414
HOWARD A. BERN
synaptic connections
u rop hysial
into renal portal
system
renal diuresis:
hormone(s)?
increased Na+ retention!
increased Na+ influx
Fig. 8. Schematic representation of possible role of urophysis in osmoregulation.
From Fridberg and Bern ( 1988 ) .
adjustments to changes in environmental salinity. This is especially true
for migratory species where the system has yet to be systematically investigated. Cytological and pharmacological criteria of activity should be
employed in the comparison of freshwater and marine stages of such
diverse teleost species as poeciliids, sticklebacks, mullets (Johnson, 1968) ,
salmonids, and eels,
The vasopressor activity in eels (see Bern et al., 1967) and the
bladder-contracting activity in trout ( Lederis, 1969) are kinetic actions
(Table I ) of considerable sensitivity; responses certainly occur within the
“physiological” dose range. The buoyancy effect described in such detail
by Enami ( 1959) has never been confirmed (Lahlou, 1966). In elasmobranchs, no physiological information has been forthcoming. It has been
reported that extracts of the spinal cord (but also of the brain) are antidiuretic in the dogfish, Mustelus canis ( Suberman and Rabinowitz, 1968),
but there is no indication that the caudal neurons may be involved.
V. PERSPECTIVES
This chapter on the urophysis is being written at a time when some
light as to its physiological significance appears finally to be breaking.
It is unreasonable to assume that this prominent system-ubiquitous at
least in elasmobranchs and actinopterygians-makes no major contribution to the vital economy of the animals possessing it. It is regrettable,
however, that we must still speak in terms of “effects” in a quasipharmacological sense rather than “role” in a physiological sense.
However, certain features of the caudal neurosecretory system underline its possible functional import. First, the Dahlgren cells show every
evidence of being actively synthetic, decidedly glandular cells, with the
type of contact with a rich vascular bed that is associated with endocrine
HOWARD A. BERN
synaptic connections
u rop hysial
into renal portal
system
renal diuresis:
hormone(s)?
increased Na+ retention!
increased Na+ influx
Fig. 8. Schematic representation of possible role of urophysis in osmoregulation.
From Fridberg and Bern ( 1988 ) .
adjustments to changes in environmental salinity. This is especially true
for migratory species where the system has yet to be systematically investigated. Cytological and pharmacological criteria of activity should be
employed in the comparison of freshwater and marine stages of such
diverse teleost species as poeciliids, sticklebacks, mullets (Johnson, 1968) ,
salmonids, and eels,
The vasopressor activity in eels (see Bern et al., 1967) and the
bladder-contracting activity in trout ( Lederis, 1969) are kinetic actions
(Table I ) of considerable sensitivity; responses certainly occur within the
“physiological” dose range. The buoyancy effect described in such detail
by Enami ( 1959) has never been confirmed (Lahlou, 1966). In elasmobranchs, no physiological information has been forthcoming. It has been
reported that extracts of the spinal cord (but also of the brain) are antidiuretic in the dogfish, Mustelus canis ( Suberman and Rabinowitz, 1968),
but there is no indication that the caudal neurons may be involved.
V. PERSPECTIVES
This chapter on the urophysis is being written at a time when some
light as to its physiological significance appears finally to be breaking.
It is unreasonable to assume that this prominent system-ubiquitous at
least in elasmobranchs and actinopterygians-makes no major contribution to the vital economy of the animals possessing it. It is regrettable,
however, that we must still speak in terms of “effects” in a quasipharmacological sense rather than “role” in a physiological sense.
However, certain features of the caudal neurosecretory system underline its possible functional import. First, the Dahlgren cells show every
evidence of being actively synthetic, decidedly glandular cells, with the
type of contact with a rich vascular bed that is associated with endocrine