12. IMMUNOLOGY OF FISH
481
for delayed hypersensitivity and transplantation reactions represented
by small lymphocytes originating in the thymus.
A. Phylogeny of the Lymphoid System
Good and several of his associates present a paper (1966) devoted
to “morphologic studies on the evolution of the lymphoid tissues among
the lower vertebrates.” This integrates present immunological knowledge
with the rather extensive and sometimes obscure literature of comparative histology and anatomy that extends back into times well before the
advent of modern comparative immunology. With respect to fish, it is
sufficient to say here that this system is found to be well established, at
least as homologues of the thymus and spleen, in primitive sharks and
rays, and that plasma cells are “first” found in the paddlefish. From
this point on up the evolutionary line, emergence, consolidation, and
reshufaing of other kinds of lymphoidal tissues occurs within patterns
too detailed to present here. As the authors note, their paper serves to
sketch a scheme for the evolution of the lymphoid system that provides
a basis for experiment and further clarification.
One tantalizing observation among the many awaiting such clarification is the nature of the lymphoidal system of chimaeroids (Fange,
1968). These fish, unlike other elasmobranchs, lack lymphoid tissue in
their excretory system, but they do have a thymus and uniquely prominent lymphoidal-like structures in the cranial region. A second observation worthy of further research, also introduced by Fange, is that a
production of lymphoid cells takes place in the excretory system of several kinds of fishes (as well as in the cyclostomes, see below), suggesting
a common origin from this type of tissue (see also A. M. Smith et aZ.,
1967). It is also possible to speculate from morphological data that the
thymus evolved from the gill region.
As to experimentation, none seems to have been done on fishes that
is directly aimed at elucidating the activities of their lymphoidal system
except the papers of A. M. Smith et uZ. (1967) and Chiller et ul. (1968)
discussed in the complement section. As Hildemann and Cooper (1963)
have noted, such experiments could readily include manipulation of the
thymus. They also might well consider the transplantation of other
lymphoidal organs into “empty” fish. The attention of the reader who
considers such studies is called to the excellent work of Hildemann and
his associates, Cohen, Haas, and Cooper, on both fish and amphibians
since this sets standards of methods and interpretations that have yet to be
481
for delayed hypersensitivity and transplantation reactions represented
by small lymphocytes originating in the thymus.
A. Phylogeny of the Lymphoid System
Good and several of his associates present a paper (1966) devoted
to “morphologic studies on the evolution of the lymphoid tissues among
the lower vertebrates.” This integrates present immunological knowledge
with the rather extensive and sometimes obscure literature of comparative histology and anatomy that extends back into times well before the
advent of modern comparative immunology. With respect to fish, it is
sufficient to say here that this system is found to be well established, at
least as homologues of the thymus and spleen, in primitive sharks and
rays, and that plasma cells are “first” found in the paddlefish. From
this point on up the evolutionary line, emergence, consolidation, and
reshufaing of other kinds of lymphoidal tissues occurs within patterns
too detailed to present here. As the authors note, their paper serves to
sketch a scheme for the evolution of the lymphoid system that provides
a basis for experiment and further clarification.
One tantalizing observation among the many awaiting such clarification is the nature of the lymphoidal system of chimaeroids (Fange,
1968). These fish, unlike other elasmobranchs, lack lymphoid tissue in
their excretory system, but they do have a thymus and uniquely prominent lymphoidal-like structures in the cranial region. A second observation worthy of further research, also introduced by Fange, is that a
production of lymphoid cells takes place in the excretory system of several kinds of fishes (as well as in the cyclostomes, see below), suggesting
a common origin from this type of tissue (see also A. M. Smith et aZ.,
1967). It is also possible to speculate from morphological data that the
thymus evolved from the gill region.
As to experimentation, none seems to have been done on fishes that
is directly aimed at elucidating the activities of their lymphoidal system
except the papers of A. M. Smith et uZ. (1967) and Chiller et ul. (1968)
discussed in the complement section. As Hildemann and Cooper (1963)
have noted, such experiments could readily include manipulation of the
thymus. They also might well consider the transplantation of other
lymphoidal organs into “empty” fish. The attention of the reader who
considers such studies is called to the excellent work of Hildemann and
his associates, Cohen, Haas, and Cooper, on both fish and amphibians
since this sets standards of methods and interpretations that have yet to be