The blood vascular architecture of the extra-adrenal chromaffin body in the adult rat: a scanning electron microscopic study of corrosion casts.

A well developed extra-adrenal chromaffin body with an axis of 200-400 micron was found in seven out of thirty adult male Wistar rats under a stereomicroscope. All seven bodies were located between the left and right kidneys. Blood vascular beds of the five bodies were reproduced with a methacrylate casting medium and observed with a scanning electron microscope. It was revealed that the extra-adrenal chromaffin body contained remarkedly numerous capillaries, which anastomosed with each other to form a conglomerated network. The blood capillaries were of small and uniform caliber and did not represent swollen sinusoids as in the adrenal medulla. The capillary network was denser than that in the adrenal medulla and had no direct vascular linkage with the adrenal cortex or an extra-adrenal cortical body. Histological examination of the two bodies treated with dichromate containing fixatives confirmed that they mainly consisted of chromaffin cells. These findings suggest that in the rat, extra-adrenal chromaffin bodies survive throughout life, actively producing catecholamines.