FISHERY BULLETIN: VOL. 76, NO. 2 



Pancreas Swim bladder 



Muscle 



Hindgut 



Notochord 



Midgut 



Brain 



Liver 



Heart 



Pancreas 



Notochord 



Swim bladder 



Hindgut 



Midgut 



Liver 



Gall bladder 



m^-^ 



N 



A RBO 



:^. itz ^a 



foodi' 



i^ BC-- 



M6 





FG . 



M K 



W ^ 



Figure l. — Trachums symmetricus larva, day 8, fed for 3 days. All 12 histological criteria graded as "healthy." 32 x. 



Figure 2. — Trachums symmetricus larva, day 8, starved for 3 days. All 12 histological criteria graded as "starved." 32 x. 



Figure 3. — Head of fed larva, graded "healthy." Mitotic activity (1 h) is indicated. Note close proximity of primitive brain cells to 

 each other. 200 x. h = histological grade = healthy. 



Figure 4. — Head of starved larva, graded "starved." Atrophied and darkly stained primitive brain cells (1 s); large intercellular 

 spaces (2 s). 200 x. s = histological grade = starved. 



Figure 5. — Day 8 fed larva. Histological features graded "healthy." 200 x . See enlargement. Figure 7. B = brain, BC = blood cells 

 (white or immature red), FG = foregut.I = Islet of Langerhans (endocrine pancreas), K = kidney, L = liver, MG = midgut, M = mus- 

 cle, N = notochord, P = exocrine pancreas, RBC = red blood cells, SB = swim bladder. 



Figure 6. — Day 8, starved larva. Histological features graded "starved." 200 x. See enlarge, Figure 8. GB = gallbladder, O = oil, 

 Y = yolk, see Figure legend 5 for rest of symbols. 



Figure 7. — Day 8 fed Trachurus symmetricus larva. Enlargement of Figure 5. Midgut cells in close union (8 h); prominent nuclei (3 

 h) and large intracellular spaces (4 h) in the liver; pancreatic nuclei distinct (6 h) and cells arranged in a circular unit (acinus) (7 h); 

 gallbladder (GB) "normal." 480 x. h = histological grade = "healthy," L = liver, MG = midgut, P = exocrine pancreas. 



406 



