Ultrastructure of Nuclear Division in Paramecium Aurelia II. Amitosis of the Macronucleus

Abstract

Ultrastructural details of macronuclear amitosis in the ciliate P. aurelia are described. During amitosis the nuclear membrane remains intact, and there are no changes in the appearance of the nucleoli and chromatin bodies of the macronucleus. At the commencement of amitosis the nucleus adopts a smoother outline and a position in the cell opposite the gullet. This usually occurs at the time when the micronuclei are in metaphase of mitosis.