Formation of microspores inside the microsporangia of seed plants, Diploid cell in microsporangium undergoes meiosis and gives rise to four haploid microspores. Four nuclei are arranged tetrahedrally are soon invested with cell walls. Each and every cell in a microspore tetrad is haploid!! Tetrad just means there are four cells all of which are haploid in nature and are formed by reduction division or meiosis in microspore mother cells.