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Fig. 26. — Miastor americana. Diagram illustrating origin and history 

 of germ cells from one generation to the next. cl.n = cleavage 

 nucleus ; ex.chr = extruded chromatin ; oog = oogonia ; p.b = polar 

 body; p.gr.c = primordial germ cell; p.o= primary oocyte; p.pl = 

 polar plasm, st.c = stem cell. (65) 



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