In glandular epithelial tissue, what is the key difference between endocrine glands and exocrine glands?

• A. Endocrine glands are always multicellular, whereas exocrine glands are always unicellular.
• B. Endocrine glands secrete only mucus, whereas exocrine glands secrete only enzymes.
• C. Endocrine glands secrete hormones into the interstitial fluid and then the bloodstream, whereas exocrine glands secrete their products through ducts onto an epithelial surface or into a lumen.
• D. Endocrine glands release their secretions through ducts to the body surface, whereas exocrine glands release hormones directly into the blood.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the basic function of glandular epithelial tissue, which is specialized for secretion of substances such as hormones, enzymes, or mucus.
2. Step 2: Identify the two main types of glands in glandular epithelium: endocrine glands and exocrine glands.
3. Step 3: Recognize that endocrine glands secrete their products (hormones) directly into the interstitial fluid, from where these hormones enter the bloodstream to reach target organs.
4. Step 4: Understand that exocrine glands secrete their products through ducts that lead either to an epithelial surface (such as skin) or into a lumen (such as the digestive tract), rather than directly into the blood.
5. Step 5: Conclude that the key difference lies in the mode and destination of secretion: endocrine glands are ductless and release hormones into the blood, while exocrine glands have ducts and release their secretions onto surfaces or into cavities.