A person's sex can be considered across various levels. To illustrate, genes, hormones, and genitalia can all be considered physical markers of a person's sex. In addition to physical markers, behaviors such as gender role, gender identity and sexual orientation can be perceived as stereotypically male or female. The purpose of this review is to summarize current knowledge of sexual differentia...

The preference to seek out a sexual partner of the opposite sex is robust and ensures reproduction and survival of the species. Development of female-directed partner preference in the male is dependent on exposure of the developing brain to gonadal steroids synthesized during critical periods of sexual differentiation of the central nervous system. In the absence of androgen exposure, a male-d...

Urbanization is among the most important and globally rapidly increasing anthropogenic processes and is known to drive rapid evolution. Habitats in urbanized areas typically consist of small, fragmented and isolated patches, which are expected to select for a better locomotor performance, along with its underlying morphological traits. This, in turn, is expected to cause differentiation in sele...

Malaria parasites have a complex life cycle with asexual multiplication in a vertebrate host and obligate sexual reproduction in the mosquito; however, commitment to sexual development begins in the vertebrate with differentiation of female and male gametocytes. In this issue of Cell, Khan et al. (2005) used elegant approaches to purify male and female gametocytes and elucidated their respectiv...

Sexual dimorphism in humans has been the subject of wonder for centuries. In 355 BC, Aristotle postulated that sexual dimorphism arose from differences in the heat of semen at the time of copulation. In his scheme, hot semen generated males, whereas cold semen made females (Jacquart, D., and C. Thomasset. Sexuality and Medicine in the Middle Ages, 1988). In medieval times, there was great contr...

We argue that estrogen feminization of the brain is the result of a series of events initiated by differential androgen exposure. There is no need to postulate a feminizing process parallel to androgen-induced masculinization to explain the findings. Fitch & Denenberg (F&D) argue that the current view of the process of sexual differentiation of mammalian brain and behavior proposed by Phoenix e...

Normal human development requires the compatibility between genetic sex (sex chromosomes), sex of gonades (tests or ovaries), genitalia (external and internal sex organs), somatic features (body characteristics) and psychic sex. The psychic sex, called frequently gender, consist of gender identity (self-estimation), gender role (objective estimation) and sexual orientation (hetero- or homosexua...

Male sexual differentiation is the result of complex mechanisms involving developmental genetics and endocrinology. Formation of the bipotential gonads and subsequently the testes is dependent on a series of sex chromosome-linked and autosomal genes. The testes secrete both peptide and steroid hormones essential for the formation of internal and external genitalia. Hormone action is mediated vi...