• Ahmad Wagih Abdel (Halim)


  • The gametes originate in the yolk sac and migrate to the gonads in the form of primordial germ cells.

  • The primordial germ cells transform into either sperm or ova depending on the individual’s sex.

Meiosis (Figs. 2.12.3 )

  • Meiosis I:
    1. 1.

      This phase begins with oogonia in females and spermatogonia in males; both types of cells have 46 chromosomes and 2 NDNA.

    2. 2.

      Meiosis I concludes with the formation of secondary gametocytes (23, 2 N).

    3. 3.

      Processes occurring during meiosis I are DNA replication and crossing over.

    4. 4.

      Note: The centromere does not divide during meiosis I.



Clinical Picture Patent Ductus Arteriosus Ventricular Septal Defect Undescended Testis Urogenital Sinus 
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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.McLaren Regional Medical CenterFlintUSA

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