Ambiguous Genitalia

      Although hermaphroditism is not uncommon in simpler organisms, it is rare in humans (approximately 500 reported cases).  In fact if you define true hermaphroditism as having fully functioning gonads, it is doubtful that it occurs in people.  However, there is no doubt that people are found that do have one ovary and one testis or at least tissue from each type of gonad (see discussion of Chimerism).  If the individual is a chimera, or the result of fusion between two different zygotes of the opposite sex, then it is possible for the individual to have a testis and an ovary due to to different lineages of the cell line.

     In fact there are various degrees and classifications of atypical genitalia.  Normally if a fetus has the full normal complement of 46 chromosomes, the gender is determined by whether or not the sex chromosomes are XX (female) or XY (male).  The Y chromosome contains the SRY gene on one arm which is primarily responsible for the cascade of events that produces a male. By twelve weeks most of this differentiation is determined.  The absence of this gene produces a female.

    Sometimes during meiosis the father's "male gene" from his Y chromosome transposes to the father's X chromosome.  If the offspring is a genetic female with a normal X chromosome from the mother, the gender is often actually a male because of the transposed gene.

     Or a person with the genotype XY may be a female because of a missing SRY gene on the Y chromosome.

     Any interference with this process can produce abnormalities in the genitalia.  Exposure to various hormones of the opposite sex can do this. This condition is sometimes called Pseudohermaphroditism.  These people have the genotype and the gonads of one sex, but the external genitalia of the opposite sex.

     In female pseudohermaphrodites the female fetus is exposed to androgens (male sex hormones) during the critical 8th to 13th week of gestation.  Male pseudohermaphrodites may have been exposed to female hormones during this time or they may have a resistance to the influence of androgens.

       It is essential because of the social/psychological implications for the individual that these conditions be recognized by the physician.