Atlas of plant and animal histology

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Virtual microscopy


Image: leaf of a camellia stained with safranin / Alcian blue.

Epidermis: it is the outermost layer of the leaf. The epidermis is a layer of cells with thin cell walls.

Parenchyma: this tissue forms most of the inner part of the leaf. It is divided into palisade and spongy parenchyma, and altogether is known as mesophyll. The parenchyma cells are large, with thin cell walls and contains many chloroplasts.

Palisade parenchyma: it is the part of the mesophyll with cells tightly packaged with their major axis perpendicularly to the epidermal surface. Palisade parenchyma show very small extracellular spaces.

Spongy parenchyma: it is the part of the mesophyll that shows many and large intercellular spaces. The spongy parenchyma may be more or less developed depending on the thickness of the leaf. It forms large extracellular spaces below the stomata.

Sclereids: they are a type of cell that appear as single cells scattered through the mesophyll. In this case, sclereids are astrosclereids because they show a star-like form. They show a very thick secondary wall stained in red that leaves very little inner space.

Sclerenchyma: in the vascular bundle of the leaf vein, a sheath of sclerenchyma fibers can be observed. They show cell walls stained in red. The main function of sclerenchyma fibers is to provide mechanical support.

Phloema: it is the vascular tissue specialized in transporting organic molecules produced during photosynthesis. Phloem is made up of small cells with thin cells walls stained in blue.

Xylem: it is the vascular tissue specialized in bringing water and minerals for photosynthesis. The xylem consists of cells with variable size that show cell walls stained in red because they are lignified.