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Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice
Thesis (MSc)--Stellenbosch University, 2026.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867614071144054784 |
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| access_status_str | Open Access |
| author | Uys, Sharnah |
| author2 | Skosana, Bongekile Trisha |
| author_browse | Skosana, Bongekile Trisha Uys, Sharnah |
| author_facet | Skosana, Bongekile Trisha Uys, Sharnah |
| author_sort | Uys, Sharnah |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/135707 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:46:11.731Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/135707 Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice Uys, Sharnah Skosana, Bongekile Trisha Marais, Erna Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Division of Medical Physiology. Thesis (MSc)--Stellenbosch University, 2026. Uys, S. 2026. Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/cf57fd1c-cc36-4e58-b690-6f5273ad443a Background: Infertility is a recognised reproductive health issue affecting individuals worldwide. An increase in male infertility has been reported, with concurrent evidence of declining semen quality. Obesity is a major contributor to infertility, with obese men presenting with decreased testosterone levels, impaired spermatogenesis and reduced sperm function. Extracellular vesicles (EVs), which facilitate cell-to-cell communication, have been discovered in various biological fluids. Specifically, in the male reproductive system, testicular-derived EVs have been reported to regulate testosterone production and spermatogenesis. There is a significant gap in knowledge regarding the effects of obesity on testicular EVs and their potential role in altering the testicular microenvironment. Therefore, examining testicular-derived EVs may provide an understanding of the association between obesity and male infertility. Methods: This study utilised a genetic mouse model of obesity (ob/ob) to investigate obesity-induced male infertility. Control (C57BL/6) and obese (ob/ob) male mice were euthanized at 16 weeks of age. Epididymides were harvested to extract sperm to measure sperm concentration, motility (total, progressive and non-progressive), kinematics (straight line velocity (VSL), curvilinear velocity (VCL), amplitude of lateral head displacement (ALH) and linearity (LIN)), and morphology via Computer-Aided Sperm Analysis (CASA). Additionally, the testes were harvested and fixed in formalin or frozen for subsequent analyses. Formalin-fixed testes underwent haematoxylin and eosin (H&E), immunohistochemistry (IHC) and immunofluorescent (IF) staining to investigate testicular morphology and assessment of EV localisation, respectively. EV-specific biomarkers such as CD63, CD9 and ANXA1 were targeted. Frozen testes were utilised for EV extraction and further western blotting (WB) analyses. Spermatogenesis was investigated via WB for spermatogenesis-related proteins (IGF1, INSL6, and PRDX2). For EV extraction, frozen testes were dissociated and underwent differential centrifugation after which WB was performed to confirm EV isolation by targeting EV-specific biomarkers. Results: At 16-weeks old, obese mice had significantly increased body weights (P<0.0001) and fasting blood glucose levels (P=0.0004). Sperm concentration remained unchanged between groups. Obese spermatozoa had significantly reduced total (P<0.0001), progressive (P=0.009) and non-progressive (P<0.0001) motility when compared to controls. Kinematic measurements indicated reduced VSL (P=0.0064), VCL (P<0.0001) and ALH (P<0.0001) parameters for obese sperm, with LIN remaining unchanged. Obese mice presented with significantly increased abnormal spermatozoa (P<0.0001) and showed significant increased head and midpiece defects (P<0.0001 and P=0.0089, respectively). Obese testicular morphology displayed decreased seminiferous tubular area (P=0.0287) and diameter (P=0.0252), decreased lumen diameter (P=0.0011), as well as a high presence of vacuolation and disorganised cellular arrangements. IHC staining showed visible differences in EV localisation between control and obese testes for CD63, CD9 and ANXA1, with IF staining showing a decreased mean fluorescent intensity for CD63 (P=0.0345) in obese testes compared to controls. WB for IGF1, INSL6 and PRDX2 remained unchanged. WB for extracted EVs (CD63, CD9 and ANXA1) could not be quantified. Conclusion: Results from this study showed obesity-induced alterations in sperm parameters. Additionally, the testes and EV localisation results suggest a significant difference in CD63 EV marker compared to controls, suggesting less EVs in the ob/ob mice. Further investigation is required to delve deeper into the association between obesity, EV dynamics and testicular functions. Masters 2026-04-08T09:54:59Z 2026-04-08T09:54:59Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135707 en Stellenbosch University 159 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Uys, Sharnah Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice |
| title | Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice |
| title_full | Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice |
| title_fullStr | Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice |
| title_full_unstemmed | Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice |
| title_short | Obesity-Induced Alterations in Sperm Quality, Testicular Morphology, and Extracellular Vesicle Localisation in Male Mice |
| title_sort | obesity induced alterations in sperm quality testicular morphology and extracellular vesicle localisation in male mice |
| url | https://scholar.sun.ac.za/handle/10019.1/135707 |
| work_keys_str_mv | AT uyssharnah obesityinducedalterationsinspermqualitytesticularmorphologyandextracellularvesiclelocalisationinmalemice |