Three-dimensional high-resolution reconstruction of the human gastro-oesophageal junction

Abstract

The aim of this study was to obtain detailed information regarding the three-dimensional structure of the gastro-oesophageal region, and, in particular, the fiber orientation of the different muscle layers of the junction. This was achieved by a study of an en bloc resection of the gastro-oesophageal junction (GOJ) harvested from a human cadaver. The excised tissue block was suspended in a cage to preserve anatomical relationships, fixed in formalin and embedded in wax. The tissue block was then processed by a custom-built extended-volume imaging system to obtain the microstructural information using a digital camera which acquires images at a resolution of 8.2 microm/pixel. The top surface of the tissue block was sequentially stained and imaged. At each step, the imaged surface was milled off at a depth of 50 microm. The processing of the tissue block resulted in 650 images covering a length of 32.25 mm of the GOJ. Structures, including the different muscle and fascial layers, were then traced out from the cross-sectional images using color thresholding. The traced regions were then aligned and assembled to provide a three-dimensional representation of the GOJ. The result is the detailed three-dimensional microstructural anatomy of the GOJ represented in a new way. The next stage will be to integrate key physiological events, including peristalsis and relaxation, into this model using mathematical modeling to allow accurate visual tools for training health professionals and patients.

Figure 1

a: A left lateral view of the fresh mounted human cadaveric gastro-oesophageal junction, prior to formalin fixation and wax-embedding. b: A left lateral view of the human cadaveric gastro-oesophageal junction, during wax-embedding. The tissue was suspended in a specially designed jig with sutures to maintain the in vivo anatomic relations. The white-dashed lines indicate the level of the cross-sectional images in Figure 2a, 2b, and 2c.

Figure 2

Cropped images showing the cross-section of the oesophagus and the diaphragmatic crura at (a) above the oesophageal hiatus (b) through the upper oesophageal hiatus and (c) through the lower oesophageal hiatus. The section bordered in red in image (b) is enlarged in (d) to illustrate the high resolution of the images obtained in this study. Muscle layers are shown in green while connective tissue is pink/purple in color. The numbers shown on the images refer to the following structures: (1) muscular diaphragm, (2) peri-oesophageal lymph nodes, (3) mesentery of the oesophagus, (4) posterior vagal nerve trunk, (5) mucosa, (6) submucosa, (7) circular muscle, (8) longitudinal muscle, (9) adventitia, (10) anterior vagal nerve fibers, (11) endo-thoracic fascia, and (12) endo-abdominal fascia.

Figure 3

Cross-sectional image showing segmented structures. Different colors were used to distinguish the segmented structures; connective tissue (orange), crura (light purple), lymph nodes (green), blood vessels (purple), longitudinal muscle (light blue), circular muscle (pink), submucosa (yellow), and epithelium (dark blue).

Figure 4

High-resolution microstructural information of the gastro-oesophageal junction in three-dimensions. a: The three-dimensional tissue block in its original texture color showing the gastro-oesophageal junction in relation to the crura and the connective tissue. b: Artificial colors were used to provide an easier method of distinguishing between the different structures of the three-dimensional tissue block.

Figure 5

The inner layer of the three-dimensional model, with muscle and submucosal layers stripped away, to demonstrate an accurate rendering of the squamocolumnar junction.

Figure 6

An anterior view onto the coronal plane of the tissue sample illustrating the extension of the POL (phreno-oesophageal ligament) from the diaphragm to the oesophagus. The POL is then divided into a prominent upper leaf and lower leaf. The fibers of the leaves extend and penetrate the wall of the oesophagus at different levels and unite with the fascial covering of the muscular wall of the oesophagus.

Figure 7

A change in the fiber direction of the CM (circular muscle) layer was observed at the squamocolumnar junction. The change in the fiber direction of the CM layer can be clearly seen as the circular fibers change into an oblique orientation. The CM layer is semicircular and incomplete anteriorly and posteriorly in the intra-abdominal region (b) compared to the intrathoracic region (a).