Histological Alterations in Gestational Day 13 Rat Embryos from Albendazole‐Treated Dams

Abstract

AbstractGestational day (GD) 13 rat embryos from dams treated p. o. with albendazole (ABZ) on GD 10–12 were examined as an experimental model for the pathogenesis of embryotoxicity induced by benzimidazole compounds. Dosage levels were 0, 10, 20 and 30 mg/kg b. w. of ABZ. At 10 mg/kg b. w., most embryos appeared macroscopically normal. However, the histological examination of a representative sample showed subtle alterations including discrete necrotic foci in the lateral and rostral telencephalon, delayed differentiation of lens, increased wavyness of the notochord caudad to the forelimb bud and absent or poorly defined apical ectodermal ridge in the forelimb bud. At 20 and 30 mg/kg b. w. a sharp, dose‐related increase in embryolethality, developmental delays and macroscopic abnormalities were accompanied histologically by marked necrotic alterations of a number of embryonic tissues. The telencephalon and neural tube were severely affected, showing also a regeneration attempt through the disordered formation of tubules. Besides neuroectoderm, necrosis and tissue depletion were mostly evident in neural crest and mesoderm‐derived structures, such as branchial bars, limb buds and paraxial mesoderm. Lesions in the somites showed a head‐to‐tail increasing gradient; the sclerotomes were consistently more affected than the dermatomes. Wavyness of the notochord cephalad to the forelimb bud and fragmented/abnormal nuclei in the erythroblasts were also noted. Examination of embryos during in vivo organogenesis may be a useful tool for investigating the pathogenesis of embryotoxicity.