INTERSEX: TRUE HERMAPHRODITISM
Intersexuality is that state in which sex chromosomes, genitalia, and/or secondary sex characteristics are neither exclusively male nor female. Intersex patients may have biologic characteristics of both the male and female sexes. Previously termed true hermaphroditism, a true intersex state is extremely rare and exists when both testicular and ovarian tissue are present in the same patient, regardless of the karyotype. There may be an ovary on one side and a testis on the other, an ovotestis on each side, or any combination of these. These disorders have been alternatively designated as disorders of sexual development.
The prevalence of intersex depends on the deﬁnition of the condition. Approximately 1% of live births exhibit some degree of sexual ambiguity. Between 0.1% and 0.2% of live births are ambiguous enough to lead to surgical correction. When the deﬁnition is restricted to conditions in which chromosomal sex differs from phenotypic sex or in which the phenotype is not classiﬁable as either male or female, the prevalence is 0.018%. True hermaphroditism is extremely rare and it is even rarer that both types of gonadal tissue function. It has been described in patients with karyotypes 47,XXY; 46,XX/46,XY; or 46,XX/47,XXY. This condition is quite distinguishable histologically from mixed gonadal dysgenesis. It is caused by (1) the division of one unfertilized egg, followed by fertilization of each haploid egg and fusion of the two embryos early in development, or (2) an egg can be fertilized by two sperm followed by trisomic rescue such that a diploid embryo results, or (3) two eggs are fertilized by two sperm cells and these zygotes fuse to form a tetragametic chimera. If a male zygote and a female zygote fuse, a true intersex state can result, or (4) abnormalities or mutations in the expression of the testis determining factor, SRY gene.
In true hermaphroditism, the phenotype of the internal and external genitalia may be predicted from gonadal lateralization. In individuals with an ovary on one side and a testis on the other, müllerian structures persist on the side of the ovary, whereas atrophy of the fallopian tube and well-developed wolfﬁan derivatives are found on the side of the testis. When ovarian and testis tissue occur on the same side, the development of wolfﬁan structures is proportional to the degree of testicular maturation. With a well-developed testis, the gonads are found in the scrotum, and there is a proportional decrease in müllerian remnants. With a rudimentary testis, the gonad is usually located in a broad ligament adjacent to a normal uterus. External genitalia are often ambiguous, depending mainly on the amount of testosterone produced by testicular tissue during organogenesis from 8 to 16 weeks of gestation.
Adolescence and secondary sexual characteristics may be expected to mirror the degree of differentiation of gonadal structures. Usually, there is some degree of masculinization. However, coincidental signs of active estrogen secretion may include breast enlargement and menstruation. There is no absolute reason why the gonads may not develop to full spermatogenesis and oogenesis. However, spermatogenesis is unlikely if estrogens are secreted in signiﬁcant quantities because of inhibition of follicle-stimulating hormone. Regardless of anatomy, the “true sex” of these individuals is the one to which they can best adapt in society, and serious reconsideration of the need and role (i.e., lack thereof) of “gender reassignment” surgery i gaining wide acceptance in the medical community.