In your body, you have only two types of bone tissue: cortical and cancellous bone. In this lesson, we will learn about the structure and function of cancellous bone, which plays a crucial role in producing blood cells and stem cells and is the primary tissue affected by osteoporosis.
balaclava (plural balaclavas) 1  A warm cap shielding the neck and head, often made out of wool. ( 2 chiefly Canada) A ski mask with holes for the eyes and, sometimes, the nose and mouth, which may be rolled up and worn like a toque or pulled over the face for greater protection.
The pith helmet (also known as the safari helmet, sun helmet, topee, sola topee, salacot or topi) is a lightweight cloth-covered helmet made of cork or pith, typically pith from the sola, Aeschynomene aspera, an Indian swamp plant, or A. paludosa, or a similar plant.