LIGHTNER: POSTMORTEM CHANGES IN BROWN SHRIMP 



organ proceeds so rapidly that by 2 to 4 h 

 postmortem, the epithelium of tubules near the 

 center of the organ showed advanced autolysis. 

 These tubules showed desquamation and cytoly- 

 sis of the lining epithelium and replacement 

 with eosinophilic debris (Figures Ic and Id). 

 Nearer the periphery of the organ, the condition 

 of the tubules and tubule epithelium appeared 

 progressively more normal, with the most 

 normal appearing tubules and acini at the 

 periphery (Figures Ic and Id). In the band of 

 tissues between the normal appearing periphery 

 and the lysed core, all stages of cell death were 

 observed. A thin band of tissue in this area con- 

 tained tubules whose epithelial cells possessed 

 scattered pyknotic nuclei and had slight cyto- 

 plasmic staining differences (Figure le). Deeper 

 to this layer the epithelial cells of tubules and 

 acini possessed scattered pyknotic nuclei and 

 had slight cytoplasmic staining differences 

 (Figure le). The cytoplasm of these cells was 

 highly vacuolated and stained variably with 

 hematoxylin and eosin but generally much less 

 basophilicily than normal (Figure Ic). At this 

 time the s])aces between adjacent tubules and 

 acini had become swollen (Figures Ic and Id). 

 Slightly deeper to this layer epithelial cell nu- 

 clei had undergone karyoi*rhexis or karyolysis 

 and disappeared. Many of the cells of this area 

 had lysed and the cellular debris stained red 

 with eosin. The supportive stroma of the hepato- 

 pancreatic tubules remained intact in some 

 areas after the epithelium had autolyzed, 

 thereby masking the former site of the hepato- 

 pancreatic tubules (Figure le). 



By 8-12 h i)ostmortem even the tubules and 

 acini at the peripheiy of the organ showed ad- 

 vanced autolytic change, and the tissue debris 

 and remnants of supportive stroma in the center 

 of the organ were liquified (Figure If). The 

 connective tissue capsule of the organ had be- 

 come ruptured and few recognizable tubules 

 were present. Past 12 h no trace of the hepato- 

 pancreas was present, and surrounding tissues 

 had also been partially or completely digested, 

 presumably by enzymes released from the auto- 

 lyzed hepatopancreas. 



Foregut and Midgut 



Autolytic changes in the foregut, particularly 

 the epithelium of the stomach (Figure la), 

 proceeded at approximately the same rate as 



changes in the hepatopancreas. Nuclear changes 

 within epithelial cells were observed at 2 h 

 postmortem with considerable change by 4 h. 

 By 8 to 12 h the epithelium of the stomach had 

 undergone nearly complete autolysis and had 

 disappeared, leaving only the cuticular elements 

 of the stomach lining intact. The cuticular 

 elements of the esophagus and stomach per- 

 sisted for the duration of the study (72 h). 



The midgut extends from the pyloric stomach 

 to the sixth abdominal segment where it joins 

 with the hindgut (Roberts, 1966). It is without 

 a lining cuticle. The first autolytic change in 

 the midgut was observed in the lining epithelium 

 at 2 to 4 h, when the epithelial cells began to 

 show changes such as scattered pyknotic nuclei, 

 changes in staining reaction from a pale baso- 

 philic reaction to a more eosinophilic one, and 

 the "blebing" of the apical ends of epithelial 

 cells into the gut lumen (Figure 2a). The epithe- 

 lium usually remained attached to the basement 

 membrane at 2 h. but in some areas portions of 

 the midgut epithelium had been sloughed into 

 the gut lumen (Figures 2b and 2c). Sloughed 

 epithelial cells were rounded and had intensely 

 pyknotic nuclei and a uniform eosinophilic 

 cytoplasm. At this time the gut lumen usually 

 contained a fibrous, eosinophilic coagulum 

 (Figure 2b). The gut wall basal to the lining 

 epithelium showed no appreciable changes by 

 4h. 



By 8 to 12 h the midgut epithelium had been 

 sloughed into the gut lumen (Figure 2d). The 

 epithelial cells in the gut lumen were rounded, 

 and some had pyknotic nuclei, but they were 

 mostly anucleate. Many of the epithelial cells 

 had lysed and left behind amorphous masses of 

 eosinophilic debris (Figure 2d). Changes in the 

 cellular elements of the wall of the midgut 

 became apparent by 8-12 h. These changes con- 

 sisted primarily of a decrease in nuclear number 

 in the muscle and connective tissue cells present 

 and pyknosis of those nuclei remaining (Figure 

 2d). In general, the cytoplasm of the cells 

 present showed increased eosinophilia. 



No trace of the lining epithelium was present 

 after 24 h (Figure 2e). The coagulum, which 

 was present in the gut lumen of some animals 

 at 2-8 h, was still present. Also present in the 

 gut lumen were large numbers of bacteria 

 (Figure 2e). No nuclei were present in the gut 

 wall, and the cellular elements remaining 

 stained intensely with eosin. 



227 



