Anatomy of finfish and shellfish

UNIT 1 - Anatomy of Fin Fish

1.5. Skin and Scales
The skin of a fish consists of two layers. The outer layer is epidermis and the inner, the dermis or corium. The epidermis is composed superficially of several layers of flattened, moist epithelial cells. The deepest layers are a zone of active cell growth and multiplication. Here cell multiplication goes on all the time to replace from with in the outermost layers of cells as it is worm off and provide for growth. These epithelial cells from the epidermis are the first to close a surface wound.

The dermal layer of the skin contains blood vessels nerves and cutaneous sense organs and connective tissue. The dermis plays the main role in the formation of sales and related integumantory structure.
Scattered among the flattened cells of the epidermis are numerous openings of the tubular and flask shaped mucous gland cells that extent into the dermis.
These cells secrete the slippery mucus that cover most fishes. The mucus lessons the drag an a fish when it swims through water.
As in other vertebrates, the skin of a fish is the envelope for the body and is the first lines of defense against disease. It also affords protection from, and adjustment to environmental factors that influence life, for it contains sensory receptors tunes to the surroundings of a fish. Further more, the skin has respiratory, excretory and osmoregulatory functions.