BMP-2 and BMP-4 signalling in the developing spinal cord of human and rat embryos.

Bone morphogenetic proteins (BMPs) are multifunctional growth factors implicated in multiple biological events. Studies on mice, chickens and other experimental animals have shown that BMP signalling plays critical role in embryonic development, in particular in the neural patterning. In our study we comparatively evaluated BMP-2 and BMP-4 protein expression in the developing spinal cord of human and rat embryos. The human and rat embryos of Carnegie stages 14, 18 and 20 were embedded in paraffin and cut serially in transversal direction. BMP-2 and BMP-4 were detected by immunohistochemical staining. Spatial and temporal expression pattern of BMP-s during early stages of spinal cord development was similar in human and rat embryos. Higher expression of BMP-s was seen in the dorsal and lower expression in the ventral part of the developing spinal cord both in human and rat embryos. However, temporal difference in the expression of BMPs in the non-neural ectoderm between human and rat embryos was noted. Staining of BMP-s in the non-neural ectoderm adjacent to the developing spinal cord in the human embryos seemed to have a tendency to decrease from earlier to later developmental stages, while in rat embryos there was an opposite tendency.