Journal of Veterinary Medical Science
Vol. 70 (2008) , No. 3 March pp.251-254
[PDF (372K)] [References]
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Distribution of the Lingual Tonsils of Cattle Designated as Specified Risk
Materials
Keiko KATO1) and Yasushi SAWADA2)
1) Animal Care and Consultation Center, Bureau of Social Welfare and Public
Health, Tokyo Metropolitan Government
2) Shibaura Meat Sanitary Inspection Station, Bureau of Social Welfare and
Public Health, Tokyo Metropolitan Government
(Received 29-Aug-2007)
(Accepted 21-Nov-2007)
ABSTRACT. The tonsils of cattle, including palatine tonsils, pharyngeal
tonsils, tubal tonsils and lingual tonsils, are designated as specified risk
materials (SRM). However, the detailed distribution of lingual tonsils in
cattle is unknown. We therefore histologically examined their distribution
in 198 tongue specimens from cattle. The examinations confirmed that the
presence of lingual tonsils was limited to the tissue of the lamina propria
on the dorsal and lateral aspects of the tongue, not reaching the muscular
layer below. More than 90% of the lingual tonsils were located between the
distribution center of the vallate papillae and the radix linguae (root of
the tongue). However, they were also found in the area extending from the
lingual torus to the rostral-most vallate papilla in an individual,
suggesting that the complete removal of the lingual tonsils requires
elimination of the lamina propria extending from the lingual torus to the
radix linguae.
KEY WORDS: BSE, cattle, lingual tonsils, specified risk materials (SRM),
tongue
DISCUSSION
There are no published reports on the accumulation of
prion proteins (PrP) in the lingual tonsils of BSE-infected
cattle. However, the tonsils of sheep have shown infectivity
or prion accumulation in the case of natural scrapie [3]. For
this reason, EC Regulation 999/2001 specifies that the
tongue be cut at the lingual torus of the basihyoid bone to
avoid food contamination by lingual tonsils. Wells et al.
[11] reported that intracerebral inoculation of palatine tonsils
of cattle experimentally infected orally with BSE ten
months earlier caused BSE infection in other cattle. They
also pointed out the possibility that tonsils in general are
infective. Furthermore, they examined the distribution of
lingual tonsils in 100 British cattle tongues marketed for
consumption and reported that lingual tonsils were still histologically
observed in the tongues after removal of the
radix linguae. Similarly, Kühne et al. [5] histologically
examined the tongues of two cattle aged more than 18
months and reported that lingual tonsils were observed in
areas distant from the most caudal vallate papilla.
Our study found that 93.5% of the lingual tonsils were
distributed between the most caudal vallate papilla and the
intermediate position between this vallate papilla and the
most rostral vallate papilla. However, in rare cases, lingual
tonsils were located near the most rostral vallate papilla or
even toward the tip of the lingual torus. Thus, our results
reconfirmed past reports.
Moreover examination of lingual tonsils located on the
dorsal and lateral aspects of the tongue showed that the tonsils
were more commonly found on the lateral aspects of the
tongue than on the dorsal aspect, but that their distribution
was limited to the lamina propria and did not extend into the
muscular layer. This finding was confirmed by the fact that
no lingual tonsils were found in the specimens with preexposed
muscular layers. Based on our findings that specimens
from individuals more than 30 months old had a low
prevalence of detection of lingual tonsils, we suggest that
lingual tonsils may regress as animals? age.
Based on the above results, we conclude that the removal
of the lingual tonsils designated as SRM would be complete
if tongues are processed by completely removing the lamina
propria layer extending from the tip of the lingual torus to
the radix linguae on the dorsal and lateral aspects. The muscular
layer can be safely consumed due to its lack of lingual
tonsillar tissue.
The study was carried out with the cooperation of 18 meat
inspection centers nationwide. The representatives of the
centers are as follows: Kazunori Nakanishi (Asahikawa City
Meat Hygiene Inspection Center), Hiroya Oyamada (Towada
Meat Inspection Center, Aomori Prefecture), Kesayo
Saito (Kenpoku Meat Inspection Office, Tochigi Prefecture),
Naomi Onuki (Kensei Meat Inspection Office, Ibaraki
Prefecture), Susumu Mabara (Kennan Meat Inspection
Office, Ibaraki Prefecture), Masakazu Katayama/Kenji Ono
(Toso Meat Inspection Station, Chiba Prefecture), Miyuki
Hara (Yokohama City Meat Inspection Center), Aki Shimazaki
(Nagoya City Meat Inspection Center), Takayoshi
Oba (Toyama Prefectural Meat Inspection Center), Yoshinori
Kaji (Kanazawa City Meat Inspection Center), Keiko
Fujita (Gifu Prefectural Meat Inspection Office), Shoichi
Yamanaka (Matsusaka Meat Inspection Office, Mie Prefecture),
Tomoyuki Nakayama (Shiga Prefectural Meat Inspection
Office), Hanjiro Kitada (Osaka City Meat Inspection
Office), Kazuyuki Okahata (Nishiharima Meat Inspection
Office, Hyogo Prefecture), Daisuke Nozaki (Kobayashi
Meat Inspection Center, Miyazaki Prefecture), Koichi
Yamada / Junko Hamada (Sueyoshi Meat Inspection Center,
Kagoshima Prefecture), and Tomoyuki Nanba (Shibaura
Meat Sanitary Inspection Station, Tokyo Metropolitan Government).
