Undescended testis

Undescended testis – Cryptorchidism (from Greek kryptos “hidden” and orchis “testis”) is the most common abnormality of male sexual development. In this condition, the testis is not located in the scrotum. It can be ectopic, incompletely descended, retractile, and absent or atrophic.

Pathophysiology

Embryology of testis development:
The embryology of testis development is critical to understanding the most common theories that explain cryptorchidism.

Shortly after 6 weeks’ gestation, the testis-determining SRY gene on chromosome Y directly affects the differentiation of the indifferent gonad into a testis. Germ cells are located in the germinal ridge close to the kidney in the retroperitoneum. Around 6-7 weeks’ gestation, Sertoli cells develop and secrete müllerian inhibitory substance (MIS; also known as antimüllerian hormone [AMH]), which leads to the regression of the female genital organs.

Around 9 weeks’ gestation, Leydig cells start producing testosterone, which promotes development of the wolffian duct into portions of the male genital tract. Concurrently, the testis organizes as a distinct organ with its distinct seminiferous tubules surrounded by vessels and encapsulated by the tunica albuginea. Owing to the differential growth of the fetus, the testicles move into the pelvis, close to the internal ring.

The testis remains in a retroperitoneal position until 28 weeks’ gestation, at which time inguinal descent of the testicle begins. Most testes have completed their descent into the scrotum by 40 weeks’ gestation.

Theories of pathophysiology of cryptorchidism:
Several potential explanations for the pathophysiology of cryptorchidism have been propsoed, including gubernacular abnormalities, reduced intra-abdominal pressures, intrinsic testicular and/or epididymal abnormalities, and endocrine abnormalities, as well as anatomic anomalies

The gubernaculum testis is a structure that attaches the lower portion of the tunica vaginalis to base of the scrotum, that aid in testicular descent.

Cryptorchidism is common in patients with some syndroms.

Another theory of testicular maldescent is based on intrinsic testicular or epididymal abnormalities.

Treatment – only treatment is surgery orchiopexy.

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