1 





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 :g : '" : "-' I 





. 



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Figure 1.— Olga Bay rhizocephalan: Cross sections of roots 

 with occluded lumens. PAS. C, cuticle; S, refractile cytoplasmic 

 spherules. Bar =10 ^m. 



mosing cells filled the lumen of some tubules, and 

 a defined epithelium was not present in these (Fig. 

 2). Roots with narrow or occluded lumens often had 

 smaller, denser nuclei in the epithelium, or an addi- 

 tional interior layer or group of cells with small, 

 dense, or condensed nuclei (Fig. 2). The occluded 

 roots may represent the distal, growing portions of 

 the organism. 



Intensity of infection varied (Table 3). In all of the 

 heavier infections and most of the medium ones, por- 

 tions of the roots were degenerate or necrotic (Fig. 

 3). Host hemocytes had aggregated in such areas and 

 often had encapsulated the degenerate roots. In 

 heavy infections with many degenerating and 

 necrotic roots, blackened areas, probably due to 

 melanin deposition in the roots, were visible with the 

 naked eye in the tissues. Sometimes hemocytes had 

 invaded the lumens of degenerate and necrotic roots, 

 and other roots had been reduced to amorphous 

 material surrounded by hemocytes (Fig. 3). In all 

 cases, roots of normal appearance were also pres- 

 ent in the same areas. In only one instance were nor- 

 mal roots surrounded by hemocytes (Fig. 2). Prob- 



st 



FISHERY BULLETIN: VOL. 84, NO. 1 



n 







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ilp 



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Figure 2— Olga Bay rhizocephalan: Normal roots, lying in an 

 area invaded by hemocytes. Note variable size of the lumen and 

 one tubule with a group of small, central nuclei and another 

 with anastomosing cells in the lumen (arrows). PAS. H, hemo- 

 cytes; T, tubular roots. Bar = 20 (jm. 



ably the section had been cut just peripherally to a 

 large area of degenerating roots. 



Ovaries of 88% (53/60) of parasitized females as 

 opposed to 46% (27/59) of normal females either con- 

 tained no oocytes or had some or all degenerate 

 oocytes (Fig. 4). Figure 5 shows a normal ovary with 

 previtellogenic oocytes. Grasped females all had nor- 

 mal oocytes that were in late vitellogenesis and en- 

 closed by a thick chorion. Of the 10 grasped females, 

 9 were in the premolt condition, and the 10th, a 

 precocious juvenile 77 mm CL, was in the intermolt. 



None of the parasitized crabs were in advanced 

 premolt, although some were judged to be in early 

 premolt because the pleopod epidermis was thick- 

 ened, and occasionally a developing epicuticle was 

 present. 



Excepting the ovary, tissues and organs appeared 

 normal in the parasitized crabs. Whether or not 

 there was reduced lipid storage in the hepatopan- 

 creas was not evident by histological examination of 

 the present series. 



180 



