Müller's Cells and the "middle Limiting Membrane" of the Human Retina

An Electron Microscopic Study

¹ Armed Forces Institute of Pathology, Washington, D. C.
² Armed Forces Institute of Pathology Washington, D. C.; Part of this work was completed while Dr. Fine was a Special Fellow of the National Institute of Neurological Diseases and Blindness, United States Public Health Service, Bethesda, Md.

Electron microscopy of 3 normal human retinas has provided evidence which generally supports the conventional ideas that have been based on light microscopy of Midler's cells. This study has revealed even greater cytoplasmic differences between the inner and outer halves of Midler's cells than has been appreciated in the past: the inner has properties of fibrous astrocytes whereas the outer resembles oligodendrocytes. Certain structural characteristics of the inner part of the outer plexiform layer give it both the appearance and properties of a limiting membrane. This structure tends to restrain the passage of hemorrhages and exudates out of the outer plexiform layer; we have proposed the name "middle limiting membrane" for this distinctive zone.