the major function of pollen is to deliver the sperm nuclei to the embryo sac . 
 it does this by germinating and producing a pollen tube and thus provides a relatively simple developmental system for study . 
 mutants for many pollen functions are accessible , as it is a haploid cell . 
 mature pollen was fractionated into diffusible proteins , soluble proteins , and proteins insolubly associated with membrane or wall ; these protein fractions have been quantified and cataloged by native and sds polyacrylamide gel electrophoresis . 
 diffusible proteins are localized in the pollen grain wall whereas soluble proteins are cytoplasmic . 
 the roles of haploid and diploid genomes in specifying these proteins is discussed . 
 pollen from maximally divergent maize lines was examined for quantitative and qualitative variation in the diffusible proteins . 
 a surprising conservation was found for these proteins indicating some functional role which is , at present , unknown . 
 initial experiments on the incorporation of 35s - methionine into germinating pollen indicate that major representatives of the diffusible proteins are made within the pollen grain itself . 
 they are presumably included in the pollen wall during development and diffuse out through the pore region . 
 studies with pollen mrna and experiments on incorporation of 35s - methionine into developing anthers are underway and will identify the origin of these proteins . 
 a knowledge of the basic developmental biology of maize pollen is a prerequisite to its judicious use as a monitor of environmental mutagens.imagesfigure 1.figure 2.figure 3.figure 4.figure 5 .