Image: leaf of a pine stained with safranin / Alcian blue.
Epidermis: it is the outermost layer of the leaf. The epidermal cells show thick cell wall stained in red.
Stomata: they are epidermal structures with cell (occlusive cells) forming a pore for the exchange of gases and water with the environment. In this case, stomata are under the surface of the epidermis.
Hypodermis: it is a layer of two or three rows of cells with thick cells walls. The hypodermis are schlerenchyma.
Mesophyll: it is the parenchyma tissue found between the hypodermis and the endodermis. It is photosynthesizing parenchyma with cells tightly packaged and very few intercellular spaces.
Endodermis: it is the cell layer underneath the mesophyll. It is a single cell layer with cells showing a slight red color in their lateral cell walls. This color corresponds to the Casparian strip, a cell wall thickening that prevent the water to cross through the intercellular spaces.
Transfussion tissue: it is the tissue found between the endodermis and the vascular tissues. Transfusion tissue is made up of parenchyma and sclerids cells. The function of this tissue is transporting substances and water from the mesophyll to the vascular bundles.
Phloem: it is the vascular tissue specialized in the uptake and transport the photosynthesized substances. The phloem is formed of small cells with thin cell wall stained in blue.
Xylem: es el tejido vascular especializado en llevar agua y minerales a la hoja para la fotosíntesis. El xilema está formado por células de tamaño similar (no hay tráqueas) con paredes celulares teñidas de rojo.
Resiniferous canal: they are glandular structures made up of living secretory cells with an inner lumen where the resin is released to.