A Histological Study on the Effect of Lead Acetate on the Developing Metanephros in Rabbit

Aim of the Work: This study was carried out to show the effect of lead acetate on the developing metanephros in rabbit. Material and Methods: A total number of 60 rabbit embryos and newborn rabbits were divided into 2 groups, control (n=30) and experimental (n=30). The pregnant mothers of the experimental group received 15 mg / kg BW lead acetate by intragastric intubation on the 10th day of pregnancy until birth. The control group received sodium acetate on the same regimen. For light microscopic study, the specimens were processed on gestational days 16, 20, and 24 and the age of newborn and stained with haematoxylin and eosin and periodic acid Schiff reagent. In two age groups, 24 days prenatal and newborn (control and treated), morphometric measurements were performed to study the diameter and the number of glomeruli and tubules. Also, the glomerular space was measured.  Kidney specimens from fetuses on gestational day 26 and from newborns were processed for transmission and scanning electron microscopic study. Results: The control animals showed that the metanephros appeared as a circumscribed mass behind the caudal part of the mesonephros at the age of 16 days prenatal. At the age of 20 days prenatal beneath the renal capsule, the metanephros showed a developed nephrogenic zone containing different stages of nephron development. In the succeeding ages, this nephrogenic zone increased in thickness until birth where it was still persistent. In the experimental group, there were dispersion and disorganization of the metanephric cells and the nephrogenic zone at early ages. In the succeeding ages, cavitations, dilated vascular spaces, increased interstitial tissues with degenerative changes in the glomeruli and tubules of the kidney were observed. At 26-day-old embryo, semithin sections showed degeneration of the cells of the proximal convoluted tubules with irregular vacuolations, clumped intracytoplasmic dark granules and severely damaged brush borders. Cells of the distal convoluted tubules were degenerated. The glomeruli showed dilated congested capillaries with some glomeruli showing dilated glomerular space. These manifestations became more apparent in leaded newborns. Ultrathin sections showed injured epithelial cells of the proximal convoluted tubules with damaged microvilli, vacuolated cytoplasm, swollen mitochondria and degeneration of their cristae. Inclusion bodies and metal deposits were observed in the cytoplasm. In leaded newborns, massive degeneration was observed. Scanning electron microscopy showed marked degeneration of the glomeruli and tubules as compared with the control. Morphometric measurements showed significant reduction in the glomerular diameter, the tubular diameter and the number of glomeruli and tubules per mm with significantly widened glomerular space in lead- treated animals in comparison with the control animals.