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.
