Figure 1.—Intestinal epithelium of a control fish (a) and a fish exposed to 48 ppm cadmium for 96 hr (b). Necrosis and sloughing of 
the intestinal epithelium is evident in the experimental animal. Note also that much cellular debris occupies the lumen. 120X; 
Mallory’s triple stain. 
contained large numbers of cells thought to be im- 
mature thrombocytes (Fig. 4). The occurrence of 
erythrophagocytosis and of hemosiderin, common in 
the kidneys of control fish, was reduced or absent in 
the kidneys of the 48 ppm group (Fig. 5). 
Gills 
The appearance of the gills of cadmium-exposed 
fish was quite variable. The following defects were 
noted in decreasing order of prevalence: epithelial 
hypertrophy, hyperplasia of interlamellar epithelium, 
and desquamation. These changes were noted at all 
levels of exposure. The gill tissue of some heavily ex- 
posed fish appeared normal and some lesions were 
seen in the control animals. Some of these lesions may 
represent postmortem changes. In view of the exten- 
sive variability of gill lesions which could not be cor- 
related with exposure levels, little emphasis was placed 
on the appearance of this tissue. 
Epidermis 
The epidermis appeared normal in fish exposed at 
levels up to 24 ppm. At 48 ppm swelling of the 
epithelial cells and a paucity of mucus secretion was 
noted (Fig. 6). 
Blood 
Obvious qualitative differences noted between 
smears from cunner exposed to 24 and 48 ppm cad- 
mium and control fish consisted of poikilocytosis and 
karoklasis (Figs. 7 and 8). 
28 
Differential leucocyte counts revealed throm- 
bocytopenia and lymphocytopenia. However, the 
percentage of neutrophils increased (Table 1). 
DISCUSSION 
The histological and hematological response of an 
estuarine teleost to cadmium has been studied by 
Gardner and Yevich (1970) using mummichog, Fun- 
dulus heteroclitus. Their experiments involved acute 
exposure to 50 ppm cadmium for up to 48 hr. The 
findings of the present study are very like those of 
Gardner and Yevich. Discrepancies which did arise 
might be related to difference in the fish species used, 
or length of exposure. 
Changes in the intestine of cunners were similar to 
those reported in mummichogs. Gardner and Yevich 
(1970) found an increase in mucus cell activity while 
the present study indicates a normal or slightly 
depressed level of activity. This difference may be at- 
tributable to the increased exposure time of cunner. 
Lymphocytic infiltration of the submucosa was not 
observed in the present study. 
Kidney 
Morphologic changes in the kidney of teleosts 
exposed to cadmium have also been documented by 
Gardner and Yevich (1970). Pathological changes in 
the kidneys of mammals exposed to cadmium are well 
known. Foster and Cameron (1963) produced renal 
lesions in rabbits with two subcutaneous injections of 
CdCl, (9 mg Cd*/kg). These lesions were limited to 
