Comparative Histology and Histochemistry of the Gastric Glands of Cats and Dogs

Okajimas Folia Anat. Jpn., 67 (4): 249-256, October 1990

Taizo SHIBATA, Masatake IMAI, Keiichi MORIGUCHI and Yoshihiko TAKADA

Department of Anatomy, Kanazawa Medical University, Uchinada-machi, Kahoku-gun, Ishikawa, 920-02 Japan

-Received for Publication, March 23, 1990-

Key words: Gastric glands, Comparative studies, Cat, Dog

Summary: We performed histological and histochemical investigations on the gastric glands of cats and dogs. So-called cardiac glands in the cat and dog have a small number of the parietal cells and the PAS-positive glandular cells in the base of these glands contain fine pepsinogen granules. Consequently, we consider them as undifferentiated gastric glands, and can find no differences between these glands in both animals. The immature chief cells in the cat gastric glands are distributed not only in the glandular body but also in the base of the glands and contain sialomucin, and weak and strong acid mucopolysaccharides. The mature chief cells in cat and dog gastric glands contain weak and strong acid mucopolysaccharides. The gastric gland region of the dog is divided into clear and dark zones, and structural differences between the two zones are recognizable. Namely, the chief cells in the glandular base in the clear zone are somewhat undifferentiated, while the chief cells in the middle and lower parts of the glandular body and those in the glandular base in the dark zone are perfectly differentiated. The structure of the gastric glands in the fundic and greater and lesser curvature regions in the cat is very similar.

We performed histological and histochemical investi- Short simple tubular glands (Fig. 9) in the above- gations on so-called cardiac glands and gastric glands mentioned region were called cardiac glands. A small in the cat and the dog and found some differences number of parietal cells are distributed in those glands between the animals. (Figs. 2 and 11). Glandular cells in the base of the glands reacted moderately or strongly to PAS , negatively or very weakly to AB(pH 2.5 and 0.5) and contained a Materials and Methods fairly large number of fine pepsinogen granules (Figs . 1 and 10). Five adult cats and seven adult dogs were used. The cats were killed with chloroform anesthesia, and the II. Gastric glands located several millimeters away dogs were killed with a rapid intravenous injection of from the esophageal orifice of the cat . about 1.5cc Nembutal. Samples were taken in as fresh The glandular cells in the basal portion of the glands a state as possible from the cardiac, fundic and greater were PAS-negative (Fig. 3), reacted moderately or and lesser curvature regions of the cat; and the cardiac strongly to AB(pH 2.5 and 0.5) (Figs . 4 and 5), region, including the esophageal end and clear and dark presented a dark color of AB with PAS-AB(pH 2.5) zones of the dog, and fixed in buffered formalin. The stain (Fig. 6) and contained a large number of dark blue tissues were embedded in paraffin and cut into sections coarse pepsinogen granules (Fig. 7). A number of PAS- of about 6 p in thickness. PAS, AB(pH 2.5 and 0.5) negative cells were found in the lower portion of the and PAS-AB(pH 2.5) stains and Bowie's staining glandular body and they were slightly smaller than those method for pepsinogen granule analysis were employed. in the glandular base. A large number of moderately or strongly PAS- positive cells were distributed not only among the PAS- Observations negative cells but also in the glandular body (Fig . 3) and various stages of the PAS-positive substance 1. Glands in a narrow cardiac region neighboring the decrease were observed in the PAS-positive cells. c,,ophageal orifice of cat and dog. Moreover, these cells reacted weakly or moderately

24) 250 T. Shibata et al.

