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Table 1 Definitions of outcome parameters

From: The Myotube Analyzer: how to assess myogenic features in muscle stem cells

Parameter

Definition

Nucleus properties

 Average RMSE

Average RMSE was calculated from orthogonal regression after nucleus clustering, with each data point representing the average value for all the clusters in one image set. It serves as an indicator for cluster linearity

 Number of clusters

The number of clusters was defined as the total number of clusters remaining after clustering

 Fusion index

The fusion index was calculated for each image set as the ratio between the number of nuclei inside MyHC-positive myotubes and the total number of nuclei present in the image

Myotube properties

 Myotube coverage

Myotube coverage was calculated for each image set as the percentage of image pixels occupied by myotubes (positive pixels for MyHC in the mask) and serves as an indicator for myotube size

 (Number of) branching points

The number of branching points was determined as the number of branches splitting off from one myotube, with each data point representing the sum of all branching points (for all myotubes combined) in the image set

 Number of myotubes

The number of myotubes was defined as the number of separate objects in the myotube mask

 Myotube diameter

Myotube diameter was defined as the average of 5 separate measurement points. Each measurement is calculated by finding the closest point on the myotube skeleton to the measurement, obtaining the intensity value from the corresponding pixel in the distance transform image, and doubling it to obtain the diameter