Animal Tissues - Epithelial Tissue

Epithelial tissue forms a continuous protective and lining layer over body surfaces and cavities, and NCERT classifies simple epithelium by cell shape into squamous, cuboidal and columnar types. Ciliated columnar epithelium consists of tall, pillar-like cells whose free surfaces bear motile cilia; the coordinated beating of these cilia moves mucus, particles or eggs in a definite direction. In the bronchioles this clears trapped dust and mucus, while in the fallopian tubes it propels the released ovum toward the uterus. Simple squamous epithelium is a thin, flat single layer suited for diffusion across walls of alveoli and blood vessels, so it cannot perform ciliary transport. Compound epithelium is multilayered and chiefly protective, found in skin and buccal cavity, and lacks the transport-oriented ciliated arrangement. Glandular cuboidal epithelium is specialised for secretion in ducts and glands, not for directional movement of material. As stated in NCERT Class 11, Chapter 7 (Structural Organisation in Animals), ciliated epithelium occurs where substances are moved across the epithelial surface. A consistency check confirms that both named organs require directional luminal movement, matching only ciliated columnar epithelium.