The sex cords are embryonic structures which eventually will give rise to the adult gonads (reproductive organs)[1]. They are formed from the genital ridges in the first 2 months of gestation which depending on the sex of the embryo will give rise to male or female sex cords[2]. 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[3]. If there is no Y chromosome present the opposite will occur, developing ovarian cords [4] .
Male Sex Cord Stuff
editOnce the genital ridge has committed to becoming male sex cords, Sertoli cells develop[3]. These cells then induce the production and organisation of cells making up the testicular cords[2]. These cords will eventually become the testes, which in turn produce hormones, in particular testosterone[5]. These hormones drive the formation of the other male sex characteristics, and induce testicular descent (out of the abdomen)[3]. These hormones also cause the development of the male reproductive tract. Embryos are formed with wolffian and mullerian ducts, which will either become the male or female reproductive tract, respectively[5]. In a male embryo, the testicular cords will induce the development of the wolffian duct into the vas deferens, epididymis and the seminal vesicle and cause the repression and regression of the mullerian duct[3]. The other male sex organs (ex. the prostate) as well as external genitalia are also formed under the influence of testosterone[3].
References
edit- ^ 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.
- ^ a b 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 1759-4820.
- ^ a b c d e Wilhelm, Dagmar; Koopman, Peter (2006-07-11). "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.
- ^ 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.
- ^ a b Coward, Kevin; Wells, Dagan, eds. (2013-10-31). Textbook of Clinical Embryology (1 ed.). Cambridge University Press. doi:10.1017/cbo9781139192736. ISBN 978-1-139-19273-6.
Not to be confused with Sex card.
| Sex cords | |
|---|---|
| Details | |
| Precursor | genital ridge |
| Gives rise to | testis cords, cortical cords |
| System | Reproductive system |
| Identifiers | |
| Latin | chorda sexualis primordialis gonadalis |
| TE | cords_by_E5.7.1.1.0.0.7 E5.7.1.1.0.0.7 |
| Anatomical terminology
[edit on Wikidata] | |
In embryogenesis, the sex cords (primitive sex cords, primitive seminiferous cords, or gonadal cords) are structures that develop from the genital ridges that further differentiate based on an embryo's sex. After sexual differentiation, at day 49, the sex cords in females become the cortical cords, also called secondary cords. After further development, they become the ovarian follicles. The sex cords in males become the testis cords by the action of the testis-determining factor protein, which helps to develop and nourish the Sertoli cells.
The testis cords are precursors to the rete testis. They play several different roles in the development of the male genitals[1]. The primitive sex cords originate from the proliferation of the epithelium of the two genital ridges. These epithelial cells (from the genital ridges) penetrate and invade the underlying mesenchyme to form the primitive sex cords[2]. This occurs shortly before and during the arrival of the primordial germ cells (PGCs) to the paired genital ridges[3].
See also
editReferences
edit- ^ Yao, Humphrey Hung-Chang; Capel, Blanche (2002). "Disruption of Testis Cords by Cyclopamine or Forskolin Reveals Independent Cellular Pathways in Testis Organogenesis". Developmental Biology. 246 (2): 356–365. doi:10.1006/dbio.2002.0663.
- ^ Sadler, Thomas W. (2010). Langman's medical embryology (11th ed.). Philadelphia: Wolters Kluwer. ISBN 978-0-7817-9069-7.
- ^ Sadler, Thomas W. (2015). Langman's medical embryology (13. ed., [international ed.] ed.). Philadelphia, Pa.: Wolters Kluwer. ISBN 978-1-4698-9780-6.