298
AUGUST EPPLE
fishes. A slow response seems to be characteristic of poikilotherms in
general (cf. Miller, 1960; Penhos et al., 1967). In cyclostomes (Petromynon fluviutilis and Myxine glutinosa), only small amounts of urinary
glucose are found after glucose loading, despite a sharp drop of the blood
sugar after several hours; Bentley and Follet (1965) and Falkmer and
Matty (1966a) conclude from this observation that the animals must have
mechanisms concerned with the control of blood glucose concentration.
However, previous islectectomy did not influence the glucose loading
curve in Myxine (Falkmer and Matty, 1966a). In several elasmobranchs
Hartman et al., 1944; Oppelt et al., 1963; W. C. Grant, Jr., 1964; Patent,
1968), in the holocephalian, Hydrolagus colliei (Patent, 1968), and in the
teleosts, Cottus scorpius (Falkmer, 1 M l ) and CZurias batruchus
(Khanna and Mehrotra, 1969b) glucose levels did not return to normal
before a period of 9 hr to several days.
b. Efects of a Glucose-Containing Medium. Kohler (1963) kept goldfish in 2% glucose or 2% fructose solutions; he observed fatty liver only in
animals kept in glucose. Addition of insulin to the medium prevented
fatty liver, and adequate controls suggest that this effect was a specific
action of the hormone. Also, in a 02% glucose solution, goldfish developed
hyperglycemia together with hepatic steatosis and an increase of the sugar
level of the muscles (Sterne, 1967). High glucose concentrations also
stimulate insulin release from toadfish islet tissue in dtro ( Watkins et al.,
1964c).
c. Zskt Changes after Glucose Injections. In lampreys, Barrington
(1942) and Ermisch (1966, 1967) observed transient glycogen infiltration
and vacuolization followed by necroses after glucose injections; the intrafollicular, colloid-containing lumina of the larval Petromyzon pluneri
disappear, but the gomori-negative granular islet cells seem practically unaffected. In M y x i w , a long-term injection of glucose led to B-cell degranulation but not to the disappearance of intrafollicular colloids (Falkmer
and Matty, 1968a). No effect of glucose injection was observed in the
pancreatic islets of Squalus acunthias and Hydrolugus colliei (Patent,
1968). In the teleost, Clurim batrachus, glucose injection caused temporary degranulation and “fusion” of the B cells (Mehrotra and Khanna,
196913 ) .
3. ISLETECTOMY AND PANCREATECTOMY
Destruction of the islet tissue of the larval Petromyzon murinus unicolor by cautery caused hyperglycemia (Barrington, 1942), while surgical removal of the islet organ of Myxine glutinosa had no effect on the
blood sugar level (Schirner, 1963~; Falkmer and Matty, 1966a). It re-
AUGUST EPPLE
fishes. A slow response seems to be characteristic of poikilotherms in
general (cf. Miller, 1960; Penhos et al., 1967). In cyclostomes (Petromynon fluviutilis and Myxine glutinosa), only small amounts of urinary
glucose are found after glucose loading, despite a sharp drop of the blood
sugar after several hours; Bentley and Follet (1965) and Falkmer and
Matty (1966a) conclude from this observation that the animals must have
mechanisms concerned with the control of blood glucose concentration.
However, previous islectectomy did not influence the glucose loading
curve in Myxine (Falkmer and Matty, 1966a). In several elasmobranchs
Hartman et al., 1944; Oppelt et al., 1963; W. C. Grant, Jr., 1964; Patent,
1968), in the holocephalian, Hydrolagus colliei (Patent, 1968), and in the
teleosts, Cottus scorpius (Falkmer, 1 M l ) and CZurias batruchus
(Khanna and Mehrotra, 1969b) glucose levels did not return to normal
before a period of 9 hr to several days.
b. Efects of a Glucose-Containing Medium. Kohler (1963) kept goldfish in 2% glucose or 2% fructose solutions; he observed fatty liver only in
animals kept in glucose. Addition of insulin to the medium prevented
fatty liver, and adequate controls suggest that this effect was a specific
action of the hormone. Also, in a 02% glucose solution, goldfish developed
hyperglycemia together with hepatic steatosis and an increase of the sugar
level of the muscles (Sterne, 1967). High glucose concentrations also
stimulate insulin release from toadfish islet tissue in dtro ( Watkins et al.,
1964c).
c. Zskt Changes after Glucose Injections. In lampreys, Barrington
(1942) and Ermisch (1966, 1967) observed transient glycogen infiltration
and vacuolization followed by necroses after glucose injections; the intrafollicular, colloid-containing lumina of the larval Petromyzon pluneri
disappear, but the gomori-negative granular islet cells seem practically unaffected. In M y x i w , a long-term injection of glucose led to B-cell degranulation but not to the disappearance of intrafollicular colloids (Falkmer
and Matty, 1968a). No effect of glucose injection was observed in the
pancreatic islets of Squalus acunthias and Hydrolugus colliei (Patent,
1968). In the teleost, Clurim batrachus, glucose injection caused temporary degranulation and “fusion” of the B cells (Mehrotra and Khanna,
196913 ) .
3. ISLETECTOMY AND PANCREATECTOMY
Destruction of the islet tissue of the larval Petromyzon murinus unicolor by cautery caused hyperglycemia (Barrington, 1942), while surgical removal of the islet organ of Myxine glutinosa had no effect on the
blood sugar level (Schirner, 1963~; Falkmer and Matty, 1966a). It re-