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Protein synthesis and transport by the rat choroid plexus and ependyma

An autoradiographic study

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Light (LM-ARG) and electron microscope (EM-ARG) autoradiographs were prepared from immature rat choroid plexus and ependyma at 5, 10, 30, and 60 min and 16 h following intraperitoneal administration of [3H]- labeled amino acid mixtures. Intracellular protein synthesis and transport were ascertained in lateral and fourth ventricle choroid plexus epithelium by quantitative EM-ARG at the several post-injection intervals. ARG were also prepared from choroid plexuses cultured for one day, pulse labeled for one hour and reincubated for various periods in nonradioactive media. Significant labeling of both attached and free apical protrusions (blebs) was observed in both choroid plexus and ependyma in vivo and in choroid plexus in vitro. This phenomenon was interpreted as a physiologically significant mechanism for protein transport (apocrine secretion) by epithelia into the cerebrospinal fluid (CSF).


Licht- (LM-ARG) und elektronenmikroskopische (EMARG) Autoradiographien des Plexus chorioideus und des Ependyms von jungen Ratten wurden nach der Injektion von Tritium-markierten Aminosäuren angefertigt. Die Ratten wurden in Zeitabständen von 5, 10, 30, 60 min und 16 h getötet. Intracelluläre Proteinsynthese und Transport wurden im Plexus chorioideus der lateralen und des vierten Ventrikels mit quantitativer Autoradiographie bestimmt. Autoradiographische Experimente wurden auch an kultiviertem Plexus chorioideus-Gewebe durchgeführt. Diese Serie wurde nach eintägigem Wachstum in vitro für 1 h mit 3H-Phenylalanin markiert, anschließend gewaschen und für weitere Zeitperioden kultiviert. Hohe Inkorporation der markierten Substanzen wurde in gestielten und freien “blebs” des Plexus chorioideus und des Ependyms in vivo und des Plexus chorioideus in vitro gefunden. Dieses Ergebnis wurde als ein physiologisch bedeutender Mechanismus des Protein-Transportes (apokrine Sekretion) von den Epithelzellen in den Liquor cerebrospinalis gedeutet.

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Correspondence to Dr. William F. Agnew.

Additional information

The authors thank Mr. J.T. Cheng for technical assistance, and Mrs. Dee Whiting for typing the manuscript

This study was supported in part by N.I.H. Research Grant NS 12906

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Agnew, W.F., Alvarez, R.B., Yuen, T.G.H. et al. Protein synthesis and transport by the rat choroid plexus and ependyma. Cell Tissue Res. 208, 261–281 (1980). https://doi.org/10.1007/BF00234876

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Key words

  • Choroid plexus
  • Ependyma
  • Apocrine secretion
  • Protein synthesis
  • Electron microscope autoradiography