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

Abstract

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.

Ultrastructure of Oogenesis in Dryopteris crassirhizoma Nakai

“…It has been questioned whether the occurrence of an egg membrane represents a higher evolutionary status and whether the thickness of this membrane at the top of the egg represents different evolutionary levels. In fact, no egg membranes have been reported in liverworts and mosses, such as Sphaerocarpus (Diers 1966), Mnium (Barier 1972), and Marchantia polymorpha L. (Zinsmeister and Carothers 1974). The egg membrane occurs in ferns, but the top of the egg membrane is thin in the primary fern O. cinnamomea var.…”

Spore Wall Formation and Chloroplast Development During Sporogenesis in the Moss Fissidens limbatus

“…This fact was observed in 1931 by Weier and later confirmed by the same author with electron microscope studies (Weier, 1963). This supposition concerning the perpetuation of the plastid by its division in moss spores, rather than by de novo origin, has since been repeatedly strengthened by many au-thors (Byrne, 1954;Geneves, 1966;Paolillo, 1964Paolillo, , 1969Schatz and Diers, 1965;Diers, 1966Diers, , 1967Byrne and Suire, 1969).…”

The proliferation of amyloplasts in meristematic cells of developing stolons of potato and apple callus: Progenitors of proplastids

“…The y proplastid has also been observed as a component of plastid clusters (Ameele, 1982;Sedgley and Buttrose, 1978). Proliferation of moss plastids by constriction was recognized at the megasporocyte stage (Diers, 1966;Maier and Maier, 1968), and similar observations were made in fern (Pettitt, 1976).…”