Incorporating sex as a biological variable in preclinical research
In the spring of 2015 the National Institutes of Health announced new guidelines for the incorporation of sex as a biological variable in any research they fund. Chromosome compliment (XX for female, XY for male in all mammals), gonadal phenotype, and gamete size define sex as a biological parameter. (In contrast, gender is a human construction based on an individual or society’s perception of sex.)