Modern ideas about the mechanisms of perilymph synthesis in the inner ear

The aim of the work was to summarize and systematize the scientific literature data on the synthesis of perilymph in the inner ear. The search for sources was carried out using the Pubmed biomedical research system and the Elibrary scientific electronic library until 01.08.2025. There are two main hypotheses for the synthesis of perilymph. Hypothesis I. – the formation of perilymph by filtration of blood plasma from the vessels of the inner ear. Arterioles branch off from the labyrinthine artery, dividing into capillaries with pores for the passage of molecules, which are filtered out by the blood-labyrinth barrier. Due to the pressure gradient, sodium and potassium ions, as well as molecules up to 100 daltons, pass through the capillaries, forming a primary blood filtrate. It enters the perilymphatic space, where its cells regulate the composition of the perilymph. The perilymph is removed from the inner ear through the perilymphatic duct into the subarachnoid space, where it mixes with cerebrospinal fluid. Hypothesis II. – formation of perilymph from cerebrospinal fluid. This is possible only if the barrier that separates the cerebrospinal fluid from the perilymph in the area of the perilymphatic duct is damaged. Such a message allows the cerebrospinal fluid to directly affect the volume and composition of the perilymph if the formation of fluid from blood plasma is difficult (for example, with hypovolemia). Cerebrospinal fluid can act as an ion buffer if the local regulation of the ionic composition is disrupted, it is a medium into which metabolic products are released from the perilymphatic space. Currently, the issue of perilymph synthesis remains not fully understood, and additional research is needed to clarify the issue. 

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