Figure 3From: Microneedle pretreatment enhances the percutaneous permeation of hydrophilic compounds with high melting points Microneedle treatment. Light microscopic images of bovine skin treated with microneedles of 200 μm (A) and 300 μm (B) needle lengths after topical administration of methylene blue solution for 6 hours; the arrows show the punctured areas with methylene blue penetration into deeper skin layers. C and D show histological images of perforated skin samples (C: 200 μm, D: 300 μm) after administration of methylene blue on the microneedle pretreated skin samples; the arrows show the punctured areas with methylene blue penetration into deeper skin layers. The bars represent 500 μm.Back to article page