title: Histologic changes in the adrenal cortex from young rats following spaceflight.
abstract: BACKGROUND
  Potential stresses associated with spaceflight include microgravity, acceleration and deceleration forces, a crowded environment and re-adaptation to normal gravity after landing.
  
  
  OBJECTIVE
  We hypothesized that spaceflight would result in histological changes in the adrenal glands of young rats.
  
  
  METHODS
  Six week old male rats were group-housed in an Animal Enclosure Module (AEM) for a 17 d shuttle flight (STS-78). Ground-based controls included a baseline group, an AEM-housed group and a vivarium group. Adrenal glands were collected from 4-6 hours after flight, fixed, embedded in plastic and sections prepared for light microscopy.
  
  
  RESULTS
  The adrenals from the baseline and vivarium groups had normal histological features. Some changes in the adrenal cortices from the ground-based AEM group included greater parenchymal cord-like formation. The adrenal weights and width of the zona fasciculata were greater in the flight group than the controls. There were also increased parenchymal cord-like formation with better demarcation of the vascular sinusoids in the zona reticularis and zona fasciculata, greater depletion of cytoplasmic lipid vacuoles, and an increased nuclear volume of the cells in the zona fasciculata when compared with the controls.
  
  
  CONCLUSIONS
  The adrenal changes in the ground-based AEM animals may be attributed to the confined space in the AEM. The adrenal enlargement and the histological changes observed in the flight animals may be attributed to spaceflight and possibly re-entry in addition to possible confinement stress in the AEM.
authors.affiliation: Department of Radiology, School of Medicine, University of Utah, Salt Lake City 84108-1218, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Howe
authors.forename: T J
authors.initials: TJ
authors.lastname: Wronski
authors.forename: B P
authors.initials: BP
authors.lastname: Halloran
authors.forename: S C
authors.initials: SC
authors.lastname: Miller
mesh_terms: D000302:Adrenal Cortex / Q000473:pathology*; D000704:Analysis of Variance; D000818:Animals; D003441:Crowding / Q000503:physiopathology; D005118:Extraterrestrial Environment; D006799:Housing, Animal; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013026:Space Flight; D013312:Stress, Physiological / Q000209:etiology / Q000473:pathology