102
JAMES CLARKE FENWICK
uptake in those fish receiving injections of pineal extract. These findings, however, could not be confirmed by Weisbart and Fenwick (1966)
who report an undisturbed blood calcium level in pinealectomized
goldfish.
Few other studies have examined the endocrine nature of the fish
pineal, and these have been conflicting. Contrary to the report of
thyroidal hypertrophy by Pflugfelder (1964), Pang (1967) found a
decreased thyroidal cell height in pinealectomized Fundulus and
Rasquin (1958), U. Holmgren ( 1959b), Fenwick ( 1970c), and Peter
(1968) report no alteration in this tissue following pinealectomy. Further, neither Peter (1968) nor Fenwick ( 1970c) could find any apparent
increase in the interrenal cells as previously reported by Pflugfelder
(1953). While the significance of these findings is not clear, the possibility that the pineal body of mammals is related to electrolyte balance
(Farrell, 1960) has never been wholly repudiated and should provide
the impetus for further investigation in this area.
Although a pineal-gonadal relationship seems well established in the
mammals (Kitay and Altschule, 1954), little research has been carried
out on the possibility of such an axis in the fishes. Krockert (1936a,b)
was able to delay the appearance of secondary sex characteristics in
young Lebistes by feeding desiccated bull pineal glands. In the same
species, Pflugfelder (1954) reports a slight acceleration in the sexual
development of males following pinealectomy. In contrast to Pflugfelders results, Schonherr (1955) and Rasquin (1958) reported unsuccessful attempts to hasten reproductive maturation by pinealectomy.
Pang (1967) described a delay in the appearance of nuptial coloration
in pinealectomized Fundulus, but noted that the controls had smaller
gonad sizes. It is not clear whether this means that his controls underwent gonadal atrophy or that his pinealectomized fish showed gonadal
hypertrophy. Recently, Peter (1968) and Fenwick (1970c), both working
with goldfish, have reported contradictory (although not totally incompatible) results. Peter (1968), in one experiment of 9-months duration,
could find no signficant differences between the gonosomatic indices
(GSI) (gonad weight/body weight x 100 = GSI) of pinealectomized,
sham-pinealectomized, and unoperated control goldfish. However, when
experiments were carried out at different stages of the yearly reproductive cycle, Fenwick ( 1 9 7 0 ~ ) found that although pinealectomy had no
effect on the size of the gonads during most of the year, the operation,
when carried out just prior to the onset of the final maturation phase
preceding the normal spawning period, did result in a highly significant
increase in the GSI relative to that found in the groups with intact
pineal. The time at which pinealectomy was found to have this effect
corresponded with that period of the reproductive cycle during which
JAMES CLARKE FENWICK
uptake in those fish receiving injections of pineal extract. These findings, however, could not be confirmed by Weisbart and Fenwick (1966)
who report an undisturbed blood calcium level in pinealectomized
goldfish.
Few other studies have examined the endocrine nature of the fish
pineal, and these have been conflicting. Contrary to the report of
thyroidal hypertrophy by Pflugfelder (1964), Pang (1967) found a
decreased thyroidal cell height in pinealectomized Fundulus and
Rasquin (1958), U. Holmgren ( 1959b), Fenwick ( 1970c), and Peter
(1968) report no alteration in this tissue following pinealectomy. Further, neither Peter (1968) nor Fenwick ( 1970c) could find any apparent
increase in the interrenal cells as previously reported by Pflugfelder
(1953). While the significance of these findings is not clear, the possibility that the pineal body of mammals is related to electrolyte balance
(Farrell, 1960) has never been wholly repudiated and should provide
the impetus for further investigation in this area.
Although a pineal-gonadal relationship seems well established in the
mammals (Kitay and Altschule, 1954), little research has been carried
out on the possibility of such an axis in the fishes. Krockert (1936a,b)
was able to delay the appearance of secondary sex characteristics in
young Lebistes by feeding desiccated bull pineal glands. In the same
species, Pflugfelder (1954) reports a slight acceleration in the sexual
development of males following pinealectomy. In contrast to Pflugfelders results, Schonherr (1955) and Rasquin (1958) reported unsuccessful attempts to hasten reproductive maturation by pinealectomy.
Pang (1967) described a delay in the appearance of nuptial coloration
in pinealectomized Fundulus, but noted that the controls had smaller
gonad sizes. It is not clear whether this means that his controls underwent gonadal atrophy or that his pinealectomized fish showed gonadal
hypertrophy. Recently, Peter (1968) and Fenwick (1970c), both working
with goldfish, have reported contradictory (although not totally incompatible) results. Peter (1968), in one experiment of 9-months duration,
could find no signficant differences between the gonosomatic indices
(GSI) (gonad weight/body weight x 100 = GSI) of pinealectomized,
sham-pinealectomized, and unoperated control goldfish. However, when
experiments were carried out at different stages of the yearly reproductive cycle, Fenwick ( 1 9 7 0 ~ ) found that although pinealectomy had no
effect on the size of the gonads during most of the year, the operation,
when carried out just prior to the onset of the final maturation phase
preceding the normal spawning period, did result in a highly significant
increase in the GSI relative to that found in the groups with intact
pineal. The time at which pinealectomy was found to have this effect
corresponded with that period of the reproductive cycle during which