The holocrine gland is characterized by the mechanism through which it releases its secretion. In holocrine glands, the entire cell undergoes disintegration and ruptures to release its contents. This means that the secretory product is comprised of the cellular material itself, as well as the substance that the gland produces. An example of a holocrine gland in the human body is the sebaceous gland, which secretes sebum for skin lubrication.
In contrast, merocrine glands secrete their products through exocytosis without any damage to the cell structure, allowing the cells to remain intact. Apocrine glands, on the other hand, release their secretions by a process that involves the shedding of a portion of the cell (apical part), but the whole cell does not disintegrate. Endocrine glands, while they also release secretions, do so directly into the bloodstream without the necessity of disintegrating the cells. These distinctions clarify why the holocrine gland is correctly identified as the type that discharges its secretion along with the entire disintegration of the cell.