Change in the developmental fate of the chick optic vesicle from the neural retina to the telencephalon. (6th March 2019)

• Record Type: Journal Article
• Authors: Shirahama, Misaki; Steinfeld, Ichie; Karaiwa, Akari; Taketani, Shigeru; Vogel‐Höpker, Astrid; Layer, Paul G.; Araki, Masasuke
• Is Part Of: Development growth and differentiation. Volume 61:Number 3(2019)
• Page Start: 252
• Page End: 262
• Publication Date: 2019-03-06
• Subjects: chick -- developmental fate -- embryonic transplantation -- neural retina -- organ culture -- telencephalon; Embryology -- Periodicals; Developmental biology -- Periodicals; