Post-mortem size and structure of the human carotid body

The weights of the carotid bodies have been measured in an unselected group of 40 successive cases coming for routine necropsy. Although the mean weight of the carotid bodies was higher in those subjects with emphysema or Pickwickian syndrome, this difference did not reach a level of statistical significance. Nevertheless, in a group of two patients with cor pulmonale and one with the Pickwickian syndrome the mean weight of the carotid bodies was significantly higher than that of the rest. Such observations would be consistent with enlargement of the glomic tissue in response to chronic hypoxia. In addition to these observations there was a significant correlation between the size of the carotid bodies and the weights of the left and right ventricles separately, while there was a substantially higher correlation between the weights of the carotid bodies and the combined weights of the two ventricles. Should such a correlation be determined by a causative link between these two measurements, a new metabolic role of glomic tissue will have to be considered. The histology of the carotid bodies was studied and differential cell counts were carried out in 21 cases. Enlargement of the carotid bodies was not accompanied by any change in the differential cell count, except that in one case with `cor pulmonale' and large carotid bodies areas of hyperplasia showed a predominance of the dark variety of type 1 (chief) cell.

The permeation of non-electrolytes through the single barnacle muscle cell

The rate of movement of non-electrolytes and tritiated water (THO) across the muscle cell membrane of the giant barnacle Balanus nubilus has been studied and permeability coefficient calculated. The rate of permeation is more closely related to the oil-water partition coefficient than to size of the molecule or degree of hydrogen bonding. Calculations based on efflux from an ideal cylinder suggest that the membrane acts as a significant barrier to movement of these molecules. The cell was unable to concentrate dimethyl sulphoxide (DMSO); the steady state was reached at about 60% of the extracellular concentration. The energies of activation for water, urea and DMSO are 7.5, 20.3 and 26.1 kcal/mol. At 4 degrees C the apparent pore size measured with urea, glycerol and DMSO was 3.5 A. At 25 degrees C the apparent pore size for urea and glycerol is unchanged but that for DMSO is 14 A.

Microanatomy of glomic tissue of the pulmonary trunk

Glomic tissue occurs at the bifurcation of the pulmonary trunk. There is controversy as to its derivation, blood supply, and function. It has been regarded as one of the coronary glomera supplied by the intertruncal branch of the left coronary artery. On the other hand, it has been described as the true glomus pulmonale supplied by blood from the pulmonary trunk. The purpose of this article is to draw attention to its existence and to establish its microanatomical structure.