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.
Narrative structure is about story and plot: the content of a story and the form used to tell the story. Story refers to the dramatic action as it might be described in chronological order. Plot refers to how the story is told. Story is about trying to determine the key conflicts, main characters, setting and events. Plot is about how, and at what stages, the key conflicts are set up and resolved.