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.
Odaka
Chikako
C
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
Morisada
Tohru
T
Oike
Yuichi
Y
Suda
Toshio
T
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