[Scanning electron microscopic investigations on the anatomy of the fetlock joint in horses].

The article discusses a study using scanning electron microscopy to examine the surface and structure of synovial components in the fetlock joint of horses. Differences in cells were noted depending on where they were sampled from within the joint.

Objective of the Study

• This study aimed to investigate the anatomy of the fetlock joint in horses, specifically focused on the synovial structures. Using scanning electron microscopy, the researchers scrutinized the surface form of the synovial cells.

Methodology

• The investigation was conducted by taking distinct synovial samples from different parts of the fetlock joint and using scanning electron microscopy to study their surfaces.

Findings of the Study

• The way the synovial layers (stratum synovial) were arranged differed, based on where the samples were taken from.
• The synovial intima (innermost layer of the synovium) appeared to be absent beneath certain tendons and ligaments, such as the long/common extensor muscle tendon, the collateral ligaments, and the sesamoidean collateral ligaments. In these areas, the subsynovial tissue formed the topmost layer.
• On the other hand, samples taken from the sides of the extensor muscle tendon, and from the synovial fold situated between the metacarpus/metatarsus and proximal phalanx, as well as from the palmar/plantar recess, were dominated by the synovial intima.
• Synovial cells were found to be primarily arranged as a single layer (monolayer) and showed variable appearances. Some of them looked similar to blackberries, while others had a very wavy surface.
• The length of the processes (protrusions or extensions) of the synovial cells ranged from 2-10 microns, and the cells’ diameter ranged from 5-10 microns.
• The gap between two cells amounted to 2-10 microns. This intercellular gap was examined in relation to the length of the cells’ processes.
• The synovial intima is believed to act as a barrier between the articular cavity (joint space) and the surrounding structures.