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36-658: Hildegard is a female name derived from the Old High German hild ('war' or 'battle') and gard ('enclosure' or 'yard'), and means 'battle enclosure'. Variant spellings include: Hildegarde ; the Polish , Portuguese , Slovene and Spanish Hildegarda ; the Italian Ildegarda ; the Hungarian Hildegárd ; and the ancient German Hildegardis . Female An organism 's sex

72-401: A cell splits itself in half. From a strict numbers perspective, a species that is half males/half females can produce half the offspring an asexual population can, because only the females are having offspring. Being male can also carry significant costs, such as in flashy sexual displays in animals (such as big antlers or colorful feathers), or needing to produce an outsized amount of pollen as

108-424: A diploid cell (the zygote ) is formed, which rapidly grows into a new organism. While the non-mammalian animal egg was obvious, the doctrine ex ovo omne vivum ("every living [animal comes from] an egg"), associated with William Harvey (1578–1657), was a rejection of spontaneous generation and preformationism as well as a bold assumption that mammals also reproduced via eggs. Karl Ernst von Baer discovered

144-513: A female sex vary between different species, having different female reproductive systems , with some species showing characteristics secondary to the reproductive system , as with mammary glands in mammals. In humans, the word female can also be used to refer to gender in the social sense of gender role or gender identity . The word female comes from the Latin femella , the diminutive form of femina , meaning " woman ", by way of

180-545: A few species. Anisogamy appears to have evolved multiple times from isogamy; for example female Volvocales (a type of green algae) evolved from the plus mating type . Although sexual evolution emerged at least 1.2 billion years ago, the lack of anisogamous fossil records make it hard to pinpoint when females evolved. Female sex organs (genitalia, in animals) have an extreme range of variation among species and even within species. The evolution of female genitalia remains poorly understood compared to male genitalia, reflecting

216-427: A long neck with a wider base containing the egg cell. Upon maturation, the neck opens to allow sperm cells to swim into the archegonium and fertilize the egg. The resulting zygote then gives rise to an embryo, which will grow into a new diploid individual, known as a sporophyte . In seed plants , a structure called the ovule contains the female gametophyte. The gametophyte produces an egg cell. After fertilization ,

252-530: A now-outdated belief that female genitalia are less varied than male genitalia, and thus less useful to study. The difficulty of reaching female genitalia has also complicated their study. New 3D technology has made female genital study simpler. Genitalia evolve very quickly. There are three main hypotheses as to what impacts female genital evolution: lock-and-key (genitals must fit together), cryptic female choice (females affect whether males can fertilize them), and sexual conflict (a sort of sexual arms race). There

288-428: A plant in order to get a chance to fertilize a female. Yet despite the costs of being male, there must be some advantage to the process. The advantages are explained by the evolution of anisogamy , which led to the evolution of male and female function. Before the evolution of anisogamy, mating types in a species were isogamous : the same size and both could move, catalogued only as "+" or "-" types. In anisogamy,

324-564: A small cross underneath, is commonly used to represent females. 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). Ovum When egg and sperm fuse during fertilisation ,

360-691: Is female ( symbol : ♀ ) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction . A female has larger gametes than a male . Females and males are results of the anisogamous reproduction system , wherein gametes are of different sizes (unlike isogamy where they are the same size). The exact mechanism of female gamete evolution remains unknown. In species that have males and females, sex-determination may be based on either sex chromosomes , or environmental conditions. Most female mammals , including female humans , have two X chromosomes . Characteristics of organisms with

396-406: Is also a hypothesis that female genital evolution is the result of pleiotropy , i.e. unrelated genes that are affected by environmental conditions like low food also affect genitals. This hypothesis is unlikely to apply to a significant number of species, but natural selection in general has some role in female genital evolution. The symbol ♀ ( Unicode : U+2640 Alt codes : Alt+12), a circle with

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432-517: Is also possible in a variety of species, including humans, to have other karyotypes . During reproduction , the male contributes either an X sperm or a Y sperm, while the female always contributes an X egg. A Y sperm and an X egg produce a male, while an X sperm and an X egg produce a female. The ZW sex-determination system , where females have ZW (as opposed to ZZ in males) sex chromosomes, is found in birds, reptiles and some insects and other organisms. The young of some species develop into one sex or

