Light and Electron Microscopic Studies of Meiosis and Basidium Ontogeny in Clavicorona Pyxidata

ABSTRACT

Basidial development in Clavicorona pyxidata was examined using light and electron microscopy. Nuclear morphology from prekaryogamy to spore production was studied with particular emphasis on the spindle pole body (SPB) cycle. Before karyogamy, one biglobular SPB is associated with each haploid nucleus, and SPBs on adjacent nuclei are often found in close proximity with intermingling globular elements. The SPBs do not fuse at the time of karyogamy; however, it is possible that fusion occurs later. In meiosis I, monoglobular SPBs contain an electron dense bar which may represent half of the prophase middle piece. Before meiosis II, the electron dense bar disappears and the meiosis II spindles are established between paired monoglobular SPBs. Following meiosis II, a biglobular SPB reappears next to the nuclear envelope and within the old monoglobular SPB. Nuclei migrate into basidiospores, and post-meiotic mitosis follows.

Key Words:

• Clavicorona pyxidata
• meiosis
• spindle pole body
• spindle apparatus
• nuclear envelope
• basidium ontogeny