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Title: Regulation of human Leydig cells : comparison with the rat
Author: Qureshi, Safia Judith
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1993
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The major aim of this thesis was to study the regulation of testosterone production in the human testis. The technique used to isolate human Leydig cells was improved, so that Leydig cells responsive to hCG were obtained consistenly in large yields. There was marked subject variation in both the basal levels of testosterone produced and in the responsiveness of the cells to hCG. Sertoli cells are believed to modulate Leydig cell function via the action of secreted factors. The nature of these factors is not known, although in the rat GnRH and AVP are potential candidates. Basal testosterone production by isolated rat Leydig cells is stimulated by GnRH and AVP, and comparable effects on isolated human Leydig cells were demonstrated. This evidence of comparable control mechanisms in the rat and human testis was supported by the finding that proteins secreted by isolated rat and human Leydig cells were remarkably similar when analysed by 2-dimensional SDS-PAGCE. In addition, rat and human Leydig cells showed comparable responses to the deleterious effects of a variety of toxicants in vitro. A morphological examination of the relationship between Leydig cells and other components of the human testis distinguished light and dark Leydig cells on the basis of differential toluidine blue staining. Morphometric analysis of testicular cellular components was correlated with the ability of isolated Leydig cells to produce testosterone in vitro. No relationship was found between either the total number of Leydig cells, or the proportion of light and dark Leydig cells per testis and testosterone production or hCG responsiveness in vitro. The number of light or dark Leydig cells showed significant positive correlations with different testicular components, perhaps indicating specific roles for these two subpopulations. In conclusion, these studies have demonstrated the isolation of human Leydig cells, which, in vitro, respond to the same stimuli as rat Leydig cells, and secrete many very similar proteins, suggesting the modulation of Leydig cell function in the two species is comparable. In the rat, one mechanism of controlling Leydig cell function in the two species is comparable. In the rat, one mechanism of controlling Leydig cell function may involve modulation by specific germ cell types, presumably mediated via Sertoli cells. The morphological analysis of the human testis, and correlations subsequently made support the existence of such an interaction in man.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available