This section of notes covers genital development. Differences in development are dependent on a protein product of the Y chromosome SRY gene.
Y Chromosome Overview
Page Links: Introduction | Some Recent Findings | Development Overview | Anti-Mullerian Hormone | References | Glossary
Related Pages: Medicine - Sex Selection | Medicine - Internal Genitalia | Molecular Development - Sry |
Sex Determination
Gonad development
SRY
Internal Genital Organs
External Genital Organs
The Wolffian or mesonephric duct is maintained by testosterone and forms the internal male genital tract.
Anti-Mullerian hormone (AMH) or Mullerian Inhibiting Substance (MIS) hormone with at least two gonadal related functions:
In males, it is produced by supporting gonadal Sertoli cells and inhibits the development of the paramesonephric (Mullerian) duct system that forms the internal female genital tract. The hormone is also involved in Leydig cell steroidogenesis.
In females, it is produced by supporting gonadal granulosa cells and is involved in ovarian follice development.
Anti-Mullerian hormone is a member of the transforming growth factor-beta (TGF-beta) superfamily that is thought to act through cell surface transmembrane serine/threonine kinase receptors (AMH type I and type II). (More? see Josso etal., 2006)
A further non-gonad function for this hormone is as a growth factor for spinal cord motor neurons, with males having up to 15% more spinal cord motor neurons than females.
Wang PY, Koishi K, McGeachie AB, Kimber M, Maclaughlin DT, Donahoe PK, McLennan IS. Mullerian inhibiting substance acts as a motor neuron survival factor in vitro. Proc Natl Acad Sci U S A. 2005 Nov 8;102(45):16421-5. "MIS was observed to support the survival and differentiation of embryonic motor neurons in vitro. During development, male-specific MIS may have a hormone effect because the blood-brain barrier has yet to form, raising the possibility that MIS participates in generating sex-specific differences in motor neurons."
Links: OMIM - AMH
Reviews
Barsoum I, Yao HH. The road to maleness: from testis to Wolffian duct. Trends Endocrinol Metab. 2006 Aug;17(6):223-8.
Kim Y, Capel B. Balancing the bipotential gonad between alternative organ fates: a new perspective on an old problem. Dev Dyn. 2006 Sep;235(9):2292-300.
Josso N, Picard JY, Rey R, di Clemente N. Testicular anti-Mullerian hormone: history, genetics, regulation and clinical applications. Pediatr Endocrinol Rev. 2006 Jun;3(4):347-58.
Articles
Wang PY, Koishi K, McGeachie AB, Kimber M, Maclaughlin DT, Donahoe PK, McLennan IS. Mullerian inhibiting substance acts as a motor neuron survival factor in vitro. Proc Natl Acad Sci U S A. 2005 Nov 8;102(45):16421-5.
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The male and female reproductive systems develop initially "indifferently", it is the product of the Y chromosome SRY gene that makes the difference.
Please email Dr Mark Hill if you wish to make a comment about this current project.