Ultrastructure and Development of Mutinus Caninus and the Occurrence of an Eight-Spored Basidium

SUMMARY

Fruit bodies of Mutinus caninus were grown in the laboratory on a special nutrient-supplemented straw medium. Fruit bodies were cryosectioned, fixed, dehydrated, critical-point dried, and observed using scanning-electron microscopy and photography. Young fruit bodies were differentiated into a peridium and an inner core from which the gleba and pseudostem differentiated. A gelatinous layer developed between the peridium and inner core and gradually increased in thickness during fruit body development. Hymenial differentiation began as a cluster of indistinct chambers. Pseudostem formation occurred after hymenial differentiation. Eight basidiospores were produced on each basidium. Numerous cells, formed in folds in the wall of the pseudostem early in development, increased in size as development proceeded. Their expansion apparently caused the elongation of the pseudostem.