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General Considerations About The Sex Glands (Gonads) And The Physiological Functions Of Androgens
A General Overview
The gonads and genital ducts intended for heterosexual reproduction develop under the influence of genetic and hormonal factors. The sex chromosomes X or Y determine the genetic sex of the offspring. Phenotypic sex (also called somatic sex) comprises the gonads and internal sex organs, external genitalia and the secondary sex characters.
The genetic composition XX or XY determines the morphological development of the gonads and other structures. The internal reproductive organs and external genitalia undergo appropriate morphological differentiation under the influence of gonadal secretions. Testosterone secreted by the testes directs the Wolffian ducts to differentiate into the male internal reproductive tract. The epididymis, vas deferns and seminal vesicles develop from the wolffian ducts. The Mullerian ducts degenerate under the influence of Mullerian-duct-inhibitor produced by the Sertoli cells of the testes.
There is increase in pituitary gonadotropic output and gonadal steroids during puberty. In addition, during pubertal years, sleep-induced LH secretion occurs. Puberty is initiated by increase in gonadal steroids. The adrenal androgens stimulate axillary and pubic hair growth (adrenarche).
The pubic hair appears and spreads to the medial surface of the thighs and the linea alba as an inverted triangle. In girls, the breasts and areola enlarge and papillae project on the areola. The pubic hair appears and spreads. Mean age for menarche in girls is 12 years, and this is 1- 2 years earlier than the age of puberty for boys. The gonadal hormones are essential for the maintenance of fertility, sexual behaviour and systemic effects in both sexes. In addition, in the female, ovulation, menstruation and nidation are maintained by gonadal steroids.
Functions Of Androgens
The following are the functions of androgens
- Masculine differentiation of external genitalia and internal organs
- Promote linear body growth, muscular development and anabolic activity in adolescents and adult men.
- Stimulate the growth of external genitalia and bring about secondary sexual characters. These are called the androgenic effects.
- Enlargement of the larynx and change of voice due to thickening of the vocal cords.
- Initiate and maintain hair growth in beard, axillary and pubic regions, recession of temporal hair and development of balding.
- Maintain libido and sexual potency.
- Produce aggressive behavious.
- Effects on organ specific proteins in tissues such as liver, kidney and salivary glands. These effects on somatic tissues constitute anabolic response.
In the female, the Mullerian ducts give rise to the fallopian tubes and the uterus. The development of external genitalia is controlled to a great extent by the hormonal profile in the individual. Sexual differentiation should be considered anomalous in any patient with ambiguous genitalia, cryptorchism, inguinal masses in apparent females, inguinal hernia, clitoromegaly or gynecomastia
© 2014 Funom Theophilus Makama