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Determinants of Testicular Echotexture in the Sexually Immature Ram Lamb

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Title: Determinants of Testicular Echotexture in the Sexually Immature Ram Lamb
Author: Giffin, Jennifer L.
Department: Department of Biomedical Sciences
Program: Biomedical Sciences
Advisor: Bartlewski, Pawel M.
Abstract: Throughout sexual maturation, dynamic changes in testicular macro- and microstructure and reproductive hormone levels occur. Future adult reproductive capability is critically dependent on these changes; therefore, regular monitoring of pubertal testicular development is desirable. However, conventional methods of assessment do not permit the frequent and non-invasive examination of testicular function. Recently, scrotal ultrasonography in conjunction with computer-assisted image analysis has emerged as a potential non-invasive alternative for male reproductive assessment. In this procedure, testicular echotexture, or the appearance of the ultrasonogram, is objectively quantified on the basis of brightness or intensity of the minute picture elements, or pixels, comprising the image. In general, testicular pixel intensity increases with age throughout sexual maturation; however, periodic fluctuations occur. Changes in testicular echotexture are related to microstructural attributes of the testes and reproductive hormone secretion, but reports on these relationships have been inconsistent. Therefore, the overall objective of the studies presented in this thesis was to investigate how testicular echotexture and its associations with testicular histomorphology and endocrine profiles may be influenced by various factors including: i) scrotal/testicular integument; ii) blood flow/content; iii) stage of development; and iv) altered spermatogenic onset. Serial scrotal ultrasonograms, testicular biopsies or castrations and blood samples were collected from early postnatal or peripubescent ram lambs and analyzed to obtain echotextural, histomorphological and endocrine data, respectively. Testicular echotextural attributes were influenced by the presence of the scrotal and testicular integument, the stage of spermatogenic development (mitotic vs. post-mitotic) and the amount of germ cell heterogeneity present with or without retinoic acid exposure, but not by blood flow or content. Tubular and luminal size of the seminiferous tubules could be predicted from testicular pixel intensity using a simple linear regression model and demonstrated a moderate strength correlation with testicular echotextural parameters, as did a number of cellular and sub-cellular histomorphological attributes and reproductive hormone levels. These results clearly demonstrate the ability of testicular echotexture to detect experimentally and clinically relevant markers of testicular function. Computerized image analysis of scrotal ultrasonograms holds promise as a non-invasive diagnostic and prognostic tool and novel monitoring device of testicular histophysiology.
URI: http://hdl.handle.net/10214/8662
Date: 2014-11
Rights: Attribution-NonCommercial-NoDerivs 2.5 Canada
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Attribution-NonCommercial-NoDerivs 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 2.5 Canada