Abnormally high numbers of eosinophilic leucocytes (general 

 leucocytosis) were apparent in 1.5% (2 of 131) of the adductor muscle 

 samples exmained. Leucocytes were generally spread throughout the 

 muscle rather than being in focal aggregations. 



Aggregated eosinophilic leucocytes were present in 1 of 131 adductor 

 muscles examined. For the purposes of this report, this aggregation was 

 classified as a focal leucocytosis although there was no central core or 

 tight concentric arrangement of leucocytes as reported from Crassostrea 

 vivg-iniaa (Armstrong et al., 1980). This may be an inflammatory response 

 to what appears to be a foreign body, possibly a nematode, at the edge of 

 the aggregation. 



Five (3.8%) of the muscles examined contained areas of degenerated 

 muscle bundles. This condition was characterized by a breakdown or 

 liquefaction of the cellular integrity. Degenerated areas contained 

 amorphous, light staining debris and fibers. No pyknotic nuclei were 

 present in surrounding whole muscle fibers and no inflammation (increased 

 number of leucocytes) was apparent. 



Unidentified sporozoans in the plasmodial stage were found in 1 of 

 the 131 muscles examined. 



2. Digestive Gland . - The digestive glands of 129 C. gigas were 

 examined. Generally, two samples were taken from each specimen at differ- 

 ent levels (anterior and posterior) of the digestive gland. 



Histopathologies were noted in 44.2% (57 of 129) of the digestive 

 gland samples examined. There were a total of 64 incidences of the 9 

 types of pathologies described below. Twenty-seven of these or 42.2% 

 apparently were not attributable to symbioses, while 37 (57.8%) were a 

 type of symbiont or were clearly attributable to symbioses (i.e. inflam- 

 mation). The distribution of these histopathologies among sampling sites 

 is summarized in Table 3. Digestive gland samples from Aber Benoit con- 

 tained more pathologies than samples from the other two sites. All 

 digestive gland samples from the December, 1978 collection at Aber Benoit 

 bore one or more pathologies. Samples from other sites over the five 

 collections had no more than 62% incidence of pathologies. 



Abnormally high numbers of eosinophilic leucocytes were dispersed 

 throughout the leydig tissue between diverticula in 5 (3.7%) of the 129 

 samples examined. In some, leucocytes were also invading the diverti- 

 cular epithelium. These cases could have been inflammatory responses 

 to parasites such as copepods which were not included in the sectioned 

 material. That is, the sections could be at the edge of an inflammatory 

 response as described below. 



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