The basic definition of sex used here is biological sex. 'Gender' has many meanings depending on the group or persuasian. It literally means 'kind' or belonging to a group. Thus it is synonomous with biological sex (reproductive anatomy), the behavioral, cultural, or psychological traits typically associated with one sex, or sexual identity, especially in relation to society or culture (see dictionary.com for a long list of explanations).
Persons with unusual genitalia were called hermapthrodites. In Greek mythology, Hermes is the son of Zeus and the nymph Maia. He is the 'messenger of the gods' and the god of land travel, merchants, weights and measures, oratory, literature, athletics and thieves. Aprhodite is the goddess of love, beauty and sexual rapture. Aprhos means 'sea foam'. She was born when Uranus was castrated by his son Cronus, who threw the genitals into the ocean, which began to churn and foam around them. Aprodite loved many gods. Her son with Hermes was Hermaphroditus, a handsome lad who caught the eye of the nymph Salmacis. Although her overtures to Hermaphroditus were rejected, she wraped herself around him and forcable kissed him. She prays to the gods that they should never part and her wish is granted - and their bodies blend into an intersexual form. He has the body of a woman and the genitals of a man.
There are many names given to animals with ambiguous or incomplete development of the genitalia. They include sexual ambiguity, intersex, hermaphroditism, sex reversal, feminizing or masculinising conditions and various combinations. It is difficult to categorize all conditions with a single definition, so I will use the term ‘'Disorders of Sexual Development (DSD)'’. This is based on the human consensus statement of the 2005 Chicago Consensus Hughes (2008)and published by Lee et al (2016) and Houk et al (2016) and adopt the scheme described by .
Meyers-Wallen (2012) subsequently published a review using this nomenclature.
Many diseases and conditions are now placed in the DSD category including cryptorchidism, hypoplasia, and segmental aplasia.
Complete characterisation of an anomaly of sexual development requires the description of the presence of sex chromosomes or genotype, the type of gonad, and the phenotype. As greater sophistication develops, there will be greater complexity in definition with identification of individual genetic, transcriptional or translational abnormalities.
In domestic animals,
we are often limited to observations of the gonads and phenotype.
Normal male mammals are XY and females are XX. For XY individuals, the gonads should be testes and for XX individuals, the gonads should be ovaries.
Just about every combination
is possible - there are XX males and XY females.
More recently, further evaluation of the gonad has changed the classification Normal (testis, ovary) gonad, hypoplastic gonad, dysplastic gonad, streak gonad and ovotestis
Houk CP, Hughes IA, Ahmed SF, Lee PA; Writing Committee for the International Intersex Consensus Conference Participants. Summary of consensus statement on intersex disorders and their management. International Intersex Consensus Conference. Pediatrics 2006; 118: 753-757.
Hughes IA Disorders of sex development: a new definition and classification. Best Practice & Research Clinical Endocrinology & Metabolism 2008 22 (1): 119-134.
Lee PA, Houk CP, Ahmed SF, Hughes IA; International Consensus Conference on Intersex organized by the Lawson Wilkins Pediatric Endocrine Society and the European Society for Paediatric Endocrinology. Consensus statement on management of intersex disorders. International Consensus Conference on Intersex. Pediatrics 2006; 118: e488-500.
Lee PA, Nordenström A, Houk CP, Ahmed SF, Auchus R, Baratz A, Baratz Dalke K, Liao LM, Lin-Su K, Looijenga LH 3rd, Mazur T, Meyer-Bahlburg HF, Mouriquand P, Quigley CA, Sandberg DE, Vilain E, Witchel S; Global DSD Update Consortium. Global Disorders of Sex Development Update since 2006: Perceptions, Approach and Care. Horm Res Paediatr. 2016; 85: 158-180. Erratum in: Horm Res Paediatr. 2016; 85: 180. Koopman, Peter [added]. Erratum in: Horm Res Paediatr. 2016;86(1):70.
According to the consensis paper by Hughes (2008), the human DSD are divided into three major groups: those with chromosomal abnormalities (the Sex chromosome DSD), those involving individuals with an XX chromosomes (XX DSD), and those with an XY chromosomes (XY DSD). This scheme is now accepted for the veterinary world.