Stranded Arrangement of Sporopollenin in the Exine of Microspores of Poa annua

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Science  17 Aug 1962:
Vol. 137, Issue 3529, pp. 526-528
DOI: 10.1126/science.137.3529.526


In the early microspore wall of the grass Poa annua L., sporopollenin is arranged in bundles of anastomosing strands. Each bundle contains at least two strands, each about 50 A in diameter, which anastomose or intertwine and look like a meshwork with pores of the mesh up to 50 A in diameter. After the early microspore stage the exine becomes homogeneous; it is similar in this respect to the exines or ornamented parts of the exines of pollen of other angiosperms examined by electron microscopy.