True hermaphroditism is a medical term for an intersex

Intersex

Intersex, in humans and other animals, is the presence of intermediate or atypical combinations of physical features that usually distinguish female from male...

 condition in which an individual is born with ovarian

Ovary

The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...

 and testicular tissue.

There may be an ovary on one side and a testis on the other, but more commonly one or both gonads is an ovotestis

Ovotestis

An ovotestis is a gonad with both testicular and ovarian aspects. In humans, ovotestes are an anatomical abnormality associated with gonadal dysgenesis.- In gastropods :...

 containing both types of tissue.

It is rare—so far undocumented—for both types of gonadal tissue to function. Encountered karyotypes are 47XXY, 46XX/46XY, or 46XX/47XXY.

Although similar in some ways to mixed gonadal dysgenesis

Mixed gonadal dysgenesis

Mixed gonadal dysgenesis is a condition of unusual and asymmetrical gonadal development leading to an unassigned sex differentiation. A number of differences have been reported in the karyotype, most commonly a mosaicism 45,X/ 46, XY...

, the conditions can be distinguished histologically.

Presentation

External genitalia are often ambiguous, the degree depending mainly on the amount of testosterone

Testosterone

Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands...

 produced by the testicular tissue between 8 and 16 weeks of gestation

Gestation

Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....

.

Causes

This condition is very rare. There are several ways in which this may occur.

• It can be caused by the division of one ovum, followed by fertilization of each haploid ovum and fusion of the two zygotes early in development.
• Alternately, an ovum can be fertilized by two sperm followed by trisomic rescue
  Trisomic rescue
  Trisomic rescue a genetic phenomenon in which a fertilized ovum containing three copies of a chromosome loses one of these chromosomes to form a normal, diploid chromosome complement. If both of the retained chromosomes came from the same parent, then uniparental disomy results....
  
   in one or more daughter cells.
• Two ova fertilized by two sperm will occasionally fuse to form a tetragametic chimera
  Chimera (genetics)
  A chimera or chimaera is a single organism that is composed of two or more different populations of genetically distinct cells that originated from different zygotes involved in sexual reproduction. If the different cells have emerged from the same zygote, the organism is called a mosaic...
  
  . If one male zygote and one female zygote fuse, a hermaphroditic individual may result.
• It can be associated with mutation in the SRY
  SRY
  SRY is a sex-determining gene on the Y chromosome in the therians .This intronless gene encodes a transcription factor that is a member of the SOX gene family of DNA-binding proteins...
  
  gene.