GENERAL HISTOLOGY

Detailed explanation-1: -The numerous permanent circular folds of mucous membrane found in the small intestine especially in the lower part of the duodenum and the jejunum are called plicae circulares. They are covered with small finger-like projections called villi which is covered with microvilli.

Detailed explanation-2: -Microvilli: The cells on the villi are packed full of tiny hairlike structures called microvilli.

Detailed explanation-3: -Circular folds (folds of plicae circulares muscle) are lined with finger-like protrusions called villi, while the surface of the villi is lined with microscopic protrusions called microvilli. All these structures increase the surface area in the small intestine which maximize nutrient absorption.

Detailed explanation-4: -In the small intestine, a 600-fold amplification of the absorptive surface is achieved by structural features, such as the circular folds of Kerckring (plicae circulares), villus-crypt architecture, and microvilli.

Detailed explanation-5: -On the surface of each columnar cell there are about 600 very fine projections called microvilli that further increase the absorptive area of each villus.