What is the fine-grained topic of the following text: The cell bodies and syncytial layer of the tegument exhibit two types of vesicles, one with fibrous contents and one with electron-dense contents; these were analysed using two cytochemical tests, the E-PTA and alcian blue methods, used for the first time on monogeneans. Only return the topic.
Cytochemical analysis of cell bodies and tegument vesicles in monogeneans.