Exocrine glands are classified as merocrine, apocrine, or holocrine based on how they secrete their glandular products. Cells of merocrine glands, such as salivary gland cells, release their products in secretory vesicles via exocytosis while the cells remain intact and prepare for additional secretions. Apocrine gland cells, such as those in the axillary sweat glands, accumulate their secretory products right below the surface. When the apex of the cell pinches off, the secretory granules are released together with a small amount of cytoplasm. The cells then regrow and repair their apices before further product release. In holocrine glands, such as sebaceous glands of the skin, superficial epithelial cells become packed with secretory vesicles. When the cell bursts, the product is released. The continuous division of underlying layers of stem cells replaces the ruptured cells.