Endocrine gland is a gland whose secretions (called hormones) are collected by the blood and reach the tissues through the circulation. The hypophysis (pituitary) and the adrenals are examples of endocrine glands. Exocrine gland is a gland whose secretions are released externally through ducts (into the skin, intestinal lumen, mouth, etc.). The sebaceous glands and the salivary glands are examples of exocrine glands.
