pollen development stage I first mitotic division stage plant_structure_development_stage Stage of microgametophyte development during which the asymmetric, first mitotic division of the microspores occurs producing a large vegetative cell and small generative cell, located near pollen wall. PO:0001014 stamen stage ST6-2 (related) PO_GIT:509 pollen stage 8 in Arabidopsis (related) GRO:0007228