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Light and electron microscopical observations on sperm cells of Guizotia abyssinica (Asteraceae)
Author(s) -
Dagne Kifle,
Heneen Waheeb K.
Publication year - 1995
Publication title -
nordic journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.333
H-Index - 33
eISSN - 1756-1051
pISSN - 0107-055X
DOI - 10.1111/j.1756-1051.1995.tb02133.x
Subject(s) - sperm , biology , cytoplasm , pollen tube , nucleus , botany , ultrastructure , pollen , microbiology and biotechnology , amyloplast , electron microscope , anatomy , stamen , endoplasmic reticulum , biophysics , chloroplast , plastid , biochemistry , physics , pollination , gene , optics
The sperm cells of Guizotia abyssinica were studied during pollen development by light microscopy and at anther dehiscence by transmission electron microscopy. During development, the nuclei change shape from spherical to elongate, thread‐like and banded. They are straight or folded, and rarely spiral‐shaped when present in the pollen tube. Electron microscopy disclosed that the elongated sperm nuclei are apparently lobate. Intermittently, they are constricted and attenuated or convoluted. The major part of the sperm chromatin is condensed and peripheral, while a minor part is dispersed and central. The scanty sperm cytoplasm contains mitochondria and starch granules. The cytoplasm is mainly restricted to spaces adjoining constricted, lobed and convoluting nuclear sites. Some cytoplasmic patches become embayed in the nucleus at these sites. The periplasm bordering the sperm cells may originate from lucid dilations of the lumen between the plasma membranes of the sperm and vegetative cells. The periplasm is sometimes partially or entirely surrounded by double‐membraned endoplasmic reticulum. Folded sperm cells with less coherent periplasm possibly represent a late stage preceding discharge into the pollen tube. The sperm cells always precede the vegetative nucleus into the pollen tube.