Use of serial sections to delineate the structure of Porthetria dispar virus in the electron microscope.

Consecutive serial sections of polyhedra obtained from gipsy moth larvae infected with P. dispar virus revealed bundles of viral rods scattered and oriented at random within the polyhedral body. Each bundle was entirely surrounded by a dense, sharply defined membrane. The rods measured 18 to 22 mmicro in diameter and averaged 280 mmicro in length. No spherical viral particles were encountered. The effects of variable compression and periodic distortion of the sections on the appearance of the virus are discussed.