Urinary System
Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard in Toxicologic Pathology, 2018
The kidneys are classified as unilobular in all of the most common species utilized in preclinical toxicologic studies. The functional unit of the kidney, the nephron, is divided into the glomerulus, proximal tubule, descending and ascending limbs of the loop of Henle, distal convoluted tubules, connecting segment, collecting ducts, interstitium, and juxtaglomerular apparatus. The kidney can also be divided into five topographic zones: cortex, outer and inner stripe of the outer medulla, inner medulla, and papilla (Figure 14.1a,b). While the inner and outer stripes are well developed in rodents, especially rats, they are less obvious in dogs and nonhuman primates. Whenever possible, toxic renal responses should be classified on the basis of structure and topographical location. Nephrons are classified based on their topographic location or functionally by the length of their loop of Henle. This includes subcapsular (short loop) nephrons and juxtamedullary (long loop) nephrons. Subcapsular nephrons are located within the outer cortex, sending their loops of Henle into the outer medulla. Juxtamedullary nephons, as their name implies, are situated at or near the corticomedullary junction and have very long loops which extend into the inner medulla before bending at various levels to return to the cortex. In dogs, all nephrons are of the long-looped variety, while in rats and mouse long-looped nephrons average only about 28% of the total.
The Urinary System and Its Disorders
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss in Understanding Medical Terms, 2020
Besides forming urine, the kidneys also have other functions. Some of the smooth muscle cells of the afferent arteriole are modified by the presence of a well-defined Goigi complex; these, together with cells of the adjacent distal convoluted tubule, form the macula densa, which secretes renin. Renin is a proteolytic enzyme that catalyzes the formation of angiotensin I from a plasma protein, which is then transformed to angiotensinII by angiotensin converting enzyme (ACE). This juxtaglomerular (juxta- = near) apparatus, through the renin—angiotensin system, plays a significant role in controlling plasma volume and blood pressure. The kidneys also produce renal erythropoieticfactor (REF), which increases erythropoietin output, increasing hemoglobin synthesis. Further, although prostaglandins are named for the prostate gland where they were first discovered, some are released by the renal medulla.
Endocrine hypertension
Philip E. Harris, Pierre-Marc G. Bouloux in Endocrinology in Clinical Practice, 2014
Although several corticosteroids produced by the adrenal gland have mineralocorticoid function (Figure 21.2), aldosterone is the most potent and predominant human mineralocorticoid. Aldosterone binds to the mineralocorticoid receptor (MR), a nuclear hormone receptor, and causes it to translocate to the nucleus, interact with the respective response elements, and induce a change in transcriptional activity that leads to an increase in activity of the epithelial sodium channel in the distal convoluted tubule (DCT) (Figure 21.3).2 Excess mineralocorticoid results in retention of sodium chloride and water, with obligate loss of potassium and hydrogen ions to maintain electrical neutrality. The resultant clinical picture is of hypertension, metabolic alkalosis, and hypokalemia.
Resveratrol: a panacea compound for diazinon-induced renal toxicity
Published in Toxin Reviews, 2023
Maryam Esfahani, Amir Hossein Rahbar, Sara Soleimani Asl, Fereshteh Mehri
Histopathological assessments of the H&E stained of the kidney tissue are shown in Figure 1(A–E). In the present study, the structure of the kidney and Bowman’s capsule was normal in the control group. The urinary space was not dilated, and the distal convoluted tubule and the proximal convoluted tubule were intact (Figure 1(A)). DZN rats had renal damage compared with control rats. The urinary space, the distal convoluted tubule, and the proximal convoluted tubule were dilated. Vascular congestion and cell infiltration were evident and the epithelial cohesion of the Bowman’s capsule was lost (Figure 1(B)). Based on the findings, the severity of lesions reduced in the DZN + different doses of Res groups. The Bowman’s capsule epithelium was more cohesive, and the dilatation of the urinary space and distal convoluted tubule represented a reduction. These changes were observed in parallel with the increasing dose of Res (Figure 1(C–E)). Accordingly, the TI index in the control group was zero and was not observed geological cases. Due to the presence of atrophy and vacuolation of the epithelium as well as cell infiltration and calcium crystals, the damage was in the severe in diazinon group. Injury rate decreased in the resveratrol groups, so that it was moderate in the low and medium dose groups and mild in the high dose group. Evaluation in regarding the extent of kidney tissue damage was used using studies conducted by Toblli et al. (1999).
Impact of betanin against paracetamol and diclofenac induced hepato-renal damage in rats
Published in Biomarkers, 2020
Tarek K. Motawi, Samia A. Ahmed, Noha A. El-Boghdady, Nadia S. Metwally, Noha N. Nasr
Regarding, the kidney, ordinary histological structure of renal cortex with normal glomerulus and normal pattern of proximal and distal convoluted tubules were observed in kidney section of NC rats (Figure 4(f)). While, kidney sections from PAR group showed a high cellularity in renal cortex with obliterated capsular space and destructed epithelial lining of proximal and distal convoluted tubules (Figure 4(g)). Additionally, ill-defined renal cortex with increased corpuscular space and swelling in the epithelial lining of proximal and distal convoluted tubules were showed in kidney section of DF group (Figure 4(i)). On the other side, Bet administration with PAR and DF counteracted the damaging effects in kidney morphology as indicated by preserved renal cortex with normal glomerulus and mild thinned epithelial lining of proximal and distal convoluted tubules (Figure 4(h,j) for PAR/Bet and DF/Bet, respectively). The Semi-quantitative assessment of the severity of reaction in the kidney was shown in Table 3.
Amelioration of renal cortex histological alterations by aqueous garlic extract in gentamicin induced renal toxicity in albino rats: a histological and immunohistochemical study
Published in Alexandria Journal of Medicine, 2021
Hala ZE Mohamed, Merry BK Shenouda
The results of the present study showed that rat renal cortex after administration of gentamicin for 21 days showed marked destructive lesions in the form of shrinkage of renal corpuscles with dilated renal spaces. These results confirm the findings of Mahmoud et al [24] who noticed complete atrophy of some glomeruli and shrinkage of glomerular capillaries in other glomeruli in gentamicin treated rats. Regarding the cells of the proximal and distal convoluted tubules this study showed marked vacuolated cytoplasm and pyknotic nuclei. Desquamated cells could be seen in the tubular lumen. This was consistent with Veljković et al. [25] who noticed that proximal convoluted tubules showed necrosis, vacuolation of cytoplasm and epithelial desquamation after gentamicin treatment. Taken into consideration that in this work cells of both proximal and distal convoluted tubules are affected. However, it was reported that distal tubules are significantly less affected by cytotoxic effects of gentamicin [26]. In our experiment this finding was interpreted by the study of Toubeau et al. [27] who stated that gentamicin could access the distal tubules with longer treatment period.
Related Knowledge Centers
- Calcium
- Collecting Duct System
- Loop of Henle
- Nephron
- Ph
- Potassium
- Sodium
- Cell Membrane
- Kidney
- Loop of Henle
- Sodium-Chloride Symporter