The Ultrastructure of the Choroid Plexus in Vitamin A Deficient Rabbits
The fire structure of the lateral choroid plexus in vitamin A deficient hydrocephalic New Zealand white rabbits has been studied with the aid of both light and electron microscopy. A special Vitamin A deficient diet was fed to all rabbits and control rabbits in addition received orally 12,500 I. U. of vitamin A powder per week. The offspring of does thus maintained for several months were studied. All rabbits were decapitated; the left lateral choroid plexus was quickly exposed, and subjected to the fixative within 90 seconds following the death of the animal. Conventional techniques of fixation, embedding, and sectioning were employed. Suitable sections were carbonized after being placed upon copper grids and studied with the aid of a modernized RCA EMU-2A electron microscope. As revealed by the light microscope, the choroid plexuses of the hydrocephalic rabbits showed an increased "vascularity" with blood in the subarachnoid space stretching the ependymal cells. The choroidal ultrastructure, as revealed by electron microscope showed in addition to the following: 1) weakened areas between endothelial cells comprising the capillaries with platelet thrombi often associated, 2) "free" red blood cells, white blood cells, thrombocytes, and precipotated plasma proteins located in the subarachnoid space, 3) large cisterane between the plasma membranes of the "stretched" ependymal cells, 4) an apparent increase in the number of parallel and whorled forms of endoplasmic reticulum, 5) an apparent increase in inclusion bodies associated with the arrays of endoplasmic reticulum. An hypothesis is set forth concerning the production of hydrocephalus in vitamin A deficiency, summarized as follows 1) choroidal capillaries are weakened at endothelial junctions and blood elements escape into the subarachnoid space, 2) hydrostatic pressure is increased beneath the ependymal cells, so with each arterial pulsation these cells are pushed further into the ventricle, 3) "stretched" ependymal cells share large cisternae between their plasma membranes through which water and electrolytes escape, 4) hydrocephalus results.
Anatomy, Choroid Plexus -- anatomy & histology; Vitamin A Deficiency
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