Abstract
Purpose :
To better understand the physiological function of the meibomian glands (MG), we tried to get deeper insights into the normal blood and lymphatic supply of the MGs of humans and mice using double immunohistochemistry and 3D reconstruction. As blood and lymph vessels are integral components of glandular tissues, fulfilling crucial roles in nutrient delivery, waste removal, immune surveillance, and overall tissue health, this may contribute to a better understanding of MG/MGD in the long run.
Methods :
Upper eyelids with MGs from body donors and from mice were analysed with antibodies. Preliminary tests showed that antibodies against von Willebrandt factor for blood vessels (BV) and podoplanin for lymphatic vessels (LV) worked best in human samples, while in mouse samples podocalyxin for BV and LYVE1 for LV were most successful. For the statistical analysis of immunofluorescence labelling, different structures within the tissue sections were measured with NDP.view2 to allow data comparison.
Results :
There were no significant differences in the number of BV and LV across different regions of the eyelid. However, noticeable variations in vessel size were observed. Vessels in the tarsus are smaller than in the loose connective tissue. The number of BV is greater than the number of LV, thus BV take up a larger proportion of the total area of the tarsus. Furthermore, in human tissue BV run closer to the surface than LV. The distance between the LV and the conjunctiva and the acini of the MGs is always greater than the distance between the BV. A comparison between different donors showed clear differences in the average size of the blood and lymph vessels.
In mice, BV occurred in the entire depth of the eyelid, while LV were present almost exclusively under the conjunctiva and epidermis. Within the tarsus, LVs occur only sporadically, while BVs were also strongly present here. There were hardly any differences in the size of the vessels within the eyelid of different mice. A more superficial course of the BVs than the LVs under the conjunctiva could not be determined here. The distance between the BVs within the tarsus and the acini of the MGs is significantly smaller than the distance between the sporadic LVs.
Conclusions :
The results show clear differences between the species. In humans in particular, they form a basis for follow-up studies on possible changes in the blood and lymphatic vessel system in the context of MGD.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.