Histophysiological Appraisal of the Testicular Functions in a Sub-Tropical Psittacine Bird, Psittacula krameri, in Relation to Annual Climatological Variables

Abstract

Annual testicular events in free-living Roseringed Parakeets were studied in relation to climatological variables over three consecutive years. Functional status of the testis was determined from paired testicular weight, seminiferous tubular diameter, spermatogenetic index, Leydig cell nuclear diameter and quantity of total testicular cholesterol. Based on these analysis the annual testicular cycle was divided into five different phases, namely regenerative or preparatory phase (May-August; resting spermatogonia present in the regressed tubules); progressive phase (Sept.-Dec.; recrudescence of gametogenesis occurs); prebreeding phase (Jan.-Feb.; spermiogenesis starts but at slow rate); breeding phase (March; active spermatogenesis occurs); and regressive phase (April-May; degenerative changes occur in the germ cells). A new generation of Leydig cells appeared during the preparatory phase and matured during the progressive phase. Signs of Leydig cell hyperactivity were detectable till the end of the breeding phase. However, statistical analysis failed to identify any environmental component that may have induced seasonal testicular maturation in free-living Roseringed parakeets.