Sexual differentiation and its disorders
How SRY drives the bipotential gonad to a testis, how AMH, testosterone and DHT build the male internal and external genitalia, and how a defect at each step (gonadal dysgenesis, CAH, 5-alpha-reductase deficiency, androgen insensitivity) produces a predictable phenotype and hormone pattern, with the 2006 Chicago consensus terminology.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Sex development has three steps: chromosomal sex (XX or XY), gonadal sex (testis or ovary), and phenotypic sex (internal ducts and external genitalia).
- SRY turns the bipotential gonad into a testis. Without it, the default is an ovary.
- The testis makes three things that matter. AMH from Sertoli cells removes the Müllerian ducts. Testosterone from Leydig cells keeps the Wolffian ducts. DHT, made peripherally by 5-alpha-reductase type 2, builds the penis, scrotum and prostate.
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Sources
- Consensus statement on management of intersex disorders (Chicago consensus). Lee PA, Houk CP, Ahmed SF, Hughes IA. Pediatrics 2006;118:e488-500Lawson Wilkins Pediatric Endocrine Society and European Society for Paediatric Endocrinology, 2006
- Global disorders of sex development update since 2006: perceptions, approach and care. Lee PA et al. Horm Res Paediatr 2016;85:158-80Hormone Research in Paediatrics, 2016
- Congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency: an Endocrine Society clinical practice guideline. Speiser PW et al. J Clin Endocrinol Metab 2018;103:4043-88Endocrine Society, 2018
- Williams Textbook of Endocrinology, 15th editionElsevier, 2024
- Hutson JM et al. Regulation of testicular descent. Pediatr Surg Int 2015 (PMID 25690562)Pediatric Surgery International, 2015
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy