208
J. N. BALL
1967). In addition, prolactin is generally considered to be a causal agent
in the induction of maternal behavior and broodiness in mammals and
birds (Riddle, 1963b), although it is not certain whether this is a direct
action or one mediated by gonadal steroids (Lehrman, 1961, 1963).
For many years, on the basis of a misunderstanding of the work of
Leblond and Noble (1937), it was accepted that the teleostean pituitary
contained a pigeon crop-stimulating factor, i.e., a typical prolactin; and
overenthusiastic interpretation of the results of Noble et al. (1936, 1938)
led to the erroneous view that fish prolactin had been shown to be involved in the causation of parental care behavior in teleosts. Reexamination of the response of the pigeon crop to fish pituitary material led
Nicoll and Bern (1964, 1965, 1968) to conclude that a typical prolactin
(i.e., a factor with full effect on the pigeon crop) does not occur in fishes,
with the significant exception of the lungfish Protoptern, although
typical prolactin reactions were obtained with amphibian glands. Study
of the mammary gland response showed that typical responses could be
elicited with amphibian and reptilean material, but not with fish pituitary
material, and in this case Protopterus pituitary was ineffective (Nicoll
et al., 1966). However, more recently, Chadwick (1966), Nicoll et al.
( 19f36), and Nicoll and Bern ( 1968) have come to consider not that there
is no pigeon crop-stimulating factor in the fish pituitary but rather that
there is present an incompletely or minimally effective stimulating factor.
The essence of the present situation is that definitive prolactin appears
only at the tetrapod stage of vertebrate organization; the position of the
dipnoans requires further elucidation, but it is probable that these
animals stand closer to amphibians than to other fishes in this respect,
as in so many others.
Apart from its historically primary pigeon crop and mammary gland
activities, purified mammalian prolactin has a specific action in inducing
the return to water (“water drive”) in hypophysectomized newts or efts,
Diemyctilus uiridescens, which normally prefer to stay on land (Grant
and Grant, 1958). Grant and Pickford (1959) were able to induce water
drive in hypophysectomized efts with fish pituitary material, and so provided the first unequivocal demonstration that the fish pituitary possesses
in full a property characteristic of tetrapod prolactin. From that time on,
interest in the presence and possible physiological actions of a kind of
prolactin in the fish pituitary has grown, and in one field, concerned with
effects of prolactin on electrolyte regulation in certain teleosts, evidence
has been obtained which substantiates the presence of a prolactinlike
hormone possessing some, but not all, of the properties of mammalian
prolactin.
Many different effects have been described following administration
J. N. BALL
1967). In addition, prolactin is generally considered to be a causal agent
in the induction of maternal behavior and broodiness in mammals and
birds (Riddle, 1963b), although it is not certain whether this is a direct
action or one mediated by gonadal steroids (Lehrman, 1961, 1963).
For many years, on the basis of a misunderstanding of the work of
Leblond and Noble (1937), it was accepted that the teleostean pituitary
contained a pigeon crop-stimulating factor, i.e., a typical prolactin; and
overenthusiastic interpretation of the results of Noble et al. (1936, 1938)
led to the erroneous view that fish prolactin had been shown to be involved in the causation of parental care behavior in teleosts. Reexamination of the response of the pigeon crop to fish pituitary material led
Nicoll and Bern (1964, 1965, 1968) to conclude that a typical prolactin
(i.e., a factor with full effect on the pigeon crop) does not occur in fishes,
with the significant exception of the lungfish Protoptern, although
typical prolactin reactions were obtained with amphibian glands. Study
of the mammary gland response showed that typical responses could be
elicited with amphibian and reptilean material, but not with fish pituitary
material, and in this case Protopterus pituitary was ineffective (Nicoll
et al., 1966). However, more recently, Chadwick (1966), Nicoll et al.
( 19f36), and Nicoll and Bern ( 1968) have come to consider not that there
is no pigeon crop-stimulating factor in the fish pituitary but rather that
there is present an incompletely or minimally effective stimulating factor.
The essence of the present situation is that definitive prolactin appears
only at the tetrapod stage of vertebrate organization; the position of the
dipnoans requires further elucidation, but it is probable that these
animals stand closer to amphibians than to other fishes in this respect,
as in so many others.
Apart from its historically primary pigeon crop and mammary gland
activities, purified mammalian prolactin has a specific action in inducing
the return to water (“water drive”) in hypophysectomized newts or efts,
Diemyctilus uiridescens, which normally prefer to stay on land (Grant
and Grant, 1958). Grant and Pickford (1959) were able to induce water
drive in hypophysectomized efts with fish pituitary material, and so provided the first unequivocal demonstration that the fish pituitary possesses
in full a property characteristic of tetrapod prolactin. From that time on,
interest in the presence and possible physiological actions of a kind of
prolactin in the fish pituitary has grown, and in one field, concerned with
effects of prolactin on electrolyte regulation in certain teleosts, evidence
has been obtained which substantiates the presence of a prolactinlike
hormone possessing some, but not all, of the properties of mammalian
prolactin.
Many different effects have been described following administration