SINDERMANN: INTERNAL DEFENSES OF CRUSTACEA 



cated guesses, since they have been based hirsely 

 on static images which may not even represent 

 the true cell pictures as they occur in riro." Both 

 types of cells (hyaline and granular) probably 

 have physiological subtypes, as suggested by the 

 work of Fisher-Piette (1931) in which explants 

 of lobster hemopoetic tissues resulted in multi- 

 plication of two types of hyaline cells— adhesive 

 ameboid and non-adhesive non-ameboid. Inclu- 

 sions of granular cells, in addition to their de- 

 fensive function mentioned earlier, may also pro- 

 vide nutrient material— as suggested by release 

 of this material into the hemolymph during ovar- 

 ian development (Lochhead and Lochhead, 

 1941). Hyaline hemocytes may also be trans- 

 formed into connective tissue or endothelial cells 

 of blood vessels (Danini, 1925, 1927; Debaisieux, 

 1952a, 1952b; Demal, 1953). Hemocyte physi- 

 ology and biochemistry are areas where addi- 

 tional studies are needed, but the extreme fra- 

 gility of certain cells once they are removed from 

 the normal animal has undoubtedly been a major 

 deterrent. 



Phagocytic activity has been ascribed in vary- 

 ing degrees to most recognized categories of 

 hemocytes (Haeckel, 1862; Hardy, 1892; Cuenot, 

 1895; Bruntz, 1905, 1907; Kollman, 1908; Tait 

 and Gunn, 1918; George and Nichols, 1948; 

 Toney, 1958; Rabin, 1970b). 



In recapitulation, the phagocytes of vertebrate 

 and invertebrate animals have been investigated 

 widely since the late 19th century, and the blood 

 cells of Crustacea have received at least propor- 

 tionate study. Cellular defenses of Crustacea 

 and other invertebrates are varied but center on 

 the phagocyte and its activities. Important also 

 are the humoral defenses, which will be consid- 

 ered in the following sections. Before proceed- 

 ing to considerations of other than cellular de- 

 fenses, however, it seems relevant to include an 

 often overlooked perimeter of defense suggested 

 by Miles (1962). Early suppression of microbial 

 numbers may be due to microbicidal activity of 

 the tissue cells themselves, either innate or in- 

 duced, or to soluble antimicrobial substances in 

 the intercellular fluid of the integument. As 

 Miles pointed out, such pre-inflammatory cellu- 

 lar defenses in no way diminish the importance 

 of phagocytes and humoral factors, but only pro- 



vide an added perimeter of defense. Antimi- 

 crobial capacities of tissues as a whole, and of 

 nonphagocytic cells in particular, may be a main- 

 stay of nonspecific resistance — in both primary 

 invasion and the determination of subsequent 

 courses of infection. Tissue defenses of this 

 nature in the invertebrates may be of great sig- 

 nificance. 



HUMORAL DEFENSE SYSTEMS 



Early studies of humoral factors in Crustacea 

 produced significant, but at times ambiguous, 

 results. Noguchi (1903) found that sera of 

 lobsters and horseshoe crabs possessed natural 

 agglutinins against various vertebrate eiythro- 

 cytes. After repeated injections, he was able to 

 demonstrate an induced hemolysin in the horse- 

 shoe crab but not in the lobster. Fredericq 

 (1910) . using a variety of antigens, was unable 

 to demonstrate precipitins in a number of dec- 

 apods (Homanis vulgaris, Palinurus mdgaris, 

 ' Carcinus maenas, Portunus puher, Cancer pa- 

 gurus, and Astacus fluviatilis) . 



The early literature on humoral mechanisms 

 of internal defense in invertebrates, and espe- 

 cially the crustaceans, was clearly dominated by 

 Cantacuzene and his students. Cantacuzene, in 

 a period covering almost 3 decades beginning in 

 1912, examined the broad picture of humoral de- 

 fences of a large number of marine invertebrates. 

 His work with Crustacea will be summarized 

 in the next few pages as background for a con- 

 sideration of subsequent studies. 



Cantacuzene (1912a) reported (in a paper 

 consisting essentially of a series of statements 

 but little supporting data) the presence of natur- 

 al agglutinins, lysins, and precipitins in serum 

 of the hermit crab, Ervpagurus prideaiixii. He- 

 molysins for sheep and rabbit erythrocytes oc- 

 curred in crab serum to a maximum titer of 250 

 and were destroyed by heat at 55° C. Aggluti- 

 nins for rabbit erythrocj-tes persisted in dilutions 

 beyond those at which hemolysis disappeared. 

 Agglutinins for bacteria (Escherichia coli and 

 Vibrio cholerae) were also present, as were weak 

 precipitins against horse and rabbit sera. Can- 

 tacuzene also stated that comparable agglutinins, 

 lysins, and precipitins were not present in Pagu- 



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