Ultrastructural development of merosporangia in the mycoparasite Syncephalis sphaerica (Mucorales)

Abstract

Transmission and scanning electron microscopy were used to study the development of Syncephalis sphaerica (Piptocephalidaceae, Mucorales) merosporangia. Merosporangia were initiated as simple evaginations of the ampulla wall. Three spores were cleaved out of each merosporangial protoplast by invaginations of the merosporangial plasmalemma. An abscission zone was formed in each cleavage zone. A fibrillar spore wall was laid down between the spore plasmalemma and the inner lining layer of the merosporangial wall. Portions of the outer merosporangial wall remained attached to the spore at the time of detachment. During late cleavage, a wall was laid down on the surface of the ampulla at the base of each merosporangium forming a scar. Mature spores remained associated with the ampulla as a spore drop.