Sexual characteristics
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Sexual characteristics are physical traits of an organism (typically of a sexually dimorphic organism) which are indicative of its biological sex. These include both primary sex characteristics and secondary sex characteristics.
Humans
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 the Y-chromosome and/or the SRY gene determine development.
Hormones that express sexual differentiation in humans include:
- estrogens
- progesterone
- androgens such as testosterone
Typical sexual characteristics
The following table lists the typical sexual characteristics in humans (even though some of these can also appear in other animals as well):
| Level of definition | Female | Male |
|---|---|---|
| Biological levels (Sex) | ||
| Sex chromosomes | XX in humans | XY in humans |
| Primary sexual characteristics | ||
| Gonads | ovaries | testes |
| Levels of sex hormones | high estrogen and gestagens (including progesterone); low androgens (including testosterone) | high androgens (including testosterone) |
| Anatomy of internal genitalia | clitoral crura, vagina, uterus, fallopian tubes | corpora cavernosa, prostate, vas deferens, seminal vesicles |
| Anatomy of external genitalia |
glans clitoridis, labia, vulva, clitoral hood perineal urethra |
glans penis, scrotum, phallus, foreskin fused perineum |
| Secondary sexual characteristics | ||
| Larger breasts, wider hips, shorter height, more body fat, 10 to 12% less lung capacity,[1] smaller heart[2] | Facial and body hair, smaller breasts, lower drop in vocal pitch frequency, development of "triangular" body form, higher height, less body fat, narrower hips, more lung capacity | |
| Both sexes | Pubic hair, underarm hair | |
Other organisms
In invertebrates and plants, hermaphrodites (which have both male and female reproductive organs either at the same time or during their life cycle) are common, and in many cases, the norm.
In other varieties of multicellular life (e.g. the fungi division, Basidiomycota) sexual characteristics can be much more complex, and may involve many more than two sexes. For details on the sexual characteristics of fungi, see: Hypha and Plasmogamy.
See also
References
- ^ Bellemare F, Jeanneret A, Couture J (2003). "Sex differences in thoracic dimensions and configuration". Am J Respir Crit Care Med. 168 (3): 305–12. doi:10.1164/rccm.200208-876OC. PMID 12773331.
- ^ Glucksman A (1981). Sexual Dimorphism in Human and Mammalian Biology and Pathology. Academic Press. pp. 66–75.
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