Ultrastructure and cytochemistry ofEucalyptus globulus(Myrtaceae) pollen grain
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چکیده
منابع مشابه
The ultrastructure and ontogeny of pollen in Helleborus foetidus L. IV. Pollen grain maturation.
The final stages of Helleborus pollen-grain ontogeny, which culminate in maturation and germination of the grain, have been investigated at the ultrastructural level. Following the deposition of primary and secondary exine, and during the early stages of intine formation, the microspore passes through a vacuolate phase, in which the cytoplasm appears devoid of most organelles other than the pro...
متن کاملThe ultrastructure and ontogeny of pollen in Helleborus foetidus L. II. Pollen grain development through the callose special wall stage.
During the early stages of microsporocyte ontogeny in Helleborus foetidus L. there is protoplasmic continuity between the cells of the tapetum and between the individual sporogenous cells, but not between the two tissues. The plasma canals and plasmodesmata are progressively sealed off by the deposition of thick callose walls, so that by the first meiotic division, each pollen mother cell is is...
متن کاملUltrastructure and cytochemistry of Miocene angiosperm leaf tissues.
Angiosperm leaf fossils (16.7-25 x 10(6) years by potassium/argon dating) referable to Zelkova were isolated from pyroclastic deposits in the Succor Creek Formation, Oregon. These fossils reveal a three-dimensional structure in mesophyll cell layers and vascular bundles, while transmission electron microscopy of fixed tissues reveals well-preserved chloroplasts with grana stacks and starch, as ...
متن کاملUltrastructure and Cytochemistry of Metabolic Dna in Tipula
A DNA body is present in the females of the fly Tipula oleracea and is formed in contact with the sex chromosomes in the oogonial interphases. At each oogonial mitosis, the DNA body follows the chromosomes to one anaphase group and is included in one of the telophase nuclei. The body increases appreciably in size during the interphase of meiosis. All oocytes have the body, but only a few nurse ...
متن کاملPollen Ultrastructure of the Tecophilaeaceae
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ژورنال
عنوان ژورنال: Grana
سال: 2008
ISSN: 0017-3134,1651-2049
DOI: 10.1080/00173130801923364