Origin of the Endoplasmic Reticulum

Abstract

To propose a mechanism of origin of the endoplasmic reticulum based on a study of yeast cytology may seem presumptuous because there is no field in which so many different opinions prevail. The variety of opinions have arisen because yeasts, like all acellular (single-celled) organisms, manifest a maximal diversity of internal organization, and a limited number of these manifestations are considered by different individuals to be typical, and because yeast cytology has engaged the interest of those who are primarily interested in yeast and only secondarily interested in cytology. But the fact that almost the entire internal organization of a small (5µ) structure may be revealed by as few as 20 serial sections, while thousands of comparable sections (each much larger) would be required to trace the internal organization of the more familiar liver cell, makes the smaller yeast cell a more useful object in respect to tracing the relationship of the reticulum to the nucleus.