Ultrastructure of splenic white pulp of the turtle, Mauremys caspica.

The ultrastructure of splenic tissue of non-immunized turtles, Mauremys cas[pica, shows two areas, namely, the white pulp which is lymphoid in nature, and the red pulp which is formed by cell cords and sinusoids, Between both areas there is always a marginal zone with gaps through which cells leak. In the white pulp, there are two blood vessel types; one with muscled walls, and the other showing thinner walls sheathed by reticular cells, Reticular cells constitute a network where there occur dendritic macrophages, lymphoblasts and small and medium lymphocytes. Mature plasma cells are scare in the white pulp.