Search results
Results From The WOW.Com Content Network
The sporophytes of plants of these groups may also have the ability to form a plant that looks like a gametophyte but with the ploidy level of the sporophyte, a phenomenon known as apospory. [6] [7] See also androgenesis and androclinesis described below, a type of male apomixis that occurs in a conifer, Cupressus dupreziana.
Megagametogenesis is the process of maturation of the female gametophyte, or megagametophyte, in plants. [1] During the process of megagametogenesis, the megaspore, which arises from megasporogenesis, develops into the embryonic sac, in which the female gamete is housed. [2]
These groups both send a nucleus to the center of the cell; these become the polar nuclei. Depending on the species, these nuclei fuse before or upon fertilization of the central cell. The three nuclei at the end of the cell near the micropylar become the egg apparatus, with an egg cell in the center and two synergids.
The mature embryonic sac of an unfertilized ovule is 7-cellular and 8-nucleate. It is arranged in the form of 3+1+3 (from top to bottom) i.e. 3 antipodal cells, 1 central cell (binucleate), 2 synergids & 1 egg cell. One sperm fertilizes the egg cell and the other sperm fuses with the two polar nuclei of the large central cell of the ...
At a minimum, two of these cells are egg cells and the rest are haploid somatic cells, but more egg cells may be present and their ploidy, though typically haploid, may vary. [14] [17] In select Gnetophyta, the female gametophyte stays singled celled. Mitosis does occur, but no cell divisions are ever made. [13]
Ploidy (/ ˈ p l ɔɪ d i /) is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here sets of chromosomes refers to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair—the form in which chromosomes ...
The list of organisms by chromosome count describes ploidy or numbers of chromosomes in the cells of various plants, animals, protists, and other living organisms.This number, along with the visual appearance of the chromosome, is known as the karyotype, [1] [2] [3] and can be found by looking at the chromosomes through a microscope.
The LURE peptides that are secreted from the synergids, which occupy the space adjacent to the egg cell, can use attractants. In mutant Arabidopsis plant embryos, specifically in those without the synergids, the pollen tubes were unable to grow [citation needed]. Pollen tube growth is toward eggs of the same species as the pollen.