THE PHYSIOLOOY OF ASCIDIANS
79
matrix and by apposition of vacuoles containing vanadium-complex
and protein.
Pori tnvtdori t v i u in( iii m i i I L wo(b w d o r
Uptnke on brarichid wall
Absorption into blood
Uptake from plasma to arnoctbocytoe
Aoc.rirritrlrit,ic,ii of vrLnticliuni 111 viwiiciltw tmviol)oc:ytcit+
rwel rocIiwt8ioti t!o i,rivtilotit fcirrri
Itisolublo gratiitlos of vatictcliiirri-~)re)t~iti-~ulphat(~
complex in signot-ring cell
Synthesis of haemovariadin in compartment cell
and production of acid
Mature morula cell (vanadocyte)
J.
3.
J.
J.
1
4
4
FIQ. 23. An outline scheme for the uptaka of venadinrn in ascidians. (Adapted from
Kalk, 1963b.)
(c) During the distribution of the vanadium-protein-complex
granules in vacuoles around the periphery the contents become acid
and soluble.
Kalk finally concludes that the ahsorption of' water and fmgarx into
the compartments convert8 the cell into IL moruls coll or vantulocytr:
where the sugars arc polymeriaud t,o form a ~'~lynacohuricl~!. Klttk'n
work is bafled almost exclu~ively on c:lootron microncopy, iming thr!
electron dense properties of vanadium as a natural tracer, and of
necessity some of her conclusions must be considered as speculative
(Fig. 23).
While the overall picture of vanadium absorption and accumulation
is becoming clear through the work of these various authors there is
considerable divergence of opinion on certain matters. Kalk's suggestion of uptake by pinocytosis for instance is in conflict with that of
Bielig and others who indicate that it must be an energy consuming
biochemical process, and indeed Rummcl et al. (1 966) provide evidence
to suggest that the vanadium passes first into the plasma and is only
79
matrix and by apposition of vacuoles containing vanadium-complex
and protein.
Pori tnvtdori t v i u in( iii m i i I L wo(b w d o r
Uptnke on brarichid wall
Absorption into blood
Uptake from plasma to arnoctbocytoe
Aoc.rirritrlrit,ic,ii of vrLnticliuni 111 viwiiciltw tmviol)oc:ytcit+
rwel rocIiwt8ioti t!o i,rivtilotit fcirrri
Itisolublo gratiitlos of vatictcliiirri-~)re)t~iti-~ulphat(~
complex in signot-ring cell
Synthesis of haemovariadin in compartment cell
and production of acid
Mature morula cell (vanadocyte)
J.
3.
J.
J.
1
4
4
FIQ. 23. An outline scheme for the uptaka of venadinrn in ascidians. (Adapted from
Kalk, 1963b.)
(c) During the distribution of the vanadium-protein-complex
granules in vacuoles around the periphery the contents become acid
and soluble.
Kalk finally concludes that the ahsorption of' water and fmgarx into
the compartments convert8 the cell into IL moruls coll or vantulocytr:
where the sugars arc polymeriaud t,o form a ~'~lynacohuricl~!. Klttk'n
work is bafled almost exclu~ively on c:lootron microncopy, iming thr!
electron dense properties of vanadium as a natural tracer, and of
necessity some of her conclusions must be considered as speculative
(Fig. 23).
While the overall picture of vanadium absorption and accumulation
is becoming clear through the work of these various authors there is
considerable divergence of opinion on certain matters. Kalk's suggestion of uptake by pinocytosis for instance is in conflict with that of
Bielig and others who indicate that it must be an energy consuming
biochemical process, and indeed Rummcl et al. (1 966) provide evidence
to suggest that the vanadium passes first into the plasma and is only