Ectopic Pancreas in the Liver of Rat by MikeJenny

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                             Ectopic Pancreas in the Liver of a Rat
                                  G. Briziarelli and J. A. Tornaben
                                       Vet Pathol 1972 9: 263
                                 DOI: 10.1177/030098587200900405

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Vet. Path 9: 263-265 (1972)




                  Ectopic Pancreas in the Liver of a Rat

                        G. BRIZIARELLI J. A. TORNABEN
                                     and

  Department of Toxicology, Warner-Lambert Research Institute, Morris Plains, N.J.




   Abstmct. Aberrant pancreatic tissue is not rarely encountered in man but has seldom
been reported in thc lower animals. I t has been described in a domestic cat, a cynomologus
monkey and in dogs. Among the several thousands of rats he examined, BARRONfound
only one instance of aberrant pancreatic tissue which was seen in the duodenal subniucosa.
The present report is the first description of aberrant pancreatic tissue in the liver of a rat.

    Ectopic pancreas has been described as an incidental operative or aiia-
tomical finding both in man and lower animals. Usually it is represented by
yellow-gray single or multiple nodules that are generally located i n the sub-
niucosa of the stomach and duodenum and less frequently i n the Meckel's
diverticulum, mesentery and biliary tract. The aberration may also consist
of the dislocation of single exocrine pancreatic cells among the duodenal
and pyloric glands of man, horse, rabbit and pig [4].
    Ectopic pancreas has little clinical significance, but inflammatory o r
mechanical effects of the aberrant tissue may cause clinical signs ; malignant
transformation has not been established [I 11. Histologically, the tissue is the
same as normal pancreas except that the islets of Langerhans may be absent.
The excretory ducts open on the surface of the mucosa but they are seldom
seen i n animals [lo].
    Ectopic pancreas is found in about 2'%,of all routine autopsies of humans
[12], but it has rarely been reported in the lower animals. The aberration
has been described in the spleen of a domestic cat [7] and along the prim-
ordial hepatic canal in an embryo of a monkey, Cercncebus cynomologus [ 5 ] .
I n this latter case, it had the form of a protuberance, but 110 histological
examination was made. Dogs seem to be more frequently affected; the gall-
bladder [6, 91, the mesentery [8], the ileum [3], and the duodenum [ I ] were
the sites involved.




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264




                   Fig. I . Cluster of pancreatic acini in thc liver of a rat.




            [2]
    BARRON reported one case of ectopic pancreas among several thousand
rats (Charles River and Long Evans strains) that he examined; the misplaced
tissue was seen grossly and microscopically i n the duodenal submucosa.




    A fciiialc weanling rat ( W i s h strain) used in a short term experiment was a~itopsied
at 45 days of age. Samples of all organs and lissues incl~idingspecimens from all liver
lobes wcrc taken for liistological examination. These were fixed in neutral buffered 10%
formalin, embedded in paraffin, c ~ i tat 5 Lini and stained with heniatoxylin and cosin.
    Tlie liver had the normal lobular architectiire characterized by cords of cells radially
arrangcd around the corresponding central vcin. Tlie liver cells, most of which wcrc poly-
gonal, had a finely gran~ilatedcytoplasm. The round nuclei contained dispersed chromatin
and onc to thrce nuclcoli. Adjacent to a vasciilar space, C L I ~longitudinally, a cluster of
acini was sccn (fig. I). It was formed by triangular cells with apices toward tlie center
of thc acini. The acidophilic cytoplasm was finely granulated, and the round darkly
staincd nuclci were located toward tlie base of the cells where the cytoplasm was soiiiewhat
less eosinophilic.




  The histological diagnosis of ectopic exocrine pancreas in the liver was
made. No excretory ducts were seen, although their presence is a natural




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                             Ectopic I'ancrcas in the Livcr o f a Rat                              265

corollary for exocrine organs. It is possible that the sections containing the
ducts were lost in the trimming of the paraifin block.
    The pathogenesis of this type of ectopia is believed to depend upon the
iiiaiiner of growth of the ventral pancreatic anlages, but the actual mechanism
of this development is not known.
    Aberrant pancreatic tissue has seldom been reported i n lower animals and
usually occurs in the duodenal submucosa. Therefore, the histological obser-
vation of this congenital aberration in the liver of a feiiiale rat represents a
rarity that, to our knowledge, has never been previously described.




  I BAIIIION, N.: Ectopic pancreas in the dog. Acta anat. 36: 344-352 (1959).
                C.
 2 BARICON, N . : Ectopic pancreas in the I-at. Path. Vet. 7;81-83 (1970).
                C.
 3 BOLDYICI.FF, E. B.: Rcpoi-t on an accessory pancreas in thc ilcum o f a dog. Anat. Rcc.
    43: 57-61 (1929).
 4 B U R K L , W. : u bcr ortsfrciiidc Pancreaszcllcn in den Pylorusdriisen bciiii Mcnschen.
    Virchows Arch. path. Anat. 318: 268-288 (1950).
 5 DEB~YIII,, : Pancreas accessoire chcz Cercochc.s ( . ? ' r i o / i i o k ) , ~ ~ ~ c .Bibl. Anat. 14:
                  A.                                                                     s.
    21 1-213 (1905).
 6 HIGGINS, . M.: A n abci-rant pancreas in the wall of tlic gall bladder of the dog.
                  G
    Anal. Rec. 33: 149-161 (1926).
 7 KUNSTSCHIK, and SALZER, G . : cited by BARIION (1970).
                     R.
 8 M A N N , F. C.: A n accessory pancreas in the dog. Anat. Rcc. 19: 263-268 (1920).
 9 M A N N ,F. C.: A n acccssoi-y pancreas in the wall of thc gall bladder of a dog. Anat.
    Rec. 23: 351-353 (1922).
10 NIEBERLE,K . and COHRS, In Tcxtboolc of the special pathological anatomy of
                                    P.:
    domestic animals, p. 560 (Pergamon Press, Oxford 1967).
1 I PINCUS, J . : I n BOCKIJSGastroenterology; 2nd ed., vol. 3, p. 890 (Saunders, Phila-
               1.
    delphia 1965).
                 S.
12 ROBBINS, L.: I n Pathology, p. 965 (Saundcrs, Philadelphia 1967).




                                                        I,
A ~ i t l i o r ' address: Dr. G . B I I I Z I A R ~ L LDepartment or Toxicology, Warner-Lambcrt
                  ~
Research Instittitc, 170 Tabor Road, Mor.ris P/cci/i.s,N J 07950 ( U S A )




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