Sensory receptors are specialized cellular structures that are closely associated with the nervous system. They convert mechanical, chemical, or electromagnetic signals from the environment into nerve impulses which can be conducted to the spinal cord and brain. These specialized epithelia are most frequently found in association with sweat, salivary, and mammary glands, and help them to secrete. The nomenclature of epithelial tissues classifies them according to the shape of their component cells, whether they are organized in sheets of single-cells or layers of many cells, and by their general functions. Simple epithelium - Cells arranged in a single layer.
Squamous cells are wider than they are tall.
Endothelium - the special term applied to the simple squamous epithelium lining blood vessels. Mesothelium - the special term applied to the simple squamous epithelium lining the thoracic, abdominal, and pericardial cavities. Regularly shaped block-like cells with spherical nuclei. Found on the surface of ovaries and thyroid. The width and height of cuboidal cells are approximately equal.