Testicular dysgenesis syndromes.

Abstract

The term testicular dysgenesis should be applied only to gonads exhibiting differentiation of testicular seminiferous tubules (but not primordial ovarian follicles) which cannot produce regression of the müllerian duct. Typical dysgenetic testes are hypoplastic with thin, insufficiently developed tunica albuginea. Degenerating seminiferous tubules and areas of cellular connective tissue are located underneath or within the tunica albuginea. Spermatogonia and mature Sertoli cells are present in the seminiferous tubules of adult patients. Testicular tumors are common in dysgenetic testes. The same kind of testicular dysgenesis is observed in patients with different karyotypes. Y chromosomal defects of XO chromosomal constitution occurs or is thought to occur in some cells in most cases. All individuals with dysgenetic testes show androgen-sensitive male pseudohermaphroditism with a uterus. Depending upon differentiation of the external genitalia, cases with ambiguous external genitalia and male (or hypospadic) external genitalia may be distinguished. Unilateral testicular dysgenesis with a contralateral streak gonad ("mixed gonadal dysgenesis") and unilateral testicular dysgenesis with an unaffected contralateral testis may be distinguished. Relationships between the karyotypes and morphogenetic pathways of gonadal differentiation are discussed.