SPREADING FACTORS 



322 



SPREADING FACTORS 



with Loeffer's methylene blue. In case 

 of thick films pour off and add more 

 blue. Rinse in tap water and blot dry 

 (S. Bayne-Jones in Simmons and Gentz- 

 kow, p. 386). 



A modification of Schaeffer's spore 

 stain. Support a small metal tray over 

 asbestos centered wire gauze. Add 

 water and heat to steaming. Slides with 

 ends resting on either side of the tray 

 should have droplets of water condense 

 on their under surface. Flood properly 

 fixed smear on slide with 5% aq. mala- 

 chite green and leave in this way on 

 steam bath 1 min. Drop in cold water, 

 rinse thoroughly and while wet add 0.5% 

 aq. safranin 30 sec. Rinse again in cold 

 water. Spores, green; vegetative cells, 

 red (Ashby, G. K., Science, 1938, 87, 

 443). 

 Spreading Factors and ground substance of 

 Mesenchyme — Written by F. Duran- 

 Reynals, Dept. of Microbiology, Yale 

 University, New Haven, Conn. Octo- 

 ber 8, 1951 — A discussion on the nature 

 and function of the spreading factors 

 (S.F.) must be indispensably preceded 

 by a survey on the newer knowledge of 

 the ground substance (G.S.) of the 

 mesenchyme, a knowledge to which, 

 precisely, the discovery of the S.F. 

 has largely contributed. 



The importance of the G.S. is easily 

 emphasized: it is impossible to have a 

 complete concept of cell function if this 

 cell is not considered together with its 

 immediate environment, namely, the 

 G.S. or other intercellular matrices 

 which, it is to be hoped, some day will 

 be known. One cannot have a clear 

 idea of the effects on cells of poisons or 

 therapeutic agents; of the portal of 

 entry and of so many other phenomena 

 in infection and defense against infec- 

 tion without a previous knowledge of 

 the initial effect of the invading agent 

 on the G.S. or, conversely, of the effect 

 of the G.S. on the infectious agent. 



The G.S. of the mesenchyme is, of 

 course, present in all mesodermic struc- 

 tures, and consequently it pervades the 

 whole animal body. It is present in 

 the skin where it spreads as a continu- 

 ous sheet underneath the epidermis; 

 and in between the follicular cells sur- 

 rounding the mammalian ovum. The 

 synovial fluid is a modified G.S., and 

 the joint cavities can be considered as 

 giant intercellular formations. The 

 G.S. is also abundantly in the vitreous 

 humor, in the umbilical cord, and still 

 other structures. 



From direct studies by a group of 

 physiologists, the following has been 

 learned about the G.S. : 



(a) It is a jelly placed between 



vessels, cells and fibers, and does not 

 contain spaces; 



(b) It does not contain free water 

 under physiological conditions. Water 

 is associated with components of the 

 jelly, which is capable of hydration 

 in different degrees; 



(c) Dyes, and presumably metabo- 

 lites, do not seem to progress through 

 the jelly proper, but following the path- 

 ways of the fibrillar structures; and 



(d) It shows a resistance to penetra- 

 tion by inoculated fluids, and this re- 

 sistance is not overcome until a pressure 

 of 8.5 cm of water has been reached. 

 Therefore, the G.S. is a barrier. 



The main, or best known, compo- 

 nents of the G.S. are mucopolysaccha- 

 rides — -linked with protein, to which 

 the G.S. owes its viscid consistency. 

 The most significant of the polysac- 

 charides is hyaluronic acid (H.A.) 



H.A. is a member of a very important 

 group of substances such as heparin, 

 mucoitin, and chondroitin sulphuric 

 acids, and still others, all of which 

 play preponderant physiological roles. 



The G.S. can be identified by means of 

 staining reactions, more or less selec- 

 tive for polysaccharides, such as peri- 

 odic acid, leuco fuchsin, toluidine blue, 

 Prussian blue, and still others. 



One may suppose that since H.A. is 

 so widely present in normal and patho- 

 logical tissues, its secretion is the work 

 of many mesenchymal cells, including 

 plain fibroblasts, in a manner perhaps 

 comparable to the formation of the acid 

 in the capsule of some bacteria, e.g. 

 streptococcus group A and C. However, 

 a variety of contributions seem to 

 incriminate specialized granule - con- 

 taining cells, identified or not to mast 

 cells as the elements responsible for the 

 formation of the G.S. in general; or of 

 synovial fluid; or hyaluronic acid in 

 particular. One may wonder whether 

 H.A., so rapidly and abundantly ac- 

 cumulated in some normal or patho- 

 logical tissues, such as in the sex skin 

 of monkeys and some tumors, is origi- 

 nated by the same cells that secrete the 

 acid present in other tissues. Be it as 

 it may, H.A. formation is controlled 

 by endocrine factors which will be re- 

 viewed later. 



The S.F. are the agents which act 

 selectively or exclusively on the G.S., 

 changing its physical and chemical 

 characteristics. They were discovered 

 in 1928 by the enhancing effect that 

 extracts from mammalian testes proved 

 to have on infection. The most im- 

 portant, or at least the best known, of 

 the S.F. is hyaluronidase (H) which is 

 present, in mammalian testes, in cer- 



