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Sperm Production by Chronically Irradiated Bulls¹

Agricultural Research Laboratory, University of Tennessee, Oak Ridge^{2, 3,}

Abstract

Effects Of Fractionated Doses Of Total-Body Gamma-Irradiation At Semi-Weekly Or Weekly Intervals On Sperm Output, Testis Histology And Blood constituents in Mature Hereford Bulls Were Studied. Treatment Groups Were: Group 1, Control; Group 2, So r Semi-Weekly (1100 r Total Dose); Group 3, 100 R Weekly (1100 r Total Dose); And Group 4, 100 R Weekly (600 r Total Dose). Sperm Output Began To Decline 9 Weeks Following The Initial Exposure And All Bulls Were Aspermic By The 16Th Week. Following 10 Weeks Of Aspermia A Gradual Recovery Began. Groups 2 And 3 Were Unilaterally Castrated At 18 And 24 Months And Group 4 At 12 And 18 Months Following The Initial Exposures. During The 5-Week Period Preceding The Final Castration Sperm Production of Groups 2, 3, And 4 Was 28, 57 And 68%, Respectively, Of The Control Level.

Testes of Bulls In Group 3 Had A Higher Percent Of Seminiferous Tubules Producing Sperm Than Did The Testes From Groups 2 And 4. Based On Sperm Production And Histological Data, Two Doses Of 50 R Per Week Were More Deleterious Than A Single Dose Of 100 r Per Week. An Accumulated Dose Of 600 r Was As Deleterious As 1100 R When Both Were Delivered At The Same Rate. Despite Histological Evidence Of Severe Damage To The Seminiferous Epithelium, The Irradiated Bulls Were Producing Sufficient Numbers Of Motile And Morphologically Normal Sperm That It Is Presumed They Would Have Been Fertile.

Hemoglobin, Hematocrit, And Platelet Values Were Not Affected; Leukocyte Numbers Were Depressed For 2 Years Following The Initial Exposure.

¹ This manuscript is published with the permission of the Director of the University of Tennessee Agricultural Experiment Station, Knoxville.

² Operated by the Tennessee Agricultural Experiment Station for the U. S. Atomic Energy Commission under Contract No. AT-40-1-Gen-242.

³ The authors wish to acknowledge the technical Assistance of J. R. Eblen, F. H. Cross and D. Rather and to express appreciation to T. S. Osborne for reading and criticism of this manuscript.