Dermal collagen fiber data for Fiber Classification by ResNet

Type I collagen is a major component of the dermis and is formed by dermal fibroblasts. The development of dermal collagen structures has not been fully elucidated despite the major presence and importance of the dermis. This Lack of understanding is due in part to the opacity of mammalian skin and it has been an obstacle to cosmetic and medical developments. We succeeded in revealing the process of dermal collagen formation using the highly transparent skin of the axolotl and fluorescent collagen probes. We clarified that epidermal cells, not dermal fibroblasts, primarily contribute to dermal collagen formation. Fibroblasts play a role in modifying the collagen fibers already built by keratinocytes. We confirmed that collagen production by keratinocytes is a widely conserved mechanism in other model organisms. Our findings demand the current consensus about dermal collagen formation to change and lead to innovations in cosmetology and skin medication.

Methods
For dimension reduction of collagen image data, we used 484 collagen images from the confocal images in axolotl dorsal skin for the analysis and adopted ResNet50 with ImageNet-pretrained weights (ResNet50_Weights.IMAGENET1K_V2 from the torchvision library) for feature extraction. We extracted image features from the last global average pooling layer. Then, linear PCA was applied to the 2048-dimensional feature vectors. We performed no training of the neural network with our data; hence, the feature extraction was agnostic on which developmental stages the images came from.