In the leaves of rice (Oryza sativa), stomatal initials arose from two asymmetric cell divisions and a symmetric division. Guard mother cells (GMCs) and long cells in stomatal files (LCSs) were formed through the first asymmetric division of the precursor cell of GMCs. Subsidiary cells (SCs) were produced by the second asymmetric division of subsidiary mother cells or LCSs. Following SC formation, GMCs divided once symmetrically to generate guard cells and then differentiated terminally to form mature stomata. The developmental patterns of long cells, prickle hairs and short cells (phellem cells and silica cells) were also examined. Interestingly, we found that the different developmental stages of stomata and epidermal cells occurred in the similar location of immature leaves of the same phyllotaxis. In addition, two spacing patterns ("one stoma, one long cell" and "one short cell row") probably exist in rice leaves.

This study describes how three-dimensional (3D) human skin tissue is reconstructed, and provides digital anatomical data for the physiological structure of human skin tissue based on large-scale thin serial sections. Human skin samples embedded in paraffin were cut serially into thin sections and then stained with hematoxylin-eosin. Images of serial sections obtained from lighting microscopy were scanned and aligned by the scale-invariant feature transform algorithm. 3D reconstruction of the skin tissue was generated using Mimics software. Fibre content, porosity, average pore diameter and specific surface area of dermis were analysed using the ImageJ analysis system. The root mean square error and mutual information based on the scale-invariant feature transform algorithm registration were significantly greater than those based on the manual registration. Fibre distribution gradually decreased from top to bottom; while porosity showed an opposite trend with irregular average pore diameter distribution. A specific surface area of the dermis showed a 'V' shape trend. Our data suggested that 3D reconstruction of human skin tissue based on large-scale serial sections could be a valuable tool for providing a highly accurate histological structure for analysis of skin tissue. Moreover, this technology could be utilized to produce tissue-engineered skin via a 3D bioprinter in the future.

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