Fig. 102. Ontogeny of a simple (reduced) ovule, Vanilla planifolia, tenuinucellate, 

 with vestigial integument. A, ovule primordium before development of archesporial 

 cell; B, archesporial cell and primordium of integument; C, spore mother cell, 

 nucellus and integument enlarging; D, dyad cells, integument complete; E, two 

 megaspores and one micropylar dyad cell; F, 2-nucleate embryo sac; G, 4-nucleate 

 embryo sac; H, nuclei of 4-nucleate sac dividing; 1, mature (6-nucleate) embryo 

 sac. {After Swamy.) 



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