Orthogonal Intercepts probe
You can use this probe to estimate membrane thickness (e.g., thickness of the interhemal membrane in the placenta that separates the maternal from the fetal blood).
Prerequisites and design
Procedure
- Place a reference point.
- Optional: Use the Serial Section Manager to keep track of the sections that should be obtained via systematic random sampling.
- Trace the region(s) of interest at low magnification (i.e., with low precision). See Tracing contours.
- Select a lens so that you can see the membrane clearly.
- Click Probes>Define Counting Frame and define the counting frame size.
- Click Probes>Preview SRS Layout to estimate the grid size (see Determining Sampling Precision). Right-click and select End preview mode to turn the preview off.
- Click Probes>Length>Orthogonal Intercepts.
- Adjust the probe settings and click OK. The program displays a grid.
- Measure within the site by drawing a series of line-segments.
- Starting at a point where the grid and the membrane wall intersect (black circle in the figure), click and drag the mouse to the other membrane wall so that line-segment (blue line with arrow head in figure) and wall meet orthogonally.
- Release the mouse. A blue line has been drawn.
- Repeat steps a and b as necessary to draw more line-segments.
To delete the last line-segment drawn, press CTRL-Z.
- Starting at a point where the grid and the membrane wall intersect (black circle in the figure), click and drag the mouse to the other membrane wall so that line-segment (blue line with arrow head in figure) and wall meet orthogonally.
- Right-click and select next scan site and repeat step 9.
- Repeat step 10 until you've visited all the sites.
- To view the results, click Probe run list: Harmonic mean, estimate using harmonic mean, arithmetic mean, estimate using arithmetic mean, and measured lengths are reported.