Acting since birth (spermatogenic onset) T3 accelerated seminal tubule maturation and spermatogonial development with stimulation of both cell degeneration and proliferation Continuously high T3 level (>/=12-fold increase) since birth (spermatogenic onset) normalised seminal tubule growth with stimulation of both cell degeneration and proliferation, with breakdown of Sertoli-germ cell junctions (toxic influence ), tubule growth inhibition and its distention SUMMARY of RESULTS