186
S. Egginton and J.C. Rankin
were made in one specimen each of Gobionotothen gibberifrons Lonnberg
and Trematomus eulepidotus Regan. Specimens of C. aceratus for
histological investigation were caught around the British Antarctic
Survey's station on Signy Island (60 0 43'S, 45°36'W) and held in
temperature controlled tanks until sampling (Tamb = 0 0c). For purposes
of comparison, rainbow trout (Oncorhynchus mykiss Walbaum) were
sampled at a trout farm during autumn (Tamb=ll 0c).
Vascular Casting
After capture specimens were injected with heparinised Ringer followed
by either Microfil (Canton Bio-Medical Products, Boulder, Colorado) or
Acrifix (Rohm, Darmstadt) via the bulbus arteriosus, or in some cases the
hypobranchial artery, and left overnight at ambient temperature. Acrifix
injected fish were kept frozen until the tissues were dissolved with
concentrated KOH. These casts were then washed with, and stored in,
distilled water. Microfil injected fish were dissected, examined and
photographed or drawn on the ship, and then preserved in formalin,
followed by dehydration in graded alcohols. Details of the techniques
were varied as it was not possible to judge which procedure gave the best
results until after the cruise. The best Acrifix filling of the pectoral
musculature was achieved in a 660 g specimen of C. hamatus. Six hours
after capture it was given an intraperitoneal injection of the vasodilator
papaverine (Sigma: 0.5 ml of 5xlO- 3 M in Ringer adjusted to pH 4 with
Hel). The heart continued beating strongly and to determine the direction
of blood flow in the hypobranchial artery (H) it was ligated before
cannulation. It swelled anterior to the ligature (preliminary experiments in
which Evans Blue was injected into anaesthetized fish had already shown
that flow in the hypobranchial artery was from the gills to the pectoral
muscles; this connectivity was confirmed in other specimens by injection
of Microfil). Blue-pigmented Acrifix (7 parts resin!3 parts hardener/0.3
parts pigment) was then injected into the cannulated H to fill the pectoral
muscle vasculature; 0.3 ml of heparinized Ringer was then injected
through the cannulated bulbus arteriosus, followed by 8.5 ml of red
Acrifix in ca. 7 min. This also entered the dorsal aorta and its branches,
most of the blue Acrifix in the pectoral musculature being displaced by
the red, which retrogradely penetrated into H.
Rainbow trout, 0. mykiss, were anaesthetized in MS222 and injected
with 500 U heparin. Following cannulation of the dorsal aorta near
complete perfusion of the trunk musculature was possible. The bulbus
arteriosus was severed to allow drainage, and heparinized saline perfused
S. Egginton and J.C. Rankin
were made in one specimen each of Gobionotothen gibberifrons Lonnberg
and Trematomus eulepidotus Regan. Specimens of C. aceratus for
histological investigation were caught around the British Antarctic
Survey's station on Signy Island (60 0 43'S, 45°36'W) and held in
temperature controlled tanks until sampling (Tamb = 0 0c). For purposes
of comparison, rainbow trout (Oncorhynchus mykiss Walbaum) were
sampled at a trout farm during autumn (Tamb=ll 0c).
Vascular Casting
After capture specimens were injected with heparinised Ringer followed
by either Microfil (Canton Bio-Medical Products, Boulder, Colorado) or
Acrifix (Rohm, Darmstadt) via the bulbus arteriosus, or in some cases the
hypobranchial artery, and left overnight at ambient temperature. Acrifix
injected fish were kept frozen until the tissues were dissolved with
concentrated KOH. These casts were then washed with, and stored in,
distilled water. Microfil injected fish were dissected, examined and
photographed or drawn on the ship, and then preserved in formalin,
followed by dehydration in graded alcohols. Details of the techniques
were varied as it was not possible to judge which procedure gave the best
results until after the cruise. The best Acrifix filling of the pectoral
musculature was achieved in a 660 g specimen of C. hamatus. Six hours
after capture it was given an intraperitoneal injection of the vasodilator
papaverine (Sigma: 0.5 ml of 5xlO- 3 M in Ringer adjusted to pH 4 with
Hel). The heart continued beating strongly and to determine the direction
of blood flow in the hypobranchial artery (H) it was ligated before
cannulation. It swelled anterior to the ligature (preliminary experiments in
which Evans Blue was injected into anaesthetized fish had already shown
that flow in the hypobranchial artery was from the gills to the pectoral
muscles; this connectivity was confirmed in other specimens by injection
of Microfil). Blue-pigmented Acrifix (7 parts resin!3 parts hardener/0.3
parts pigment) was then injected into the cannulated H to fill the pectoral
muscle vasculature; 0.3 ml of heparinized Ringer was then injected
through the cannulated bulbus arteriosus, followed by 8.5 ml of red
Acrifix in ca. 7 min. This also entered the dorsal aorta and its branches,
most of the blue Acrifix in the pectoral musculature being displaced by
the red, which retrogradely penetrated into H.
Rainbow trout, 0. mykiss, were anaesthetized in MS222 and injected
with 500 U heparin. Following cannulation of the dorsal aorta near
complete perfusion of the trunk musculature was possible. The bulbus
arteriosus was severed to allow drainage, and heparinized saline perfused