From which tissue do glands derive?

• A. Muscle tissue
• B. Nervous tissue
• C. Glandular epithelium
• D. Connective tissue

Answer: (C)

Glands derive from glandular epithelium, a specialized epithelial tissue dedicated to secretion. During development, parts of the epithelial lining invaginate into underlying tissue to form the secretory units (and, in many cases, ducts). This epithelial origin explains why glands are classified with epithelia: their cells are organized with typical epithelial polarity and surface characteristics, but are specialized for producing and releasing substances. Exocrine glands maintain ducts to surfaces, while endocrine glands secrete into the bloodstream; in both cases, the starting tissue is epithelial. In contrast, muscle tissue specializes in contraction, nervous tissue in signaling, and connective tissue provides support and structure, so they are not the source of glands.