Search results
Results from the WOW.Com Content Network
In humans, the presence of the Y chromosome is responsible for triggering male development; in the absence of the Y chromosome, the fetus will undergo female development, except with various exceptions such as individuals with Swyer syndrome, that have XY chromosomes and a female phenotype, and de la Chapelle Syndrome, that have XX chromosomes ...
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]
The accepted hypothesis of XY and ZW sex chromosome evolution in amniotes is that they evolved at the same time, in two different branches. [84] [85] No genes are shared between the avian ZW and mammal XY chromosomes [26] and the chicken Z chromosome is similar to the human autosomal chromosome 9, rather than X or Y.
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.
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.
Sperm also have only one set of 23 chromosomes and are therefore haploid. When an egg and sperm fuse at fertilization, the two sets of chromosomes come together to form a unique diploid individual with 46 chromosomes. [2] The sex chromosome in a human egg is always an X chromosome since a female only has X sex chromosomes.
Females normally have two X chromosomes while males typically have an X and a Y chromosome. The X chromosome is more active and encodes more information than the Y chromosome, which has been shown to affect behavior. [14] Genetic researchers theorize that the X chromosome may contain a gene influencing social behaviours. [15] [better source needed]
The IBA said its rules prevent athletes with XY chromosomes from competing in women’s events. Most men are born with one X and one Y chromosome, and most women are born with two X chromosomes ...