Which glands are unicellular and perform exocrine secretion without ducts?

• A. Endocrine glands
• B. Multicellular glands
• C. Unicellular glands
• D. Paracrine glands

Answer: (C)

Unicellular glands consist of a single secretory cell nested in an epithelium and release their product directly onto a surface, without forming a duct. This is exocrine secretion, but there is no duct system because the secretory unit is just one cell. A classic example is goblet cells in the intestinal and respiratory mucosa, which secrete mucin that becomes mucus on the surface. This differs from endocrine glands, which release hormones into the bloodstream and are typically organized as multicellular structures without ducts. Multicellular glands usually develop ducts to carry secretions to surfaces or cavities. Paracrine signaling, on the other hand, involves local cell-to-cell communication rather than a true glandular secretion system.