Gender variations in the optical properties of skin in murine animal models

Abstract

Gender is identified as a significant source of variation in optical reflectance measurements on mouse skin, with variation in the thickness of the dermal layer being the key explanatory variable. For three different mouse strains, the thickness values of the epidermis, dermis, and hypodermis layers, as measured by histology, are correlated to optical reflectance measurements collected with elastic scattering spectroscopy (ESS). In all three strains, males are found to have up to a 50% increase in dermal thickness, resulting in increases of up to 80% in reflectance values and higher observed scattering coefficients, as compared to females. Collagen in the dermis is identified as the primary source of these differences due to its strong scattering nature; increased dermal thickness leads to a greater photon path length through the collagen, as compared to other layers, resulting in a larger scattering signal. A related increase in the observed absorption coefficient in females is also observed. These results emphasize the importance of considering gender during experimental design in studies that involve photon interaction with mouse skin. The results also elucidate the significant impact that relatively small thickness changes can have on observed optical measurements in layered tissue.

Comparative evaluation of differential laser-induced perturbation spectroscopy as a technique to discriminate emerging skin pathology

“…13,14 This has been shown to be associated with race, age, sex, air temperature, and even deformation of the tissue when applying the probe. 13,[15][16][17][18][19][20][21] The results of this patient and sampling variability include fluctuations in absolute emission intensity, emission peak shifts, and changes in the scattering and absorption properties of the tissue, among other effects.…”

Implantable, multifunctional, bioresorbable optics

“…The approach was used to calculate the backscattered signal intensity in the presence of the silk MPA reflector. In this simulation, the silk device was postulated to provide 100% reflectivity and to be located at a depth of 0.6 mm under the skin surface with a scattering coefficient of μ s = 12 mm −1 and an absorption coefficient of μ a = 0.01 mm −1 , typical of skin and muscle tissues in the near-infrared wavelength range (650-850 nm) (21), showing a predicted increase in reflected signal in agreement with what is observed experimentally (∼3× reflectivity enhancement) (SI Appendix, Fig. S13).…”

Vascular patterning of subcutaneous mouse fibrosarcomas expressing individual VEGF isoforms can be differentiated using angiographic optical coherence tomography

“…Development of these cell lines has been described previously [16]. Female nude mice were chosen due to their absence of hair, and having slightly thinner dermis/hypodermis skin layers than male nude mice [14]. OCT imaging of each tumor was performed daily, with the mice under isoflurane anesthesia.…”

“…Most notably, OCT offers depth penetration of up to ~1mm within tissue and is capable of extracting depth encoded data such that individual layers of tissue can be visualized at a high resolution. Compared to human skin, which can be many millimeters thick; female CD-1 nude mice generally exhibit superficial tissue layers approximately ~550μm in thickness (~30μm epidermis, ~220μm dermis, ~300μm hypodermis) [14]; thus the superficial vasculature of subcutaneously implanted tumors may be visible and within the field of view of OCT. Speckle-variance OCT (svOCT) can be used to extract volumetric flow information from four-dimensional OCT data sets (X-Y-Z-Time), with multiple data points being collected at each spatial location [15]. This is based on the fact that a fluid pixel will display rapidly evolving temporal variations in the OCT signal (speckle patterns) when compared to solid tissue pixels.…”