Immunohistochemistry, light and electron microscopy of the testis from the albino Swiss rat following vasectomy

Dobson, Craig Charles (2001) Immunohistochemistry, light and electron microscopy of the testis from the albino Swiss rat following vasectomy. PhD thesis, University of Glasgow.

Abstract

Previous work in our laboratory has reported degeneration of the testes following left unilateral vasectomy in the Albino Swiss rat. This degeneration can be ipsilateral to the side of vasectomy or bilateral. We paid particular attention to the ultrastructure of the seminiferous tubules nine months or more following vasectomy in an attempt to elucidate the aetiology of the degeneration. There were marked differences between degenerated tubules following vasectomy and healthy tubules from sham operated controls or following vasectomy. The seminiferous epithelium in degenerated tubules rarely contained any recognisable sperm precursors. It consisted of Sertoli cells with few vacuoli and nuclei with deep intranuclear clefts displaying peripheral clumps of heterochromatin which were often found more central in the tubule than those from controls. The boundary zones from degenerated tubules were also greatly different from controls. The Sertoli cell basal laminae were thrown into marked folds as were those of the myoepithelial cell. The latter often had nuclei with triangular profiles as did the outer lymphatic endothelium. The basal lamina of these cells also appeared detached in places from the soma. There was no ultrastructural difference observed between unilateral and bilateral degeneration. The degenerated tubules were found to be smaller, often containing more Sertoli cells than controls. The similarity of these findings to those reported following other insults suggested that the findings may not be specific for vasectomy. The similarity observed between degeneration following vasectomy and that following maternal in utero flutamide administration supported the notion of these changes being due to shrinkage of the tubule. The only difference being the presence of immunocompetent cells in the boundary zone of degenerated tubules following vasectomy. Despite the gross change in Sertoli cell appearance, we were able to demonstrate that both healthy and degenerated tubules following vasectomy retained typical Sertoli-Sertoli cell tight junctions as were found in sham operated controls. We used lanthanum as an intercellular tracer to test the function of these junctions. Both healthy and degenerated tubules following vasectomy were able to exclude lanthanum from the lumen as in controls. It would appear that the blood-testis barrier remains intact in rats nine to fifteen months following vasectomy or sham procedure, even in degenerated tubules. There was no difference demonstrated between bilateral and ipsilateral degeneration. Immunohistochemical investigation of testis three weeks, three months, six months and one year following vasectomy compared with sham operated controls revealed the presence of low numbers of immunocompetent cells in the testis of healthy control testes. We were also able to described the pattern of MHCI and II distribution in healthy testis. Degenerated testes following vasectomy contained focal areas of immunocompetent cells which expressed T-suppressor, T-Helper and macrophage markers. Such accumulations could be centred on degenerated tubules or on blood vessels. They were also found in the grossly healthy right testis of one animal with unilateral degeneration. There also appeared to be an increased number of immunocompetent cells in sections from degenerated testis, however, this may be partly accounted for by slirinkage of the testis. MHC I expression was markedly different in degenerated testis following vasectomy compared with healthy tubules from sham operated controls or following vasectomy. In degenerated tubules the intratubular and interstitial cells were labelled where as healthy tubules had only limited staining of intratubular late spermatids as well as in the interstitium. This suggests that degenerated tubules contained Sertoli cells which expressed MHC I and may therefore play a role in the activation of the immune response demonstrated by the focal accumulations of immunocompetent cells. In contrast, there was no observed change in MHC II bearing cells. Taken together, our results suggest that the morphological changes to the boundary zone and Sertoli cells following unilateral vasectomy are the same for unilateral and bilateral degeneration and probably represent a non specific effect from tubal shrinkage. The aetiology of these degenerations remains unclear but the blood-testes barrier remains intact. There may be a role for the immune system as evidenced by the appearance of focal accumulations of immunocompetent cells and expression of MHC I by Sertoli cells in degenerated testis. The role of these MHC I bearing Sertoli cells unclear but they are capable of phagocytosis and possibly therefore antigen presentation.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Cellular biology, Histology
• Colleges/Schools: College of Medical Veterinary and Life Sciences
• Supervisor's Name: McDonald, Dr. Stuart
• Date of Award: 2001
• Depositing User: Enlighten Team
• Unique ID: glathesis:2001-72148
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 17 May 2019 12:47
• Last Modified: 28 Jun 2022 13:13
• Thesis DOI: 10.5525/gla.thesis.72148
• URI: https://theses.gla.ac.uk/id/eprint/72148