Sexual differentiation in the context of Reproductive

A gender symbol is a pictogram or glyph used to represent sex and gender, for example in biology and medicine, in genealogy, or in the sociological fields of gender politics, LGBT subculture and identity politics.

In his books Mantissa Plantarum (1767) and Mantissa Plantarum Altera (1771), Carl Linnaeus regularly used the planetary symbols of Mars, Venus and Mercury (♂, ♀ and ☿) for male, female and hermaphroditic (perfect) flowers, respectively. Botanists now use ⚥ for the last.

The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. Unlike most organ systems, the sexes of differentiated species often have significant differences. These differences allow for a combination of genetic material between two individuals, which allows for the possibility of greater genetic fitness of the offspring.

The development of the urinary system begins during prenatal development, and relates to the development of the urogenital system – both the organs of the urinary system and the sex organs of the reproductive system. The development continues as a part of sexual differentiation.

The urinary and reproductive organs are developed from the intermediate mesoderm. The permanent organs of the adult are preceded by a set of structures which are purely embryonic, and which with the exception of the ducts disappear almost entirely before birth. These embryonic structures are on either side; the pronephros, the mesonephros and the metanephros of the kidney, and the Wolffian and Müllerian ducts of the sex organ. The pronephros disappears very early; the structural elements of the mesonephros mostly degenerate, but the gonad is developed in their place, with which the Wolffian duct remains as the duct in males, and the Müllerian as that of the female. Some of the tubules of the mesonephros form part of the permanent kidney.

The New Mexico whiptail (Aspidoscelis neomexicanus) is a female-only species of lizard found in New Mexico and Arizona in the southwestern United States, and in Chihuahua in northern Mexico. It is the official state reptile of New Mexico. It is one of many lizard species known to be parthenogenetic. Individuals of the species can be created either through the hybridization of the little striped whiptail (A. inornatus) and the western whiptail (A. tigris), or through the parthenogenetic reproduction of an adult New Mexico whiptail.

The hybridization of these species prevents healthy males from forming, whereas males exist in one parent species (see sexual differentiation). Parthenogenesis allows the all-female population to reproduce. This combination of interspecific hybridization and parthenogenesis exists as a reproductive strategy in several species of whiptail lizard within the genus Aspidoscelis to which the New Mexico whiptail belongs.

Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. The smaller of these, the microspore, is male and the larger megaspore is female. Heterospory evolved during the Devonian period from isospory independently in several plant groups: the clubmosses, the ferns including the arborescent horsetails, and progymnosperms. This occurred as part of the process of evolution of the timing of sex differentiation. Four extant groups of plants are heterosporous; Selaginella, Isoetes, Salviniales and seed plants.

An antigonadotropin is a drug which suppresses the activity and/or downstream effects of one or both of the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This results in an inhibition of the hypothalamic-pituitary-gonadal (HPG) axis, and thus a decrease in the levels of the androgen, estrogen, and progestogen sex steroids in the body. Antigonadotropins also inhibit ovulation in women and spermatogenesis in men. They are used for a variety of purposes, including for the hormonal birth control, treatment of hormonally-sensitive cancers, to delay precocious puberty and puberty in transgender youth, as a form of chemical castration to reduce the sex drives of individuals with hypersexuality or pedophilia, and to treat estrogen-associated conditions in women such as menorrhagia and endometriosis, among others. High-dose antigonadotropin therapy has been referred to as medical castration.

The best-known and widely used antigonadotropins are the gonadotropin-releasing hormone (GnRH) analogues (both agonists and antagonists). However, many other drugs have antigonadotropic properties as well, including compounds acting on sex steroid hormone receptors such as progestogens, androgens, and estrogens (due to negative feedback on the HPG axis), as well as steroid synthesis inhibitors such as danazol and gestrinone. Since progestins have relatively little effect on sexual differentiation compared to the other sex steroids, potent ones such as cyproterone acetate, medroxyprogesterone acetate, and chlormadinone acetate are often used at high doses specifically for their antigonadotropic effects.

In biology and medicine, feminization is the development in an organism of physical characteristics that are usually unique to the females of the species. This may represent a normal developmental process, contributing to sexual differentiation. Feminization can also be induced by environmental factors, and this phenomenon has been observed in several animal species. In the case of transgender hormone therapy, it is intentionally induced medically.

Sexual differentiation in humans is the process of development of sex differences in humans. It is defined as the development of phenotypic structures consequent to the action of hormones produced following gonadal determination. Sexual differentiation includes development of different genitals and internal genital tracts; body hair also plays a role in sex identification.

The development of sexual differences begins with the XY sex-determination system that is present in humans, and complex mechanisms are responsible for the development of the phenotypic differences between male and female humans from an undifferentiated zygote. Females typically have two X chromosomes, and males typically have a Y chromosome and an X chromosome. At an early stage in embryonic development, both sexes possess equivalent internal structures. These are the mesonephric ducts and paramesonephric ducts. The presence of the SRY gene on the Y chromosome causes the development of the testes in males, and the subsequent release of hormones which cause the paramesonephric ducts to regress. In females, the mesonephric ducts regress.

Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens.

Virilization is a medical term commonly used in three medical and biology of sex contexts: prenatal biological sexual differentiation, the postnatal changes of typical chromosomal male (46, XY) puberty, and excessive androgen effects in typical chromosomal females (46, XX). It is also the intended result of androgen replacement therapy in males with delayed puberty and low testosterone.