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In both males and females, the sex organs consist of two structures: the internal genitalia and the external genitalia. In males, the gonads are the testicles and in females, they are the ovaries . These are the organs that produce gametes (egg and sperm), the reproductive cells that will eventually meet to form the fertilized egg ( zygote ).
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.
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.
In humans, sex organs or primary sexual characteristics, which are those a person is born with, can be distinguished from secondary sex characteristics, which develop later in life, usually during puberty. The development of both is controlled by sex hormones produced by the body after the initial fetal stage where the presence or absence of ...
[9] [10] [11] Puberty that starts earlier than usual is known as precocious puberty, and puberty which starts later than usual is known as delayed puberty. Notable among the morphologic changes in size, shape, composition, and functioning of the pubertal body, is the development of secondary sex characteristics, the "filling in" of the child's ...
The increased secretion of testosterone from the testes during puberty causes the male secondary sexual characteristics to be manifested. [23] Testosterone directly increases size and mass of muscles , vocal cords , and bones , deepening of the voice , and changing the shape of the face and skeleton . [ 1 ]
Another set of significant physical changes during puberty happen in bodily distribution of fat and muscle. This process is different for females and males. Before puberty, there are nearly no sex differences in fat and muscle distribution; during puberty, boys grow muscle much faster than girls, although both sexes experience rapid muscle ...
The activation of the HPG axis in both males and females during puberty also causes individuals to acquire secondary sex characteristics. This process, known as gonadarche, is preceded by adrenarche, the maturation of the adrenal glands, which contributes to the production of androgens responsible for some pubertal changes.