First of all, an optical drive can be a CD, DVD, or BluRay drive. The button isn't invisible, it's just hidden in plain site by design. The previous pictures show its location, but here is one more. This is a picture of the top of a 660 showing 2 drives.
What is difference between an osteon and osteocyte? An osteon is the functional unit of cortical bone. Osteons contain osteocytes, which are cells that produce bone matrix.
Overview. The Extracellular Matrix (ECM) is a complex structural system that supports and protects animal cells, and is often referred to as the connective tissue. The meshlike structure of the ECM is composed of mainly from collagen proteins connected to glycoprotein.he Extracellular Matrix (ECM) is a complex structural system that supports and protects animal cells, and is often referred to as the connective tissue. The meshlike structure of the ECM is composed of mainly from collagen proteins connected to glycoprotein.