106
IVAN GOODBODY
Welsh and I,oveland (l!Hi%) found no trace of the substance in the
ganglion of Giona inteefinnlitq but found it in the gut ( 0 4 9 pg/g wet wt
of tissue), pharynx (0.12 &g), cndostyle (1.67 pg/g) and heart (0.53
pg/g). They suggest t.hat it may not have been revealed in the ganglion
if it occurred in very small traces. The high levels in the cndostyle are
puzzling but Welsh and Lovelimd suggest that both here and in the
pharynx it may play some role in ciliary co-ordination. They believe
that in the oesophagus the 5-liydroxytryptamine may be localized in
the chromafin ( d s identified by Lison (1933) and Gerzeli (1963) and
point out’ that such a localization would be comparable to that found in
vertebrates. Whether or not this is true it is clear that the localization
of 5-hydroxytryptamine in these ascidians is not such as to suggest that
it is an important neurotransmitter. On the other hand, its localization
in pharynx, endostyle and oesophagus, the areas of maximum ciliary
activity in ascidiuns, may be particularly significant. (For a discussion
of 5-hydroxytryptiimine arid other transmitters, see E’lorey, 1961 .)
G. Neuroswretion
111 order to prove i i neurosecretory function in any aiiimal it must be
posdile to tlemonstrate thc productioll of a secretion in nerve cells, that
this secretion is liberat,ed from the re11 or the terminal point of its axon
and that i t directly or indirectly activates an effector organ or metabolic process in tile body. No such function has been unequivocally
demonstratctl in ciscidians, but several workers have reported the
presence of granules in ncrve cells and axous of the cercbral ganglion
(Dawsoii t i n t i Hisaw, 1064 ; Thiebold and llloul, 1966 ; Lane, 1968 ;
Chatnbost, 1!)6D), dthoiigh Schurrer ( 1953) was rrnablc to tlemonstrate
such granules in Ciona inteelinalis.
In a detailed study of ten species of asoitlians, Ihwson arid Hitlaw
found granule bearing cells amongst other nerve cells at the periphery
of the cercbrd ganglion. The granular material Htained with Halmi’s
(1952) modification of Gomori’s (1980) aldehyde fuchsin, but the appearance of the granules was irregular and inconsistent, perhaps
indicating cyclical activity. Two quite distinct types of granular cell
were identified, one in pleurogonid ascidians, the other in enterogonid
forms. In the Pleurogona there are large secretory cells in which the
granular mtlterial is dispersed throughout the celi and stains purple ;
the granular material is sometimes partially displaced in the cell by a
vacuole. Tn the Enterogona the granular material stains green, and is
always paranticlear and there are no vacuoles. There is no proof that
these grnnules are concerned with true neurosecretion, but if they are
their most likely function would be associated with reproduction. It is
IVAN GOODBODY
Welsh and I,oveland (l!Hi%) found no trace of the substance in the
ganglion of Giona inteefinnlitq but found it in the gut ( 0 4 9 pg/g wet wt
of tissue), pharynx (0.12 &g), cndostyle (1.67 pg/g) and heart (0.53
pg/g). They suggest t.hat it may not have been revealed in the ganglion
if it occurred in very small traces. The high levels in the cndostyle are
puzzling but Welsh and Lovelimd suggest that both here and in the
pharynx it may play some role in ciliary co-ordination. They believe
that in the oesophagus the 5-liydroxytryptamine may be localized in
the chromafin ( d s identified by Lison (1933) and Gerzeli (1963) and
point out’ that such a localization would be comparable to that found in
vertebrates. Whether or not this is true it is clear that the localization
of 5-hydroxytryptamine in these ascidians is not such as to suggest that
it is an important neurotransmitter. On the other hand, its localization
in pharynx, endostyle and oesophagus, the areas of maximum ciliary
activity in ascidiuns, may be particularly significant. (For a discussion
of 5-hydroxytryptiimine arid other transmitters, see E’lorey, 1961 .)
G. Neuroswretion
111 order to prove i i neurosecretory function in any aiiimal it must be
posdile to tlemonstrate thc productioll of a secretion in nerve cells, that
this secretion is liberat,ed from the re11 or the terminal point of its axon
and that i t directly or indirectly activates an effector organ or metabolic process in tile body. No such function has been unequivocally
demonstratctl in ciscidians, but several workers have reported the
presence of granules in ncrve cells and axous of the cercbral ganglion
(Dawsoii t i n t i Hisaw, 1064 ; Thiebold and llloul, 1966 ; Lane, 1968 ;
Chatnbost, 1!)6D), dthoiigh Schurrer ( 1953) was rrnablc to tlemonstrate
such granules in Ciona inteelinalis.
In a detailed study of ten species of asoitlians, Ihwson arid Hitlaw
found granule bearing cells amongst other nerve cells at the periphery
of the cercbrd ganglion. The granular material Htained with Halmi’s
(1952) modification of Gomori’s (1980) aldehyde fuchsin, but the appearance of the granules was irregular and inconsistent, perhaps
indicating cyclical activity. Two quite distinct types of granular cell
were identified, one in pleurogonid ascidians, the other in enterogonid
forms. In the Pleurogona there are large secretory cells in which the
granular mtlterial is dispersed throughout the celi and stains purple ;
the granular material is sometimes partially displaced in the cell by a
vacuole. Tn the Enterogona the granular material stains green, and is
always paranticlear and there are no vacuoles. There is no proof that
these grnnules are concerned with true neurosecretion, but if they are
their most likely function would be associated with reproduction. It is