Stratum basale is the deepest epidermal layer. It contains melanocytes, i.e. pigment-producing cells.

Onychomycosis refers to the fungal infection of nails. It causes nail abnormalities.

The hypodermis, known as the subcutaneous layer, is a layer beneath the skin. It is not the part of skin. It acts as an energy reserve.

The natural occurrence of Beau's lines indicates aging.

The crescent-shaped area at the base of nail is called the lunula (small moon). It is the visible part of the matrix at the base of the visible nail.

Merkel cells are oval receptor cells found in the skin of vertebrates that are associated with the sense of light touch and discrimination of shapes and textures.

The nerve fibers attach to the root hair in subcutis layer.

Birbeck granules are present in Langerhans cells. Their function is still not certain but they migrate to the periphery of the Langerhans cells and release its contents into the extracellular matrix.

The root of the nail lies at nail sinus, i.e. the base of nail underneath the skin.

Dermis is composed of areolar connective tissue such as collagen with elastin arranged in a diffusely bundled and woven pattern.

Fibrous septae, so called cellulite, may form dimples in the skin. Septae are the structures which separate the lobules of fat cells.

Langerhans cells act as APC on infection with a microbe. Langerhans cells break the allergen into smaller pieces and then migrate from the epidermis into the dermis. They find their way to lymphatic and blood vessels before eventually reaching the lymph nodes. Here they present the allergen to immune cells called lymphocytes.

In reticular layer of dermis, dense irregular connective tissues are found.

The paronychium is the border tissue around the nail.

This is the correct match. In March 2007, Langanin (a protein found in Langerhans cells) was published as natural barrier to HIV-1; Merkel cells were considered to be APUD (Amine Precursor Uptake Decarboxylase ) cells; tyrosinase is required for melanocytes to produce melanin from the amino acid tyrosine; and a sunburn cell is a keratinocyte with a pyknotic nucleus.