full text ;
http://www.jstage.jst.go.jp/article/jvms/70/3/251/_pdf
TSS
Vol. 70 (2008) , No. 3 March pp.251-254
[PDF (372K)] [References]
----------------------------------------------------------------------------
----
Distribution of the Lingual Tonsils of Cattle Designated as Specified Risk
Materials
Keiko KATO1) and Yasushi SAWADA2)
1) Animal Care and Consultation Center, Bureau of Social Welfare and Public
Health, Tokyo Metropolitan Government
2) Shibaura Meat Sanitary Inspection Station, Bureau of Social Welfare and
Public Health, Tokyo Metropolitan Government
(Received 29-Aug-2007)
(Accepted 21-Nov-2007)
ABSTRACT. The tonsils of cattle, including palatine tonsils, pharyngeal
tonsils, tubal tonsils and lingual tonsils, are designated as specified risk
materials (SRM). However, the detailed distribution of lingual tonsils in
cattle is unknown. We therefore histologically examined their distribution
in 198 tongue specimens from cattle. The examinations confirmed that the
presence of lingual tonsils was limited to the tissue of the lamina propria
on the dorsal and lateral aspects of the tongue, not reaching the muscular
layer below. More than 90% of the lingual tonsils were located between the
distribution center of the vallate papillae and the radix linguae (root of
the tongue). However, they were also found in the area extending from the
lingual torus to the rostral-most vallate papilla in an individual,
suggesting that the complete removal of the lingual tonsils requires
elimination of the lamina propria extending from the lingual torus to the
radix linguae.
KEY WORDS: BSE, cattle, lingual tonsils, specified risk materials (SRM),
tongue
DISCUSSION
There are no published reports on the accumulation of
prion proteins (PrP) in the lingual tonsils of BSE-infected
cattle. However, the tonsils of sheep have shown infectivity
or prion accumulation in the case of natural scrapie [3]. For
this reason, EC Regulation 999/2001 specifies that the
tongue be cut at the lingual torus of the basihyoid bone to
avoid food contamination by lingual tonsils. Wells et al.
[11] reported that intracerebral inoculation of palatine tonsils
of cattle experimentally infected orally with BSE ten
months earlier caused BSE infection in other cattle. They
also pointed out the possibility that tonsils in general are
infective. Furthermore, they examined the distribution of
lingual tonsils in 100 British cattle tongues marketed for
consumption and reported that lingual tonsils were still histologically
observed in the tongues after removal of the
radix linguae. Similarly, Kühne et al. [5] histologically
examined the tongues of two cattle aged more than 18
months and reported that lingual tonsils were observed in
areas distant from the most caudal vallate papilla.
Our study found that 93.5% of the lingual tonsils were
distributed between the most caudal vallate papilla and the
intermediate position between this vallate papilla and the
most rostral vallate papilla. However, in rare cases, lingual
tonsils were located near the most rostral vallate papilla or
even toward the tip of the lingual torus. Thus, our results
reconfirmed past reports.
Moreover examination of lingual tonsils located on the
dorsal and lateral aspects of the tongue showed that the tonsils
were more commonly found on the lateral aspects of the
tongue than on the dorsal aspect, but that their distribution
was limited to the lamina propria and did not extend into the
muscular layer. This finding was confirmed by the fact that
no lingual tonsils were found in the specimens with preexposed
muscular layers. Based on our findings that specimens
from individuals more than 30 months old had a low
prevalence of detection of lingual tonsils, we suggest that
lingual tonsils may regress as animals? age.
Based on the above results, we conclude that the removal
of the lingual tonsils designated as SRM would be complete
if tongues are processed by completely removing the lamina
propria layer extending from the tip of the lingual torus to
the radix linguae on the dorsal and lateral aspects. The muscular
layer can be safely consumed due to its lack of lingual
tonsillar tissue.
The study was carried out with the cooperation of 18 meat
inspection centers nationwide. The representatives of the
centers are as follows: Kazunori Nakanishi (Asahikawa City
Meat Hygiene Inspection Center), Hiroya Oyamada (Towada
Meat Inspection Center, Aomori Prefecture), Kesayo
Saito (Kenpoku Meat Inspection Office, Tochigi Prefecture),
Naomi Onuki (Kensei Meat Inspection Office, Ibaraki
Prefecture), Susumu Mabara (Kennan Meat Inspection
Office, Ibaraki Prefecture), Masakazu Katayama/Kenji Ono
(Toso Meat Inspection Station, Chiba Prefecture), Miyuki
Hara (Yokohama City Meat Inspection Center), Aki Shimazaki
(Nagoya City Meat Inspection Center), Takayoshi
Oba (Toyama Prefectural Meat Inspection Center), Yoshinori
Kaji (Kanazawa City Meat Inspection Center), Keiko
Fujita (Gifu Prefectural Meat Inspection Office), Shoichi
Yamanaka (Matsusaka Meat Inspection Office, Mie Prefecture),
Tomoyuki Nakayama (Shiga Prefectural Meat Inspection
Office), Hanjiro Kitada (Osaka City Meat Inspection
Office), Kazuyuki Okahata (Nishiharima Meat Inspection
Office, Hyogo Prefecture), Daisuke Nozaki (Kobayashi
Meat Inspection Center, Miyazaki Prefecture), Koichi
Yamada / Junko Hamada (Sueyoshi Meat Inspection Center,
Kagoshima Prefecture), and Tomoyuki Nanba (Shibaura
Meat Sanitary Inspection Station, Tokyo Metropolitan Government).
full text ;
http://www.jstage.jst.go.jp/article/jvms/70/3/251/_pdf
TSS