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The development of the circulating blood volume of the chick embryo
Insights
Chick embryo blood volume increases exponentially until day 16, then slightly decreases. Researchers used radioisotope dilution to track blood volume changes during development.
Area of Science:
- Developmental Biology
- Physiology
- Hematology
Background:
- Understanding chick embryo development is crucial for avian research.
- Previous studies on chick embryo blood volume have provided baseline data.
- Accurate measurement methods are essential for developmental studies.
Purpose of the Study:
- To determine the circulating blood volume of chick embryos from day 4 to day 18.
- To analyze the growth curve of blood volume during embryonic development.
- To investigate potential mechanisms for blood volume changes near hatching.
Main Methods:
- Radioisotope dilution method utilizing iodine-131 (I131) bound to albumin.
- Blood volume measurements were taken from the 4th to the 18th day of hatching.
- Analysis of growth patterns and peak values of blood volume.
Main Results:
- Circulating blood volume shows a near-exponential growth curve, with increasing doubling time.
- Blood volume peaks between the 16th and 18th day of incubation.
- A slight decrease in blood volume is observed towards the end of the hatching period.
- Postulated reduction in red cell volume and hemoglobin due to involution of extraembryonic circulation.
- Erythrocyte destruction suggested in the endodermal epithelium of the proximal yolk sac, with iron accumulation observed.
Conclusions:
- Chick embryo blood volume follows a predictable, though not perfectly exponential, growth pattern.
- The observed changes in blood volume near hatching are linked to developmental shifts in circulatory systems.
- The yolk sac may play a role in erythrocyte turnover during late embryonic development.
Abstract:
The circulating blood volume of the chick embryo was determined from the 4th up to the 18th day of hatching. In contrast to former studies, there was employed a radioisotope dilution method with albumin-bound I131. The findings are in close correspondence to those of the earlier studies. The blood volume does not display an entirely perfect curve of exponential growth, i.e., the doubling time increases steadily. The blood volume attains a peak value between the 16th and 18th day and decreases somewhat toward the end of the hatching period. There has been postulated a reduction of total red cell volume and hemoglobin caused by the involution of the extraembryonic circulatory system. The destruction of the erythrocytes seems to take place in the endodermal epithelium of the proximal yolk sac, where an accumulation of iron could be demonstrated on the 19th and 20th days.