How Can We Standardize Peritoneal Thickness Measurements in Experimental Studies in Rats?

Abstract

Objective The various methods of measuring peritoneal thickness in experimental studies in rats have yielded conflicting results. Also, no standard method exists to assess histologic findings in peritoneal morphology. We therefore undertook the present study to create a reproducible and standard method for assessing rat peritoneal histology in experimental studies. Methods Parietal peritoneal samples from 61 Wistar albino rats were used in the study. Excepting the skin, the whole abdominal wall from each rat was cut two-dimensionally (longitudinally and horizontally), fixed in formalin, and processed routinely for light microscopy. Slides were divided into two groups according to the direction of the inner abdominal muscle fibers in the sections. Longitudinal and horizontal sections of abdominal muscle were evaluated. For every section, one histopathology image was captured from a light microscope to an IBM-compatible computer. Peritoneal thickness (mean of the maximum and the minimum) and submesothelial area (SMA) were drawn on the image. A computer program then automatically performed measurements. Two different measurement methods were compared, based on the same sections. Results The mean peritoneal thickness was 91 ± 8 μm in the longitudinal sections and 75 ± 7 μm in the horizontal sections ( p < 0.05). Measurements of the SMA were found to be 47,762 ± 4,374 μm2 for the longitudinal sections and 40,389 ± 3,631 μm2 for the horizontal sections ( p < 0.05). In both types of sections, a positive correlation (96% for longitudinal and 90% for horizontal) was found between the SMA and the peritoneal thickness ( p < 0.01). The SMA measurements correlated significantly with functional properties [ratio of the dialysate concentration of glucose initially and after a 1-hour dwell (D1/D0 glucose), ultrafiltration, and protein loss; p < 0.01]. Conclusion Peritoneal thickness can be measured as a mean of the minimum and maximum values. That measurement strongly correlates with submesothelial area. Both types of sections can be used, but the horizontal and longitudinal sections show systematic differences. All samples in a study should be taken using the same section pattern, either longitudinal or horizontal.

Laparotomy causes loss of peritoneal mesothelium prevented by humidified CO2 insufflation in rats

“…Mesothelial cell loss and bulging was then evaluated on a semiquantitative three-level scale, as described for SEM. The thickness of submesothelial connective tissue was measured perpendicular to the peritoneal surface 44 in the widest portion cut parallel to the underlying muscle fibers 45 using the software package LAS, v 4.3 (Leica Microsystems, Wetzlar, Germany) at 322Â magnification.…”

Technical Aspects in Studying Peritoneal Morphology in Animal Models of Peritoneal Dialysis

“…Neither other's nor our older studies mention these differences (7,10,11). In our previous study (12), we suggested that both types of sections can be used, but that the horizontal and longitudinal sections showed systematic differences. All samples in a study should be taken using the same section pattern, either longitudinal or horizontal.…”

“…The growing interest in the study of the morphology, physiology, and pathophysiology of the peritoneum during PD is therefore not surprising. Different peritoneal tissue samples, including anterior abdominal wall, liver, diaphragm, intestine, and omentum, may be used for this purpose (7)(8)(9)(10)(11)(12).…”

Zinc supplementation inhibits the high glucose‑induced EMT of peritoneal mesothelial cells by activating the Nrf2 antioxidant pathway

“…Image-Pro Plus version 6.0 (Media Cybernetics, Inc.) was used to analyze the images. ‘Peritoneal thickness’, which indicated the extent of fibrosis, was defined as the thickness of the submesothelial zone measured from the inner surface of the abdominal muscle to the mesothelium (21). The average of five random visual fields was used to quantify the thickness of each section.…”