MICROANATOMY

Detailed explanation-1: -Simple squamous epithelium lines air sac or alveoli. These squamous epithelial cells are permeable and allow the oxygen from the air to enter the blood in the capillaries of the lung, So, the correct answer is option ‘Squamous epithelium’.

Detailed explanation-2: -Simple squamous epithelia are found lining the cavities of the body including the pericardial, pleural, and peritoneal cavities, or in areas where passive diffusion occurs, such as glomeruli in the kidney and alveoli in the respiratory tract.

Detailed explanation-3: -Simple squamous epithelium lining the alveoli in the lungs allows the gas exchange between the alveoli and the blood vessels while also forming a barrier between the outside and the internal body fluids.