Physiological Response of the Cunner, Tautogolabrus adspersus, 
to Cadmium. 
VI. Histopathology 
MARTIN W. NEWMAN and SHARON A. MacLEAN' 
ABSTRACT 
The histopathological effects of acute exposure of cunner, Tautogolabrus adspersus, to 
water containing cadmium chloride were manifested in the kidney, intestine, hemopoietic 
tissue, epidermis, and gill. Few significant changes were noted in fish exposed to concen- 
trations less than 48 ppm for 96 hr. The results implicate renal failure as the probable cause of 
death after acute exposure to cadmium. 
INTRODUCTION 
The histopathological aspects of this study were 
undertaken in the hope of contributing to our 
knowledge of the effects of heavy metals at the level of 
the cells and tissues. Elucidation of the mechanisms 
of observed physiological and behavioral responses, 
and development of baseline information useful for in- 
terpretation of specimens which may be collected 
from naturally occurring mortalities were further 
goals. Only Gardner and Yevich (1970) have 
systematically examined blood and tissues of a teleost 
exposed to cadmium. While the exposure levels used 
in that study and the present one were similar, the 
fish species and the length of exposure (96 vs. 48 hr) 
were different. 
MATERIALS AND METHODS 
Techniques used in handling the cunner, 
Tautogolabrus adspersus, in this study have been 
described by Calabrese, Collier, and Miller (this 
report, Part I). Blood smears were prepared from 
heart blood (see Thurberg and Dawson, this report, 
Part III) and stained by Giemsa or Wright’s methods. 
Differential white cell counts were performed using 
the first 250 leucocytes encountered on each smear. 
All thrombocytes seen while counting leucocytes were 
also enumerated. Tissue samples were removed for 
physiological and biochemical studies (Thurberg and 
Dawson; Gould and Karolus, this report, Parts II and 
V respectively). The remainder of each fish was fixed 
in Davidson’s (AFA) fixative for 48-96 hr then 
transferred to 70% EtOH. Tissues were embedded in 
paraffin, sectioned at 6 um, and stained with a variety 
of techniques including Giemsa, PAS, PAS-Alcian 
Blue, Mallory triple-stain, and Perl’s Prussian blue 
' Oxford Laboratory. Middle Atlantic Coastal Fisheries Center, 
National Marine Fisheries Service, NOAA, Oxford, MD 21654. 
27 
reaction. Tissues from each of six fish exposed to 0, 6, 
12, 24, and 48 ppm cadmium, or a total of 30 fish were 
examined. 
RESULTS 
Intestine 
Pathological changes were seen in the intestinal 
epithelium of cunners exposed to high concentrations 
of cadmium. In the 24 ppm exposure group, there was 
some swelling of the intestinal epithelium. At 48 ppm, 
five of six fish exhibited varying degrees of 
pathological change. The columnar cells were swollen. 
Nuclei were hypertrophied and occupied a position 
farther from the basement membrane than those of 
unexposed fish. Nucleoli became very prominent. 
Numbers of mucus secreting cells appeared about 
equal to or slightly less than in the control animals. In 
two of the above five fish, the intestinal epithelium 
was sloughed from the basement membrane in many 
places and the lumen contained much cellular debris 
and mucus (Fig. 1). 
Kidney 
One of six fish exposed at the 24 ppm level had 
some cloudy swelling in a few scattered areas of the 
proximal tubules. At 48 ppm, the kidneys of five of six 
fish examined showed some degree of pathological 
change. Three of the fish exhibited diffuse tubular 
necrosis (Fig. 2), one exhibited focal tubular necrosis, 
and one only a few scattered necrotic lesions. The 
proximal segments of the tubules appeared to be most 
affected. The lumina of more distal areas of the 
tubules often contained sloughed epithelial cells or 
were filled with a hyaline eosinophilic material (Fig. 
3). 
Glomeruli appeared normal. The blood spaces in 
kidneys of fish exposed to 24 and 48 ppm cadmium 
