Development of the knee joint was morphologically investigated, and the process of cavitation was analyzed by using episcopic fluorescence image capture (EFIC) to create spatial and temporal three-dimensional (3D) reconstructions.
Knee joints of Wister rat embryos between embryonic day (E)14 and E20 were investigated. Samples were sectioned and visualized using an EFIC. Then, two-dimensional image stacks were reconstructed using OsiriX software, and 3D reconstructions were generated using Amira software.
Cavitations of the knee joint were constructed from five divided portions. Cavity formation initiated at multiple sites at E17; among them, the femoropatellar cavity (FPC) was the first. Cavitations of the medial side preceded those of the lateral side. Each cavity connected at E20 when cavitations around the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were completed.
Cavity formation initiated from six portions. In each portion, development proceeded asymmetrically. These results concerning anatomical development of the knee joint using EFIC contribute to a better understanding of the structural feature of the knee joint.