440
JOHAN B. STEEN
vagus
Pneumatic
duct artery
Pneumatic
duct vein
( A )
( 8 )
Fig. 13. ( A ) Normal appearance of the eel swim bladder. ( B ) Its appearance
after stimulation for 5 min of the left vagus. The secretory part is contracted and
the resorbent part relaxed. From Fange (1953).
relax the resorbent areas (Fig. 13) or cause an opening of the oval.
Adrenaline had the same effect on the resorbent part but caused the
secretory bladder to contract. Acetylcholine has no effect on the secretory
bladder, but it has a contracting influence on the resorbent bladder.
Stray-Pedersen (1969) has shown that the blood flow through the
secretory bladder of the eel is especially reduced by adrenaline and to
some extent by acetylcholine. The vascular resistance of the rete was
unaffected by acetylcholine, but it increased on adrenaline injections.
The reabsorbent bladder showed increased circulation when adrenaline
was added to the perfusate.
It may appear, therefore, that reabsorption of gas is stimulated by
catecholamines, while deposition is increased by the absence of such
stimuli. It is difficult to find support for the presence of “secretory
cholinergic stimuli.”
REFERENCES
Alexander, R. McN. (1959a). The physical properties of the swimbladder in intact
Alexander, R. McN. (195Qb). The densities of Cyprinidae. J. ErptZ. Biol. 36,
Cypriniformes. 1. Erptl. B i d . 36, 315332.
333-340.