vukrot.blogg.se - Sexual symbol for female male

In birds and some reptiles, by contrast, it is the female which is heterozygous and carries a Z and a W chromosome while the male carries two Z chromosomes. One of the female's X chromosomes is randomly inactivated in each cell of placental mammals while the paternally derived X is inactivated in marsupials. Most mammalian females have two copies of the X chromosome, while males have only one X and one smaller Y chromosome some mammals, such as the platypus, have different combinations. Mammary glands are present in all mammals, although they are normally redundant in males of the species. Mammary glands are obvious in humans, because the female human body stores large amounts of fatty tissue near the nipples, resulting in prominent breasts. Mammary glands are modified sweat glands that produce milk, which is used to feed the young for some time after birth. clean-shaven pubic regions.Ī distinguishing characteristic of the class Mammalia is the presence of mammary glands. Note that both models have partially shaved body hair to show anatomy e.g. Photograph of an adult female human, with an adult male for comparison. In Thor manningi, primary females coexist with primary males and protandrous hermaphrodites. In a few species, female individuals coexist with males and simultaneous hermaphrodites this sexual system is called trioecy. In some species, female and hermaphrodite individuals may coexist, a sexual system termed gynodioecy. Species that are divided into females and males are classified as gonochoric in animals, as dioecious in seed plants and as dioicous in cryptogams. In land plants, female and male designate not only the egg- and sperm-producing organisms and structures, but also the structures of the sporophytes that give rise to male and female plants. The concept is not limited to animals egg cells are produced by chytrids, diatoms, water moulds and land plants, among others. Other than the defining difference in the type of gamete produced, differences between males and females in one lineage cannot always be predicted by differences in another.

There is an argument that this pattern was driven by the physical constraints on the mechanisms by which two gametes get together as required for sexual reproduction.

Oogamous species, which include humans, in which the female gamete is much larger than the male and has no ability to move.

Anisogamous species with gametes of male and female types,.

Isogamous species with two or more mating types with gametes of identical form and behavior (but different at the molecular level),.

Generally, a female cannot reproduce sexually without access to the gametes of a male, and vice versa, but in some species females can reproduce by themselves asexually, for example via parthenogenesis. Defining characteristicsįemales produce ova, the larger gametes in a heterogamous reproduction system, while the smaller and usually motile gametes, the spermatozoa, are produced by males. Female can refer to either sex or gender or even the shape of connectors, such as screws, or electrical and technical equipment. The word female comes from the Latin femella, the diminutive form of femina, meaning " woman" it is not etymologically related to the word male, but in the late 14th century the spelling was altered in English to parallel the spelling of male. "fæmnan," an Old English word for 'female' In humans, the word female can also be used to refer to gender or gender identity. Female characteristics vary between different species with some species having pronounced female characteristics, such as the presence of pronounced mammary glands in mammals. Most female mammals, including female humans, have two X chromosomes. In species that have males and females, sex-determination is based on either chromosomes, or environmental conditions.

The exact mechanism of female gamete evolution remains unknown. Females and males are results of the anisogamous reproduction system, wherein gametes are of different sizes, unlike isogamy where they are the same size.

It also stands for the planet Venus and is the alchemical symbol for copper.įemale (symbol: ♀) is the sex of an organism that produces the large non-motile ova (egg cells), the type of gamete (sex cell) that fuses with the male gamete during sexual reproduction. The symbol of the Roman goddess Venus is used to represent the female sex in biology.