To our knowledge the ovule is the source of the megagametophyte
and the progenitor of the seed (Reiser and Fischer 1993).
2007.Shoot bud differentiation from megagametophyte
cultures of Cycas circinalis L.
This cell, the embryo sac, is the mature megagametophyte
. The eight nuclei are normally arranged with four at the micropyle end and four at the opposite end of the embryo sac.
Chavez VM, Litz RE (1999) Organogenesis from megagametophyte
and zygotic embryo explants of the gymnosperm Dioon edule Lindley (Zamiaceae, Cycadales).
Preliminary microscopic examination of methacrylate-embedded ovaries (not shown) indicated that few (3 of 20) contained a complete megagametophyte
Variations of the megagametophyte
in the Papilionoidea.
embryo sac: Mature megagametophyte
; contains eight haploid nuclei.
Apomixis (i.e., asexual reproduction by seeds) is a common trait in the genus, being apospory (in which a non reduced megagametophyte
originates from a somatic cell, usually a nucellar cell) the most frequent type, and diplospory (in which a non reduced megaspore originates from the reproductive cell itself, with the later failing to successfully complete meiosis) only of occasional occurrence (Quarin, 1992).
Both the embryo and the haploid megagametophyte
were genotyped to distinguish maternal and paternal alleles in these seeds.
Comparative ovule and megagametophyte
development in Hydatellaceae and water lilies reveal a mosaic of features among the earliest angiosperms.
development in Lotus corniculatus, L.
We used electrophoresis of megagametophyte
and embryo pairs to analyze the mating system in two populations, Cerro de la Cruz and Arroyo del Infierno.
The embryos together with the suspensor were carefully dissected from the female gametophyte (megagametophyte
) and fixed in a mixture of 50% ethanol, acetic acid and formaldehyde in the ratio of 9:1:1 by volume.
Such paternal environmental effects differ from maternal environmental effects because only the male gametophyte is affected; in contrast, maternal environmental effects may act on any of the maternally derived tissues within a developing seed: the megagametophyte
, seed coat, endosperm, embryo, or megasporophyte tissue.
farineacous; embryo with two cotyledons and a coiled