INTERÏPRETATIÔN OF ULTRASÏ‘RUCTURÈ
137
of freons or hydrosarbons increased
these available with the fast'est of
the componentsîin themixture.
;:ê .- î'
-
'
Ÿ
;
'
É
_
_
2
>
,
_
'
_
lt is quite clear to us after considerabkefôrft that one can hardly hopétosùrpass .freeZing
rates availablewith liquid propane if one.:stays
nitrogentemperaturerange for
cooling. We hadplanned
liquid—helium Hwas suggested by Fer—'
nandez—Moran (1959) but
by both Luyet {personalîcommuniä
cation) and—_;Bullivat
.
(1965 «and personal communication) indiCat‘ed that
heliumfH
gave c001i‘ng velocities;
times those available
-
and this
is»very much
withpro‘pane. Frèezing rates aVailable with frräezingànitrogä
(i.e.,
equilibrium with its solid) are about
X those'ofliquid nitrogen at its
boiling' point and thus, are notnearlyœasgoodas. F12…(Luyet,l9él)i
t'wf—
During the above-experiments With Cooling uids, it was noticed that
passage of the thermocouplc;thr0ughthe vap0r above, e. g., pr0pane,:côüld-.;—reduäe’ the temperature tofO.
the thermoCoupleactuay entered the uid—. Inàddition,zthe depth-tc)
which the thermocouple was immersed made a difference, probably by alwaysrmoving‘ the
thermocouple to fresh, cool uid, since generally the deeper the penetration the greater
the cooling rate up to about 30 mm penetration.T his is not due to a
rature since the uid was kept stirring by an Archimedes screw (Bell,
measurements idiCatedï=a uniform temperature at all levels
uid}
'
‘
Based on these observations, we developed a rapid freeZihg method for tissues. We
wished to introduce the tissue into the quenching uid as rapidly as possible and
do
it without holding a large forceps in the
usually done. Wewloume our complete
technique after some
on water _eyap0ratioh from cells and the tech— .
m… fdhydt ff11
'
…
:: :
B Low Temperaüme Dehydraüon
Î
Q;
Because? of the possibility…oicé:*cfyStala formation
attempted attemp era—tures below _—.- -79
dry—10e “For this
a,— double cascade freezer was
doiveStLltmaté-z:tèmperature *oÏapproximately
——< 120, °C. There is a considerable.problem,frhowever,
whiehWill-dä:hydtä _
materials at this low
cannot be
its Îee‘zigîp0in-bf
'
approximately —— 96 .°C although _weahàve:u‘sedit ifn‘ theiahge of:——‘r*90:°GäîTètïa£hydofüfä
«
was used as dehydrating.agentfatrapproXuimate‘ly…—3+ 100
appréciablty
uid (its freezing point is: about
°C).
vis‘cous belowÇ…—— 100 °C.
50
quite uid at
105 °C: audWas
as
of the Wide range of temperatures where it
nel, ethanol, acetone, tetrahÿdrofuran and, nally, the acetone—ethanol’ mixture just
mentioned. In all experiments, the
__was usedbothaloneandmthl%
0804 di8801Ved in it (sec Fe…det and Siÿ‘dman4
°°mpansonofthetwotypes°fmateŒï
smcçtheæ1salwaysthepess1bnythatüssaeadequatelyfrœæmaythawdmngtransfer
from thecoohngbathtothedehydraügwatechmquewasworkedwtwmh
tiæùë tobehandledmhqmd nitrogen vapor 'at
‘
.
-
137
of freons or hydrosarbons increased
these available with the fast'est of
the componentsîin themixture.
;:ê .- î'
-
'
Ÿ
;
'
É
_
_
2
>
,
_
'
_
lt is quite clear to us after considerabkefôrft that one can hardly hopétosùrpass .freeZing
rates availablewith liquid propane if one.:stays
nitrogentemperaturerange for
cooling. We hadplanned
liquid—helium Hwas suggested by Fer—'
nandez—Moran (1959) but
by both Luyet {personalîcommuniä
cation) and—_;Bullivat
.
(1965 «and personal communication) indiCat‘ed that
heliumfH
gave c001i‘ng velocities;
times those available
-
and this
is»very much
withpro‘pane. Frèezing rates aVailable with frräezingànitrogä
(i.e.,
equilibrium with its solid) are about
X those'ofliquid nitrogen at its
boiling' point and thus, are notnearlyœasgoodas. F12…(Luyet,l9él)i
t'wf—
During the above-experiments With Cooling uids, it was noticed that
passage of the thermocouplc;thr0ughthe vap0r above, e. g., pr0pane,:côüld-.;—reduäe’ the temperature tofO.
the thermoCoupleactuay entered the uid—. Inàddition,zthe depth-tc)
which the thermocouple was immersed made a difference, probably by alwaysrmoving‘ the
thermocouple to fresh, cool uid, since generally the deeper the penetration the greater
the cooling rate up to about 30 mm penetration.T his is not due to a
rature since the uid was kept stirring by an Archimedes screw (Bell,
measurements idiCatedï=a uniform temperature at all levels
uid}
'
‘
Based on these observations, we developed a rapid freeZihg method for tissues. We
wished to introduce the tissue into the quenching uid as rapidly as possible and
do
it without holding a large forceps in the
usually done. Wewloume our complete
technique after some
on water _eyap0ratioh from cells and the tech— .
m… fdhydt ff11
'
…
:: :
B Low Temperaüme Dehydraüon
Î
Q;
Because? of the possibility…oicé:*cfyStala formation
attempted attemp era—tures below _—.- -79
dry—10e “For this
a,— double cascade freezer was
doiveStLltmaté-z:tèmperature *oÏapproximately
——< 120, °C. There is a considerable.problem,frhowever,
whiehWill-dä:hydtä _
materials at this low
cannot be
its Îee‘zigîp0in-bf
'
approximately —— 96 .°C although _weahàve:u‘sedit ifn‘ theiahge of:——‘r*90:°GäîTètïa£hydofüfä
«
was used as dehydrating.agentfatrapproXuimate‘ly…—3+ 100
appréciablty
uid (its freezing point is: about
°C).
vis‘cous belowÇ…—— 100 °C.
50
quite uid at
105 °C: audWas
as
of the Wide range of temperatures where it
nel, ethanol, acetone, tetrahÿdrofuran and, nally, the acetone—ethanol’ mixture just
mentioned. In all experiments, the
__was usedbothaloneandmthl%
0804 di8801Ved in it (sec Fe…det and Siÿ‘dman4
°°mpansonofthetwotypes°fmateŒï
smcçtheæ1salwaysthepess1bnythatüssaeadequatelyfrœæmaythawdmngtransfer
from thecoohngbathtothedehydraügwatechmquewasworkedwtwmh
tiæùë tobehandledmhqmd nitrogen vapor 'at
‘
.
-