The fine structure of dormant, ungerminated basidiospores of pluteus cervinis (fr.) kummer and agrocybe acericola (pk.) sing.
The fine structure of the basidiospores of Pluteus cervinus and Agrocybe acericola is described using TEM, SEM, and light microscopy.The basidiospore wall of Pluteus cervinus is bipartite. No surface ornamentation or germ pore is present. The protoplasm is surrounded by a typical membrane which lacks distinct invaginations. Spores contain much stored lipid, which is centrally located. Spores are uninucleated with the nucleus closely appressed to the cell membrane, located at the base of the spore near the hilar appendage. Mitochondria with few, well-delineated plate-like cristae are present. Endoplasmic reticulum (ER) is scant. Ribosomes occur regularly attached to the ER and outer mitochondrial membrane, as well as being densely packed throughout the cytoplasm. Various sized vacuoles containing an electron dense material are present. Microbody-like organelles are observed, which are probably glyoxysomes, since assays of malate synthase, a maker enzyme of the glyoxylate cycle, are positive.The basidiospore wall of Agrocybe acericola is composed of two distinct layers, both layers are continuous around the spores, at the germ pore the outer wall is very thin and the inner wall becomes thicker. The plasma membrane is appressed to inner wall and lacks invaginations. The protoplasm is densely packed with small granules, probably ribosomes and/or glycogen. Spores contain very little lipid with bipolar distribution. Mitochondria are well-defined and distributed in cytoplasm. Spores are binucleate with the two nuclei lying on a line nearly perpendicular to the long axis of the cell. Various size single membrane-bound vacuoles are widely distributed in the cytoplasm. These vacuoles were shown to contain acid phosphatase indicating lysosomal activity. Microbodies, probably glyoxysomes, are observed. Malate synthase assays are positive indicating the occurrence of the glyoxylate cycle.