Impact of pubertal imidacloprid exposure on the genital tract of Japanese quail (Coturnix Coturnix japonica): Histomorphometric and ultrastructural study

Abstract

Background: The effects of exposure to the neonicotinoid pesticide, imidacloprid (IMI), on the histopathology and ultrastructure of the genital tracts of pubertal male and female Japanese quails (Coturnix Coturnix japonica) were investigated.

Methods: Pubertal quail (n = 28), commencing at 5 weeks post-hatching, were orally gavaged with 1.55 (low), 3.1 (medium), and 6.2 (high) mg/kg IMI, dissolved in distilled water, twice a week for four weeks. Control birds received distilled water only. Samples collected from male and female genital tracts included epididymal duct and magnum and shell gland. Histopathology, histometric measurements, as well as transmission and scanning electron microscopy were performed.

Results and conclusion: The medium and high IMI doses induced pathomorphological changes in the epithelial cells of the magnum and shell gland, which included a ciliary loss, presence of intracytoplasmic vacuoles, mitochondrial damage, and fewer secretory granules. In addition, there were cytoplasmic vacuoles detected in the efferent ducts and epididymal ducts of quails treated with medium and high IMI doses. The epithelial heights of the magnum, shell gland, rete testis and proximal efferent duct were reduced (P ≤ 0.05) in all IMI treatment groups. In addition, the epididymal duct epithelial heights decreased (P ≤ 0.05) at medium and high IMI doses, but changes in the distal efferent ducts were only observed in the high dose group. Overall, the results confirmed that pubertal exposure to IMI induced dose-dependent pathomorphological changes in male and female quail genital tracts, suggesting that IMI might impact their fertility and reproductive function.

Keywords: Epididymal region; Imidacloprid; Japanese quail; Magnum; Reproductive toxicity; Shell gland.