FINE STRUCTURAL STUDY OF ANNULATE LAMELLAE COMPLEXES IN HUMAN TUMORS

Abstract

Specific intracytoplasmic organelles, annulate lamellae and radial clsternae, have been studied In several human tumors. Annulate lamellae are observed In all cases of leiomyoma, leiomyosarcoma, rhabdomyosarcoma and malignant melanoma, whereas radial clsternae are only found in a case of leiomyosarcoma. Annulate lamellae are characterized by stacks of parallel arrayed long clsternae showing alternative arrangement of annuli and sacs. Some of these clsternae are connected directly with rough‐surfaced endoplasmic reticulum and there is continuity with the lumen and membrane. Radial clsternae are mainly composed of two structures: numerous short clsternae, which are a variant of annulate lamellae, and numerous spherical particles derived from the clsternae. The clsternae are arranged parallel or radially around particles measuring up to 1100 A in diameter. These particles consisting' of an amorphous high electron dense material without distinct limiting membrane are organized in groups and vary In number. There is no evidence of a direct relationship between these structures and viral infection.