Serous Membrane
Visceral and parietal division, approximately equal surface area. Each is 1 layer of mesothelial cells, basement membrane, connective tissue, microvessels and lymphatics

Mesothelial Cells
Single layer, pleomorphic. Surface microvilli, more dense on visceral side of pleura

Opening between cells, 2-12 um, only on the parietal surface. The usual exits into lymphatic lacunae for liquid, protein, and cells

Blood Supply
Some controversy. Human visceral pleura supplied by systemic bronchial vessels, drain through fairly large capillaries to pulmonary veins. Parietal blood from adjacent chest wall, drainage to bronchial veins; diaphragmatic pleura supply from nearby arteries, drainage to inferior vena cava and brachiocephalic trunk

More dense lower and toward the mediastinum. Drainage toward hilum either via lung or pleura itself. Stomata lead to lacunae which form valves. Drain to mediastinum via intercostal route depending on origin. Visceral pleural drainage to middle mediastinal nodes or posterior (lower lobes)