222 



Fishery Bulletin 93(2), 1995 



Q> 8 



„ 2500 

 3 2000 



.!? 1500 

 d> 



J 1000 



0) 



>, 

 HI 



38 



36 



B 



140 <9. 



130 a. 



120 3 



3.5 



> 



2.5 5 



> 



400 

 300 

 200 

 100 



72 



72 



120 



Time (h) 



Figure 3 



Summer flounder, Parahehthys dentatus, 33-day-old larvae. Morphometric, gravi- 

 metric, and biochemical changes during ad libitum feeding ( ) or starvation ( • ). 

 (A) standard length; (B) dry weight; (C) eye diameter/head height ratio; (D) pec- 

 toral angle; (E) RNA:DNA ratio; (F) total proteins. Symbols represent the arith- 

 metic mean of samples of 9-10 animals ±Standard Error. Asterisks indicate a 

 statistically significant difference between fed and starved groups at a particu- 

 lar sampling time. 



The acinar arrangement of pancreatic cells was 

 sensitive to starvation. In fed larvae, the typical aci- 

 nar structure was well defined and symmetrical; cells 

 were arranged around central intercellular lumina 

 (Fig. 5E). Under food deprivation, the acinar struc- 

 ture became increasingly disorganized (Fig. 5F). In 

 6, 16, and 33-day-old larvae, symptoms of pancre- 

 atic degeneration were discernible as early as 24 hours 

 after food deprivation. In 60-day-old juveniles, this ef- 

 fect was detectable after 144 hours of starvation. 



The intestinal mucosa of fed larvae was continu- 

 ous and uninterrupted. A distinct brush border com- 

 posed of microvilli was evident. The intestinal lu- 

 men was wide and the columnar enterocytes were 

 systematically arranged and deeply folded. Cytoplas- 

 mic vesicles and vacuoles, suggestive of pinocytosis 

 and intracellular protein digestion, were present in 

 varying numbers and sizes (Fig. 6C). In the starved 

 group, the intestinal mucosa was discontinuous, less 



compact, and had irregular cells and intercellular 

 spacing. The brush border was not smooth and signs 

 of cell sloughing were evident from the necrotic de- 

 bris in the lumen. The enterocytes were shrunken 

 and collapsed resulting in a severe reduction of the 

 entire mucosal thickness. The intestinal lumen was 

 comparatively occluded. Cytoplasmic vesicles were 

 not present (Fig. 6D). 



The mean cell height of the anterior intestinal 

 mucosa was significantly different between starved 

 and fed groups of all ages. In all cases, these differ- 

 ences were detectable from the first sampling time 

 (* 18 =2.99, P=0.008, at 24 h in 6-day-old larvae; 

 £ 18 =8.20, P<0.001, at 24 h in 16-day-old larvae; 

 * 18 =6.06, P<0.001, at 24 h in 33-day-old larvae; and 

 1 10 =H.O, P<0.001, at 72 h in 60-day-old juveniles; Fig. 

 7, A, C, E, and G, respectively). 



Differences in the cell height of the posterior in- 

 testinal mucosa of starved and fed groups were also 



