Elektronenmikroskopische Untersuchungen über die Eizellbildung und Eizellreifung des Lebermooses Sphaerocarpus donnellii Aust.

Diers, Lothar

doi:10.1515/znb-1965-0811

Cited by 20 publications

(6 citation statements)

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“…Nuclear evaginations, similar in essentials to but differing in detail from those in Pteridium, have now been seen in the ferns Dryopteris ji'lix-mas and D. ubbreviutu (Bell, 1974c), and in the liverworts Sphuerocurpus (Diers, 1965) and Murchantiu (Bell, 1975c;Zinsmeister & Carothers, 1974). They may prove t o be a general feature of the maturing eggs of the homosporous archegoniates, but they have yet t o be detected in mosses and Equisetum (Morgan & Duckett, in progress).…”

Section: The Significance O F Tlie Nucleocy Toplasniic Inteructionmentioning

confidence: 80%

Gametogenesis and fertilization in Pteridium

Bell

Duckett²

1976

Botanical Journal of the Linnean Society

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The principal events in spermatogenesis, in particular those occurring in the final stage in which the isodiametric spermatocyte is transformed into the helical spermatozoid, are described. The origin of the blepharoplast remains obscure, but its subsequent development is now well known. Firm information is still lacking concerning the manner of growth of the microtubular ribbon and flagella, and the nature of the forces shaping the nucleus. The spermatozoid of Pteridium has much in common with those of other archegoniates, and there are significant parallels with the motile cells of chaetophoralean algae. Oogenesis involves extensive cytochemical changes, as well as ultrastructural ones, extending over three cell generations. The mature egg contains relatively large amounts of cytoplasmic deoxyribo‐ and ribo‐nucleic acids, part of the latter informational in nature. Considerable autophagy, including partial elimination of cytoplasmic organelles, occurs early in oogenesis. Termination of this stage is marked by the secretion of an acetolysis‐resistant membrane around the maturing egg, completing its isolation from the gametophyte. Maturation also involves nucleolar activity, bodies of nucleolar origin entering nuclear evaginations. Most evaginations are sac‐like; others, formed by an overarching sheet of nucleus, hood‐like. The fate of the evaginations is problematical. Some may become free and differentiate into mitochondria or plastids. The contents of the egg nucleus remain less dense than the cytoplasm and the chromatin highly dispersed. Only very few eggs are viable at fertilization. The manner of syngamy is not yet clear. Immersion of the male gamete in the female cytoplasm causes freeing of the nucleus from the microtubular ribbon, and reconstitution of its envelope. It now falls into irregular loops within the funnel formed by the coiled ribbon. Orientation of this funnel such that the anterior end of the male nucleus contacts the female is probably essential for karyogamy. Following the formation of an orifice, the male chromatin moves into the female nucleus. The male nuclear envelope is probably resorbed, and the other parts of the spermatozoid eventually digested. The special egg membrane becomes incorporated into the common wall between the gametophyte and zygote, and may prevent the transference of complex molecules.

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Section: The Significance O F Tlie Nucleocy Toplasniic Inteructionmentioning

confidence: 80%

Gametogenesis and fertilization in Pteridium

Bell

Duckett²

1976

Botanical Journal of the Linnean Society

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“…Many mitochondria are present, which show no intramitochondrial granules. One observes lipid droplets frequently lying together in groups (Diers, 1965 b). In contrast to the plastids in the maturing and fully developed egg cells, the plasdds in the cells of the archegonial venter are differentiated into chloroplasts with a distinct internal membrane system (Fig.…”

Section: Diers Plaslids Mitochondria and Cell Constituents During 06genesismentioning

confidence: 99%

“…In the material investigated here, this involucre reaches about halfway up the archegonium neck when the egg is mature, and the neck-canal is open to spermatozoids. A detailed description of archegonium development is given elsewhere (Diers, 1965 a, and b).…”

Section: On the Development Of The Archegoniummentioning

confidence: 99%

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On the Plastids, Mitochondria, and Other Cell Constituents During Oögenesis of a Plant

Diers

1966

The Journal of Cell Biology

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In the liverwort Sphaerocarpus donnellii Aust., the behavior of the cell constituents, especially of mitochondria and plastids, was studied by electron microscopy during the development of the egg and its preceding ceils. A degeneration and elimination of mitochondria and plastids was not found in any of the developmental stages. In all growth phases of the archegonium, the plastids may deposit starch which becomes especially frequent in the maturing egg cell. No indications have been observed that new mitochondria or plastids generate from the nuclear evaginations, which often penetrate deeply into the cytoplasm of the maturing and fully developed eggs. A quantitative investigation based on general micrographs elucidates the numerical aspects of the cell constituents during o6genesis. With the increase of cell volume, the numbers of dictyosomes, mitochondria, plastids, and lipid bodies increase. From the stages of the mother cell of the axial row up to that of the mature egg, the cell volume enlarges about 8 times and the nucleus volume about 15 times. Simultaneously, the numbers of mitochondria and plastids increase up to 8 to 15 times. On the basis of these findings, mitochondria and plastids with three-dimensional narrow constrictions are interpreted as divisional stages.

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“…of archegonial development in Sphaerocarpus. (Diers, 1965). and in the capsule and male gametes of Polytrichum (Paolillo et al .• 1968 a;1968 b).…”

Section: Microscopymentioning

confidence: 99%