PLATE 3 



EXPLANATION OP FIGURES 



All figures on this plate are of primary oocytes 



27 Primary oocyte, first maturation-division spindle established. Spindle 

 still centrally located in egg mass. (X 1700) 



28 Polar view of metaphase plate of first maturation spindle, showing eight- 

 een chromosomes. (X 1700) 



29 Lateral view of late metaphase plate of first maturation spindle. Spindle 

 fibers arranged in bundles for each clu'omosome. (X 4050) 



30 Amoeboid sperm penetrating vitelline membrane of primary oocyte. 

 (X 1700) 



31 Sperm almost completely within the egg. Spindle figure migrating to- 

 ward the periphery of the egg. Male centrosome seen imbedded in side of sperm 

 nucleus. (X 1700) 



32 Spindle at periphery of egg. Fertilization membrane formed. Sperm 

 beginning to lose its outline. Large vacuoles in oocytic cytoplasm becoming 

 peripheral in position. (X 1700) 



33 Spindle lying parallel to a tangent to the surface of the egg. Male centro- 

 some divided and its halves connected by a 'centro-desmus.' (X 1700) 



34 Polar view of metaphase plate of first maturation spindle. Sperm losing 

 its sharp outline. Centrosomes widely and somewhat precociously separated. 

 (X 1700) 



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