Difference between revisions of "Sexual Differentiation - Anatomy & Physiology"

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* The '''Y''' chromosome is required to '''initiate male development'''.
 
* The '''Y''' chromosome is required to '''initiate male development'''.
 
* In absence of the Y chromosome, female gonads (Ovaries) will develop.
 
* In absence of the Y chromosome, female gonads (Ovaries) will develop.
* The prime male determining gene is '''SRY''' (sex determining region of the Y chromosome). * SRY is a very small piece of DNA that acts as a molecular switch to regulate structural genes and autosomal chromosomes, determining if and when they are to be activated.  
+
* The prime male determining gene is '''SRY''' (sex determining region of the Y chromosome.  
 +
 
 +
* SRY is a very small piece of DNA that acts as a molecular switch to regulate structural genes and autosomal chromosomes, determining if and when they are to be activated.  
 
* The presence of SRY alone is sufficient to ensure development of male gonads (Testes).
 
* The presence of SRY alone is sufficient to ensure development of male gonads (Testes).
 
* Female is the default sex, in absence of SRY female gonads (Ovaries) will develop.
 
* Female is the default sex, in absence of SRY female gonads (Ovaries) will develop.

Revision as of 09:23, 3 July 2008

Genetic Sex

  • Established at the time of fertilisation.
  • The foetus receives its genetic endowment in two equal portions from the male gamete (Spermatozoon) and female gamete (Oocyte).
  • The X sex chromosome is larger than the Y sex chromosome.
  • Females have XX chromosomes. All oocytes contain one X chromosome, they are the homogametic sex.
  • Males have XY chromosomes. Spermatozoa form two distinct populations, one containing X chromosomes and one containing Y chromosomes. They are the heterogametic sex.


  • The Y chromosome is required to initiate male development.
  • In absence of the Y chromosome, female gonads (Ovaries) will develop.
  • The prime male determining gene is SRY (sex determining region of the Y chromosome.
  • SRY is a very small piece of DNA that acts as a molecular switch to regulate structural genes and autosomal chromosomes, determining if and when they are to be activated.
  • The presence of SRY alone is sufficient to ensure development of male gonads (Testes).
  • Female is the default sex, in absence of SRY female gonads (Ovaries) will develop.


  • Subsequent gonadal development is dependent on a normal population of germ cells.

Internal Genetalia

External Genetalia

Turner's Syndrome
Kleinfelter's Syndrome
Testicular Feminisation
Adrenogenital Syndrome
Bovine Freemartinism