Histological cross sections of HSC using 3D culture condition 3D-CC-III; N = 2, n = 3. Upper (A, B, C, D), middle (A′, B′, C′, D′), and lower (A′′, B′′, C′′, D′′) panels (images at different magnifications) showed H&E-stained histological micrographs of HSCs raised for 10 days, 15 days and 20 days at ALI, respectively. The longer the ALI cultivation period, the better a structured stratification of the epidermis from stratum basale to stratum corneum can be recognised (cf. labelling in Fig. 6).