Sex cords

Not to be confused with Sex card.
2 and 5 sex cords
A depiction of the migration of the cells which will give rise to the sex cords into the genital ridge where they will become the gonads of the embryo

Sex cords are embryonic structures which eventually will give rise (differentiate) to the adult gonads (reproductive organs).[1] They are formed from the genital ridges - which will develop into the gonads - in the first 2 months of gestation (embryonic development) which depending on the sex of the embryo will give rise to male or female sex cords.[2] These epithelial cells (from the genital ridges) penetrate and invade the underlying mesenchyme to form the primitive sex cords.[3] This occurs shortly before and during the arrival of the primordial germ cells (PGCs) to the paired genital ridges.[3] If there is a Y chromosome present, testicular cords will develop via the Sry gene (on the Y chromosome): repressing the female sex cord genes and activating the male.[4][5] If there is no Y chromosome present the opposite will occur, developing ovarian cords.[6][7] Prior to giving rise to sex cords, both XX and XY embryos have Müllerian ducts and Wolffian ducts.[2] One of these structures will be repressed to induce the other to further differentiate into the external genitalia.[2]

  1. ^ Kanai, Yoshiakira; Kurohmaru, Masamichi; Hayashi, Yoshihiro; Nishida, Takao (1989). "Formation of male and female sex cords in gonadal development of C57BL/6 mouse". The Japanese Journal of Veterinary Science. 51 (1): 7–16. doi:10.1292/jvms1939.51.7. ISSN 0021-5295.
  2. ^ a b c Reyes, Alejandra P.; León, Nayla Y.; Frost, Emily R.; Harley, Vincent R. (2023). "Genetic control of typical and atypical sex development". Nature Reviews Urology. 20 (7): 434–451. doi:10.1038/s41585-023-00754-x. ISSN 1759-4812. PMID 37020056. S2CID 257984306.
  3. ^ a b Sadler, T.W. (2015). Langman's medical embryology (13th ed.). Philadelphia: Wolters Kluwer. ISBN 9781469897806. OCLC 885475111.
  4. ^ Wilhelm, Dagmar; Koopman, Peter (2006). "The makings of maleness: towards an integrated view of male sexual development". Nature Reviews Genetics. 7 (8): 620–631. doi:10.1038/nrg1903. ISSN 1471-0056. PMID 16832429. S2CID 20339526.
  5. ^ Gubbay, John; Collignon, Jérôme; Koopman, Peter; Capel, Blanche; Economou, Androulla; Münsterberg, Andrea; Vivian, Nigel; Goodfellow, Peter; Lovell-Badge, Robin (1990). "A gene mapping to the sex-determining region of the mouse Y chromosome is a member of a novel family of embryonically expressed genes". Nature. 346 (6281): 245–250. Bibcode:1990Natur.346..245G. doi:10.1038/346245a0. ISSN 0028-0836. PMID 2374589. S2CID 4270188.
  6. ^ Fouquet, J. P.; Dang, D. C. (1980). "A comparative study of the development of the fetal testis and ovary in the monkey (Macaca fascicularis)". Reproduction Nutrition Développement. 20 (5A): 1439–1459. doi:10.1051/rnd:19800804. ISSN 0181-1916. PMID 7349493.
  7. ^ Chassot, Anne-Amandine; Gillot, Isabelle; Chaboissier, Marie-Christine (2014). "R-spondin1, WNT4, and the CTNNB1 signaling pathway: strict control over ovarian differentiation". Reproduction. 148 (6): R97–R110. doi:10.1530/REP-14-0177. ISSN 1470-1626. PMID 25187620.