to AB(pH2.5 and 0.5), presented a light purple or violet and the strongly PAS-positive cells in the glandular base color with PAS-AB(pH 2.5) stain and contained small contain fine pepsinogen granules. Accordingly, these claret colored pepsinogen granules (Fig. 8). glands are not simple mucous glands but are undif- The pit depth of various regions in the gastric glands ferentiated gastric glands, and there are no differences was nearly the same. in the characteristics of the glands between cat and dog. Incidentally, there were no remarkable differences in the characteristics of the gastric glands located in II. Gastric glands in the cat. various regions. However, the PAS-positive cells were A large number of the PAS-positive cells are dis- large in number in the lesser and greater curvature tributed in the glandular body as well as in the base regions. of the glands, and various stages of the PAS-positive substance decrease were observed in these cells. They III. Glands in the clear zone of the dog. contain fine pepsinogen granules. Accordingly, these This zone is located several millimeters away from cells are immature chief cells. The distribution of a large the esophageal orifice. The gastric pits were deep and number of these immature chief cells in the glandular occupied about half the thickness of the mucous mem- base is one of the important characteristics of the cat brane. Consequently, the gastric glands were short (Fig. gastric gland. 12). The mucous neck cells and cells in the glandular PAS-negative cells are usually distributed in the body reacted strongly to PAS (Fig. 12); the former was glandular base. In addition, a number of fairly small violet and the latter was deep red with PAS-AB(pH 2.5) PAS-negative cells are found in the lower portion of stain (Fig. 18). Both contained fine, claret colored the glandular body. These PAS-negative cells contain pepsinogen granules. PAS-positive cells in the glandular a large number of coarse pepsinogen granules. They are body reacted moderately to AB(pH 2.5 and 0.5) (Figs. mature chief cells, and the above-mentioned immature 14 and 16). Occasionally, these cells were also chief cells are distributed among the mature chief cells. distributed in the glandular base. Moderate or strong reaction to AB(pH 2.5 and 0.5) in Cells in the glandular base were nearly all PAS- the mature chief cells is a very important characteristic negative (Fig. 12). However, they contained a large of the cat gastric gland. number of small PAS-positive granules (Fig. 19) and The pit depth is almost the same in the various fine light blue pepsinogen granules (Fig. 21). These cells regions of the gastric glands. This differs from the same reacted negatively or weakly to AB(pH 2.5 and 0.5), glands in the dog. presented a light color of AB and granules were violet with PAS-AB(pH 2.5) stain (Figs. 18 and 19). III. Gastric glands in the clear zone of the dog. Glandular clels in the basal part of the gastric glands IV. Glands in the dark zone of the dog. are nearly all PAS-negative, however, contain a number This zone is situated between the clear zone and the of PAS-positive coarse granules exhibited sialomucin pyloric gland zone. The gastric pits in this area were reaction. They also contain a large number of fine very shallow. Accordingly, the glands occupied a great pepsinogen granules. portion of the mucous membrane (Fig. 13). Cells in the The PAS-positive substance in the immature chief basal part of the glands and those in the middle and cells reduces in quantity due to their progressive lower parts of the glandular body were PAS-negative differentiation, and they change into PAS-negative (Fig. 13). They reacted weakly or moderately to AB(pH mature chief cells in swine2), horses4), cats5i7), dogs6), 2.5 and 0.5) (Figs. 15 and 17), presented a light color cows, rabbits, rats and mice (unpublished) and, occa- of AB with PAS-AB(pH 2.5) stain (Fig. 20) and con- sionally, in humans3). However, the glandular cells in tained a large number of coarse dark blue pepsinogen the basal portion of the glands in humans3), Japanese granules (Fig. 22). macaques') and