Lymphatic tissue changes in rats flown on spacelab life sciences-2 . Congdon, C. C., Z. Allebban, L. A. Gibson, A. Kaplansky, K. M. Strickland, T. L. Jago, D. L. Johnson, R. D. Lange, and A. T. Ichiki. University of Tennessee Medical Center at Knoxville, Department of Medical Biology, Knoxville, Tennessee, 37920, U.S.A. and *Institute for Biomedical Problems, Moscow, Russia, 123007
APStracts 2:0453A, 1995.
Thymus, spleen, inguinal lymph node and bone marrow specimens from rats flown on the 14 day Space Life Sciences-2 mission were examined after staining of tissue sections. The primary observation was a transient retrogressive change in lymphatic tissues in the rats within a few hours after landing. There was a diffuse increase in tingible body containing macrophages in the cortex of the thymus, thymus-dependent areas of the spleen white pulp and inguinal lymph node. This was not observed nine days after recovery. The in situ labeling of fragmented DNA strands catalyzed by exogenous terminal deoxynucleotidyl transferase (TdT) with ApoTag reagents (Oncor, Inc., Gaithersburg, MD) inside the tingible body containing macrophages indicated the process was one of apoptosis. No increase in tingible body macrophage activity was noted in thymus and spleen tissue obtained from rats in flight on flight day 13. The reaction to gravitational stress from readaptation to 1G is the most likely explanation of the transient retrogressive change in lymphatic tissues.

Received 25 July 1995; accepted in final form 2 October 1995.
APS Manuscript Number A813-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95