Gonadal dysgenesis is any inherited developmental disorder of the reproductive system characterized by a progressive loss of primordial germ cells on the developing gonads of an embryo. This loss leads to extremely hypoplastic (underdeveloped) and dysfunctioning gonads mainly composed of fibrous tissue, hence the name streak gonads - i.e., a form of aplasia in which the ovary is replaced by a functionless tissue. The accompanying hormonal failure also prevents the development of secondary sex characteristics in either sex, resulting in a sexually infantile female appearance and infertility.
The first type of gonadal dysgenesis discovered was Turner syndrome.
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