Ultrastructural observation of the stratum corneum lipids in hairless mouse epidermis characterized by ruthenium tetroxied fixation / 医学研究生学报

Objectives: To reveal the morphological features of the stratum corneum lipids in hairless mouse epidermis. Methods: Ruthenium tetroxide and osmium tetroxide were compared as post fixative in the preparation of hairless epidermis for transmission electron microscopic examination. Results: Both reagents reveled characteristic membrane coating granules within the granular layer. Whereas, the transformation of the membrane coating granule contents into multiple lamellae at the interface between the granular and cornified layers and the persistence of these lamellae through all levels of the stratum corneum were demonstrated only by ruthenium tetroxide fixation. Conclusions: The distinctive patterning of the intercellular lamellae reflects the nonrandom organization of the stratum corneum lipids. In addition, the ruthenium tetroxide postfixation technique is a useful method in the investigation of the morphological features of the stratum corneum lipids.

The Ultrastructural Changes of Stratum Corneum Lipids after Application of Oleic Acid in Propylene Glycol

BACKGROUND: The stratum corneum presents a significant barrier to transdermal drug delivery. Approaches to improve percutaneous absorption of drugs have included iontophoresis and skin penetration enhancers. Oleic acid has been studied as a skin penetration enhancer for drugs, primarily via its action mainly on the stratum corneum lipid structure. OBJECTIVE: The purpose of this study was to assess the interaction between oleic acid and stratum corneum lipids in vivo. METHODS: Male hairless mice were treated topically with oleic acid. Barrier function was assessed by transepidermal water loss measurement and ultrastructural observation with ruthenium tetroxide (RuO₄) staining. RESULTS: Oleic acid in propylene glycol had a profound effect on epidermal barrier function and was found to be concentration dependent. Moreover, ultrastructural examination with RuO4 post-fixation demonstrated that there were marked alterations in the stratum corneum lipid structure. CONCLUSION: This study provides direct evidence that oleic acid increases the epidermal permeability through a mechanism involving the stratum corneum lipid membrane perturbation via the lacunae formation within the stratum corneum.

Water-Impermeable Occlusion Effect to Intercorneocyte Lipid Layers in Hairless Mice

BACKGROUND: Stratum corneum lipids are arranged as intercellular membrane bilayers presumed to mediate the epidermal permeability barrier. Acute disruption in barrier function will initiate epidermal lipid synthesis, which can be prevented by occlusive membrane. Whereas, occlusion of the skin is known to cause an increased transepidermal water loss(TEWL) and enhanced percutaneous absorption of a variety of compounds. OBJECTIVE: Previous reports with electron microscopy showed varying sizes of lacunae and disorganized intercorneocyte lipids after tape stripping and occlusion with a water impermeable membrane on the murine skin. Hence we studied the effects on stratum corneum lipids and changes in barrier function after occlusion with a water-impermeable membrane. METHODS: Male hairless mice were occluded with one finger of a Latex glove for 24, 48 and 60 hours. After occlusion, TEWL was measured and biopsy specimens were taken from skin. For electron microscopic examination the samples were treated with osmium tetroxide, ruthenitum tetroxide, and tracer (lanthanum) and infrared spectroscopy were also applied. RESULTS: Occlusion with a water-impermeable membrane on the skin induced higher TEWL Values and greater penetration of the tracer than normal. Alterations of the lipid bilayer membrane and lacunae forwation in the stratum corneum interstices were also induced after 24 hours of occlusion. However, the orderness of the lipid alkyl chain in the stratum corneum was not changed until 60 hours of occlusion. CONCLUSION: These studies indicate that the increased epidermal permeability after occlusion may be due to the abnormal lipid membrane structures and volume expansion of existing lacunar domains in the stratum corneum interstices.

The Iontophoresis Effect on Recovery After Acute Epidemal Barrier Disruption / 대한피부과학회지

BACKGROUND: The stratum corneum(SC) has a permeability barrier function which regulates percutaneous absorption by the inhibition of transepidermal water loss(TEWL). Acute mechanical or chemical disruption of the SC induces the impairment of the permeability barrier and so increases the TEWL. The calciumtion has been recognized as an important ion in the recovery of the skin barrier. Recently the main delivery pathway of iontophoretic drugs have been suggested by SC interstices. However the morphologic changes in the SC interstices and calcium after iontophoresis have not been reported. OBJECTIVE: The aim of our study is to confirm that iontophoresis may induce changes in the SC interstices and delay the recovery of the barrier after disruption. MATERIALS AND METHODS: After tape stripping the hairless mouse flank skin, the iontophoresis power supply (6V, 0.6mA) was connected to the patch atiached for 2.5 hours to the stripped site. We checked the THWL 0, 2.5, 6, 12, 18, 24 hours after the tape stripping and obtained specimens and performed osmium tetroxide, ruthenium tetroxide postfixation and calcium ion-capture cytochemical stains for electron microscopic study. RESULTS: The recovery rate of the TEWL in iontophoresis was lower than in the control. This was especially so in the anouse which had received anode iontophoresis for 6 hours. It showed statistically lower TEWL than in the control(p<0.05). Anode iontophoresis induced low calcium in stratum granulosum (SG), but cathode iontophoresis induced high calcium in SC. After iontophoresis there were changes in the SC interstices structures. CONCLUSION: Iontophoresis can induce changes in the SC interstices and calcium distribution and so may help the topical drug delivery system.