Observations on the fine structure of the nuclear apparatus of Blepharisma intermedium bhandary (Ciliata: Spirotricha)

Abstract

An electron-microscope study of the macronucleus and the micronucleus of Blepharisma intermedium Bhandary has been made. Sections show that the macronucleus is bounded by a double membrane. Inside, there are two types of bodies: (a) small irregular bodies, from 0.05 to 0.2 μ in diameter, and (b) larger bodies, from 0.4 to 0.6 μ in diameter. The former are intrepreted as cut ends of long, branching filaments traversing the nuclear cavity in all directions. They correspond to the DNA filaments obtained by centrifugation and KCN action on the macronucleus. Each filament is made of fibrils aboue 150 Å thick. The large bodies correspond to the nucleoli; they also show a fibrillar structure. They offer the added interest of displaying dense particles, from 100 to 800 Å in size, whose nature and significance are obscure. The micro-nucleus has a double membrane, and the contents are divisible into an electron-dense network and a material of low density which fills the interstices of the network.