropenis occurs when there is insufficient androgen stimulation for growth of the external genitalia. Micropenis is usually caused by primary hypogonadism or hypothalamic or pituitary dysfunction.
Bifid penis ( double penis) may occur if the genital tubercle splits.
External Genitalia in the Female
External Genitalia in the Female
External Genitalia in the Female
Descent of the Testes
Descent of the Testes
Toward the end of the second month, the urogenital mesentery attaches the testis and mesonephros to the posterior abdominal wall. With degeneration of the mesonephros, the attachment serves as a mesentery for the gonad.
Descent of the Testes
Caudally, it becomes ligamentous and is known as the caudal genital ligament. Also extending from the caudal pole of the testis is a mesenchymal condensation rich in extracellular matrices, the Gubernaculum .
The Gubernaculum
Factors controlling descent of the testis
The process is influenced by hormones, including androgens. During descent, blood supply to the testis from the aorta is retained, and testicular vessels extend from their original lumbar position to the testis in the scrotum.
Processus vaginalis
Hence the processus vaginalis, accompanied by the muscular and fascial layers of the body wall, evaginates into the scrotal swelling, forming the Inguinal canal.
Clinical Correlates
Hernias and Hydrocele
Hernias and Hydrocele
Cryptorchidism
Descent of the Ovaries
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