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Some basic chemical components of the cerebrospinal fluid in developing chick embryos
Insights
Cerebrospinal fluid (CSF) in chick embryos shows higher chloride levels than plasma, with glucose and protein concentrations changing inversely with development. CSF remains hyperosmolar to plasma throughout embryogenesis.
Area of Science:
- Developmental biology
- Neuroscience
- Comparative physiology
Background:
- Understanding the developmental changes in cerebrospinal fluid (CSF) composition is crucial for avian embryology.
- Investigating the relationship between plasma and CSF during embryonic development provides insights into physiological regulation.
Purpose of the Study:
- To investigate the developmental trends of chloride ion, glucose, and total protein concentrations in chick embryo CSF.
- To compare these concentrations with those in blood plasma during embryonic development.
- To assess the osmolarity of CSF relative to plasma.
Main Methods:
- Analysis of chloride ion, glucose, and total protein concentrations in CSF and plasma of chick embryos (11-21 days).
- Calculation of plasma/CSF ratios for each analyte.
- Determination of total osmolarity based on ion and glucose concentrations.
Main Results:
- Chloride concentration was consistently higher in CSF than plasma, with a decreasing plasma/CSF ratio during development.
- CSF glucose concentration decreased until day 19, then increased before hatching, while plasma glucose rose throughout.
- Plasma total protein increased, whereas CSF total protein decreased during the latter half of incubation.
- CSF was permanently hyperosmolar compared to plasma, with a stable plasma/CSF osmolarity ratio.
Conclusions:
- Distinct developmental patterns exist for chloride, glucose, and total protein in chick embryo CSF and plasma.
- The developing chick embryo maintains a hyperosmolar CSF relative to plasma, suggesting active regulatory mechanisms.
- These findings contribute to understanding the physiological maturation of the avian central nervous system.
Abstract:
The development of the chloride ion, glucose and total protein concentration was investigated in the cerebrospinal fluid of 11- to 21-day-old chick embryos and compared with their development in the blood plasma. Developmental changes in the chloride concentration in the plasma and CSF were very small, but it was always higher in the CSF than in the plasma. The plasma/CSF ratio fell during development, from 0.906 in 11-day-old embryos to 0.778 at the end of incubation. The CSF glucose concentration fell up to the 19th day of incubation, but a significant increase was recorded shortly before hatching. The plasma glucose concentration rose throughout the whole of the investigated period of embryogenesis. Up to the 19th day the P/CSF ratio rose from 1.59 to 4.05 and in 21-day-old embryos fell to 2.47. The developmental increase in the plasma total protein concentration was accompanied by the reverse process in the CSF. During the second half of incubation the P/CSF ratio rose from 1.88 to 7.9 Calculation of total osmolarity from the Na+, K+, Ca2+, Cl- and glucose concentration showed permanent hyperosmolarity of the CSF compared with the plasma. The P/CSF ratio was maintained within limits of 0.94 to 0.98.