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XY complete gonadal dysgenesis, also known as Swyer syndrome, is a type of defect hypogonadism in a person whose karyotype is 46,XY. Though they typically have normal vulvas , [ 1 ] the person has underdeveloped gonads, fibrous tissue termed " streak gonads ", and if left untreated, will not experience puberty .
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]
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] Thus, male mammals typically have an X and a Y chromosome (XY), while female mammals typically have two X chromosomes (XX).
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.
Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. [1] [2] Sex determination is often distinct from sex differentiation; sex determination is the designation for the development stage towards either male or female, while sex differentiation is the pathway towards the development of the phenotype.
Complete androgen insensitivity syndrome causes a genetic male to have a vagina (often incompletely developed, nearly always blind-ending), breasts, and a clitoris; people with this form are raised as females. [25] Aphallia – a rare condition where a XY male is born without a penis. As of 2017, only 100 cases have been reported in literature ...
Protogynous sex change is the female to male gonadal redifferentiation, and it is often found within species that practice haremic polygyny, or one male reproducing with many females. When socially dominant males disappear, larger initial phase female fish will undergo sex change to become terminal phase males.
Two use homomorphic male heterogamety, one uses XX/XY, one uses ZZ/ZW. Remarkably, the X and Z chromosomes are homologous, and the Y and W as well. Dmrt1 is on autosome 1 and not sex-linked. This means that an XX female individual is genetically similar to a ZZ male individual, and an XY male individual is to a ZW female individual.