Fig. 3From: SCO-spondin, a giant matricellular protein that regulates cerebrospinal fluid activityScheme of the CNS of zebrafish, mouse, and chick embryos, highlighting the localization of SCO. A Zebrafish embryos 48 h post-fertilization (hpf). In zebrafish, the RF is formed early in development by SCO-spondin secreted from the SCO and the floor plate. Violet arrows: Direction of CSF flow at this early stage [229]. B Chick embryos at 4 days of embryonic development (E4). SCO-spondin is secreted into eCSF from E3.5 and remains soluble until E11, where at least some SCO-spondin aggregates to form the RF. The localization of the first penetrating vessels is shown in red, at the basal region, just in front the SCO [22]. The red arrows represent substances entering to the eCSF through this incipient blood–brain barrier. C Mouse embryo at E14. In mouse embryos, the differentiation of the SCO begins at E11, SCO-spondin is secreted into CSF from E14, and the RF forms during the first postnatal week. The first penetrating vessels (in red) enter the mouse brain embryo at the location at which the SCO began differentiating 2 days prior [63]. Di Diencephalon, F Forebrain, FP Floor plate, H Hindbrain, M Midbrain, Mes Mesencephalon, RF Reissner fiber, SCO Subcommissural organ, Tel TelencephalonBack to article page