Document Type
Book Chapter
Publication Date
4-25-2025
Keywords
anatomy, basic structures, chromosome, external genitalia, female, fetus, fetuses, gonadal differentiation, male, pregnancy, sex differentiation, SRY gene, ultrasound imaging, womb, week 6, week 8, week 20, XX chromosomes, Y chromosome
Disciplines
Developmental Psychology
Abstract
Sex differentiation occurs while a baby is still in the womb. Before week six of the pregnancy, all fetuses have the same basic structures resembling those of a female. Between 6 and 8 weeks, gonadal differentiation occurs, starting with the SRY gene, which is located on the Y chromosome of a male, therefore is absent in females. The SRY gene stimulates the fetus to begin transitioning from its current female-like anatomy to that of a male. Because the SRY gene is absent in the XX chromosomes of a female, no signal occurs and the anatomy remains female. By week 20 of the pregnancy, the external genitalia are fully formed and the sex of the fetus can be determined via ultrasound imagining.
Recommended Citation
Tobin, Casey T., "Infancy and Childhood Sexuality" (2025). Essays in Developmental Psychology. 85.
https://nsuworks.nova.edu/edp/85