The gametophyte generation is multicellular, haploid (n) very small in size, does not have conducting tissues and is dependent upon the sporophyte. The sporophytes of all gymnosperms are heterosporous since they produce two types of spores, namely the microspores and megaspores. The microspores are produced in structures, called microsporangia which are produced by modified fertile leaves called microsporophylls. The microsporophylls are compactly arranged in male cones or male strobili. In a microsporangium there are special diploid cells called microspores mother cells which undergo meiosis or reduction division to produce haploid microspores. Within the microspore, a reduced few celled male gametophyte generation develops. This entire structure is in the pollen grain which develops within the microsporangia. The megaspores are produced in megasporangia or ovules which are produced by modified fertile leaves called megasporophylls.