Three of eleven (27%) crabs examined had evidence of baculovirus related nuclear pathology in hepatopancreatic epithelial cells. The three infected crabs had been held in a seawater recirculating system for at least 84 days before examination. The crabs with no infections had been held for shorter periods. No other infections or abnormalities were detected histologically in tissues from the 11 crabs. On histological examination there was a focal distribution of virus infected hepatopancreatic tubule cell nuclei. Up to 36 cells in one transverse section of a tubule could show nuclear pathology while adjacent tubules were normal. Infected cells were usually R-cells, though nuclear pathology was seen in other
.d lead cit.1
differentiating cells. Infected nuclei were irregular to round in shape, greatly hypertrophied, and up to five times normal size (Fig. 6). The strongly or weakly staining basophilic inclusions entirely occupied the nucleus and tended to be amorphous, though a finely granular structure could be seen occasionally. Scattered strands of nucleolar material were present in some of the inclusions. The earliest nuclear changes detected were a slight hypertrophy of the nucleus, a pale nucleolus or marginal nucleolar fragments, a thin marginal band of strongly basophilic chromatin, and infrequent fine eosinophilic granules scattered through a nonstaining nucleoplasm (Fig. 6). An intermediate stage was represented by hypertrophied nuclei containing a single, pale purplred to reddish amorphous inclusion. These nuclei had a distinct mar- gin of basophilic chromatin and a central nucleolus or circle of nucleolar remnants. The marginal chromatin stained strongly with the carbol fuschin counterstain in Gram’s stain. Inclusions in the advanced infections had a diffuse red reticulum throughout with the same stain. Inclusions did not stain with PAS, Giemsa, or alcian blue and were Feulgen-negative. Virus related nuclear pathology was only seen in the hepatopantreas. All affected nuclei examined under elec