LIGHTNER: POSTMORTEM CHANGES IN BROWN SHRIMP 



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Figure 8. — a. Normal antenna! gland. 100 X . b. Anlennal gland at 4 h postmortem. A few epithelial cells have been sloughed 

 into the tubule lumens. 100 X. c. The tubule epithelium of the antennal gland at 12 h postmortem showing intense nuclear 

 pyknosis. 150 X. d. Antennal gland at 24 h postmortem. The tubule epithelium has lysed filling the tubule lumens with 

 eosinophilic debris and nuclear remnants. 150 X . 



become rigid. Whether this was due to desic- 

 cation of the tissues or actual rigor of the mus- 

 cles was not determined. In the present study, 

 freshly killed juvenile shrimp became rigid 

 in sealed glass jars containing water-saturated 

 air and when totally submerged in water. Desic- 

 cation was not possible. The time of onset of 

 rigidity was, as in vertebrates, temperature- 

 dependent, occurring earlier at higher tempera- 

 tures than at lower temperatures. 



Flick and Lovell (1972) in studying post- 

 mortem biochemical changes in penaeid shrimp 

 reported that shrimp tails remained soft and 

 did not exhibit any of the characteristics com- 

 monly associated with rigor mortis during a 

 storage period of 10 days at 0°C. Perhaps the 

 effect of freezing or near-freezing temperature 

 on shrimp muscle either masks or inhibits the 

 onset of physical rigor. 



The rate of autolysis of the hepatopancreas is 

 extremely rapid. The organ is a large, multi- 

 functional organ believed to produce the bulk 

 of enzymes used in the digestive process in 

 shrimp and to have some absorptive and storage 

 function. The hepatopancreas connects to the 

 midgut near its origin from the pyloric 

 stomach. The gut is a short, nearly straight tube. 

 and, hence, enzymatic digestion must occur as 

 rapidly as possible if the shrimp is to utilize 

 its food efficiently. Even careful handling of 

 shrimp to avoid stress before fixation, opening 

 of the cuticle over the hepatopancreas, or exci- 

 sion and bisection of the gland to enhance fixa- 

 tion, frequently failed to provide adequate 

 penetration and fixation of the organ when 

 Formalin fixatives were used. The remaining 

 tissues of shrimp are generally adequately fixed 

 for light microscopy with Formalin, provided 



235 



