Wet stigma - category of stigma, Biology

Wet Stigma - Category of Stigma

Petunia shows several randomly distributed 2-celled papillae on its surface. In a developing stigma, the epidermis is covered by a continuous, thin cuticle and the subepidermal cells are densely cytoplasmic, without any intercellular spaces. In a mature stigma, the cells of the subepidermal zone elongate to form a secretory zone with large schizogenous cavities filled with a lipoidal secretion. The secretory zone is delimited from the basal part of the stigma by a storage zone.

The cells of the stigma contain numerous amyloplasts and a large amount of lipid globules which gradually coalesce and migrate to the peripheral part of the cytoplasm and eventually out of the cell. The lipoidal exudate accumulates between the cell wall and the cuticle. In the secretory zone the exudate fills the large intercellular, schizogenous cavities. At the time of anthesis, the epidermis becomes disorganized, the cuticle is discarded in the form of flakes and the accumulated exudate spreads over the entire surface of stigma. A very thin layer of water is also trapped.

Posted Date: 1/23/2013 3:05:25 AM | Location : United States







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