Spatial Change of Cruciate Ligaments in Rat Embryo Knee Joint by Three-Dimensional Reconstruction

Three-Dimensional Imaging Analysis of the Developmental Process of Posterior Meniscofemoral Ligaments in Rat Embryos

INTRODUCTION

The posterior meniscofemoral ligament (pMFL) of knee joint is a ligament that runs posterior to the posterior cruciate ligament and it is known that the height of the pMFL attachment site causes meniscus avulsion. Therefore, understanding the three-dimensional (3D) structure of the pMFL attachment site is essential to better understand the pathogenesis of meniscus disorders. However, the developmental process of pMFL has not been well investigated. The purpose of this study was to analyze pMFL development in rat knee joints using 3D reconstructed images produced from episcopic fluorescence image capture (EFIC) images and examine its relationship with other knee joint components.

METHODS

Knee joints of Wistar rat embryos between embryonic day (E) 16 and E21 were observed with HE-stained tissues. Serial EFIC images of the hind limbs of E17-E21 were, respectively, captured from which 3D images were reconstructed and the features of pMFL structure: length and angle were measured. Besides, the chronological volume changes and the volume ratio of the knee joint components compared to E17 were calculated to identify the differences in growth by components.

RESULTS

pMFL was observed from E17 and was attached to the medial femoral condyle and lateral meniscus at all developmental stages, as in mature rats. The lack of marked variation in the attachment site and angle of the pMFL with the developmental stage indicates that the pMFL and surrounding knee joint components developed while maintaining their positional relationship from the onset of development.

CONCLUSION

Current results may support to congenital etiology of meniscus disorder.

Quantitative Image Processing for Three-Dimensional Episcopic Images of Biological Structures: Current State and Future Directions

Episcopic imaging using techniques such as High Resolution Episcopic Microscopy (HREM) and its variants, allows biological samples to be visualized in three dimensions over a large field of view. Quantitative analysis of episcopic image data is undertaken using a range of methods. In this systematic review, we look at trends in quantitative analysis of episcopic images and discuss avenues for further research. Papers published between 2011 and 2022 were analyzed for details about quantitative analysis approaches, methods of image annotation and choice of image processing software. It is shown that quantitative processing is becoming more common in episcopic microscopy and that manual annotation is the predominant method of image analysis. Our meta-analysis highlights where tools and methods require further development in this field, and we discuss what this means for the future of quantitative episcopic imaging, as well as how annotation and quantification may be automated and standardized across the field.

A 3D Scanning System for Inverse Analysis of Moist Biological Samples: Design and Validation Using Tendon Fascicle Bundles

In this article, we present the design and validation of a non-contact scanning system for the development of a three-dimensional (3D) model of moist biological samples. Due to the irregular shapes and low stiffness of soft tissue samples, the use of a non-contact, reliable geometry scanning system with good accuracy and repeatability is required. We propose a reliable 3D scanning system consisting of a blue light profile sensor, stationary and rotating frames with stepper motors, gears and a five-phase stepping motor unit, single-axis robot, control system, and replaceable sample grips, which once mounted onto the sample, are used for both scanning and mechanical tests. The proposed system was validated by comparison of the cross-sectional areas calculated based on 3D models, digital caliper, and vision-based methods. Validation was done on regularly-shaped samples, a wooden twig, as well as tendon fascicle bundles. The 3D profiles were used for the development of the 3D computational model of the sample, including surface concavities. Our system allowed for 3D model development of samples with a relative error of less than 1.2% and high repeatability in approximately three minutes. This was crucial for the extraction of the mechanical properties and subsequent inverse analysis, enabling the calibration of complex material models.

Cartilage attachment morphology of the fetal cruciate ligaments of the knee: an immunohistochemical study using human fetal specimens

Fetal cruciate ligaments of the knee provide two types of cartilage attachments: to a cartilage fovea or a simple continuation to the perichondrium. To examine a difference in matrix substance between a ligament attachment to the fovea and another attachment to the perichondrium. We histologically observed 12 human fetal femurs in which the posterior (or anterior) cruciate ligament provided a fovea-type (or a perichondrium-type) attachment. Immunohistochemistry of matric substances (aggrecan, versican, tenascin-c) was performed. In the knees, aggrecan was consistently positive in any cartilage, versican was in the joint surface and tenascin-c in the perichondrium. In contrast to the femoral attachment, the anterior and posterior cruciate ligaments consistently continued to the perichondrium at the tibial attachment (versican-, tenascin+). In the femoral condyles, tenascin-immunoreactivity was seen in both of a fovea-type and a perichondrium-type attachments, but versican was not in both. During development of the cartilage fovea, the growing ligament seemed to push the perichondrium into the cartilage and, much or less, the tenascin-positive perichondrium was likely to be involved into the fovea.