There are many discordances between the anatomic development of the external and internal sex organs, the chromosomal patterns, the gonadal morphology and the secondary sexual development. The psychosexual orientation is not predetermined by any of these, but depends largely upon the gender role assigned to a child in early life. It is, therefore, most important to select in early life the sex to which the child can best adapt.
The abnormalities of sex differentiation are: 1) Gonadal dysgenesis, in which there are various widely differing defects in the embryonic development of the gonads. These conditions are often due to chromosomal aberrations. There is a low familial incidence. 2) Male pseudohermaphroditism, in which testes are morphologically fairly well developed, but have defective secretion of "male organizing substance." 3) Female pseudohermaphroditism, in which masculinization of the external genitalia of females is due to androgens of the fetal adrenals or transmitted from the mothers during pregnancy.
Ambiguity of the external genitalia is usually the finding which arouses a suspicion of an abnormality of sex differentiation. However, the finding of firm masses in the groins or labia of apparent females or the absence of gonads in apparent males are also indications for more extensive diagnostic studies.
The study of the nuclear chromatin pattern of cells in smears of the buccal mucosa is the most important diagnostic screening test. A chromatin-positive pattern indicates that the patient is either a female pseudohermaphrodite, a true hermaphrodite or a case of "testicular dysgenesis." In chromatin-positive cases the urinary excretion of 17-ketosteroids should be measured to determine whether or not the patient has virilizing adrenal hyperplasia. Patients with a chromatin-negative pattern have either male pseudohermaphroditism, true hermaphroditism or some form of gonadal dysgenesis. Exploratory laparotomy with gonadal biopsies is necessary to establish the diagnosis. When the diagnosis is made in early infancy, all types of female pseudohermaphrodites should be reared as females. In male pseudohermaphroditism the assignment of the gender role depends largely upon the degree of phallic development. In true hermaphroditism one must take into consideration both the anatomy of the external genitalia and the type of development of the gonads. The explanations to be given to the parents and the hazards of changing the gender role in later life are discussed.
The relative incidence of the various types of abnormalities of sex differentiation are shown. It is pointed out that among 242 patients of all types, there were only 20 cases in which the assignment of a male role would have been preferred.