Tokyo Medical University
Department of Paediatircs
Genetics Study Group
Hironao NUMABE, M.D.


Japanese Page is Here.

Animations of Meiosis and Fertilization:

Here, I present the process of nondisjunction in the first meiotic division of Down syndrome (trisomy 21).
Similar nondisjunction in the second meiotic division may occur in the case of Down syndrome.
The nondisjunction may occur in spertomatogenesis as well as in ovogenesis.
cf. Animation of Translocation Type Down Syndrome

These animations are generalized images and are not reliable.

crossing over in meiosis(176K)

normal meiotic division and fertilization(244K)

nondisjunction in Down syndrome(247K)

meiosis and fertilizaiton in normal and Down syndrome
(PowerPoint 2002: 601K)

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