Morphological and functional variations of leydig cells in testis of the domestic pig during the different biological stages of development

The relationship of morphometrical and androgen receptor evaluations of the main testicular interstitium cellular element (Leydig cells) in the domest ic pig provided interesting numerical and morphological features during the different aging stages. As early as 25 days (a period in which the pig is sexually immature) there was a low number of Leydig cells (1.46 x 10(8)) wi th respect to a 78% and 35% increase in the adult (2.48 x 108) and aged (1. 78 x 108) animal, respectively. Interestingly, when the volume density of L eydig cells was considered, the average volume of these cells seemed to be high (75%) in the aged pig with respect to the young immature animal wherea s a lower increase (27%) was observed for the adult animal. Moreover, the e valuation of testosterone receptor binding sites in the testis at the vario us stages of development also displayed a differentiated pattern since elev ated testosterone receptor binding levels of the high dissociation affinity type were obtained for the adult pig. Thus, from the combined morphologica l variations of Leydig cells and testosterone receptor binding activity, it appears that this androgenic receptor component exerts distinct autocrine effects on the different functional features of some testicular tissue cons tituents at the different aging stages of the domestic pig. (C) 2000 Wiley- Liss,Inc.