Glandular epithelia can be classified based on several criteria:
Number of Cells: Glands can be unicellular (e.g., goblet cells) or multicellular (e.g., salivary glands). Method of Secretion: Glands can be merocrine (secretion by exocytosis), apocrine (partial cell loss), or holocrine (entire cell disintegration). Nature of Secretion: Glands can produce serous (watery, enzyme-rich fluid), mucous (viscous, glycoprotein-rich fluid), or mixed secretions.