crab-eating monkeys" react weakly to The mucous neck cells and cells in the upper part PAS. of the glandular body reacted strongly to PAS (Fig. 13). We consider that the perfectly differentiated chief The former were violet and the latter were deep red with cells (mature chief cells) are PAS-negative. Accordingly, PAS-AB(pH 2.5) stain (Fig. 20); both contained fine the chief cells in the glandular base of humans and pepsinogen granules. macaques and the same cells distributed in the clear zone of the dog remain in imperfect differentiation. Incidentally, the PAS reaction in midi fferciitiatecl chief Discussion cells of man fficl macaque appcats ccinally in the cytoplasm, while the PAS-positi% in tit,' (kw 1. The simple tubular glands distributed in a narrow is n1nh1lllOFifl. cardiac region neighboring the esophageal orifice of the Occasiorrillv, PAS-puni\ c cells HI liii iiiic eat and the dog ha‘,(2 ;1 1);11tual gI(IIIII1c, ;II(' lowid ;iiiwtir IR 1,,,\( 10(11 Comparative Histology and Histochemistry of the Gastric Glands of Cats and Dogs 251 tioned imperfectly differentiated chief cells in the clear and present a color of violet with PAS-AB(pH 2.5) zone of the dog. These cells are immature chief cells stain. This means that those cells contain sialomucin and are usually distributed in the glandular body. and weak and strong acid mucopolysaccharides. We Therefore, we presume that the clear zone in the dog know from our investigations on the above-mentioned is an area of undifferentiated chief cells. matter, that the same cells in the macaque!), swine2), human3), horse4) and dog6) have no mucosubstances IV. Gastric glands in the dark zone of the dog. similar to those in the cat. Accordingly, the immature Gastric pits in the dark zone are shallow and the chief cells of the cat and dog, which belong to the Order glands are long. Glandular cells distributed in the basal Carnivora, show characteristics which are different part of the glands and those in the middle and lower from those of the other animals investigated above. parts of the glandular body are PAS-negative and contain a number of coarse dark blue pepsinogen granules. These cells are perfectly differentiated mature chief References cells. Accordingly, the mature chief cells in the dark zone possess a wide distribution area, and this zone is 1) Imai, M., Shibata,T. and Shimano,J.: Do the CardiacGlands Exist? 1. The macaque.Okajimas Fol. Anat. Jpn., 64: 59-70, a zone of more differentiated chief cells than the clear 1987. zone. 2) Imai, M., Shibata, T. and Moriguchi, K.: Do the Cardiac The imperfectly differentiated chief cells in the clear Glands Exist? 2. The swine.Okajimas Fol. Anat. Jpn., 65: zone of the dog gastric glands react negatively or weakly 19-28,1988. to AB(pH 2.5 and 0.5); the mature chief cells in the 3) Imai, M., Shibata,T., Moriguchi,K. and Yamamoto,M.: Do the Cardiac Glands Exist? 3. Humans. Okajimas Fol. Anat. dark zone react weakly or moderately to AB(pH 2.5 Jpn., 66: 51-70,1988. and 0.5). However, the mature chief cells in the cat react 4) Imai, M., Shibata, T. and Moriguchi,K.: Do the Cardiac moderately or strongly to the same AB. Such reactions Glands Exist? 4. The horse. Okajimas Fol. Anat. Jpn., 66: were not seen in our investigations on the Japanese 245-254,1988. macaque°, crab-eating macaque°, swine2), humans3), 5) Imai, M., Shibata,T., Moriguchi,K. and Kinbara,M.: A New DifferentiationType of the Chief Cells in the Cat Gastric horse4), cow, rabbit, rat and mouse (unpublished). Gland. Okajimas Folia Anat. Jpn., 66: 161-170,1989. These are very interesting characteristics in the cat and 6) Imai, M., Shibata,T., Moriguchi,K. and Yamamoto,M.: Do dog, which belong to the Order Carnivora. the Cardiac GlandsExist? 5. The Dog. OkajimasFol. Anat. All PAS-positive cells (immature chief cells) Jpn., 66: 363-371,1990. distributed in the body and basal portions of the cat 7) Imai, M., Shibata, T., Moriguchi, K., Yamamoto, M. and Kinbara, M.: Do the Cardiac Glands Exist? 6. The Cat. gastric glands react moderately to AB(pH 2.5 and 0.5) Okajimas Fol. Anat. Jpn., 67: 31-36, 1990. 252 T. Shibata et al.

