Disorders of Development

Abstract

Development problems may occur at any of the following stages of development of the female genitalia:

• 1 Sex determination: Sex is determined by the complement of sex chromosomes from the male and female gametes. All human somatic cells contain 46 chromosomes: 22 homologous pairs and 2 sex chromosomes. It is the chromosomes that determine the sex of an individual. The normal female has two X (XX) and the normal male an X and a Y (XY) chromosome. The sex chromosome complement is determined at fertilization.

  • a Before Fertilization, male and female germ cells undergo meiosis. This reduces the original set of 22 autosomes and 2 sex chromosomes to half that number

  • b Hence the (male) smermatozoon carries either an X or a Y chromosome, whereas the (female) oocyte always contains an X chromosome

  • c Fertilization by a spermatozoon containing a Y chromosome produces a male (XY) zygote; fertilization by a spermatozoon containing an X-chromosome produces a female (XX) zygote