Exocrine glands release their secretions through ducts directly onto an epithelial surface, such as skin or mucous membranes. This characteristic is essential for their role in delivering substances like sweat, saliva, or digestive enzymes to specific target areas. In contrast, endocrine glands secrete hormones directly into the bloodstream without ducts. Understanding this distinction is crucial in surgical procedures involving glandular tissue, as damage to exocrine ducts can disrupt normal secretory function and lead to complications such as fistulas or infections. Proper identification and preservation of these ducts are vital during gland excision or reconstruction surgeries.

Reference: Gray's Anatomy, Standring S., 42nd Edition.