Cryptorchidism Cryptorchidism Cryptorchidism is the absence of one or both testes from the scrotum. The word is from the Greek κρυπτός, "kryptos", meaning hidden, and ὄρχις, "orchis", meaning testicle. It is the most common birth defect of the male genital tract. About 3% of full-term and 30% of premature infant boys are born with at least one undescended testis. However, about 80% of cryptorchid testes descend by the first year of life (the majority within three months), making the true incidence of cryptorchidism around 1% overall. Cryptorchidism may develop after infancy, sometimes as late as young adulthood, but that is exceptional.
Tunica vaginalis Tunica vaginalis The tunica vaginalis is the pouch of serous membrane that covers the testes. It is derived from the vaginal process of the peritoneum, which in the fetus precedes the descent of the testes from the abdomen into the scrotum. After its descent, that portion of the pouch which extends from the abdominal inguinal ring to near the upper part of the gland becomes obliterated; the lower portion remains as a shut sac, which invests the surface of each testis, and is reflected on to the internal surface of the scrotum; hence it may be described as consisting of