Female

From Wikipedia for FEVERv2
Jump to navigation Jump to search

For other uses, see Female (disambiguation). Female_sentence_0

Female (symbol: ♀) is the sex of an organism, or a part of an organism, that produces non-mobile ova (egg cells). Female_sentence_1

Barring rare medical conditions, most female mammals, including female humans, have two X chromosomes. Female_sentence_2

Female characteristics vary between different species with some species containing more well defined female characteristics, such as the presence of pronounced mammary glands. Female_sentence_3

There is no single genetic mechanism behind sex differences in different species and the existence of two sexes seems to have evolved multiple times independently in different evolutionary lineages. Female_sentence_4

The word female comes from the Latin femella, the diminutive form of femina, meaning "woman"; it is not etymologically related to the word male. Female_sentence_5

Female can also be used to refer to gender. Female_sentence_6

Defining characteristics Female_section_0

Females produce ova, the larger gametes in a heterogamous reproduction system, while the smaller and usually motile gamete, the spermatozoon, is produced by the male. Female_sentence_7

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. Female_sentence_8

There is no single genetic mechanism behind sex differences in different species and the existence of two sexes seems to have evolved multiple times independently in different evolutionary lineages. Female_sentence_9

Patterns of sexual reproduction include: Female_sentence_10

Female_unordered_list_0

  • Isogamous species with two or more mating types with gametes of identical form and behavior (but different at the molecular level),Female_item_0_0
  • Anisogamous species with gametes of male and female types,Female_item_0_1
  • Oogamous species, which include humans, in which the female gamete is very much larger than the male and has no ability to move. Oogamy is a form of anisogamy. 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.Female_item_0_2

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. Female_sentence_11

The concept is not limited to animals; egg cells are produced by chytrids, diatoms, water moulds and land plants, among others. Female_sentence_12

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. Female_sentence_13

Mammalian female Female_section_1

A distinguishing characteristic of the class Mammalia is the presence of mammary glands. Female_sentence_14

The mammary glands are modified sweat glands that produce milk, which is used to feed the young for some time after birth. Female_sentence_15

Only mammals produce milk. Female_sentence_16

Mammary glands are most obvious in humans, as the female human body stores large amounts of fatty tissue near the nipples, resulting in prominent breasts. Female_sentence_17

Mammary glands are present in all mammals, although they are seldom used by the males of the species. Female_sentence_18

Most mammalian females have two copies of the X chromosome as opposed to males which have only one X and one smaller Y chromosome; some mammals, such as the platypus, have different combinations. Female_sentence_19

To compensate for the difference in size, 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. Female_sentence_20

In birds and some reptiles, by contrast, it is the female which is heterozygous and carries a Z and a W chromosome whilst the male carries two Z chromosomes. Female_sentence_21

Intersex conditions can also give rise to other combinations, such as XO or XXX in mammals, which are still considered as female so long as they do not contain a Y chromosome, except for specific cases of mutations in the genes of XY individuals while in the womb. Female_sentence_22

However, these conditions frequently result in sterility. Female_sentence_23

Mammalian females bear live young, with the exception of monotreme females, which lay eggs. Female_sentence_24

Some non-mammalian species, such as guppies, have analogous reproductive structures; and some other non-mammals, such as sharks, whose eggs hatch inside their bodies, also have the appearance of bearing live young. Female_sentence_25

Etymology and usage Female_section_2

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. Female_sentence_26

Female can refer to either sex or gender or a shape of connectors. Female_sentence_27

Symbol Female_section_3

Main article: Gender symbol Female_sentence_28

The symbol ♀ (Unicode: U+2640 Alt codes: Alt+12), a circle with a small cross underneath, is commonly used to represent females. Female_sentence_29

Joseph Justus Scaliger once speculated that the symbol was associated with Venus, goddess of beauty because it resembles a bronze mirror with a handle, but modern scholars consider that fanciful, and the most established view is that the female and male symbols derive from contractions in Greek script of the Greek names of the planets Thouros (Mars) and Phosphoros (Venus). Female_sentence_30

Sex determination Female_section_4

Main article: Sex-determination system Female_sentence_31

The sex of a particular organism may be determined by a number of factors. Female_sentence_32

These may be genetic or environmental, or may naturally change during the course of an organism's life. Female_sentence_33

Although most species have only two sexes (either male or female), hermaphroditic animals have both male and female reproductive organs. Female_sentence_34

Genetic determination Female_section_5

The sex of most mammals, including humans, is genetically determined by the XY sex-determination system where males have X and Y (as opposed to X and X) sex chromosomes. Female_sentence_35

During reproduction, the male contributes either an X sperm or a Y sperm, while the female always contributes an X egg. Female_sentence_36

A Y sperm and an X egg produce a male, while an X sperm and an X egg produce a female. Female_sentence_37

The ZW sex-determination system, where males have ZZ (as opposed to ZW) sex chromosomes, is found in birds, reptiles and some insects and other organisms. Female_sentence_38

Members of Hymenoptera, such as ants and bees, are determined by haplodiploidy, where most males are haploid and females and some sterile males are diploid. Female_sentence_39

Environmental determination Female_section_6

The young of some species develop into one sex or the other depending on local environmental conditions, e.g. many crocodilians' sex is influenced by the temperature of their eggs. Female_sentence_40

Other species (such as the goby) can transform, as adults, from one sex to the other in response to local reproductive conditions (such as a brief shortage of males). Female_sentence_41

See also Female_section_7

Female_unordered_list_1


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Female.