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Development of the liquor system
Last reviewed: 06.07.2025
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The nervous system initially develops as a hollow tube containing amniotic fluid. The cerebrospinal fluid system develops simultaneously with the formation of the nervous tissue itself.
The vascular plexuses begin to form approximately at the 2nd month of embryonic development. The vascular plexuses are laid down in a certain sequence - first in the third and fourth ventricles, then in the lateral ones. This reflects the needs of the developing stem structures first, and then the cerebral hemispheres.
The choroid plexuses of all ventricles develop by inward eversion of part of the walls of the cerebral vesicles, which is due to the more rapid growth of certain cells.
Up to 5 months of embryonic life, the brain cavities, which are the remains of the cavities of the brain vesicles, are a closed system in which the cerebrospinal fluid produced by the plexuses causes the expansion of the ventricles - a stage of physiological intracervical hydrocephalus. The cerebrospinal fluid soaks the brain tissue like a "sponge", washing the elements of the parenchyma and glia. These movements of the cerebrospinal fluid are the first emerging rhythm of the brain, ensuring its development.
In this period, the median fluid cavities are well expressed, increasing the area of contact of the cerebrospinal fluid with the brain: the cavity of the septum pellucidum and the cavity of Verge. These cavities are limited above by the corpus callosum, and below by two fornices. The point where the fornices converge delimits the cavity of the septum pellucidum and the cavity of Verge from each other, which freely communicate with each other. The cavity of Verge begins to close in utero around the 6th month of gestation. Closure occurs from back to front, and by the time of birth or during the first two months of life, the cavity of the septum pellucidum also closes.
The characteristics of the secreted cerebrospinal fluid in the early stages of human brain development are an extremely high concentration of amino acids and proteins, approximately 20 times higher than in adults, and a high glucose content.
By the 6th month of intrauterine development, three openings appear in the area of the fourth ventricle: the median opening of Magendie and two lateral openings of Lushka. These openings connect the system of ventricular cavities with the subarachnoid space, the cerebrospinal fluid entering there stratifies the soft membrane into two layers and begins to circulate through the subarachnoid spaces of the convex. At this time, Pachion's granulations are laid down and the resorptive apparatus of the brain begins to develop, but it is fully formed by the age of one year.
Around the 7th month of intrauterine life, the brain's nutrition becomes cerebrospinal fluid-capillary, and by birth - predominantly capillary.
In a newborn child in the first days of life, the amount of cerebrospinal fluid in the subarachnoid spaces and ventricles is 40-60 ml. In adults, 90-200 ml. The production of cerebrospinal fluid is 0.37 ml per minute and does not depend on the age of people. In adults, cerebrospinal fluid is renewed 4-5 times a day.
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