134 



MACROMOLECULAR COMPLEXES 



Fig. 9. Myelin sheath segment from transverse thin section of frog sciatic 

 nerve, showing granular fine-structure (arrows) in dense and intermediate lines 

 of concentric layers. Nerves equilibrated in glycerol before rapid freezing in 

 liquid helium II. Osmium-cryofixation preparation. X270,000. 



studies, and a systematic survey of the usefulness of certain protec- 

 tive agents like glycerol for the preservation of tissue ultrastructure 

 therefore became one of the major practical objectives of our in- 

 vestigations. 



Effects of Protective Glycerol Treatment on Myelin Ul- 

 trastructure. Pursuing earlier studies of the histological applica- 

 tions of glycerol (Fernandez-Moran, 1952, 1957), a series of interest- 

 ing observations has been made, demonstrating the general effects 

 of glycerol treatment on the ultrastructure of the myelin sheath. 

 The remarkable effects of glycerol which protect living cells against 

 the damaging action of freezing and thawing (Harris, 1954; Parkes, 

 1951 ) have been primarily ascribed to the water-binding properties 

 and salt-buffering potentiality (Lovelock, 1953) of this agent, in 

 addition to its lack of toxicity and other unique features. Although 

 numerous investigations of the effects of glvcerol treatment on 

 extra- and intracellular crystallization have been carried out with 



