Testicular growth and functional capability after 4-24 weeks of continuous exposure to 11 ATA He-O2

A study of testicular developmental and functional capabilities was made of rats continuously exposed for 4, 8, 12, 16, 20, or 24 weeks to 1 ATA He-O2, 11 ATA He-O2, or ambient pressure air environmental conditions. Other groups of rats were exposed for 24 sequential weeks to the same three sets of environmental conditions with brief interruptions for decompression and recompression at the end of each 4 weeks. The rats were comfortably housed and adequately fed in accord with earlier investigations. Visual observations of the testes at the time of slaughter, dry matter content of the testes, and histological examinations--all revealed normal growth and active spermatid formation from healthy germinal epithelia in all semeniferous tubules. The stress of hyperbaria or of helium to 11 ATA did not inhibit or destroy male germinal epithelial functional capabilities.