Analysing nuclear shape as a function of relative spatial position in the femoral insertion of the medial collateral ligament.

Quantification of biological structure by morphometry facilitates the correlation of structure to biological function. To test a hypothesis concerning the correlation of a gradient in cell and nuclear shape and a corresponding gradient in mechanical stress within a ligament insertion into bone, a computerized approach was developed for quantifying mean nuclear shape as a function of position within this insertion. Three femoral insertions of the medial collateral ligament of the rabbit were prepared for histology. Commercially available software was used to measure nuclear perimeter and area by video-based planimetry on microscopic images, then custom software was used to define an overlying mesh of polygons on each insertion, to normalize the geometry of the insertion, and to calculate the mean nuclear roundness (a function of area and perimeter) for each polygon in the mesh. This approach allows the comparison of mean nuclear roundness of different polygons and among different animals that would be extremely difficult to do manually. In addition, these morphometry results can be used to correlate with functional data.