b) Adrenocortical Tissue
Amphibian adrenocortical tissue appears to be able to secrete principally two steroids, aldosterone and corticosterone (Table 6.4) both of which are also found in
birds and reptiles. Other stero id s have been identified in incubates of amphibian
adrenocortical tissues but, except for cortisol, they have not been identified in
the circulation. The latter steroid has been found in adrenal effluent blood of th e
anuran, Xenopus laevis , and the urodele, Amphiuma tridactyla (CHESTER JON ES,
PHILLIPS, and HOLMES, 1959). Both aldosterone and corticosterone have been
identified in the blood of toads, Bufo marinus, and bullfrogs, Rana catesbeiana
(CRABBE, 1961 a; JOHNSTON et al., 1967). The phyletic spread of such observations
among the Amphibia is thus somewhat limited, especially in urodeles. In view of
the presence of cortisol as well as corticosterone, but not aldosterone, among the
fishes a closer examination of corticosteroids in the Amphibia would be most interesting.
Table 6.4 Distribution of the adrenocorticosteroids in the Amphibia
Anura
Rana catesbeiana' , 2':(American bullfrog)
Rana pipiens 3
(Leopard frog)
Bufo marinus'"
(Toad)
Xenopus laeuis' "
(South African clawed toad)
Urodela
Amphiuma tridactyla
6 . '
(Congo eel)
Aldosterone
+
+
+
Corticosterone
+
+
+
Cortisol
+ Cortisol
" Identified in the blood; others from adrenal tissue incubation.
lCARSTENSEN et al, (1959; 1961); 2JOHNSTON et al. (1967); 3KRAULIS and BIRMINGHAM (1964);
4CRABBE (1961 a); SPHILLIPS and CHESTER JONES (1957); 6CHAN and EDWARDS (1970);
7CHESTER JONES et al. (1959).
1. Water Exchange
a) Skin
Skin plays a major role in the osmoregulation of the Amphibia, due not only to
its high permeability to water and salts, but also to the fact that such permeation
may var y in different species and be subject at times to physiological regulation.
a) In w ater. Amphibians do not drink, except in certain non-physiological situations
as when they are placed in hyperosmotic salt solutions. Instead, water moves across
168
Amphibian adrenocortical tissue appears to be able to secrete principally two steroids, aldosterone and corticosterone (Table 6.4) both of which are also found in
birds and reptiles. Other stero id s have been identified in incubates of amphibian
adrenocortical tissues but, except for cortisol, they have not been identified in
the circulation. The latter steroid has been found in adrenal effluent blood of th e
anuran, Xenopus laevis , and the urodele, Amphiuma tridactyla (CHESTER JON ES,
PHILLIPS, and HOLMES, 1959). Both aldosterone and corticosterone have been
identified in the blood of toads, Bufo marinus, and bullfrogs, Rana catesbeiana
(CRABBE, 1961 a; JOHNSTON et al., 1967). The phyletic spread of such observations
among the Amphibia is thus somewhat limited, especially in urodeles. In view of
the presence of cortisol as well as corticosterone, but not aldosterone, among the
fishes a closer examination of corticosteroids in the Amphibia would be most interesting.
Table 6.4 Distribution of the adrenocorticosteroids in the Amphibia
Anura
Rana catesbeiana' , 2':(American bullfrog)
Rana pipiens 3
(Leopard frog)
Bufo marinus'"
(Toad)
Xenopus laeuis' "
(South African clawed toad)
Urodela
Amphiuma tridactyla
6 . '
(Congo eel)
Aldosterone
+
+
+
Corticosterone
+
+
+
Cortisol
+ Cortisol
" Identified in the blood; others from adrenal tissue incubation.
lCARSTENSEN et al, (1959; 1961); 2JOHNSTON et al. (1967); 3KRAULIS and BIRMINGHAM (1964);
4CRABBE (1961 a); SPHILLIPS and CHESTER JONES (1957); 6CHAN and EDWARDS (1970);
7CHESTER JONES et al. (1959).
1. Water Exchange
a) Skin
Skin plays a major role in the osmoregulation of the Amphibia, due not only to
its high permeability to water and salts, but also to the fact that such permeation
may var y in different species and be subject at times to physiological regulation.
a) In w ater. Amphibians do not drink, except in certain non-physiological situations
as when they are placed in hyperosmotic salt solutions. Instead, water moves across
168