LIGHTNER: POSTMORTEM CHANGES IN BROWN SHRIMP 



By 48 h, the gut wall had become thin and 

 was frequently interrupted. The gut lumen was 

 filled with bacteria and other debris (Figure 2f). 

 By 72 h, all traces of the gut. including the gut 

 wall, had disappeared leaving the former site 

 of the gut marked only by masses of bacteria 

 and amorphous eosinophilic cellular debris. 



Heart and Major Vessels 



In shrimp the heart lies immediately dorsal 

 and slightly caudad to the large hepatopancreas. 

 Only the thin connective tissue coverings of the 

 two organs separate them. Hence, autolysis 

 of the hepatopancreas and release of its proteo- 

 lytic enzymes results in a rapid destruction 

 of the rather loose tissues of the shrimp heart 

 (Figure 3a). The hepatopancreas showed con- 

 siderable autolytic change by 4 h postmortem 

 leaving the heart barely recognizable (Figure 

 3b). By 8 h the heart was not distinguishable 

 from the other tissue debris present at the heart's 

 former location in the cephalothorax. Vessels 

 in the vicinity of the hepatopancreas and heart 

 also disappeared by 4-8 h, but vessels elsewhere, 

 such as in the abdomen, persisted much longer, 

 some still recognizable after 24 h. However, by 

 48 h vessels were not usually demonstrable 

 anywhere in the body of a shrimp. 



to that of vertebrate striated muscle (Figure 4a). 

 The muscles of the cephalothorax in the vicinity 

 of the hepatopancreas underwent rapid autolytic 

 change, apparently due to digestion by enzymes 

 released on lysis of the hepatopancreas. Further 

 from the hepatopancreas, the rate of autolytic 

 change in the muscle was much slower. The 

 earliest observed postmortem change in the 

 muscle was at 4 h when some individual muscle 

 fibers had a slightly "frayed" appearance. 

 There was a pronounced swelling, presumably 

 edematous, between adjacent muscle fibers 

 (Figure 4b). By 8-12 h, muscle cell nuclei had 

 become pyknotic. After 24 h muscle cells had 

 become anucleate, highly eosinophilic, and the 

 edematous swelling between adjacent muscle 

 cells had decreased. Cross striations within 

 muscle fibers were especially evident (Figures 

 4d, 4e, and 4f). 



In some, but not all, of the shrimp studied, 

 bacterial growth was evident between muscle 

 bundles, especially in the vicinity of the gut. 

 The presence of large numbers of bacteria 

 greatly increased the rate of tissue deterioration 

 (Figure 4c), while muscle not heavily invaded 

 by bacteria remained recognizable as muscle 

 tissue at 72 h (Figure 4f). 



Integument 



Musculature 



Shrimp locomotory muscle is striated and 

 presents a histologic appearance that is similar 



The integument, consisting of epidermis and 

 an overlying cuticle, underwent rapid degen- 

 eration in the area of the cephalothorax that 

 surrounds the hepatopancreas, leaving only 



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Figure 3. — a. Normal heart. llOx. b. Heart al 4 h postmortem showing considerable autolytic change and loss of struc- 

 tural detail. 100 X . 



229 



