Ultrastructural study on a variety of non-neural cells immunoreactive for nerve growth factor receptor in developing...

The occurrence of nerve growth factor receptor (NGFR) immunoreactivity was newly demonstrated in mesenchymal cells of lung bud and lateral palatine processes. Nerve fibers and enclosing Schwann cells with or without immunoreaction were present only in the periphery of the immunoreactive mesenchymal cell aggregation, but were not found within them. The NGFR-immunoreactive cells in immature skeletal muscles were revealed by immunoelectron microscopy to be perimysial cells without myofilament bundles, but not myoblastic cells. NGFR immunoreactivity was detected in noninnervated epithelial cells performing the invagination such as epithelial cells of the renal glomerulus and the lens placode. The immunoreactivity was also expressed in the innermost cells of the theca cell layer of the postnatal ovary and they contained no lipid droplets. In postnatal lymphatic tissues, NGFR-immunoreactive cells were identified as the interdigitating cells which were located in the internodular and deep cortex of the lymph nodes, in the marginal zone of the splenic white pulp, and in the medulla of the thymus. These findings suggest a potentially more widespread involvement of nerve growth factor and NGFR in the program of ontogeny than expected.