Macroscopic and Histological Analysis of Ovarian Follicular Development in Wistar Rats Treated with Chlorpyrifos: An Endocrine Disruption Study

Chlorpyrifos is an organophosphate pesticide widely used in Nigerian agriculture and implicated as a potent endocrine disruptor. Reproductive toxicity of chlorpyrifos has been reported in rodent models, but histological characterisation of its effects on ovarian follicular development in doses relevant to Nigerian agricultural exposure levels has not been undertaken. This study aims to evaluate ovarian morphology and follicular development in female Wistar rats treated with chlorpyrifos at doses representative of occupational and dietary exposures in vegetable-farming communities of Ogun State, South West Nigeria. Twenty-four adult female Wistar rats will receive chlorpyrifos by gavage at low, medium, and high doses for eight weeks. Ovarian sections stained with haematoxylin and eosin will be examined for primordial follicle density, primary follicle count, antral follicle number, atretic follicle rate, and corpus luteum frequency. Ovarian weight and macroscopic characteristics will be recorded. Serum oestradiol and luteinising hormone levels will be measured to complement histological findings. The study anticipates providing histological evidence of dose-dependent ovarian follicular disruption attributable to chlorpyrifos exposure, supporting advocacy for stricter pesticide safety regulations in Nigerian agriculture.

Keywords: chlorpyrifos, ovarian morphology, follicular development, endocrine disruptor, organophosphate