Although many investigations about microcirculation of the cochlea have been reported, less knowledge such as blood volume or blood supply of each turn has been obtained. This study was originated to find out dynamic blood supply to each turn of the guinea pig cochlea. Points of study were as follows:
1) Distribution and numbers of the radial arteriole of each turn with the use of India ink.
2) Blood volume determination of each turn with the perfusion of 10% Evan's blue, and the ratio of blood volume and dry weight of each membraneous cochlea.
3) Blood flow speed of each turn indicated by numbers of running leucocytes in radial arteriole for one minute.
The results obtained were as follows:
1) Radial arterioles of 5 to 6 in apex turn, 9 to 13 in 3rd turn, 17 to 22 in 2nd turn and 33 to 40 in 1st turn were observed. The ratios of radial arteriole's numbers of apex, 3rd, 2nd and 1st turn were 1.0, 2.0, 3.6 and 6.7.
2) The ratios of blood volume in apex, 3rd, 2nd and 1st turn were 1.0, 2.2, 6.7 and 16.6. The 1st turn was really rich in blood volume, though which was less than 0.1μl. On the other hand, the dry weights of membraneous cochlea of each turn were 30γ in apex turn, 48γ in 3rd, 62γ in 2nd and 85γ in 1st. The ratios of blood supply per dry weight in apex, 3rd, 2nd and 1st were 1.0, 1.4, 3.2 and 5.9, which were similar to that of radial arteriole in each turn.
3) The mean number of running leucocytes in radial arteriole for one minute was 62 in apex turn, 31 in 3rd, 48 in 2nd and 64 in 1st. The dynamic blood supply in every turn of the cochlea will be considered in consequence of the studies about numbers of radial arteriole, speed of blood flow and blood volume per tissue weight. The ratios of the dynamic blood supply in apex, 3rd, 2nd and 1st turn were 1.0, 0.7, 2, 6 and 5.9. Therefore, it was concluded that the dynamic blood supply of 1st turn was six times higher than that of apex.
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