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The XY sex-determination systemis a sex-determination systempresent in many mammals, including humans, some insects (Drosophila), some snakes, some fish (guppies), and some plants (Ginkgotree). In this system, the sexof an individual usually is determined by a pair of sex chromosomes. Typically, females have two of the same kind of sex ...
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).
Male sterility likely arises first as an adaptation to prevent selfing. Once male sterility has reached a certain prevalence, then female sterility may have a chance to arise and spread. [13] In the domesticated papaya (Carica papaya), three sex chromosomes are present, denoted as X, Y and Y h. This corresponds with three sexes: females with XX ...
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.
The common pathway of sexual differentiation, where a productive human female has an XX chromosome pair, and a productive male has an XY pair, is relevant to the development of intersex conditions. During fertilization, the sperm adds either an X (female) or a Y (male) chromosome to the X in the ovum.
Sex differences in human physiology are distinctions of physiological characteristics associated with either male or female humans. These differences are caused by the effects of the different sex chromosome complement in males and females, and differential exposure to gonadal sex hormones during development. Sexual dimorphism is a term for the ...
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. The cause is a lack or inactivation of ...
The fundamental autosomal number or autosomal fundamental number, FNa[36]or AN,[37]of a karyotype is the number of visible major chromosomal arms per set of autosomes(non-sex-linked chromosomes). Ploidy. [edit] Ploidyis the number of complete sets of chromosomes in a cell. Polyploidy, where there are more than two sets of homologous chromosomes ...