Hyaluronic acid is used as a dermal filler in cosmetic surgery. Those blood vessels provide nourishment and waste removal for both dermal and epidermal cells. This is due to atrophy of the subcutaneous tissue and dermal fibrosis. The biopsy should include the epidermal, dermal, and subcutaneous layers of the skin. The dermis is covered with separate dermal placoid scales. In primary cutaneous T cell lymphoma, blood and dermal eosinophilia are often seen. There are two different kinds of melasma, epidermal and dermal. Abnormal healing and dermal inflammation create the scar. In modern agnathans, the body is covered in skin, with neither dermal or epidermal scales. Vinyl chloride can have acute dermal and ocular effects. Chemically lightened skin is also more highly susceptible to sun damage and dermal infection. The ground tissue of plants includes all tissues that are neither dermal nor vascular. A skin biopsy may be taken to determine capillaritis of dermal vessels. The three tissue types are ground, vascular, and dermal. Acute toxicity looks at lethal effects following oral, dermal or inhalation exposure.