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Testosterone is the primary male sex hormone and androgen in males. [3] In humans, testosterone plays a key role in the development of male reproductive tissues such as testicles and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair.
After the testes have differentiated, male sex hormones, called androgens, are secreted from interstitial cells (cells of Leydig). The major androgens secreted by these cells is testosterone and secretion begins 8 to 10 weeks after conception.
Each ovary contains hundreds of egg cells or ova (singular ovum). Approximately every 28 days, the pituitary gland releases a hormone that stimulates some of the ova to develop and grow. One ovum is released and it passes through the fallopian tube into the uterus. Hormones produced by the ovaries prepare the uterus to receive the ovum.
A gonad, sex gland, or reproductive gland [1] is a mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. [2] The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells
Dehydroepiandrosterone (DHEA) is a steroid hormone produced in the adrenal cortex from cholesterol. [5] It is the primary precursor of both the androgen and estrogen sex hormones. DHEA is also called dehydroisoandrosterone or dehydroandrosterone. Androstenedione (A4) is an androgenic steroid produced by the testes, adrenal cortex, and ovaries.
The gradual growth in sex difference throughout a person's life is a product of various hormones. Testosterone is the major active hormone in male development while estrogen is the dominant female hormone. These hormones are not, however, limited to each sex. Both males and females have both testosterone and estrogen. [107]
The female reproductive system has two functions: The first is to produce egg cells, and the second is to protect and nourish the offspring until birth. The male reproductive system has one function, and it is to produce and deposit sperm. Humans have a high level of sexual differentiation.
Anisogamy is the form of sexual reproduction that involves the union or fusion of two gametes which differ in size and/or form. [12] The smaller gamete is considered to be male (a sperm cell), whereas the larger gamete is regarded as female (typically an egg cell, if non-motile).