results also show a connection between many of the altered genes via their relation to a wide
range of physiologic processes, including stress and immune response (Lebsack 2010).
Space radiation and microgravity effects on regulation of lung tissue
NASA has reported pulmonary abnormalities in crew members on space missions, but changes
in lung tissue have not been fully documented. CBTM-2 evaluated the health effects on the
lungs resulting from increased levels of radiation, inhalation of possible pathogen, and low
oxygen levels. Tissue examination showed profibrosis-like (excess growth of fibrous connective
tissue) changes occurred in flown mice, more abundant collagen accumulation around blood
vessels, and thicker walls compared with lung samples from ground mice. However, no marked
abnormality was found in bronchiolar and alveolar lining. The findings suggest that the flight
mice may have experienced some degree of lung remodeling. Taken together, the data
demonstrate that significant changes can be readily detected shortly after return from
spaceflight in the expression of factors that can adversely affect lung function. The study
concludes that compromised lung function that is due to spaceflight may result from
disturbance of the balance between deposition and breakdown of connective tissue within the
lungs. In the future, investigations should be performed on samples taken during flight, after
long-term missions, and at later time points after landing to fully document the take-off,
residence in space, landing and oxygen availability effects on lung morphology (Tian 2009).
Ovarian follicular and luteal development in the spaceflight mouse
This study aimed to assess changes in the gross morphology of the ovarian tissue from mice
flown on shuttle mission STS-118 and tissues from corresponding control animals. The
experiment consisted of 3 groups of animals: 2 sets of control animals and 1 set of flight
animals (each set contained 12 mice). The results showed that there was a presence of
developing follicles (structures that contain immature eggs) at all stages as well as the presence
of corpora lutea (structure formed after the release of the egg) in all 3 treatment groups
indicating no significant gross morphological changes occur within ovarian tissue when exposed
to spaceflight for 13 days or less. Flight tissue was morphologically indistinguishable from both
ground control and baseline tissue.
Future studies of this nature should consider the stages of the estrous cycle for each mouse
both pre and postflight. This should be confirmed with hormonal data as well as by vaginal
smears. Mice should be housed in as small groups as possible. The scent of male excreta could
be introduced to the environment to circumvent the Lee-Boot effect, where the estrous cycle
of female mice is prolonged or halted in crowded environments or those that lack a male.
Analysis of the ovarian tissue should go beyond gross morphology and should look at indicators
such as capillary density and kit ligand, a signaling molecule important in the formation of eggs,
and expression (Smith 2012).
Effects of spaceflight on the expression of liver proteins in the mouse
The aim was to investigate changes in the profile of major liver proteins of the mouse that
are introduced by conditions associated with spaceflight. Raw data was derived from mass
spectroscopic analyses of formalin-fixed paraffin-embedded tissue sections of liver from mice.