Histological characteristics of the development of aortic baroreflex afferents in rats: preliminary report.

Abstract

To elucidate the postnatal development of aortic baroreflex afferents, we examine the cross sections of the left aortic nerves (ANs) in rat neonates with light- and electron-microscopy. We took the pictures of transverse cross sections of left ANs and made these montages (approx. x13K at final magnification) after the observation of semi-thin sections for light microscopy. The number of unmyelinated fibers of left ANs was 258, 594, 454 or 841 in the 9 days old group (n=4), and that in the 25 days old group (n=5) was 87,187, 212, 407 or 424, respectively. These results show that there is a lot of unmyelinated fiber in the ANs in the early stage of postnatal growth, suggesting that these fibers seem to be eliminated partly in accordance with the functional development of baroreflex in the rat. [J Physiol Sci. 2008;58 Suppl:S181]