The human splenic microcirculation is entirely open as shown by 3D models in virtual reality. Supplementary files

These materials supplement our paper "The human splenic microcirculation is entirely open as shown by 3D models in virtual reality".

Summary

The human spleen is equipped with an organ-specific microcirculation. The initial part of the venous circulation is formed by spleen-specific large microvessels, the sinuses. Sinuses eventually fuse to form venules and veins. For more than 170 years there have been debates, whether splenic red pulp capillaries join sinuses, i.e., whether the microcirculation is closed or open - or even simultaneously closed and open. We have now solved this question by three-dimensional reconstruction of a limited number of immunostained serial sections of red and white pulp areas, which were visualized in virtual reality. Splenic capillaries have special end structures exhibiting multiple small diverging endothelial cell processes, which always keep a certain distance to the walls of sinuses. Only very few capillary ends were difficult to diagnose. Positive identification of these end structures permits to conclude that the human splenic microcirculation is entirely open. This is also true for the perifollicular capillary network and for capillaries close to red pulp venules. Follicles are supplied by a relatively dense open perifollicular capillary net, which is primarily, but not exclusively, fed by sheathed and few non- sheathed capillaries from the surrounding red pulp network.

Interactive models

Each file_sX.zip contains a 3D model, registered sequence of serial sections (the input data to generate and validate the model), and an interactive / VR viewer. After you have unzipped the file, there are multiple batch files. Any of them can be used for an interactive model display on a normal monitor, but we recommend the file start_index.bat. Now, if you have a virtual reality headset or a 4K monitor, there are better options:

• If you have a HTC Vive-compatible headset (i.e., the "wand" controllers, typically coming with HTC Vive, Vive Pro, Vive Pro 2, etc.), please use start_vive.bat.
• If you have a Valve Index headset (i.e., the "knuckles" controllers, should also work with Oculus devices), please use start_index.bat.
• If you have a high-resolution monitor (4K or better), please use start_interactive_4k.bat for a high-resolution interactive model.

In the zip-file is also a README.txt file with instructions on the controls for the interactive and VR viewer. It is also available in the viewer at press of F1 button. In a nutshell: 

• ASWD control the movement
• I (the "i" key) turns the sections on and off
• JK advance the sections
• CV adjust the height
• E turns the model on and off.

The viewer executables are built for Windows. They work with Windows 10, should work with previous versions of Windows (64 bit) and also with future versions, such as Windows 11. Users of other OS, such as MacOS or Linux, can use MeshLab to look at the model. Any image viewer can be used to inspect the sections in the img folder of the unpacked zip file. However, in this case, no VR experience and no simultaneous view of both 3D reconstruction and the sections is possible.

Videos

The videos with the same content are mostly supplied in three versions:

• On any modern hardware you should be able to play the H.265 videos, ending in ...4K_h265_10bit.mov, there are in 4K resolution
• If it is not the case, but you want 4K resolution, use the H.264 version, ending in  ...4K_h264_10bit.mov, it is also in 10 bit quality
• A fallback for weaker hardware and maximal compatibility is the H.264 FullHD version. It should play anywhere. Those files end in ...1080p_h264.mov.

Supplementary Figures S1 and S2

The supplementary figures with their legends are available in the file supp.pdf.

3D models corresponding to Figs. 4a-d

Supplementary file S1. 3D model of ROI 1 with open capillary ends in red

Supplementary file S2. 3D model of ROI 2 with open capillary ends in red

Supplementary file S3. 3D model of ROI 3 with open capillary ends in red

Supplementary file S4. 3D model of ROI 4 with open capillary ends in red

File corresponding to Fig. 7a

Supplementary file S5. 3D model of sinus network and open capillary ends in red

Files corresponding to Figs. 9a,b

Supplementary file S6. 3D model of ROI 2 with perifollicular capillary network in red correspondig to Fig. 9a

Supplementary file S7. 3D model of ROI 2 with perifollicular capillary network in red and open ends in yellow corresponding to Fig. 9b

Videos corresponding to Figs 5a-f

Supplementary video S1. Two capillaries with open ends in Fig. 5a-c

Supplementary video S2. Capillary with at least two open ends in Fig. 5d-f

Videos corresponding to Figs 6a-d

Supplementary video S3. Quality control of open ends shown in Fig. 5a-c and Fig. 6a,b

Supplementary video S4. Quality control of open end shown in Fig 5d-f and Fig. 6c,d

Videos corresponding to Fig. 4d and Figs 8a-f

Supplementary video S5. Control of open capillary end shown in Fig. 8a-c

Supplementary video S6. Control of open capillary end shown in Fig. 8d-f