FERTILIZATION 7 



It is the first polar body. The other contains the other 

 half of the chromatin and almost all the cytoplasm. It 

 is the secondary oocyte. The first maturation division is 

 now completed. 



Without any change in the form of the chromatin ma- 

 terial, a new spindle is formed in the secondary oocyte. 

 The first polar body may or may not divide. 



Draw a secondary oocyte in a metaphase stage and label 

 all the parts. 



d. Each dyad di\'ides into tw^o parts called monads. 

 One monad from each dyad moves to one pole of the 

 spindle and the other one moves to the other pole of the 

 spindle. 



Draw a secondary oocyte in an anaphase stage and label 

 all the parts. 



e. When the monads have reached the poles there is 

 a second unequal division of the egg. This division is 

 similar to the first one. The small cell is the second 

 polar body and the large one is the matured ovum. 



Draw a matured ovum showing the second polar body and 

 label all the parts. 



3. Fertilization 



In Ascaris the spermatozoan penetrates the v-itelline 

 membrane before the maturation divisions occur. It 

 may be seen in the cytoplasm of the egg either as an 

 indefinite dark blotch or as unchanged in shape. After 

 maturation is completed the chromatin of the egg changes 

 into the so-called resting condition and is called the 



