A sexual organ ( latin Organum genital ; interchangeably reproductive organs , genitals , genitalia , sex , date and especially the external genitalia concerning also genitals ) is a body of living organisms having two or more mating types ( families ), which is used directly in sexual satisfaction and reproduction. The sexual organs are also known as the primary sexual characteristics.
Functionally, a distinction is made between the sexual organs - organs that are used for sexual intercourse - and the reproductive organs that ensure reproduction. Sexual arousal is required for the genital organs to perform their physiological functions . This provides a multiple reaction of the limbic system in the brain represents and builds the pairing request (see also sexual response cycle , Human Sexual Response cycle ).
The old term "Gemächt" (from Middle High German maht / gemëht / gemëhte ) denotes the male genitals, but was also used in the meanings genital part (s), genital organs, penis, testicles (sac) and (for both women and men) "Procreative member" used.
Ontogenetic development of the genital organs
In typical prenatal development, the sex organs come from a common system during early pregnancy and are divided into male and female genders. The SRY gene , which is usually on the Y chromosome and codes for the testicular determinant, determines the direction of this differentiation. The absence of it allows the gonads to develop into ovaries.
After that, the development of the internal and external reproductive organs is determined by hormones produced by certain fetal gonads (ovaries or testes) and the response of cells to them. The initial appearance of the fetal genitals is generally feminine: a pair of urogenital folds with a small bulge in the middle and the urethra behind that bulge. When the fetus has testicles, and when the testes produce testosterone , and when the cells of the genitals respond to the testosterone, the outer urogenital folds swell and merge in the midline to produce the scrotum; the protuberance becomes larger and straighter to shape the penis; the internal urogenital swellings grow, wrap around the penis, and merge in the midline to form the penile urethra.
Every sex organ in one sex has a homologous counterpart in the opposite sex. In a broader perspective, the whole process of sexual differentiation also includes the development of secondary sexual characteristics such as patterns of pubic and facial hair and female breasts that arise during puberty. In addition, there are differences in brain structure that influence behavior, but not necessarily determine it.
Intersexuality arises from the development of genitals between typical male and female phenotypes. Once the child is born, the parents are faced with decisions that are often difficult to make, such as: B. whether they change the genitals, assign the child as male or female or leave the genitals unchanged. Some parents give their doctors a choice. If they decide to modify the genitals, they have about a 50% chance of getting genitals that match the child's gender identity. If they choose the wrong one, their child may begin to show symptoms of transsexualism, which can lead them to a life of discomfort until they are able to resolve the problem.
Because of the strong sexual selection that affects the structure and function of the genitals, they form an organ system that develops faster than any other. A great variety of genital forms and functions can therefore be found in animals.
Differentiation into female and male genitals
Male and female organs of the human reproductive system are related and share a common developmental path. That makes them biological homologues : in both sexes there are structures that have a counterpart in the other sex. Male and female sexual organs differ both in their externally visible and internal structures.
Female reproductive organs of mammals
The female genital organs ( Organa genitalia feminina ) are classified as follows:
External genital organs
The outer labia include the labia minora, the vaginal vestibule , the exit of the urethra and the clitoris including the clitoral hood . The vaginal vestibule represents the connection to the internal female sexual organs.
Internal genital organs
The vagina , also known as the sheath, is the connection between the external and internal female sexual organs. It opens below into the vaginal vestibule and is closed above by the external cervix , which leads into the cervix ( cervix uteri ). The cervix is the lower part of the uterus in which fertilized egg cells or blastocysts can implant ( nidation ).
Studies on mouse models have shown that the Hox genes , especially HOXA9, A10, A11 and A13, play an essential role in the development of the urogenital tract. In the animal model it could be shown that HOXA10 are responsible for the uterine development, HOXA11 for the caudal uterus and cervix, HOXA13 for the upper vagina and HOXA9 for the fallopian tube development as transcription factors .
Accessory sex glands
Male reproductive organs of mammals
The following classification of the male genital organs ( Organa genitalia masculina ) may surprise you at first glance: The testicles are on the outside, but are still part of the internal genital organs. This classification is based on the fact that the testes initially develop in the abdomen and in most mammals only migrate into the scrotum at or after birth (testicular descent, descensus testis ).
External genital organs
The scrotum (scrotum) is a sac of skin beneath the penis. It envelops the internal genital organs, the testes , the epididymis and the lower part of the spermatic ducts, which begins at the epididymis .
Internal genital organs
The testicles are the male gonads. They are the tissue that forms the male reproductive cells, the sperm , and are also hormonal glands . The internal sex organs also include the epididymis , vas deferens , the prostate and a few other glands.
Accessory sex glands
In mammals, up to four paired accessory (additional) sex glands are formed along the seminal duct. These are the spermatic duct ampoule , the seminal bladder gland , the prostate and the bulbourethral gland . They produce a large part of the seminal fluid ( ejaculate ).
Genital organs of man
Internal reproductive organs of women ( The woman as a family doctor , 1911)
- Uwe Gille: urinary and genital apparatus, urogenital apparatus . In: Franz-Viktor Salomon u. a. (Ed.): Anatomy for veterinary medicine. Enke, Stuttgart 2004, ISBN 3-8304-1007-7 , pp. 368-403.
Duden: sexual organ
- Gerhard Truig: German dictionary. 2nd Edition. Munich 1986, p. 539.
- Nabil Osman (ed.): Small lexicon of undergone words. Word extinction since the end of the 18th century. Munich 1971; 13th, unchanged edition, ibid. 2003, ISBN 3-406-45997-8 , p. 101 f.
- Lykke Aresin , Helga Hörz , Hannes Hüttner , Hans Szewczyk (eds.): Lexikon der Humansexuologie. Verlag Volk und Gesundheit, Berlin 1990, ISBN 3-333-00410-0 , p. 75 ( Gemach ).
- See also Joseph Hyrtl : The old German made-up words of the anatomy. Vienna 1884; Reprint Munich 1966, p. 59 f. (there “female pubis”, testicles, genitals).
- SJ Robboy, T. Kurita, L. Baskin, GR Cunha New insights into human female reproductive tract development. In: Differentiation. September - October 2017, Volume 97, pp. 9-22, doi : 10.1016 / j.diff.2017.08.002 .
- Anne Fausto-Sterling: Sexing the Body: gender politics and the construction of sexuality. 1st edition, Basic Books, New York 2000, ISBN 0-465-07714-5 .
- Menno Schilthuizen: Nature's Nether Regions: What the Sex Lives of Bugs, Birds, and Beasts Tell Us About Evolution, Biodiversity, and Ourselves. Viking, New York NY 2014, ISBN 978-0-670-78591-9 ( at Google-books ).
- Female genital malformations. AWMF Register No. 015/052 Class: S1 + IDA, guideline of the German Society for Gynecology and Obstetrics (DGGG), publishing specialist society in cooperation with the Working Group for Child and Adolescent Gynecology, the German Society for Urology, the German Society for Children's and adolescent medicine, the German Society for Gynecological Endocrinology and Reproductive Medicine and the German Society for Human Genetics. [In revision], p. 4 
- German Ethics Council: Intersexuality - Opinion. Berlin, February 23, 2012, ISBN 978-3-941957-27-5 , pp. 30–31 ( full text as PDF file ( memento of March 18, 2016 in the Internet Archive )).