الفهرس 
ACKNOWLEDGMENT
Embryonic gutOnly 14 pages are availabe for public view
 |  | from | 236 |  |  |
| | | from | 236 | | |
Abstract
The present work studied the development of the glandular stomach in the Japanese quail. It was carried out on 130 embryos. The collected material covered most of the embryonic stages. The main results obtained were summarized as follows:
►Concerning the stomach
-The primordium of the quail stomach appeared on the 2nd day of incubation as the most expanded part of the gut.
-On the 3rd day, the stomach was distinguished into two parts; a small cranial part (prospective glandular stomach) and a large caudal part (prospective muscular stomach).
►Concerning the compound glands
-The primordium of thecompoundproventricular glands appeared on the 4th day as evaginations of the lining epithelium.
-On the 6th day, the epithelium lining the glands was pseudostratified columnar in some areas and simple columnar in others with distinguished apical portions in the form of finger like projections.
-On the 7th day, the glands elongated and increased in number.Some of apical portions of the glandular epithelial cells sloughed off.
-On the 8th day,the proventricular glands began to branchwhile, on the 10th day, the primary duct of the gland divided into two secondary ones.
-On the 11th day, the proventricular glands became well established as multilobularcompound tubuloalveolar glands within the lamina propriaforming the thickest portion of the proventricular wall.
-On the 12th day, diffuse lymphocytic infiltration was observed in the lamina propria.
-On the 15th day, the secretory units of the compound glands became lined solely with simple cuboidal epithelium (oxynticopeptic cells) after the sloughing off the apical portions of the cells.
-On the 17th day, parts of the lining epithelium showed a dentate appearance.
►Concerning the simple tubular glands
- On the 11th day, the primordia of the simple tubular glands were detectedas localized down-growths of the luminal epithelial cells into the lamina propria forming solid cords. In the succeeding days, they increased in number and began to be canalized.On the 15th day, many of the simple tubular glands showed complete canalization,
►Concerning themucosal folds
- On the 8th day,mucosal folds with intervening depressions appeared.
- On the 11th day, the mucosal folds became more developed and the adjacent folds approached each other and connected to surround the openings of the proventricular glands forming the mucosal papillae.
- Onthe 15th day, more rings were added in concentric manner around mucosal papillae.
►Concerning theendocrine cells
- On the 7th day, an open-type endocrine cell wasobserved in the luminal and glandular epithelium. On the 13th day, closed- type endocrine cells was observed in theluminalepithelium.By the end of incubation period, they appeared in the glandular epithelium only.
►Concerning the smooth muscle layer
- On the 8th day, the muscular coat was differentiated into lamina muscularis mucosae and tunica muscularis. The lamina muscularis mucosae consisted of thin discontinuous inner layer and continuous outer one with few muscle fibers extending between the glands. The tunica muscularis consisted of two layers; thick inner circular layer and thin discontinuous outer longitudinal one. The tunica submucosa was very thin lying between the outer layer of muscularis mucosae and the inner layer of tunica muscularis.
- The muscularis mucosae of the esophagus diverged at the esophago-proventricular junction into inner and outer layers which continued with the inner and outer layers of the muscularis mucosae of the proventriculusthen re-joined prior to the isthmus and continued with that of the gizzard.
►Concerning thetelocytes
- Telocyteswith long processes (telopodes) were observed under the epithelium of the stomach primordium on the 2nd day of incubation. Up to the end of the incubation period, these cells form a network in the mesenchyme under the luminal epithelium, around the glands, the muscles and the blood vessels. They were connected with each other and with the surrounding structures. By scanning electron microscope, the telopodes could be observed consisting of alternating thin segments (podomeres) and dilations (podoms) giving it a beading appearance.
►Concerning thehistochemicalreactions
- The lining epithelium of the proventriculus as well as the primary ducts of the glands and the simple tubular glands gave strong PAS and moderate AB positive reactions at the early stages of development. These reactions increased with the advancement of the fetal age. The primordia of the compound glands showed strong PAS and moderate AB positive reactions at the 5th and 6th days of incubation, these reactions became weak at the 8th day and negative afterwards.
- The reactions for acid phosphatase and ATPase enzymes were weak at 5th day of incubation and increased with the advancement of the fetal age.
- The present study showed an intense blue staining with mercury bromphenol and increased with age.