Electron microscopy of swelling and germinating conidiospores of Aspergillus niger.

Abstract

The first visible stage in germination of the conidia of Aspergillus niger was their increase in size. At this stage the shedding of the irregular outer layer, which was the peculiar structural component of dormant conidia, occurred. The swollen conidia contained a large number of mitochondria and en endoplasmic reticulum, while the dormant ones comprised only a nucleus and sparse mitochondria. The emergence of the germ tube was initiated by a slight projection of the cytoplasm, and the spore coat (or outer spore wall) ruptured at the place where the tube was about to emerge. The intermediate layer (or inner spore wall) stretched to accommodate the rapid protrusion of the germ tube. The cell wall of the advanced germinant consisted of 2 layers similar to those observed in the hyphae. The appearance of numerous mitochondria of various shapes and sizes was especially noticeable throughout the course of germination.The present paper also describes some observations on the peculiar intracytoplasmic organelles...