Study On The Development Of Lymphocyte In Chicken Crop

In this text, the fresh crops of10chickens each were quickly removed on the1st,4th,7th,14th,21st,27th,35th,56thpost-hatching day in order to study the characteristics anddevelopment process of the organization structure of chicken crop by HE staining. In themeantime, the immunohistochemistry method, softwares of image analysis and data statisticswere applied to study the distribution, migration, location and the quantity change`s regularpattern of T lymphocytes and its subpopulations, B lymphocytes and mononuclearmacrophages in chicken crop over the same period. The aim of this study was tocomprehensive the immune status in chicken crop at different ages, explore the establishmentof fundamental immunity in chicken crop and provide a theoretical basis for vaccinatingdevelopment and prevention and treatment of chicken gastrointestinal disease.The anatomical observation of chicken crop indicated that chicken crop located beforegetting into the chest between the right entrance of chest and in front of the pectorales as thestructural of sacculate thin-walled diverticulum which divided oesophagus into cervical andthoracic parts. Chicken crop`s structure was bilateral symmetry, we could see the junction ofthe cervical part of esophagus and crop and the junction of crop and the thoracic part ofesophagus had obviously longitudinal folds by the naked eye, and the trend of folds in theventral projection of crop was almost perpendicular to the trend of folds in the junction partsof crop. Under the stereoscopic microscope, circular mucous glands were observed in all partsof crop except the ventral projection of crop.The result of studying the variations of organization structure in chicken crop by HEstaining showed that the structure of chicken crop was similar to chicken oesophagus and itswall was composed of four layers: tunica mucosa, tunica submucosa, tunica muscularis andtunica adventitia. Chicken crop glands belonged to compound tubular glands. Moreover, allparts of crop possessed glands except the ventral projection of crop. The submucosa waspoorly deveoped, being composed of indistinct layer of loose connective tissue. The tunicamuscularis was composed of entirely smooth muscle fibres and had two layers: an innercircular and an outer longitudinal layer. It was observed that the thickness of tunicamuscularis increased with the progress of age. Externally, the chicken crop had a layer ofloose adventitial connective tissue. In addition, the morphological characteristics of chickencrop were age-dependent maturation. As the increase of age, the structure of chicken crop wasgradually complete, and an increasing number of lymphocytes concentrated in the tunica mucous layer. The distinct four layers of crop have appeared in the1stday after post-hatching;the lymphoid aggregates was first observed at the7thday after post-hatching; until27thdayafter post-hatching, the structure of crop was almost mature; at the35thday afterpost-hatching, the structure of crop developed mature virtually almost.By immunohistochemisty staining to study different parts of chicken crop, the resultsshowed that CD3+, CD4+, CD8+and MA+cells have appeared in the1stday afterpost-hatching. Bu-1b+cells were observed at the4thday. CD3+cells mainly distributed in theepithelium and lamina propria, and the lymphoid aggregates covered by CD3+cells was firstobserved at the7th day after post-hatching. CD4+cells are located in the lamina propria.CD8+cells initially mainly distributed in the lamina propria of the mucosa, with the ageincreasing, CD8+cells slightly migrated and infiltrated to the epithelium of the mucosa, whichare transformed to the lymphoepithelium; Bu-1b+cells mainly distributed in the lamina propria,especially around the vessels. The germinal center which covered by the Bu-1b+cells was firstobserved at35th day after post-hatching. MA+cells distibuted uniformly in lamina propria oftunica mucosa, tunica submucosa and tunica muscularis of chicken crop. Later period, a smallquantity of MA+cells were observed in the lymphoid aggregates and some MA+cellsinfiltrated to the epithelium of the mucosa. The amount of CD3+, CD4+, and CD8+cells keptincreasing with the age, the amount of parts of positive cells decreased in the14th and21thday, it increased after this date, and reached mature level around56th day. Bu-1b+cellscontinuously kept increasing with age, it`s rising rate was higher than T lymphocytes duringthe later period.At the1stday, the quantity of MA+cells were far more then that of CD3+,CD4+, CD8+and Bu-1b+. It reached the peak at the27thday, after that, the quantity of MA+cells experienced a decrease at56thday.The research showed: The morphological characteristics of chicken crop wereage-dependent maturation, at the35thday after post-hatching, the structure of crop developedmature virtually almost. As a part of the digest system in the chicken, the crop posses themucosal immunity which consisting of the lymphoid aggregates and the lymphocytes.Thecrop is an important part of gut-associated lymphoid tissue(GALT).