0 a layer of cells covering all the surfaces of the body except the interior of blood and lymph vessels
Its surface is at first smooth and shiny, but as necrosis of the tissue elements takes place in the centre, it becomes concave, and in many cases the epithelium is shed, and an ulcer is formed.
The cells composing the columns and filling the alveoli vary with the character of the epithelium in which the cancer originates.
The middle layer, on the contrary, forms nerves and muscles, vessels and connective tissue, and little or no epithelium.
They are distributed through every tissue of the body, except the epidermis and its products, the epithelium, the cartilages, and the substance of the teeth.
Owing to their lower affinity for the epithelium, spermatozoa that become capacitated are released from the storage site.
The apical lamellae and basal invaginations are characteristic features of trematode excretory epithelium and are believed to be concerned with its absorptive capacity.
The cornea is frequently involved, with 353 in this series having multiple small dendritic or stellate lesions and 294 granular deposits under the corneal epithelium.
