PLG (50:50; lot number LP-353; average MWt 15 kDa; IV 0.15–0.25 dL/g) and PEG (average MWt 6 kDa) were purchased from Lakeshore Biomaterials (Birmingham, AL) and Acros Organics (Morris Plains, NJ), respectively. Polyvinyl alcohol (PVA; 87%–89% hydrolyzed; MWt 31–50 kDa), mannitol, Nile Red, and type 2 mucin from porcine stomach were obtained from Sigma Chemical (St. Louis, MO). Methylene chloride and acetone in high purity were purchased from Fisher Scientific (Pittsburgh, PA). Hanks buffered saline solution (HBSS) was obtained from Mediatech (Manassas, VA). Optimal cutting temperature (OCT) compounds, generally used as embedding media for frozen tissue specimens, were obtained from Sakura Finetek USA (Torrance, CA) and used as the microparticle embedding media for cryosectioning. Proparacaine HCl (0.5% ophthalmic solution) was purchased from Bausch & Lomb (Tampa, FL). Anesthetics for subcutaneous injection to the rabbits (ketamine, xylazine, and acepromazine) were obtained from Fort Dodge Animal Health (Fort Dodge, IA), Lloyd (Shenandoah, IA), and Boehringer Ingelheim (St. Joseph, MO), respectively.