The possession of only one form of spore. This gives rise to a single gametophyte generation carrying both male and female reproductive organs. A stage of nuclear division in eukaryote cells, occurring once in mitosis and twice in meiosis. This phase begins when all of the centromeres line up at the equatorial plane. A small canal in the integument surrounding the ovule of a flowering plant, through which the pollen tube usually enters the ovule on the way to the embryo sac.
Water enters the seed via the micropyle prior to germination.
In Tracheophytes the microspore is the pollen grain. The stages conserve chromosome number by equally allocating replicated chromosomes to each of the daughter cells. A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents. In the life cycle of a plant or alga undergoing alternation of generations, a meiotically produced haploid cell that divides mitotically, generating a multicellular individual, the gametophyte, without fusing with another cell. The multicellular diploid form in organisms undergoing alternation of generations that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation.