Axons of retinal ganglion cells (RGCs) relay visual information from the retina to lateral geniculate nucleus (LGN) and superior colliculus (SC), which are two major image-forming visual nuclei. Wiring of these retinal projections completes before vision begins. However, there are few studies on retinal axons at embryonic stage due to technical difficulty. We developed a method of embryonic intravitreous injection of dyes in mice to visualize retinal projections to LGN and SC. This study opens up the possibility of understanding early visual circuit wiring in mice embryos.

Recent outbreaks of infectious neuro-developmental diseases such as congenital Zika syndrome - have led to a demand for prognosis data from animal models. We developed an intra-amniotic injection mice model that allows Zika virus (ZIKV) infected mice to grow to puberty. In this system, ZIKV is injected into the amniotic fluid of pregnant mice and infected embryos thereafter. ZIKV-infected mice show several symptoms of clinical ‘congenital Zika syndrome’, including decreased brain volume and mis-laminated retina. We also evaluated several behavioral functions of these ZIKV-infected mice, for example, after the mice reach puberty, they have visual and motor defects. This technique can be used to screen and evaluate drug candidates and may help evaluate the prognosis of infectious neuro-developmental diseases.