The bursa of Fabricius and the thymus are "central lymphoid organs" in the chicken, essential to the ontogenetic development of adaptive immunity in that species. Surgical removal of one or both of these organs in the newly hatched chicken, followed by sublethal X-irradiation the next day, has permitted recognition of two morphologically distinct cell systems in the "peripheral lymphoid tissues" of the spleen, gut, and other organs, and clear definition of the separate functions of each cell system.

The thymus-dependent development is represented morphologically by the small lymphocytes of the circulation and the white pulp type of development in the tissues. As in mammals, the thymus-dependent tissues of the chicken are basic to the ontogenesis of cellular immunity: graft versus host reactions, responses of delayed hypersensitivity and homograft rejection; and play a less clearly defined role in the antibody response to at least some antigens. Thymectomized-irradiated chickens are deficient in all these responses, and grow more slowly than any of the other experimental groups. In these animals germinal centers, plasma cells, and capacity for immunoglobulin synthesis remain intact.

The bursa-dependent development is represented morphologically by the larger lymphocytes of the germinal centers and the plasma cells, and functionally by the immunoglobulins. Bursectomized-irradiated chickens are agammaglobulinemic and unable to produce detectable antibody despite intense, repeated stimulation with bovine serum albumin and Brucella abortus organisms. The thymus-dependent development in these animals seems to be normal; they have adequate numbers of lymphocytes in the circulation and tissues, are able to reject skin homografts, though more slowly than usual, and to exercise graft versus host reactions. The short life span of these chickens has precluded adequate study of responses of delayed hypersensitivity.

There was no evidence of significant impairment of reticuloendothelial function in either the bursectomized-irradiated or the thymectomized-irradiated group, as judged by the clearance of colloidal gold and I131-tagged keyhole limpet hemocyanin.

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The functions of the thymus system and the bursa system in the chicken

ABSmAcr.-We investigated the effects of dietary protein quality on the development and functioning of the immune system in four-week-old Northern Bobwhite (Colinus virginianus) chicks. Chicks were fed isocaloric diets containing 8, 15, or 33% protein over a three-week period. Significant reductions in the rate of body growth were evident in chicks receiving 8 and 15% protein. Development of the bursa of Fabricius and spleen was significantly depressed in the 8% protein group compared to the other two treatments. Lymphocyte yields from dissociated lymphoid organs of chicks fed 8% protein were substantially reduced compared to birds fed higher levels of protein. In vitro lymphoproliferative responses of cultured splenocytes to mitogenic stimulation (concanavalin A, pokeweed mitogen, and Salmonella typhimurium), white-blood-cell counts, and in vivo measures of humoral immunity did not differ among dietary treatments. Cell-mediated immune function, as measured by an in vivo hypersensitivity response to an intradermal injection of a T lymphocyte-dependent mitogen (phytohemagglutinin), was significantly suppressed in the 8% protein group compared to the other two treatments. Several measures of immune-system development and function were significantly correlated with body mass change during the trial. Results indicated that four-week-old Northern Bobwhite chicks fed an 8% protein diet for three weeks may have difficulty expressing a competent immune response to pathogenic challenge in the wild. Received 30 January 1992, accepted 25 November 1992.

Relationship Between Protein Nutritional Status and Immunocompetence in Northern Bobwhite Chicks

Model of physiological stress in chickens 1. Response parameters.

Tilapia are a commonly aquacultured fish yet little is known about their normal physiology and response to disease. In this study we determined the results of complete hematologic (n = 40) and plasma bio- chemical profiles (n = 63) in production tilapia (Oreochromis hybrids). The fish were raised in recirculating systems with a high stocking density (120 g/L), and were in the middle of a 15-month production cycle. Blood was analyzed using standard techniques, and reference intervals were determined using nonparametric meth- ods. Non-production tilapia (n = 15) from low-density tanks (4 g/L) also were sampled; the clinical chemistry results were compared to reference intervals from the fish raised in high-density tanks. Differences were noted in plasma protein, calcium and phosphorus concentrations, such that reference intervals for high-den- sity production tilapia were not applicable to fish raised under different environmental and management con- ditions. (Vet Clin Pathol 2000;29:7-12)

Hematology and plasma chemistry reference intervals for cultured tilapia (Oreochromis hybrid).

This review examines the avian heterophil leucocyte and provides a morphological and cytochemical profile drawn from light and electron microscopy studies of these cells and their characteristic cy...

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/3AA18D1DEC0189AB937A4FD3F87335A2/S0043933998000166a.pdf/div-class-title-the-avian-heterophil-leucocyte-a-review-div.pdf

The avian heterophil leucocyte: a review

A New Blood Diluent for Counting the Erythrocytes and Leucocytes of the Chicken

The Effect of Cecal Coccidiosis on the Blood Cells of the Domestic Fowl I. A Comparison of the Changes in the Erythrocyte Count Resulting from Hemorrhage in Infected and Mechanically Bled Birds. The use of the Hematocrit Value as an Index of the Severity of the Hemorrhage Resulting from the Infection

The symptoms of cecal coccidiosis are many and varied and their severity is dependent upon numerous factors which include previous exposure to the parasite, the numbers of oocysts swallowed, and the age and genetic background of the host. One of the early symptoms is the loss of appetite. Other symptoms such as loss of weight, anemia, reduced cloacal temperature and metabolic rate become progressively more marked reaching a climax with the hemorrhage into the cecal pouches on the fifth day after infection. At this time the host appears to avoid activity by standing listlessly in an isolated corner of the cage and is incapable of sustained action when disturbed. The host is apparently incapable of shivering but spontaneous erratic twitching of the muscles often occurs. The debilitation becomes increasingly severe until the host can no longer stand. Death appears to result from respiratory failure and is accompanied by only a slight struggle. If it is killed by decapitation or by breaking its neck, the vigorous convulsive contractions common to control chickens are markedly reduced. Muscular weakness, therefore, seemed to be such an important factor in the syndrome of this and other parasitic diseases that the work which muscles of chickens infected with cecal coccidia could perform was measured and is herewith reported.

The effects of protozoan parasite Eimeria tenella on the ability of the chicken to do muscular work when its muscles are stimulated directly and indirectly.

Chester A. Herrick

Papers

A New Blood Diluent for Counting the Erythrocytes and Leucocytes of the Chicken

The effects of protozoan parasite Eimeria tenella on the ability of the chicken to do muscular work when its muscles are stimulated directly and indirectly.

The Effect of Cecal Coccidiosis on the Blood Cells of the Domestic Fowl 2. The Changes in the Blood Volume During the Course of the Infection

Sulphur and Rickets