Final answer:
The ruffled border of osteoclasts, which aids in bone resorption, is formed on the side of the plasma membrane that faces the bone. This increases the area available for digestive enzymes and acidification, essential for breaking down bone tissue.
Step-by-step explanation:
The question asks on which side of osteoclasts does the plasma membrane form a ruffled border. Osteoclasts are bone-resorbing cells, and they form a ruffled border on the side of the cell that is facing the bone. These cells are critical in the process of bone resorption, where they break down the bone tissue. The ruffled border increases the surface area for secretion of digestive enzymes and for the acidification of the bone microenvironment, which dissolves the inorganic minerals and degrades the organic matrix.
The ruffled border is formed by deep infoldings of the plasma membrane and is where the osteoclast attaches to the bone, creating a sealed zone. Within this sealed zone, the osteoclast secretes hydrochloric acid and enzymes like cathepsin K to digest the bone matrix. In contrast, on the opposite side of where the ruffled border is formed, the plasma membrane will be smoother and known as the basolateral side, which interfaces with other cells and bodily fluids.