[Solved] Naked mole rats are highly in breed having an 'r' of: A) 0.61 B) 0.71 C) 0.81 D) 0.91 Primary Capillary Networks: The initial network of capillaries where exchange of gases, nutrients, and wastes occurs between the blood and surrounding tissues. Venous Sinuses: Large veins found in the brain and heart that collect deoxygenated blood to return it to the right atrium of the heart. Capillary Wall: The thin, permeable layer of tissue that forms the boundary of capillaries, allowing for the exchange of gases, nutrients, and waste between blood and tissues. Endothelium: The thin layer of cells that lines the interior surface of blood vessels and lymphatic vessels.