Tissue distribution of the laminin β1 and β2 chain during embryonic and fetal human development

Here, the authors investigated the tissue distribution of the laminin b1 and b2 chains on the protein level in various developing embryonic and fetal human organs between gestational weeks 8 and 12. The laminin b1 chain was ubiquitously expressed in the basement membrane zones of the brain, ganglia, blood vessels, liver, kidney, skin, pancreas, intestine, heart and skeletal system. Furthermore, the laminin b2 chain was present in the basement membrane zones of the brain, ganglia, skin, heart, and skeletal system. The findings of this study support and expand upon the theory that these two laminin chains are important during human development. In cartilage, the laminin b1 chain was expressed from gw 10 onwards but not during gw 8 and 9, whereas the detection of the laminin b2 chain was limited to gw 8 and 9. This indicates a developmental switch in the laminin b chain and suggests that the laminin b1 chain does not play a role in human cartilage development until the fetal stage. In human fetal cartilage (gw 17 and 24), a strong pericellular immunohistochemical reaction for laminin 111 was shown. In embryo chick sternum and mouse limb bud, laminin b1 and b2 chains are present in the cytoplasm of chondrocytes.