Ependymal secretion, especially in the hypothalamic region.
D000818:Animals; D004805:Ependyma / Q000166:cytology / Q000378:metabolism*; D000882:Haplorhini; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D007031:Hypothalamus / Q000378:metabolism*; D008854:Microscopy, Electron; D009489:Neurosecretion