5) Davis (1966) classified the embryo sac
development into 11 types: Polygonum, Oenothera, Allium, Endymion, Plumbago, Peperomia, Fritillaria, Drusa, Adoxa, Penaea and Plumbagella.
However, and as a difference with recent reviews, I will pay special attention in this review to the other two, less known alternatives: male-derived haploid embryogenesis within the embryo sac
, and meiocyte-derived callogenesis.
Year-to-year variation in the developmental stage of the embryo sac
at anthesis in flowers of apricot (Prunus armeniaca L.
After multiple tests, the researchers found that during embryo sac
formation, auxin concentrations did indeed follow a gradient, with the highest levels occurring in the ovule at the end of the embryo sac
where the pollen enters and lowest levels occurring at the opposite end of the sac.
In one aspect of this work, the scientists are investigating how such messages may help the growing pollen tube find its way to the embryo sac
Two polar nuclei met in the middle of the embryo sac
and fused to form a single large central cell before fertilization (Fig.
Even though the extra fertilized egg later dies off -- and the nonflowering Ephedra's embryo ultimately feeds on its embryo sac
cells -- Friedman says this is evidence of how endosperm once formed.
Besides, the inner integument remains uniformly two layered which include numerous starch grains at the stage of mature embryo sac
A total of 472 ovaries, fixed at monthly intervals throughout a complete flowering season, showed over 76% of the mature ovules bearing one meiotic embryo sac
The outermost (dermal) layer undergoes mainly anticlinal divisions at first, although it may later proliferate at the micropylar end to form a nucellar cap, and sometimes may also proliferate around and below the embryo sac
Mitotic divisions take placed in the functional megaspore and resulted to form a two nucleated embryo sac
This 4-h period may be enough time to allow the unreduced egg cell to be fertilized before the onset of parthenogenesis because the time required from pollination until the pollen tube enters the embryo sac
is between 2 and 3 h for most buffelgrass accessions (Shafer et al.