[The role of the endoplasmic reticulum in the formation of specialized cellular organelles in parasitic Sarcosporidia]

Abstract

A cytological study was made of participation of the endoplasmic reticulum in the formation of specific cell organelles in Sarcocystis muris zoites. The data presented in this paper confirm our earlier assumption (Radchenko, 1987) that the Golgi adjunct is a structure made of four membranes of the smooth endoplasmic reticulum (ER) channels. This organelle appeared to be available in all the three cell types recognized within the sarcocyst: metrocytes, intermediate cells and merozoites. In the dividing metrocytes and intermediate cells the Golgi adjunct is turning progressively in a polar ring, whose membranes are covered with a fibrillar material from which subpellicular microtubules are formed. It has been first shown that ER channels are involved in the formation of amylopectin granules and immediate glycoprotein regions around them. Large spiral structures, composed of the ER channels, were seen in the zoite cytoplasm. Besides, micronemes were also made of closely packed ER channels. It looks likely that individual micronemes may be connected to each other through these channels.