Complex sentence: Hardened plates in the exoskeleton are called sclerites, which are subdivisions of the major regions-tergites, sternites and pleurites, for the respective regions tergum, sternum, and pleuron.
Split into simpler sentences: Hardened plates in the exoskeleton are called sclerites. Sclerites that are subdivisions of the major regions are tergites, sternites and pleurites, for the respective regions tergum, sternum and pleuron.