However, the structure of lymphatic tissues vary according to the particular type of lymphatic tissue or organ they form a part of - (a), (b) or (c) above, and possibly also it's location in the body-especially in the case of (c) Lymph (Fluid).
The exposition is the portion of a story that introduces important background information to the audience; for example, information about the setting, events occurring before the main plot, characters' back stories, etc.
A subplot is a secondary plot or storyline that coexists with the main story. Subplots add depth and complexity to stories and thereby increase the tension, which is a state of increased interest and uncertainty about the events in the story.