2 ) alternatively , formation of the trigeminal primordium and the motor root of the trigeminal nerve and evagination of the neurohypophysis occur earlier in the baboon and rhesus monkey ( i.e. , stages 12-13 , stage 14 , and stage 15 , respectively ) than observed in the human embryo ( stage 14 , stage 15 , and stage 16 , respectively ) ;
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primordium
C0868971
human embryo