Puberty

The sexual maturity is defined as the part of the ontogeny considered a single system when it has reached its adulthood and can reproduce. In humans it is also the name for the target point and state of “sexual maturation ” (also: pubescence ) at a point in time during puberty ; in men after reaching the sperm arche and in women from the first ovulation after menarche . The process of developing organs and function carriers in the body is then largely complete. For each multicellular animal (metazoon) the phases last different lengths.

Sexual maturation

In mammals , the developmental physiological process of sexual maturation (pubescence) with its aim of developing sexual maturity is primarily controlled by the effects of the thyroid gland and the hormone thyroxine formed by it . In the further course of this maturation process, the male sex begins to produce sperm (Spermarche), while the female sex is enabled to form fertilizable egg cells and either carry them to term after fertilization or, otherwise, flush them out with a menstrual period . In a female adolescent, a first withdrawal bleeding without previous ovulation ( menarche ) signals that sexual maturity, which usually takes place after a few more irregular anovulatory bleeding, with a first ovulation and thus the completion of a first real ovulation cycle , starts around the middle of puberty . In addition, the secondary sex characteristics are clearly visible in both sexes .

Of Darwinian perspective the reaching sexual maturity at a plurality of offspring is a criterion for the existence of the respective phenotypes in competing with Comparative individuals.

Sexual maturation of man

In humans , sexual maturation is considerably delayed compared to other (also long-lived) primates .

The development of the human sexual characteristics towards sexual maturity before and then especially during puberty is controlled primarily in women by estrogens and in men by androgens . In addition to the onset of the outwardly barely perceptible internal development before puberty, external and thus also visible changes occur with puberty. In male adolescents, this includes, for example, enlargement of the penis , testicles and scrotum , later voice breakage and the beginning of pubic hair ; in female adolescents, for example, the growth of the female breast and also the pubic hair.

However, sexual maturation usually does not come to an end when sexual maturity is reached. Even after that, the primary and secondary sexual organs and their function continue to develop in healthy adolescents. In healthy male adolescents, for example, after the sperm march, the number and quality of sperm in the ejaculate increases continuously, as does the amount of secretion from the so-called accessory sex glands up to a maximum that varies greatly from person to person. In both sexes, pubic hair can increase in the course of puberty after reaching sexual maturity. Furthermore, various skin changes are possible not only on the face (here pimples ), but also in the area of ​​the secondary sexual characteristics (e.g. stronger pigmentation ).

Disorders or consequences of illness

In the case of defects in the testosterone receptors or damage to the controlling nerve centers in the hypothalamus or due to tumors , sexual maturity may not occur.

In a cerebral induced overproduction of regulatory hormones Geschlechtshormonsekretion that an excessive secretion of gonadotropins result, or in pathological processes (e.g., tumors of the pituitary gland ), wherein reactive or ectopic hormone production (for example, hypothyroidism ), and a genetically -related disposition can puberty and thus sexual maturity occurs earlier in both sexes (so-called pubertas praecox ).

Removal of the thyroid causes slower growth and delays the process of sexual maturity.

Examples

• Sharks sometimes only reach sexual maturity at the age of 30.

See also

• Ejakularche
• Polluarche
• Pubarch
• Tanner stages
• Thelarche

literature

• Wolf D. Keidel (Ed.): Brief textbook of physiology. 6th, revised edition. Thieme, Stuttgart / New York NY 1985, ISBN 3-13-358606-8 , (first edition 1970).
• Erwin J. Haeberle: The sexuality of humans: manual and atlas. (Original title: The Sex Atlas. German translation, assisted by Ilse Drews), de Gruyter, Berlin / New York NY 1983, ISBN 3-11-008753-7 (as updated paperback edition: Erwin J. Haeberle, Jörg Mair (illustration ): dtv-Atlas Sexualität (= dtv 3235 ). DTV, Munich 2005, ISBN 978-3-423-03235-3 ).

Web links

• Norbert Kluge (University of Koblenz-Landau): Ripe earlier and earlier . On: Wissenschaft.de from May 26, 2006; last accessed on September 24, 2015.

Individual evidence

1. ↑ Wolf D. Keidel (Ed.): Brief textbook of physiology. 2nd Edition. Thieme, Stuttgart 1970, p. 208.