Islands of cartilage and bone at the margin of the carotid bodies of rats.

Islands of mature cartilage or bone were observed in 6 respectively 7 out of 1395 carotid bodies of rats studied. They were found only in spontaneously hypertensive rats of the Okamoto-Aoki stain and situated regularly at the margin of the carotid bodies. The bone islands were bigger than those of cartilage. The presence of such tissue components in the carotid bodies of rats is discussed in connection with the embryology of this peripheral arterial chemoreceptor, especially its mesodermal origin.