Image: it is a primary stem of a monocot plant, stained with safranin and Alcian blue.
Epidermis: it is the outer layer of the stem. The epidermis consists of small cells with slightly cutinized cell walls.
Sclerenchyma: it is a layer of cells below the epidermis. In this case, the sclerenchyma is replacing the colenchyma as supporting tissue.
Parenchyma: most cortical and medullary regions, as well as those among the vascular bundles, are made up of parenchyma cells. They are large cells with thin primary cell walls.
Vascular parenchyma: a few parenchyma cells are observed among the xylem and phloem cells.
Protoxylem: it is the first functional primary xylem. Protoxylem cells are observed in the vascular bundles as stretched or sometimes broken cells close to the sclerenchyma vascular sheath.
Metaxylem: it is the functional xylem, specialized in transporting water and minerals. In each vascular bundle, metaxylen consists of two large cells with secondary cell walls.
Sclerenchyma in vascular bundles: it consists of sclerenchyma fibers that provides mechanical support to the vascular tissues. The sclerenchyma forms a sheath surrounding the vascular bundle, known as xilary sclerenchyma.
Primary phloem: it is the vascular tissue specialized in transporting photosynthesized molecules. This phloem is largely formed of metaphloem, since the protophloem is squeezed against the vascular sheath, and it is hardly visible.