Testis

Abstract

During the 7th week, XY male gonads begin to differentiate under the influence of a series of testis-determining genes. Sertoli cells surround germ cells to form testis cords, which nourish primordial germ cells and direct them into the pathway for male gametogenesis. In testes, germ cells (before spermatogonia) undergo mitotic arrest and are blocked from entering meiosis until after birth.

The etiology of primary ascending testis is unclear, but there are two different explanations: mechanical tethering and low-lying undescended testis. The first case of ectopic testis was reported for the first time by John Hanter in 1786; it is a rare congenital anomaly with incidence ranging from 1 to 5% of all cases of undescended testis. Crossed testicular ectopia is a rare but well-known congenital anomaly that was first reported by von Lenhossek in 1886, with an estimation of global incidence of about 1:4 million. Anorchia is defined as the absence of testes in a 46,XY individual with a male phenotype. Monorchia is a term applied for unilateral cases; it is a normal phenomenon in nonhuman animals, notably in beetles. Polyorchidism is an uncommon congenital anomaly defined as the presence of more than two histologically proven testes; most patients with supernumerary testicles are asymptomatic and have painless groin or scrotal masses; triorchidism is the commonest variety of polyorchidism, and it is frequently reported on the left side. Accessory spleen in the scrotum (Lienotesticular fusion) is virtually always on the left side where immature splenic tissue adheres to the developing gonad, epididymis, or vas deferens. The splenic tissue is subsequently pulled in a caudal direction with descent of the gonad; surgical exploration is generally needed to rule out malignancy especially in patients with intratesticular mass. If the surgical intervention is performed, orchiectomy is generally not indicated, and splenic tissue can be dissected out of the gonadal structure and the testis can be saved. Persistent mullerian duct syndrome (PMDS) is characterized by the presence of a uterus, cervix, and fallopian tubes in an otherwise normally differentiated 46.XY male.

Vas deferens anomalies usually present as agenesis of the vas, which may be associated with unilateral or bilateral hypoplasia or absence of other portions of the Wolffian duct derivatives and duplication of vas deferens. Testicular and epididymal appendages were once considered anatomic anomalies; however, some other authors report that these structures are present in the majority of normal individuals, but it revealed itself only along other pathologies as cryptorchidism.