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Are Glands Present in Goose Pancreatic Ducts?A Light Microscope Study

Nurhayat Gulmez

Division of Histology and Embryology, Veterinary Faculty, Kafkas University. Kars, Turkey

ABSTRACT

Objective The objective of the present studywas to investigate the histological structure ofgoose pancreatic ducts.

Design Tissue samples from the lobes andducts of the pancreas were dissected underdeep ether anesthesia.

Interventions Sections were stained usingCrossmon’s connective tissue method forgeneral observations and Gomori’s methodfor pancreatic islet cells.

Results The glands were found intermittentlyinside the connective tissue of the ductsstarting from the interlobular ducts to thepoint where the pancreas emptied its contentsinto the duodenum as well as inside themuscular layer of the pancreatic ducts. Thoseglands contained centro-acinar cells and alsohad the same staining features as the acinus.

Conclusions To our knowledge, this was thefirst report of the presence of glands in theducts of goose pancreas.

INTRODUCTION

The avian pancreas is located on the right sideof the abdominal cavity in all birds. It istightly bound by mesentery and blood vesselspositioned between the descending and theascending duodenal loops [1]. It is composedof two main lobes, dorsal and ventral, which

extend from the apex of the duodenal loop tothe point where the pancreatic ducts enter thedistal duodenum. Another smaller lobe,extending from the head of the pancreastowards the spleen has been termed as thesplenic lobe [2]. A further subdivision of thelobes of the pancreas has been made byMikami and Ono [3] who divide the ventrallobe into the ventral lobe proper and the thirdlobe on the basis of the latter’s independentform and peculiar distribution of islets. Bothdorsal and ventral lobes have ducts extendingalmost the full length of their course and thereis also a third, smaller duct leading from thethird lobe. Pancreatic ducts from the acinus tothe point where it empties its contents into theduodenum are arranged in following order:intercalated ducts (the smallest in size),intralobular ducts, interlobular ducts andpancreatic ducts (main ducts) [4, 5]. Theobjective of the present study was toinvestigate the histological structure of goosepancreatic ducts.

MATERIALS AND METHODS

Five adult geese (Anser anser) obtained fromthe Kafkas University Veterinary FacultyFarm were used in the current study. Tissuesamples from the lobes and ducts of thepancreas were dissected under deep etheranesthesia. Samples were fixed in Bouin’sfluid and then routinely processed forembedding in paraffin. Tissue blocks were cutinto 6-micrometer thick sections using amicrotome. The sections were stained usingCrossmon’s connective tissue method for

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general observations and Gomori’s methodfor pancreatic islet cells.

ETHICS

Tissues were harvested in compliance with anapproved Kafkas University Animal Care andUse Committee Protocol.

RESULTS

In the present study, the goose pancreas wasfound to be located between the duodenalloops and had dorsal, ventral, third andsplenic lobes. All the pancreatic lobes had

their own intercalated ducts, intralobularducts (Figure 1) and interlobular ducts (Figure2). In addition, there were only two mainducts (dorsal and ventral pancreatic ducts)extending from the pancreas (Figure 3) to thepoint where it emptied its contents into theduodenum.Intercalated ducts lined with a simpleflattened epithelium reach intralobular ductslined with tall columnar epithelium.Intralobular and interlobular ducts arecomposed of two main tissues, a columnarepithelium which lines up inside the ducts andconnective tissue surrounding outside theducts. Furthermore, interlobular ducts havethin muscle layers surrounding the connectivetissue. However, the main ducts of thepancreas are composed of three layers: first,the mucosa lined with columnar epithelialtissue, then inside longitudinally and outsidecircularly arranged muscle tissue and, finally,externally adventitial connective tissue.Furthermore, basophilic staining on the apicalsurface of the goose pancreatic ducts startingfrom the interlobular ducts (Figure 2) to thepancreatic ducts (Figures 3 and 4) indicatespossible secreting functions of those tissues.Interestingly, the glands were foundintermittently inside the connective tissue ofthe ducts starting from the interlobular ducts(Figure 2) to the point where the pancreasemptied its contents into the duodenum

Figure 1. Intralobular duct (D). Centro-acinar cells(arrows). Crossmon’s staining method (Bar: 50 µm).

