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In the XY sex-determination system, the female-provided ovum contributes an X chromosome and the male-provided sperm contributes either an X chromosome or a Y chromosome, resulting in female (XX) or male (XY) offspring, respectively. Hormone levels in the male parent affect the sex ratio of sperm in humans. [25]
XX male syndrome, also known as de la Chapelle syndrome, is a rare intersex condition in which an individual with a 46,XX karyotype develops a male phenotype. [2] Synonyms for XX male syndrome include 46,XX testicular difference of sex development (or 46,XX DSD) [3] [4] [5] [6]
The International System for Human Cytogenomic Nomenclature (ISCN; previously the International System for Human Cytogenetic Nomenclature) is an international standard for human chromosome nomenclature, which includes band names, symbols, and abbreviated terms used in the description of human chromosome and chromosome abnormalities.
The X and Y sex chromosomes are different in shape and size from each other, unlike the rest of the chromosomes , and are sometimes called allosomes. In some species, such as humans, organisms remain sex indifferent for a time during development ( embryogenesis ); in others, however, such as fruit flies, sexual differentiation occurs as soon as ...
Most mammals, including humans, have an XY sex-determination system: the Y chromosome carries factors responsible for triggering male development. In the absence of a Y chromosome, the fetus will undergo female development. This is because of the presence of the sex-determining region of the Y chromosome, also known as the SRY gene. [5]
NHS. Claus Højbjerg Gravholt, a professor of genetic endocrinology, said it is impossible to state everyone with a Y chromosome is a male and everyone with an X chromosome is a female.
Sex chromosomes evolve from standard pairs of autosomal chromosomes. [28] In a large number of organisms, the sex-determination systems presently observed are products of sex chromosome turnover. Sex chromosome turnover is a process defined as when the type of the sex chromosome changes as a product of a change in the identity of the sex ...
In writing, the term "Determination of sex" peaked in usage around 1910. [5] [6] The term "sex determination" increased in usage after 1900. [7]In the 1960 and early 70's the term "sex assignment" came into prominent use as a colloquially word for "determination of sex" and "sex determination".