468-421: Is called trioecy . In Thor manningi (a species of shrimp), females coexist with males and protandrous hermaphrodites . A distinguishing characteristic of the class Mammalia is the presence of mammary glands . Mammary glands are modified sweat glands that produce milk, which is used to feed the young for some time after birth. Only mammals produce milk . Mammary glands are obvious in humans , because

504-462: Is the default sex, while in the poplar genus Populus the default is male. The sex of a particular organism may be determined by genetic or environmental factors, or may naturally change during the course of an organism's life. The sex of most mammals, including humans, is genetically determined by the XY sex-determination system where females have XX (as opposed to XY in males) sex chromosomes . It

540-418: The formative yolk ; and the nutritive yolk or deutoplasm , made of rounded granules of fatty and albuminoid substances imbedded in the cytoplasm. Mammalian ova contain only a tiny amount of the nutritive yolk, for nourishing the embryo in the early stages of its development only. In contrast, bird eggs contain enough to supply the chick with nutriment throughout the whole period of incubation. In

576-406: The oviparous animals (all birds , most fish , amphibians and reptiles ), the ova develop protective layers and pass through the oviduct to the outside of the body. They are fertilized by male sperm either inside the female body (as in birds), or outside (as in many fish). After fertilization, an embryo develops, nourished by nutrients contained in the egg. It then hatches from the egg, outside

612-409: The 1870s suggested that the production of oocytes (immature egg cells) stops at or shortly after birth. A review of reports from 1900 to 1950 by zoologist Solomon Zuckerman cemented the belief that females have a finite number of oocytes that are formed before they are born. This dogma has been challenged by a number of studies since 2004. Several studies suggest that ovarian stem cells exist within

648-434: The 21st century, the noun female is primarily used to describe non-human animals, to refer to biologically female humans in an impersonal technical context (e.g., "Females were more likely than males to develop an autoimmune disease"), or to impartially include a range of people without reference to age (e.g., girls ) or social status (e.g., lady ). As an adjective, female is still used in some contexts, particularly when

684-535: The Old French femelle . It is not etymologically related to the word male , but in the late 14th century the English spelling was altered to parallel that of male . It has been used as both noun and adjective since the 14th century. Originally, from its first appearance in the 1300s, female exclusively referred to humans and always indicated that the speaker spoke of a woman or a girl. A century later,

720-445: The aid of a microscope or other magnification device. The human ovum measures approximately 120 μm (0.0047 in) in diameter. Ooplasm is like the yolk of the ovum, a cell substance at its center, which contains its nucleus , named the germinal vesicle , and the nucleolus , called the germinal disc . The ooplasm consists of the cytoplasm of the ordinary animal cell with its spongioplasm and hyaloplasm , often called

756-504: The blue colour after GUS staining reveals. Soon after fertilisation the FIE gene is inactivated (the blue colour is no longer visible, left) in the young embryo. In algae , the egg cell is often called oosphere. Drosophila oocytes develop in individual egg chambers that are supported by nurse cells and surrounded by somatic follicle cells. The nurse cells are large polyploid cells that synthesize and transfer RNA, proteins, and organelles to

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792-478: The corresponding plugs male . Females produce ova , the larger gametes in a heterogamous reproduction system , while the smaller and usually motile gametes, the spermatozoa , are produced by males. 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 . Patterns of sexual reproduction include: Other than

828-417: 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. The concept is not limited to animals; egg cells are produced by chytrids , diatoms , water moulds and land plants , among others. In land plants, female and male designate not only the egg- and sperm-producing organisms and structures, but also

864-468: The egg nucleus. The resulting zygote develops into an embryo inside the ovule. The ovule, in turn, develops into a seed and in many cases, the plant ovary develops into a fruit to facilitate the dispersal of the seeds. Upon germination , the embryo grows into a seedling . In the moss Physcomitrella patens , the Polycomb protein FIE is expressed in the unfertilised egg cell (Figure, right) as

