Distribution of lymphatic vessels in mouse thymus: immunofluorescence analysis.
Thymic blood and lymphatic vessels in humans and laboratory animals have been investigated in morphological studies. However, occasionally a clear distinction between blood vessels and lymphatic vessels cannot be made from morphological characteristics of the vasculature. To visualize thymic lymphatics in normal adult BALB/c mice, we used antibodies against specific markers of lymphatic endothelial cells. Expression of vascular endothelial growth factor receptor-3 (VEGFR-3) was detected throughout the thymus, i.e., the capsule, cortex, and medulla. Most thymic lymphatics were present in capillaries of ~20 mum in caliber. The plexuses of lymphatic capillaries were occasionally detectable. Lymphatic vessels were frequently adjacent to CD31-positive blood vessels, and some lymphatic vessels were seen in the immediate vicinity of or within the perivascular spaces around postcapillary venules. The identity of VEGFR-3-positive vessels as lymphatics was further confirmed by staining with additional markers: LYVE-1, Prox-1, neuropilin-2, and secondary lymphoid tissue chemokine (SLC). The distributions of LYVE-1 were similar to those of VEGFR-3. Most lymphatic vessels were also identified by Prox-1. Neuropilin-2 was restricted to lymphatic vessels in the thymus. The most abundant expression of SLC in the thymus was in medullar epithelial cells; SLC was also expressed in lymphatic vessels and blood vessels. Thus, lymphatic endothelium in mouse thymus was characterized by positive staining with antibodies to VEGFR-3, LYVE-1, Prox-1, neuropilin-2, or SLC, but not with an antibody to CD31. Our results suggest the presence of lymphatic capillary networks throughout the thymus.
Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan. odaka@nih.go.jp
Chikako
C
Odaka
Tohru
T
Morisada
Yuichi
Y
Oike
Toshio
T
Suda
D000818:Animals; D000906:Antibodies / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D054421:Chemokine CCL21; D019742:Chemokines, CC / Q000378:metabolism; D005260:Female; D006023:Glycoproteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D042601:Lymphatic Vessels / Q000276:immunology* / Q000378:metabolism; D008297:Male; D026901:Membrane Transport Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D039943:Neuropilin-2 / Q000378:metabolism; D013950:Thymus Gland / Q000098:blood supply* / Q000378:metabolism; D014018:Tissue Distribution; D025521:Tumor Suppressor Proteins; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000378:metabolism; D000098551:Prospero-Related Homeobox 1 Protein
D000906:Antibodies; D015415:Biomarkers; D054421:Chemokine CCL21; D019742:Chemokines, CC; D006023:Glycoproteins; D018398:Homeodomain Proteins; D026901:Membrane Transport Proteins; D039943:Neuropilin-2; D025521:Tumor Suppressor Proteins; D040321:Vascular Endothelial Growth Factor Receptor-3; D000098551:Prospero-Related Homeobox 1 Protein; C515479:Ccl21c protein, mouse; C492273:LYVE1 protein, mouse