The effects of in utero exposure to biosolids on ovine testicular histology and semen quality in F1 offspring

Tanner, Lucy and UNSPECIFIED (2023) The effects of in utero exposure to biosolids on ovine testicular histology and semen quality in F1 offspring. MRes thesis, University of Nottingham.

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Human male fertility has been put under a microscope in recent decades, due to a rise in reproductive disorders and decline in semen quality. Exposure to individual anthropogenic environmental chemicals (ECs), has been associated with reproductive dysregulation during gestation and into adulthood. ‘Real-life’ exposure in humans encompasses a complex cocktail of ubiquitous ECs. This study examined ovine prepubertal testes and pubertal ram semen from sheep that were exposed in utero to a mixture of ECs. Pregnant ewes were grazed on pastures treated with biosolids fertiliser (processed human sewage sludge) eight weeks prior to mating until parturition. Prepubertal testes (n= 22) were subjected to immunohistochemical staining of Sertoli cells and Leydig cells for specific biomarkers (AMH and CYP17A1 respectively) and index of proliferation (PCNA). No significant changes in testicular stained area were reported for AMH, CYP17A1 or PCNA. Examination of pubertal ram semen (n=16) using a new portable CASA platform (iSperm), revealed a significant increase in sperm motility within fresh samples from biosolids exposed males. No significant changes in sperm motility or kinematic parameters were reported in cryopreserved semen from the same rams. An evaluation of the iSperm was conducted to review the three methodologies (i.e., Dropper, Dipper and Pipette methods) for semen analysis and compared the iSperm to a validated CASA system (IVOS II). Upon review of the three methodologies, the Pipette method produced the most consistent readings across the measured semen analysis parameters. The Dropper method had unreproducible results and continually gave higher readings for percentage sperm motility and progressive motility. The IVOS II CASA comparison showed no agreement in sperm motility or kinematic parameters between the two systems. This study indicated that exposure to ECs throughout gestation had little to no significant effect on prepubertal testicular histology or adult semen quality. This proves controversial to previous studies and could inspire future work to explore compensatory effects during fetal development to restore the testicular phenotype, which might mitigate reproductive effects in adulthood.

Item Type: Thesis (University of Nottingham only) (MRes)
Supervisors: Sinclair, Kevin
Lea, Richard
Keywords: Environmental chemical exposure; Male fertility; Semen quality; Reproductive models; Sheep; Rams
Subjects: Q Science > QP Physiology > QP1 Physiology (General) including influence of the environment
S Agriculture > SF Animal culture
Faculties/Schools: UK Campuses > Faculty of Science > School of Biosciences
Item ID: 73039
Depositing User: Tanner, Lucy
Date Deposited: 22 Jul 2023 04:40
Last Modified: 07 Mar 2024 04:30

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