900-416: The female human body stores large amounts of fatty tissue near the nipples, resulting in prominent breasts . Mammary glands are present in all mammals, although they are normally redundant in males of the species. 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. One of

936-654: The female's X chromosomes is randomly inactivated in each cell of placental mammals while the paternally derived X is inactivated in marsupials. 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. In mammals, females can have XXX or X . Mammalian females bear live young , with the exception of monotreme females, which lay eggs. Some non-mammalian species, such as guppies , have analogous reproductive structures; and some other non-mammals, such as some sharks , also bear live young. In sex determination for mammals, female

972-406: The mammalian ovary. Whether or not mature mammals can actually create new egg cells remains uncertain and is an ongoing research question. In all mammals , the ovum is fertilized inside the female body. Human ova grow from primitive germ cells that are embedded in the substance of the ovaries . The ovum is one of the largest cells in the human body, typically visible to the naked eye without

1008-572: The mammalian ovum in 1827. The fusion of spermatozoa with ova (of a starfish) was observed by Oskar Hertwig in 1876. In animals, egg cells are also known as ova (singular ovum , from the Latin word ovum meaning ' egg '). The term ovule in animals is used for the young ovum of an animal. In vertebrates, ova are produced by female gonads (sex glands) called ovaries . A number of ova are present at birth in mammals and mature via oogenesis . Studies performed on humans, dogs, and cats in

1044-496: The mating cells are called gametes. The female gamete is larger than the male gamete, and usually immotile. Anisogamy remains poorly understood, as there is no fossil record of its emergence. Numerous theories exist as to why anisogamy emerged. Many share a common thread, in that larger female gametes are more likely to survive, and that smaller male gametes are more likely to find other gametes because they can travel faster. Current models often fail to account for why isogamy remains in

1080-405: The meaning was expanded to include non-human female organisms. For several centuries, using the word female as a noun was considered more respectful than calling her a woman or a lady and was preferred for that reason; however, by 1895, the linguistic fashion had changed, and female was often considered disparaging, usually on the grounds that it grouped humans with other animals. In

1116-478: The mother's body shortly before birth, or just after the egg leaves the mother's body. Some fish, reptiles and many invertebrates use this technique. Nearly all land plants have alternating diploid and haploid generations. Gametes are produced by the haploid generation, which is known as the gametophyte . The female gametophyte produces structures called archegonia , and the egg cells form within them via mitosis . The typical bryophyte archegonium consists of

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1152-400: The mother's body. See egg for a discussion of eggs of oviparous animals. The egg cell's cytoplasm and mitochondria are the sole means the egg can reproduce by mitosis and eventually form a blastocyst after fertilization. There is an intermediate form, the ovoviviparous animals: the embryo develops within and is nourished by an egg as in the oviparous case, but then it hatches inside

1188-462: The other depending on local environmental conditions, e.g. the sex of crocodilians is influenced by the temperature of their eggs. 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). The question of how females evolved is mainly a question of why males evolved. The first organisms reproduced asexually, usually via binary fission , wherein

1224-403: The ovule develops into a seed containing the embryo. In flowering plants , the female gametophyte (sometimes referred to as the embryo sac) has been reduced to just eight cells inside the ovule . The gametophyte cell closest to the micropyle opening of the ovule develops into the egg cell. Upon pollination , a pollen tube delivers sperm into the gametophyte and one sperm nucleus fuses with

1260-500: The sex of the person is relevant, such as female athletes or to distinguish a male nurse from a female one. Biological sex is conceptually distinct from gender , although they are often used interchangeably. The adjective female can describe a person's sex or gender identity . The word can also refer to the shape of connectors and fasteners , such as screws, electrical pins, and technical equipment. Under this convention, sockets and receptacles are called female, and

1296-449: The structures of the sporophytes that give rise to male and female plants . 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 some species, female and hermaphrodite individuals may coexist, a sexual system termed gynodioecy . In a few species, female individuals coexist with males and hermaphrodites ; this sexual system

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