Autologous tissue patch rich in stem cells created in the subcutaneous tissue

Figure 4 Histology of the de novo tissue patch at various times after implantation of the inert body in the subcutaneous space (trichrome stained). Black arrows show the inner aspect of the tissue in contact with the inert body. A: The tissue at day 4 showed an inner layer consisting of one or two-cell thick mononuclear cells but devoid of blood vessels. The medial layer was 4-6 cell thick and contained microvessels (red arrows) and fibrous matrix (blue stain). The outer layer consisted of loose connective tissue; B: At day 7-14 the tissue was histologically better organized into inner, medial and outer layers. The inner layer in contact with the inert material was thicker, consisted of mononuclear cells but devoid of extracellular matrix and blood vessels. The medial layer was thicker than at day 4, consisting of fibroblastic cells, rich network of microvessels (shown in Figure 5) and extracellular matrix. The outer layer remained loose but contained large blood vessels (white arrows); C: Between day 35-42 the granulation tissue appeared slightly thicker and more compact than day 7-14 tissue with the inner layer becoming less distinguished than at day 7-14 and merging with the medial layer. Also, this layer showed reduced number of blood vessels and increased amounts of extracellular matrix arranged in parallel sheets. The outer layer remained unchanged.