I. The pre-granulomatous stage—mini size, early inflammation (stage a) |
a. Minimal disorganized aggregation of immune cells |
b. No fibroblasts or extracellular matrix, no collagen fibers |
c. Few eggs deposited |
II. The granulomatous stages |
(1) Early stage—small size, acute inflammation (stage b) |
a. Infiltration of organized immune cells including monocytes, eosinophils, etc., around eggs |
b. No fibroblasts or collagen fibers, with few or without extracellular matrix |
c. Many eggs deposited |
Note: Stage b1: several organized immune cell infiltration; stage b2: many organized immune cell infiltration, without or with few extracellular matrix |
(2) Mature stage—big size, chronic and fibrotic inflammation (stage c) |
a. Clear outer granuloma rim which is composed of a dense population of immune cells |
b. Many recruited fibroblasts and their products including apparent extracellular matrix and collagen fibers inside the granuloma |
c. Live or dead miracidium within the deposited eggs |
(3) Late stage—small size, recovery (stage d) |
Some pigmented macrophage infiltration |
Disintegrated granuloma structure |
Dead and calcified eggs |