Swelling of intercellular lipid lamellar structure with short repeat distance in hairless mouse stratum corneum as studied by X-ray diffraction.

Lamellar structures of intercellular lipids in stratum corneum of hairless mouse were studied at various water contents by small-angle X-ray diffraction. At room temperature there are at least two lamellar structures, long and short lamellar structures, with repeat distances of 13.6 and around 6 nm, respectively. The long lamellar spacing is almost constant over the water content from 0% w/w to 80% w/w that is consistent with the previously reported results. For the short lamellar structure we found that with increasing the water content the lamellar spacing becomes larger, that is, from 12 to 50% w/w the short lamellar spacing increases from 5.8 to 6.6 nm. In addition to the previously reported result that at the water content of about 20% w/w the X-ray diffraction peak for the long lamellar structure becomes sharp, we found that this is also the case for the short lamellar structure. Below the water content of about 12% w/w the X-ray diffraction peak for the short lamellar structure dies out and conversely above the water content of about 50% w/w it becomes weak and finally merges into the second-order diffraction peak for the long lamellar structure. Considering the matching of the long lamellar spacing that is unchanged with the water content and twice the short lamellar spacing that changes as a function of the water content, it is likely that the swelling of the short lamellar structure plays an important role in the regulation of water stored in stratum corneum.