BACKGROUND
BACKGROUND
Studies about the uptake and dissemination of PrPSc in natural scrapie showed that mucosal associated lymphoid tissues are the first organs contaminated. During the lymphoinvasion phase, the pathogen is amplified by follicular dendritic cells (FDCs) in the lymphoid follicles. It's generally well accepted that pathogens reach the central nervous system via an ascending propagation along the autonomic nervous system. Nevertheless, if Peyer's patches are well documented, the pattern of innervation in tonsils is poorly described.
OBJECTIVE
OBJECTIVE
In this preliminary approach, we examined the topography of the pattern of innervation in ovine tonsils, first potent target sites for the disease-causing agents replication.
MATERIAL AND METHODS
MATERIAL AND METHODS
Palatine and pharyngeal tonsils were removed from healthy sheep of which the race, age and PrP genotype are known. Cryosections were processed for immunohistochemistry and incubated in a range of primary antibodies directed against neurofilaments, sympathetic nerve fibres and glial cells.
Distribution and frequency of nerves fibres in palatine and
Distribution and frequency of nerves fibres in palatine and
pharyngeal tonsils.
pharyngeal tonsils.
Targets Primary Antibodies Peroxidase Secondary Antibodies Fluorescent Secondary Antibodies FDCs FDC-B1 mouse anti-bovine AEC kit goat anti-mouse Alexa 546 goat anti-mouse Neurofilaments H Anti-Neurofilaments H AEC kit Goat anti-rabbit Alexa 488 goat anti-rabbit Neurofilaments L Anti-Neurofilaments L Neurofilaments M Anti-Neurofilaments M Giail cells Anti -GFAP Sympathetic
fibres
Anti- thyrosine hydroxilase
Lymphoid Follicles
FDCs Peripheral nerves fibres
Central
Nervous
System
?
RESULTS
RESULTS
Our preliminary results detect the presence of nerves fibres inside the palatine and pharyngeal tonsils. The lymphoid compartments seem to be poorly innervated. Nevertheless, rare contacts between nerve fibres and FDC network have been demonstrated. To complete our overview of the innervation of tonsils, researches are carried out on sheeps of different ages and genotypes, in order to point out how these parametres influence the innervation pattern and the rate of contacts between nerves fibres and FDCs.
Toppets V1, Piret J1, Defaweux V2, Dorban G2, , Grobet L1, Antoine N1.
1. Department of Morphology and Pathology (DMP), Laboratory of Animal Histology and Embryology, Faculty of Veterinary Medicine (FMV), University of Liege (Ulg), Belgium; 2. Laboratory of Human Histology, Faculty of Medicine, ULg, Belgium.
Graph 1
Graph 2
Palatine tonsil. Th+ fibres (red) are located in the interfollicular
area. Gx100 (b) (c) (d)
After quantitative analyses on palatine and pharyngeal tonsils, it appears that the lymphoid compartments are poorly innervated. The majority of nerves fibres were located in the connective tissue surrounding these organs. Some TH (a) and GFAP (b) positive fibres and in less proportion, heavy neurofilaments (c) were detected in the interfollicular area. Occasionally, they were present in the mantle zone and in the germinal centre of lymphoid follicles. Neurofilaments L and M were almost absent in the lymphoïd tissues.
(d) Some proven contacts (yellow fluorescence points) between FDCs and GFAP+ fibres were highlighted by a combined approach of image and spectral analyses.
CONCLUSION
CONCLUSION
(a)Pharyngeal tonsil. GFAP+ fibres (red) are located in the interfollicular area. Gx200.
Pharyngeal tonsil. Immunofluorescence. GFAP+ fibres (green) overlap FDCs network (red). Contacts between both structures is prooven by the superposition of the peaks of fluorescence (graph1: green; graph 2: red). Gx800. Pharyngeal tonsil.
Immunofluorescence.The FDC network (red) is located exclusively in the germinal centre of the follicle. Neurofilaments H+ (green) run between the follicles. Gx400.
