Chapter 2：Intersex and Binary Genital Anatomy
Development of the Reproductive System
Mammal embryonic development is one of the remaining mysteries in biology. A 4-day old chicken embryo is hardly distinguishable from a human embryo of the same age. The same applies for weeks old male- and female human embryos. The developmental blueprint of mammals is feminine. In the absence of the Y chromosome, embryos follow female development. Around 6 to 8 weeks after fertilization, the gene encoding for Sex-determining Region Y protein (SRY) on the Y chromosome causes the development of primary male sex gonads (testicles). It is under the influence of the hormone testosterone produced by the testicles that embryos undergo male sex development. Sexual development continues after birth throughout live, and especially gains momentum during puberty. It is a multidimensional fascinating and fluid interplay determined by: chromosomes, genes, gonads (ovaria and testicles), external genitalia, the brain, and last but not least the psyche, daily experiences, and emotions of each individual.
The hidden parts of the clitoris
There are striking resemblances in the anatomy of the penis and the clitoris that persist after the embryonic development into adulthood. Although large parts of the clitoris (the spongious body and the cavernous body) are under the skin lining the vaginal wall, they play a big role in sexuality. Like the penis that becomes erect during sexual arousal, the inner parts of the clitoris cause the vagina to become wet and play a major part in sexual pleasure. It is a misconception that the clitoris is only the small visible button on top of the vagina.
Intersex Variations
The outcome of sexual development is a non-binary spectrum that can change in time. Intersex outcome is part of human nature and can occur in the many aforementioned dimensions (chromosomes, genes, gonads, external genitalia, the brain, the psyche and emotions). Intersex persons are individuals with a variation of the binary male/female pattern in the genital, the gonadal, the genetic and/or chromosomal sex. This is sometimes, characterized by gonadal absence, and ambiguous genitalia.