Table 1.
Samples used in the present study.
Fig 1.
Methods used in the present study.
(A) Selection of histological sections for the analysis of the urinary collecting system (UCS) epithelium according to the generation number. Three-dimensional reconstruction of metanephros and UCS centerline tree was used for histological evaluation. Representative generation branches were selected. Matched epithelium sections were cropped at 40× magnification. Illustrative data were obtained from a representative metanephros sample (CS23: ID 9026). (B) Illustration indicating the sections observed on the urinary tract. UPJ, ureteric pelvis junction; UCS Gn, urinary collecting system generation number. (C) Measurements of epithelium height and lumen diameter. The height of the epithelium and the size of the lumen are determined by averaging the lengths measured at four positions (indicated by black bidirectional arrows) and three positions (indicated by red bidirectional arrows) on the UCS, respectively.
Table 2.
Histological characteristics and differentiation scores of the UCS.
Fig 2.
Three-dimensional reconstruction of metanephros at stages CS18-CS23.
Green, zeroth to the fifth generation; orange, sixth to the end generation. The specimens at CS23 are divided into two categories: the pre-expanded pelvis group (CS23P) and the expanded pelvis group (CS23E), leading to an enlargement of the pelvis. Data was obtained from representative specimens at each Carnegie stage (CS19: ID923, CS20: ID567; CS21: ID2021; CS22: ID5685; CS23: ID9026).
Fig 3.
Epithelium height in the UCS in relation to generation number.
(A) Change in the epithelium height according to the generation number. The mean thickness vs. generation number between CS18 and CS22 is indicated on the left, and the data value at each sample at CS23P and CS23E is indicated on the right. (B) Comparison of the epithelium heights between CS18 and CS23E by generation number. CS, Carnegie stage; CS23.P, Carnegie stage 23 pre-expanded pelvis; CS23.E, Carnegie stage 23 expanded. The measurement data was provided in S1 Data.
Fig 4.
Lumen size in the UCS according to generation number.
(A) Change in the lumen size according to the generation number. The mean lumen size vs. generation number between CS18 and CS22 is indicated on the left, and the data values for each sample at CS23P and CS23E are indicated on the right. (B) Comparison of the epithelium lumen sizes between CS18 and CS23E by each generation. CS, Carnegie stage; CS23P, Carnegie stage 23 pre-expanded pelvis; CS23E, Carnegie stage 23 expanded. The measurement data was provided in S2 Data.
Fig 5.
Scatter plots showing the relationship between epithelium height and lumen size of the UCS during CS18-CS23E.
Scatter plots are provided for five representative generation numbers: 0th, 3rd, 6th, 9th, and 11th. The measurement data was provided in S3 Data.
Fig 6.
Histological examination according to the Carnegie stage and generation number.
(A) Each panel indicates the type of epithelium, presence of glycogen, percentage of migrated nuclei, percentage of cells in mitosis, and mesenchyme surrounding the epithelium. Each criterion is explained in the Materials and Methods section. (B) The differentiation score was obtained from the six histological examinations. Histological images used in Fig 7 are highlighted by rectangles.
Fig 7.
Representative histological images depicting the UCS differentiation scores (S).
The generation number is mentioned in each image. Histological images presented here are highlighted by rectangles in Fig 6.
Fig 8.
Histological findings in the ureter.
(A) Panels indicate the epithelium type, presence of glycogen, nuclei position, and surrounding mesenchyme at the junction and the peripheral side. (B) Representative histological images of the ureter. E1, pseudostratified epithelium; E2, simple cuboidal epithelium; BL, bi-layered epithelium; G, glycogen; AC, apical-central; ACB, apical-central-basal; CT, connective tissue. Purple (in A) indicates the repartition of each feature by the Carnegie stage. Arrowheads indicate glycogen. Numbers represent Carnegie stage (CS); images shown on higher magnification (40×) ureter epithelium; scale bar = 20 μm. UPJ; ureteric pelvic junction, Distal; the distal side of the ureter.
Fig 9.
Histological findings on the bladder.
(A) The panel indicates the epithelium type, presence of glycogen, and surrounding mesenchyme at the neck and dome of the bladder. SL, single layer; BL, bi-layers; ML, multilayers; G, glycogen; CT, connective tissue. (B) Representative histological images at CS18, CS21, and CS23E from the whole bladder (left), magnified neck (middle), and dome region (right). Arrows indicate the opening of the ureter. From left to right, respectively: lower magnification (10×) of sagittal section of whole bladder, scale bar = 100 μm; higher magnification (40×) showing neck and dome of bladder epithelium, scale bar = 20 μm. D, dome; N, neck; R, rectum; CA, abdominal cavity.