Effects of ischaemia on the caput epididymis and its relationship to higher epididymal obstruction: a qualitative study in the ram

Abstract

The objective of this study was to determine if localized ischaemia of the caput epididymis in the ram causes morphological changes similar to those characteristic of higher epididymal obstruction in humans. This was tested by performing unilateral occlusion of the superior epididymal artery in 10 rams. At the end of 4 (n = 5) or 28 weeks (n = 4), rams were castrated and the testes and epididymides were weighed. Analysis of histological sections at the light microscope level provided quantitative data on lumen diameter and epithelial cell height of the efferent ducts. Qualitative analysis and specific histochemical stains for identification of lipofuscin pigment provided further information on tissue changes. Electron microscopy was performed on the efferent ducts to assess ultrastructural changes. The results revealed that localized ischaemia of the proximal epididymis caused a dramatic change in tubule calibre of the efferent ducts and initial segment resulting in obstruction of the distal lumina. These changes were more severe following 28 weeks of arterial occlusion. The epithelial cells of the proximal region showed an increase in the number of lysosomes and they became active in phagocytosis of spermatozoa. Lipofuscin pigment accumulated within the epithelial cells and also in macrophage-like cells that had invaded the lumina, interstitium and intra-epithelial regions of the ducts. On the basis of these observations we conclude that the tissue changes which occur in the ram epididymis as a result of localized ischaemia show a striking similarity to those seen in men exhibiting higher epididymal obstruction. This suggests the possible implication of vascular disorders in the aetiology of obstructive azoospermia in men.