TABLE 1.

Classification of samples for data analysis

Category	Samples in category	Subcategory	Samples in subcategory
Early (E)	E9–E10	E9–E10	E9–E10
Middle (M)	E10.5–E12	Based on stage	E10.5
			E11
			E11.5
			E12
		Based on tissue	Cochlea (Coch)
			Vestibular organ (V)
Late (L)	E12.5–E15	Based on stage	E12.5
			E13
			E13.5
			E14
			E14.5
			E15
		Based on tissue	Cochlea (C)
			Utricle (U)
			Saccule (S)

Samples were assigned to three categories (early, middle, and late) on the basis of how many individual IE substructures at a particular developmental stage could be distinguished and separated from one another. Each category was then divided into subcategories on the basis of tissue type and developmental stage. Category E had only one subcategory consisting of arrays from E9 to E10. The M category had six subcategories (four based on stage and two based on tissue type). The L category had nine (six based on stage and three on tissue type).