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possible exception of a small subset mentioned above) and responsiveness
to PHA (and Con A). The data also suggest that the T-like lymphocyte
subpopulation in the alligator is the major lymphocyte population present
in the peripheral blood, similar to mammalian T-cells.
In_ vitro studies of antibody production suggest that the necessary
cells for antigen recognition, antigen processing and antibody formation
are present in the peripheral blood of the alligator. An assessment of
the functional activities of the different subpopulations may be pos
sible by modifying the population of cells subjected to antigenic, stimu
lation In vitro (Mishell-Dutton type assays) with the various fractiona
tion procedures described. If both the T-like and B-like populations
are required before antibody production is obtained, functional activi
ties of the cell populations could be assigned.
The Alligator as an Experimental Model
The preliminary data presented suggest that the alligator may be
very similar to the chicken in terms of the architecture of the lymphoid
organs, as well as general characteristics of the isolated lymphocytes.
Thymus,: spleen, bursa, and gut associated lymphoid aggregates have been
previously reported in the alligator (36,37). With the exception of the
gut associated lymphoid tissue these results were confirmed in the histo
logical studies of the two sacrificed alligators. In addition a lymphoid
aggregate possibly equivalent to the Harder's gland was found in the
orbital sinus. Also, the in vitro characteristics of the lymphocyte sub
populations discussed in the previous section very closely resemble the
general characteristics of T- and B-cells in the birds, so that immuno-
logically the alligator may be nothing more than a "cold blooded chicken."
If further functional analysis of the lymphoid organs and cell types