To observe collagen fibers, samples can be stained with Masson trichrome (MT), Elastica van Gieson (EVG), or Elastica Masson (E-M); however, distinction between collagen fiber types I and III is not possible with this method. In drug discovery research, quantitative evaluation of the collagen fibers is required, so it is necessary to be able to distinguish between collagen fiber typesⅠand III. Researchers in this field are turning their attention to polarized light observation of collagen fibers stained with Picrosirius Red because this method allows the required distinction between the two fiber types.
Problems with Polarized Light Observation of Collagen Fibers Stained with Picrosirius Red
In this method, collagen fibers are identified by interference color, so daylight white is indispensable as an illumination color, and light intensity adjustment is also required for visual observation. In drug discovery research, collagen fibers containing polarization components should be selectively detected against a dark background.
In polarized light observation, thick fibrous collagen type I appears as bright yellow to orange, while thin collagen type III containing reticular fiber appears green. A commonly used halogen lamp is dimmable by using a ND filter or controlling the voltage. In the former case, however, dimming can only be done in a stepwise fashion (4 steps) meaning that fine control is impossible. In the latter case, the collagen fiber type III in the interference color of green cannot be identified because the color component of the lamp in yellow to orange is stronger than that of green under the low intensity light. This effect is demonstrated in the spectral characteristics below.
>> Download the full Application Note as PDF
Newsletters
Receive the latest pathology news, personalities, education, and career development – weekly to your inbox.
