Abstract
It is very important to know the critical pressure which causes a living body to bring about histological damage or destructive metabolism when the hyperbaric effect is studied. Therefore, a histological examination was made on hydrostatic pressure effect on the muscle in the tadpole tail of the bullfrog (Rana catesbiana) by using an animal chamber which is able to compress a liquid from 1 to 500 atmospheric absolute (ATA). More than 200 tadpoles were compressed at the different depth of pressure between 7 and 500 ATA. The results of the experiment may be summarized as follows: (1) The interstices between the muscular fibers are found at above 50 ATA for 10 minutes, and at 500 A TA for 30 seconds. (2) Stiffness is seen at 500 A TA for 60 seconds or over. (3) The “rounding fibers” are often found by exposure to 100 AT A for 10 minutes, and more often found at over 300 ATA. (4) The macroscopic stiffness is due to the histological “rounding fibers”. (5) The damage to the muscle is caused more by decompression than by the compression effect.