Explanation of Figures

Plate I

(All relate to cat)

Fig. 1. Pepsinogen granules in the so-called cardiac glands. Bowie's staining method for pepsinogen granules. x 825 Fig. 2. Parietal cells in the so-called cardiac glands. PAS stain. x 230 A: Esophageal epithelium. B: Gastric pit. : parietal cell. Fig. 3. Gastric glandular cells in the fundic region react strongly to PAS (immature chief cells). These cells are distributed not only in the glandular body but also in the base of glands. PAS stain. x 57.5 : PAS-negative cells (mature chief cells). Fig. 4. Gastric glands in the fundic region. PAS-positive cells in the body and base of the glands react weakly or moderately to AB(pH 2.5), PAS-negative cells in the glandular base react moderately or strongly to the same stain. AB(pH 2.5) stain. x 82.5 Fig. 5. Gastric glands in the fundic region. The same glandular cells in Fig. 4 react the same to AB(pH0.5). AB(pH 0.5) stain. x 82.5 Fig. 6. Gastric glands in the fundic region. PAS-positive cells (immature chief cells) present light purple or violet (A) with PAS-AB (pH 2.5) stain. PAS-negative cells (mature chief cells) present dark color of AB(B) with the same stain. x 57 Fig. 7. PAS-negative cells (mature chief cells) contain a large number of coarse dark blue pepsinogen granules. Bowie's staining method for pepsinogen granules. x 575 Fig. 8. PAS-positive cells (immature chief cells) contain some fine claret-colored pepsinogen granules ( t). Bowie's staining method for pepsinogen granules. x 575 Comparative Histology and Histochemistry of the Gastric Glands of Cats and Dogs 253 Plate I 254 T. Shibata et al.

Plate II

(All relate to dog) Fig. 9. So-calledcardiac glands(A). Allgrandular cellsreact stronglyto PAS. Someesophageal glands (B) are distributedin the cardiac regions. PAS stain. x 25 f : Esophagocardiacjunction. Fig. 10. Pepsinogengranules in the so-calledcardiac glands. Bowie's staining method for pepsinogengranules . x 825 Fig. 11. Parietal cells in the so-calledcardiac glands. PAS stain. x 230 A: Esophagealepithelium. t : Parietal cell. Fig. 12. Gastric glands in the clear zone. Gastric pits are deep and immature chief cell zone is thick. Zimmermannstain. x 57.5 A: Mucous neck cells. B: Immature chief cells in the glandular body. C: Mature chief cellsin the glandular base. Fig. 13. Gastric glands in the dark zone. Gastric pits are shallow.Immature chief cell zone is thin and mature chief cell zone is very thick. Zimmermann stain. x 57.5 A: Mucous neck cells. B: Immature chief cells in the upper portion of the glandular body. C: Mature chief cells in the middle and lower portions of the glandular body. D: Mature chief cells in the glandular base. Fig. 14. Gastric glands in the clear zone. Immature chief cells react moderatelyto AB(pH 2.5). AB(pH 2.5) stain. x 82.5 Fig. 15. Gastric glandsin the dark zone. Cellsin the glandular base and those in the middle and lower parts of the glandularbody react weakly or moderatelyto AB(pH 2.5). AB(pH 2.5) stain. x 82.5 Fig. 16. Gastric glandsin the clearzone. Cellsdistributed in the lowerportions of the glands react weaklyor moderatelyto AB(pH0.5). A B(pH 0.5) stain. x 82.5 Comparative Histology and Histochemistry of the Gastric Glands of Cats and Dogs 255

Plate II 256 T. Shibata et al.

Plate III

(All relate to dog)

Fig. 17. Gastric glands in the dark zone. Cells distributed in the lower portions of the glands react weakly or moderately to AB(pH 0.5). AB(pH 0.5) stain. x 82.5 Fig. 18. Gastric glands in the clear zone. Mucous neck cells are violet, cells in the glandular body (immature chief cells) are deep red, and mature chief cells present a light color of AB with PAS-AB(pH 2.5) stain. x 82.5 A: Immature chief cells. B: Mature chief cells. Fig. 19. Somewhat undifferentiated mature chief cells in the clear zone contained a large number of fine granules. These present a color of violet with PAS-AB(pH 2.5) stain. x 825 Fig. 20. Gastric glands in the dark zone. Mature chief cells (B) present a light color of AB with PAS-AB(pH 2.5) stain; immature chief cells (A) are deep red with the same stain. PAS-AB(pH 2.5) stain. x 57.5 Fig. 21. Pepsinogen granules in undifferentiated mature chief cells. They are smaller than those in the mature chief cells in the dark zone (Fig. 22). Bowie's staining method for pepsinogen granules. x 825 Fig. 22. Pepsinogen granules in the mature chief cells in the dark zone. Bowie's staining method for pepsinogen granules. x 825