Three megaspores in the tetrad degenerated and the chalazal
megaspore became functional (Fig.
Subepidermal mesotesta, inner epidermis and central cells of the chalazal
region undergo collapse in the nine species (Figure 2B).
The raphe is large and expanded at the chalazal
end of the seed, a hypostase is present, endosperm is apparently free nuclear (Biradar and Mahabale, 1976), and the cotyledons of the embryo are straight.
The hypostase is situated above the chalazal
vasculature and, depending on the form of the nucellar base, it may be present as cluster of cells, or a disk- or cuplike cell (BOUMAN, 1984).
Each megaspore initiates a pattern of free nuclear development, but only the gametophyte located in the most chalazal
(basal) position will continue to develop and eventually participate in fertilization [ILLUSTRATION FOR FIGURE 3C OMITTED].
Inspection of capsules, after hatching, shows that larvae hatch through an opening in the capsule along one of the chalazal
strands [ILLUSTRATION FOR FIGURE 2F OMITTED].
The functional megaspore near the chalazal
end developed into mature embryo sac which was of Polygonum type.
Seed coat structure and histochemistry of Abelmoschus esculentus chalazal
region and water entry.
Brief heat shock between 80 [degrees] to 120 [degrees] C is sufficient to induce imbibition by loosening cells in localized regions such as the hilum, chalazal
cap, or strophiolar plug, or possibly denaturing inhibitors (e.
Only one megaspore functions and it is one of the chalazal
members of the tetrad.
from the chalazal
portion of the ovule (Singh & Johri, 1972; Singh,
Whereas, in sexual embryo sacs, a cell wall only covered the micropylar end of the reduced egg cell and the plasma membrane of the cell was exposed on the chalazal
2d) and finally results in a linear-shaped tetrad of megaspores that the chalazal
megaspore is functional one.
Seeds without tails (0); seed with tails (expanded portion of testa at hilum and chalazal
ends) (1) 85.
megaspore enlarged to become the functional megaspore and the three members nearest to the micropyle degenerated.