30
J. N. BALL AND BRIDGET I. BAKER
be attributed to increased release of growth hormone, since the (Y cells
in the guppy, as in P . latipinnu, showed no response to thyroxine by itself.
Most probably thyroxine synergizes peripherally with normal levels of
growth hormone to cause growth enhancement, in the same way that
exogenous bovine TSH and hake GH synergize in hypophysectomized
Fundulus heteroclitm (Pickford and Atz, 1957).
Treatment with cortisol causes regression of the (Y cells in the eel,
while surgical stress activates them (Olivereau, 1967a; Olivereau and
Olivereau, 1968), although not the stress of anesthesia and bleeding
( Olivereau, 1967b). Surgical removal of the eel interrenal did not appear
to activate the a! cells any more than the sham operation (Olivereau and
Olivereau, 1968), although the adrenocortical inhibitor SU 4885 slightly
increased the a! granulation (Olivereau, 1965). At sexual maturity the
female eel a cells are reduced in number, which may correspond to a
reduced growth such as commonly accompanies sexual maturation (Olivereau, 1967a). Sokol (1961) described a marked cycle in the (Y cells of
the female guppy in relation to gestation, the cells being mainly inactive
during the greater part of the month-long gestation period, but showing
transient activity at the time of parturition, while in the unrelated
viviparous Zoarces Oztan (1966a) described marked activation of these
cells during gestation and regression following parturition.
Eels with small skin lesions exhibited hyponatremia accompanied by
strong activation of the (Y cells (Olivereau, 1966d, 1967b), while, surprisingly, extreme activation of these cells was found in eels maintained
in deionized water for up to 46 days (Olivereau, 196713). Prolonged exposure to deionized water leads to marked ionoregulatory disturbances in
the eel, apart from hyponatremia, including a fall in plasma calcium with
a rise in plasma potassium levels that seems to result from movement of
potassium from muscles to plasma ( Olivereau and Chartier-Baraduc,
1966; Chan et a!., 1967; Henderson and Chester Jones, 1967). Olivereau
suggested that the increased secretion of growth hormone in deionized
water might represent a response designed to oppose this internal shift of
potassium, since the rise in plasma potassium occurs more rapidly in hypophysectomized eels than in intact animals (Olivereau and ChartierBaraduc, 1966), but for the moment the real significance of this reaction
of the eel a cells is uncertain, and its explanation awaits a full-scale investigation of the possible role of growth hormone in teleostean electrolyte
metabolism.
The a! cells were reduced in number and relatively inactive in pituitary
transplants in Poecilia forrnosa (Olivereau and Ball, 1966), and in
correlation these cells frequently regressed in the trout pituitary cultured
in vitro (Baker, 1963a).
J. N. BALL AND BRIDGET I. BAKER
be attributed to increased release of growth hormone, since the (Y cells
in the guppy, as in P . latipinnu, showed no response to thyroxine by itself.
Most probably thyroxine synergizes peripherally with normal levels of
growth hormone to cause growth enhancement, in the same way that
exogenous bovine TSH and hake GH synergize in hypophysectomized
Fundulus heteroclitm (Pickford and Atz, 1957).
Treatment with cortisol causes regression of the (Y cells in the eel,
while surgical stress activates them (Olivereau, 1967a; Olivereau and
Olivereau, 1968), although not the stress of anesthesia and bleeding
( Olivereau, 1967b). Surgical removal of the eel interrenal did not appear
to activate the a! cells any more than the sham operation (Olivereau and
Olivereau, 1968), although the adrenocortical inhibitor SU 4885 slightly
increased the a! granulation (Olivereau, 1965). At sexual maturity the
female eel a cells are reduced in number, which may correspond to a
reduced growth such as commonly accompanies sexual maturation (Olivereau, 1967a). Sokol (1961) described a marked cycle in the (Y cells of
the female guppy in relation to gestation, the cells being mainly inactive
during the greater part of the month-long gestation period, but showing
transient activity at the time of parturition, while in the unrelated
viviparous Zoarces Oztan (1966a) described marked activation of these
cells during gestation and regression following parturition.
Eels with small skin lesions exhibited hyponatremia accompanied by
strong activation of the (Y cells (Olivereau, 1966d, 1967b), while, surprisingly, extreme activation of these cells was found in eels maintained
in deionized water for up to 46 days (Olivereau, 196713). Prolonged exposure to deionized water leads to marked ionoregulatory disturbances in
the eel, apart from hyponatremia, including a fall in plasma calcium with
a rise in plasma potassium levels that seems to result from movement of
potassium from muscles to plasma ( Olivereau and Chartier-Baraduc,
1966; Chan et a!., 1967; Henderson and Chester Jones, 1967). Olivereau
suggested that the increased secretion of growth hormone in deionized
water might represent a response designed to oppose this internal shift of
potassium, since the rise in plasma potassium occurs more rapidly in hypophysectomized eels than in intact animals (Olivereau and ChartierBaraduc, 1966), but for the moment the real significance of this reaction
of the eel a cells is uncertain, and its explanation awaits a full-scale investigation of the possible role of growth hormone in teleostean electrolyte
metabolism.
The a! cells were reduced in number and relatively inactive in pituitary
transplants in Poecilia forrnosa (Olivereau and Ball, 1966), and in
correlation these cells frequently regressed in the trout pituitary cultured
in vitro (Baker, 1963a).