17 Trajectory Controls (tracked mice); 5 Untreated; 4 Flight Backup; 3 Environmental
(K02) Controls; 3 Implanted Controls
Hemorrhage had occurred in the middle ear cavity of mice subjected to increased
oxygen partial pressure in K02 tests during hardware verification, and hemorrhage
and/or exudative materials were noted in all flight and flight backup mice.
The main objective was to determine if hemorrhagic materials in the middle ear
cavities and the cellular reaction thereto differed in any way in the flight
animals compared to the flight backup controls. This study was also to investigate
if the otoconial apparatus of mice flown on Apollo 17 had been altered as a
result of weightlessness, and to determine whether any structures of the inner
ear had been injured by cosmic ray particles.
Two canisters were prepared with five pocket mice in each. One canister
was used in the flight experiment; the other was used as a ground control, undergoing
the same stress as the flight canister. In addition, several control mice exposed
to increased oxygen partial pressure in K02 tests during hardware verification
were also examined. Examinations were conducted at a rostral level of the middle
ear. Heads were decalcified, embedded, serially sectioned to 10 µm, and stained;
the second section (of eight) on every fourth slide throughout the middle ear
cavity was examined. Criteria were established to evaluate the findings from
the middle ear cavity based on histological features of linings in untreated
animals. To sample leukocytic response quantitatively in a manner that would
introduce the least bias, the procedure was adopted to start counting air cells
that contained hemorrhagic materials (i.e. plasma, protein material, blood clots,
unidentified remnants of exudative material).
No evidence was found that the inner ear had been damaged, although poor fixation
precluded a detailed study. The distribution of hemorrhagic materials in flight
and flight backup middle ear cavities differed from animal to animal in both
groups. Extraneous factors that might be held accountable for the occur- rence
or nonoccurrence of hemorrhage would include the amount of food in the mouth
or being swallowed at the of pressure excursion and the degree of respon- siveness
of the mouse to autoinflation of the middle ear cavity. Either the active feeding
state or torpor could be expected to influence the patency of the nares and
Eustachian tubes at the time of pressure excursion. There was no increase in
leukocyte population along the paths of the 23 cosmic ray particles registered
as traversing the middle ear in the dosimeters. The increased exudation and
the greater response by leukocytes in the flight mice may have been causally
related to the lesions found in their olfactory mucosa, but there was no data
in support of this possibility.
Haymaker, W. et al.: The Effects of Cosmic Particle Radiation on Pocket Mice
Aboard Apollo XVII: X. Results of Ear Examination. Aviation, Space, and Environmental
Medicine, vol. 46, no. 4, sec. II, 1975, pp. 582-606.
Leon, H.A. et al.: The Effects of Cosmic Particle Radiation on Pocket Mice
Aboard Apollo XVII: V. Preflight Studies on Tolerance of Pocket Mice to Oxygen
and Heat: Part I. Physiological Studies. Aviation, Space, and Environmental
Medicine, vol. 46, no. 4, sec. II, 1975, pp. 514-520.¥
Lindberg, R.G. et al.: The Effects of Cosmic Particle Radiation on Pocket Mice
Aboard Apollo XVII: II. Characteristics and Tolerances of the Pocket Mouse and
Incidence of Disease. Aviation, Space, and Environmental Medicine, vol. 46,
no. 4, sec. II, 1975, pp. 482-493.¥
Look, B.C. et al.: The Effects of Cosmic Particle Radiation on Pocket Mice
Aboard Apollo XVII: IV. Engineering Aspects of the Experiment and Results of
Animal Tests. Aviation, Space, and Environmental Medicine, vol. 46, no. 4, sec.
II, 1975, pp. 500-513.¥
¥ = publication of related ground-based study