part of exocrine system exocrine gland A gland that secretes products (excluding hormones and other chemical messengers) into ducts (duct glands) which lead directly into the external environment. Typical exocrine glands include sweat glands, salivary glands, mammary glands, stomach, liver, pancreas FMA:9596 MESH:D005088 NCIT:C12712 UMLS:C0015282 gland