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In Chara tomentosa during mid spermiogenesis (phases V, VI, VII) when the amount of nuclear protamine-type proteins increases, while the amount of histones decreases, in connection with chromatin remodelling, an extensive RER system filled with dark, fine-granular substance is observed. The intermembranous space of the nuclear envelope is filled with a homogenous substance which looks similar. The most extensive ER system can be observed in phase V, which is at the beginning of nuclear protein exchange. The results presented in this paper correspond with the earlier suggestion based on Chara vulgaris spermioge nesis studies, that ER takes part in a protamine-type protein synthesis, which enter a nucleus by endocytosis, through an inner nuclear envelope membrane.
The DNA content after Feulgen reaction in the guard cells and epidermis of Omithogalum umbellatum ovary was cytophotometrically measured in different phases of flower development. Only in bud of flowers guard cells DNA content was 2C while in full blown flowers it was higher, between 2C-4C. This observation was supported by autoradiographic studies with 3H-thymidine which was incorporated into guard cell nuclei in the ovary epidermis of newly developed flowers. Thus DNA level in O. umbellatum guard cells was higher than those in other plants described in literature. On the other hand, DNA content in the epidermis cells increased gradually with ovary growth reaching the maximum level of 8C in some cells.
Ultrastructural changes of manubria of Chara vulgaris during spermiogenesis were studied. The changes (as compared to the antheridial filament proliferation stage) involve thickening of the content of secretive vesicles and changes in their consistency, the disappearance of rough endoplasmic reticulum (ER) and appearance of smooth ER, increases in the number and size of plastoglobules in plastids, condensation of mitochondria, and significant cell vacuolization. Autoradiography with 3H-fucose pulse incubation showed that during spermatogenesis it was incorporated into the manubria. Their radioactivity decreased after 2 h postincubation in nonradioactive fucose during spermiogenesis. This was not observed during proliferation of antheridial filament cells. It is suggested that polysaccharide secretion into the internal antheridial space increases during spermiogenesis, perhaps connected with the thickening of secretive vesicle content observed by electron microscopy.
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