Growth of Spermatogenetic Colonies in the Mouse Testis after Irradiation with Fission Neutrons

• Published in: Radiation research 1982-01, Vol.89 (1), p.150-165
• Main Authors: G. J. M. J. van den Aardweg, de Ruiter-Bootsma, A. L., Kramer, M. F., Davids, J. A. G.
• Format: Article
• Language: English
• Subjects: Animals; Cell growth; Diameters; Epithelium; Fast Neutrons; Irradiation; Male; Mice; Mice, Inbred CBA; Models, Biological; Neutrons; Radiation Dosage; Seminiferous Tubules - pathology; Solar X rays; Spermatogenesis - radiation effects; Spermatogonia; Spermatozoa - physiology; Spermatozoa - radiation effects; Stem cells; Testes; Testis - pathology; Testis - physiopathology; Testis - radiation effects; Time Factors; Whole-Body Irradiation
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3575692

After irradiation, radioresistant stem cells in CBA mouse testes give rise to colonies of spermatogenetic cells, which repopulate the tubules by longitudinal outgrowth. The mode of growth was followed in histological testis sections from 3 to 20 weeks after doses of 100 and 300 rad neutrons by measuring the length of the colonies (1) directly, (2) stereologically, and (3) with use of the repopulation index (RI) method (A. L. de Ruiter-Bootsma, M. F. Kramer, D. G. de Rooij, and J. A. G. Davids, in Biological Effects of Neutron Irradiation, pp. 325-334, IAEA, Vienna, 1974; Radiat. Res. 67, 56-68, (1976)). The direct method showed that the number of colonies present after 300 rad is stable from 4 weeks on. After this dose great variation in individual colony length was found at 4 weeks, and it was even greater at 15 weeks. Once formed, the colonies apparently have intrinsic growth rates which differ widely. From the stereological measurements a total repopulating tubular length $(L_{{\rm r}})$ could be calculated. In the first 6 weeks after 100 rad neutrons the increase in L r is exceeded by tubular shrinkage, caused by cell depletion, resulting in a constant L r. Once cell depletion has finished, L r increases linearly with a growth rate of 6.7 μm/colony/day from 50% of the total tubular length at 6 weeks to 80% at 20 weeks. After a dose of 300 rad neutrons cell depletion finishes within 3 weeks and hence the growth of the colonies is directly reflected in an increase of L r. The colony growth is linear up to 8 weeks with a rate of 33 μm/colony/day. Despite the low number of colonies present, their growth gradually slows over longer postirradiation times. The results of the direct and stereological methods agree very well on L r. In testes where cell depletion has finished, the increase of L r is directly reflected in an increase of the fraction of repopulated tubuli in a testis section (RI). Thus the RI appears to be a valid parameter for L r in the whole period investigated after 300 rad and from 5 weeks on after 100 rad.