Lysosomes, ultrastructural organelles of the cytoplasm

Abstract

Scope of Study: The study of lysosomes began after the advent of the electron microscope, and, as a part of the cells ultrastructure, lysosomes have been an item of scientific conjecture as various researchers have offered hypotheses concerning the structure and function of these "organelles". Throughout the data gathering process no reference to lysosomes in plant tissue was found; all of the work surveyed concerned animal tissue, even when limited to lower organisms. This study is a discussion of the development of lysosome study as it has led from hypothesis to hypothesis, with a steady trickling of information from researchers in varied disciplines of the general field.

Findings and Conclusions: There is still no real conclusions by most current authorities as to the definite status of these organelles, or for that matter, whether they may be considered true and constant cell organelles. Lysosomes form a special group of cytoplasmic particles with a mean diameter of 0.4 microns and an average density of 1.15. They are characterized by a variety of acid hydrolases capable of degrading proteins, nucleic acids, and mucopolysaccharides. These enzymes are retained within the particles, and prevented from acting on surrounding substrates, by a lipoprotein membrane impermeable to these substrates. The simultaneous release of all internal enzymes in soluble and fully active form follows injury to the membrane. Whether or not they are finally classed as organelles, they are functionally important in many tissues and may hold the key to certain pathological phenomena of cell activities, and thus, of whole organisms.