Figure 2. Glands (G) in the interlobular duct andbasophil staining on the apical surface of the ductusepithelium (arrows), indicating secretory functions ofthese cells. Gomori’s staining method (Bar: 100 µm).

Figure 3. Glands (G) inside the connective andmuscular tissues of the pancreatic duct and their owninterlobular ducts (arrow heads). Gomori’s stainingmethod (Bar: 200 µm).

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(Figure 5) as well as inside the muscular layerof the pancreatic ducts (Figure 3). Thoseglands contained centro-acinar cells (Figure6) and also had the same staining features asthe acinus. Moreover, those glands had theirown intercalated ducts (Figure 4), intralobularducts (Figure 5) and interlobular ducts (Figure3). It appeared that the glands inside the wallof the ducts were structurally similar to theexocrine part of the goose pancreas.Furthermore, no endocrine island was noticedamong those glands.

DISCUSSION

We found that the goose pancreas, as in otheravian species [2], was located between the

duodenal loops and had dorsal, ventral, thirdand splenic lobes. Mikami and Ono [3]demonstrated that the dorsal, ventral and thirdlobes had their own ducts, whereas Mc Leodet al. [6] showed that the third lobeoccasionally consisted of its own duct.Additionally, it was shown that there wereusually two pancreatic ducts (main ducts) inthe goose pancreas, even though the presenceof a third one was reported [7].We also demonstrated that, in the goosepancreas, there were only two main ductsextending from the pancreas to the duodenum.This finding is in agreement with the resultsof Mc Leod et al. [6], and Nickel-Schummerand Seiferle [7].The structure of the goose exocrine glandsfound in the present study agrees with theresults of previous studies [3, 4, 8, 9, 10]. Infact, as in other vertebrates, the avianpancreas was mainly composed of exocrineglands (about 99%), [3, 8]. Those glandsconsisted of tall columnar epithelial tissueswhich had acidophilic zymogen granules ontheir apical surface [4, 9, 10]. Moreover,small centro-acinar cells without granuleswere observed in the central lumen of theacinus [10].The structure of the ducts in the goosepancreas was found to be similar to thatdescribed in previous studies [4, 11]. Inaddition, the presence of basophilic stainingon the apical surface of the goose pancreatic

Figure 4. Intercalated duct (arrow) inside the glands ofthe pancreatic duct. Gomori’s staining method (Bar: 50µm).

Figure 5. Glands and their own intralobular duct(arrow head) inside the wall of the pancreatic ductwhere it opens into the duodenum,. Arrows indicateintestinal glands (Liberkuhn). Crossmon’s stainingmethod (Bar: 100 µm).

Figure 6. Centro-acinar cells (arrows) inside the glandsof the interlobular duct. Crossmon’s staining method(Bar: 50 µm).

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ducts starting from the interlobular ducts tothe pancreatic ducts was also found inchickens [12].To our knowledge, this was the first report ofthe presence of glands in the ducts of thegoose pancreas. Thus, it would be of interestto study in more detail the structure of thoseglands using either electron microscopic orimmunohistochemical techniques to clarifytheir possible functions.

Received January 24th, 2003 - Accepted April10th, 2003

Keywords Anatomy; Animal; AnimalStructures; Endocrine Glands; Geese;Histology; Histology, Comparative; Islets ofLangerhans; Microscopy; Pancreas;Pancreatic Ducts

CorrespondenceNurhayat GulmezKafkas ÜniversitesiVeteriner FakültesiHistoloji-Embriyoloji Anabilim DalıKars, 36100TurkeyPhone: +90-474-242.6800 Ext: 1121Fax: +90-474-242.6853E-mail address: ngulmez@hotmail.com

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