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PubMed1981

Circulating levels of corticosterone in the serum of developing chick embryos and newly hatched chicks.

Circulating levels of corticosterone were determined in chick embryos from 10 to 21 days of incubation using eggs from a Leghorn breeder flock. In Experiment 1, eggs were incubated from 10 to 20 days for daily embryonic blood collection. To verify stage of development with day of incubation, embryo right middle toe lengths were measured concurrent with blood sampling. Serum from three embryos was pooled into one sample and the corticosterone content of 10 samples per day of incubation was determined using a radioimmunoassay procedure. The levels of corticosterone from day 10 to 14 fluctuated slightly and then increased rapidly until 16 days of incubation. At this time serum corticosterone remained relatively constant through day 18 with an apparent increasing trend up to day 20. The use of toe lengths to assure no day-to-day overlap in embryonic development proved effective. In Experiment 2, newly hatched (day 21) chicks were sorted into four 3-hr periods ranging from early to late hatching. Blood samples were collected from five individual chicks during four 15-min sampling periods for each of the four hatch times. Serum corticosterone levels were not affected by sampling periods or hatch times.

Animals↗
PubMed1976

Antibody-mediated immuno-regulation in chick embryos and baby chicks.

Two- and three-week old chicks that received at hatching serum from either unimmunized birds or from chickens immunized with bovine serum albumin responded with normal hemagglutinin titers to immunization with mouse erythrocytes (MRBC). Other chicks administered at hatching or as embryos with homologous serum high in anti-MRBC activity responded poorly to MRBC immunization. When donor serum samples collected on different days after immunization were tested, the immunosuppressive capacity was negligible the first two days, increased in potency thereafter to a maximum level by the end of the week. The increase with time in the inhibiting property of the donor serum paralleled the serum anti-MRBC hemagglutinin response profile. The immune capacity of the antibody-treated recipients was severely depressed for over two weeks. By the fourth week, however, the immune responsiveness to MRBC, as measured by serum hemagglutinin titers and production of antigen sensitive units, had recovered to near normal levels.

Animals↗
PubMed1992

Alterations in cellular calcium handling as a result of systemic calcium deficiency in the developing chick embryo: I. Erythrocytes.

Chick embryos rendered calcium (Ca) deficient by shell-less (SL) culture develop hypertension and tachycardia. Since hypocalcemia is accompanied by hypernatremia systemically but not by lower cellular Ca (Koide and Tuan, 1989), we speculate that cellular Ca handling may be altered in the SL embryo, perhaps involving Na transport. Using erythrocytes (RBC) from day-14 SL and normal (NL) embryos as the experimental cell, cellular Ca handling was studied under varying extracellular osmotic and ionic conditions by analyzing 45Ca uptake and cell volume regulation. Two agents, p-chloromercuriphenylsulfonate (PCM), and inosine/iodoacetamide (INI) were used to treat the RBCs to modify plasma membrane ion permeability and to deplete cellular ATP, respectively. Other cellular functions and activities related to Ca homeostasis, including ATP content and Ca(2+)-ATPase activity, were also analyzed. These analyses showed: (1) in NaCl, Ca uptake was similar in NL and SL cells, except after INI treatment, which resulted in slower Ca uptake by the SL cells, (2) in choline and sucrose, Ca uptake by SL RBCs was higher, (3) Ca uptake by RBCs of both embryos changed depending on the osmotic agent (Na < K < or = choline < sucrose), (4) Ca(2+)-ATPase activity was higher in SL RBC, although there was no change in the size or charge of the enzyme, and (5) in any osmotic agent, cellular Na was significantly lower, whereas cellular K was higher, in SL RBC. Based on these results, three features of RBC Ca handling were apparent: (1) Na-Ca exchange was functional and was more active in SL RBCs, (2) Ca uptake was dependent on the total ionic electrochemical gradient but not on bulk H2O movement, and (3) Ca pumping out capacity was directly correlated with Ca(2+)-ATPase activity. Elevated Ca uptake in sucrose-treated SL RBC is therefore indicative of its greater ion permeability. Taken together, these findings indicate that cellular Ca handling of the RBCs of SL chick embryos is characterized by a more active Na-Ca exchange system, greater ion permeability, and higher Ca pumping out capacity, thereby suggesting an up-regulated Ca handling function in the SL RBCs. The abnormal cellular Ca handling may be a direct result of the systemic Ca deficiency of the SL chick embryo and may be functionally related to its hypertension and tachycardia.

Adenosine Triphosphate↗
PubMed1979

The septation of the arterial pole of the heart in the chick embryo. III. Development of the truncus arteriosus of the heart of chick embryos from 5 1/2 to 7 days of incubation.

At the end of the fifth day of incubation the mesenchymal truncus arteriosus is completely divided into aorta and pulmonary trunk. During the first half of the sixth day the septation process starts in the distal part of the myocardial truncus by the ingrowth of the dense mesenchyme of the aortico-pulmonary septum into the dorsal and ventral-right truncus ridges. During the second half of the sixth day this septation process extends into proximal direction. Proximally to the ingrowing aortico-pulmonary septum the dorsal and ventral-right ridges fuse. In these fused ridges the aortico-pulmonary septum extends proximally for some distance. During the first half of the seventh day the left ventricular outlet is separated from the right ventricular inlet by the downward extension of the right caudal side of the atrioventricular cushion-mass, which continues into the right proximal truncus ridge (at the transition into the distal ventral-right ridge). In the meantime the fusion of the dorsal and ventral truncus ridges continues in proximal direction. This process comes to be completed in the second half of the seventh day by the fusion of the left (dorsal) and right (ventral) truncus ridges up to the level where the left one continues along the free border of the interventricular septum into the right limb of the dorsal extension of the atrioventricular cushion-mass. During the sixth and seventh day the origins of aorta and pulmonary trunk rotate from their right and left positions in younger stages to an almost dorsal and ventral position respectively in older stages. The septum trunci lying in between the left and the right ventricular outlet in the truncus appears to be a straight septum and does not rotate.

Animals↗