Spore Ultrastructure of the Myxomycete Physarum polycephalum

Abstract

Spores of the true slime mold Physarum polycephalum were examined at several stages of their development by means of scanning and transmission electron microscopy. The spores were globose, spine-covered structures produced within a sporangium enclosed in a tough, noncellular peridium. Cytologically, the spore represented a typical eukaryotic cell, having discrete organelles similar to spores of other myxomycetes. The presence of dictyosomes, helical filaments, and microbodies in these cells, as well as the further elucidation of the cell wall and the "polysaccharide-containing" areas, represent new contributions to the ultrastructure of the myxomycete spore. Of special interest were observations of metaphase nuclei just prior to spore cleavage, interphase nuclei in young spores, and nuclei in mature spores containing synaptonemal complexes. These observations indicate that in Physarum polycephalum mitosis occurs just prior to spore cleavage, and meiosis takes place after spore cleavage.

Ultrastructure of the Pseudocapillitium and Spores of the Myxomycete Lycogala Epidendrum. Liceales

“…The observations reported here on the surface features of the spores and pseudocapillitium of L. epidendrum confirms those published by Schoknecht and Small (1972). Furthermore, outer electron dense spore layers similar to those cited here for L. epidendrum were reported by Wohlfarth-Bottermann (1959), Schuster (1964), Aldrich and Mims (1970), Mims (1971), Scheetz (1972), Keller et al (1973), Randall and Lynch (1974), and Gaither (1974a, b). Among the Myxomycete spore walls previously examined, the thickness of the outer wall in L. epidendrum is comparable to the same wall component in Arcyria cinerea (Mims, 1971).…”

“…3-6) are almost identical morphologically to some of those reported by Frederick, et al (1968) and Frederick and Newcomb (1969). Myxomycete spores containing microbodies were first reported by Mims (1972) and more recently by Randall and Lynch (1974). Whether these bodies are typically encountered in Myxomycete spores is questionable.…”

“…3,5,6). Lipid bodies have been previously reported in the spores of Myxomycetes by Schuster (1964), Aldrich (1967), Mims (1971), and Randall and Lynch (1974). Because the observations reported here are limited to mature nongerminated spores, the function of these bodies is Fig.…”

“…Spore ultrastructure in the Myxomycetes has also received minimal attention, but information on spore ultrastructure is contained in the published work of Schuster, (1964), Aldrich, (1967), Aldrich and Mims, (1970), Mims, (1971, Keller, et al, (1973), Randall and Lynch, (1974), and Gaither, (1974a, b). Only an abstract (Gaither, 1974a) includes information on spore ultra- to aluminum stubs with electroconductive paint and then coating them with gold.…”

A Morphometric Analysis of Cytological Changes During Spore Maturation in the Myxomycete Didymium Iridis

“…VARIOUS WORKERS (Aldrich, 1967(Aldrich, , 1974Aldrich andMims, 1970: Aldrich andCarroll, 1971;Haskins, Hinchee and Cloney, 1971;Mims, 1971Mims, , 1972aMims, , b, 1973Scheetz, 1972;Cronshaw and Charvat, 1973;Gaither, 1974Gaither, , 1976Haskins and Hinchee ,1974;Mims and Rogers, 1973;Randall and Lynch, 1974;Demaree and Kowalski, 1975;Laane and Haugli, 1976;Laane, Haugli and Mellum, 1976;Bechtel, 1977;Lacorre-Arescaldino, 1977) have used transmission electron microscopy (TEM) to examine myxomycete spores. While most investigations have concentrated on either spore wall development or nuclear events within maturing spores, some attention has also been focused upon the cytoplasmic components of these spores.…”