Sexual differentiation in humans
From The Art and Popular Culture Encyclopedia
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"It is strongly to be expected on evolutionary grounds that, where the sexes differ, it should be the males that advertise and the females that are drab. Modern western man is undoubtedly exceptional in this respect." --The Selfish Gene |
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Human sex refers to the processes by which an individual becomes either a male or female during development.
Complex mechanisms are responsible for male sex determination and differentiation. The steps of formation of the testes are dependent on a series of Y-linked, X-linked and autosomal genes actions and interactions. After formation of testes the gonads secrete hormones, which are essential for the formation of the male genitalia. Hormones are transcription regulators, which function by specific receptors. Ambiguous genitalia are result of disruption of genetic interaction. This review describes the mechanisms, which lead to differentiation of male sex and ways by which the determination and differentiation may be interrupted by naturally occurring mutations, causing different syndromes and diseases.
The Jost Paradigm
Under typical circumstances, the sex of an individual will be determined and expressed through the following mechanisms:
- Chromosomal Sex (genetic): Presence or absence of Y chromosome
- Gonadal Sex (Primary Sex Determination): Controlled by presence or absence of testis determining factor (TDF)
- Phenotypic Sex (Secondary Sex Differentiation): Determined by the hormonal products produced by the gonads.
See also
