There are many exocrine glands they secrete their products (excluding hormones and other chemical messengers) into ducts which lead directly into the external environment. They are the counterparts to endocrine glands, which secrete their products directly into the bloodstream or release hormones that affect only target cells nearby the release site.
secretions of some exocrine glands are as follows;
Serous cells secrete proteins, often enzymes. Examples include chief cells and Paneth cellsMucous cells secrete mucus. Examples include Brunner's glands, esophageal glands, and pyloric glandsMixed glands secrete both protein and mucus. Examples include the salivary glands, although parotid gland is predominantly serous, the sublingual gland is predominantly mucous and the submandibular gland is both serous and mucous.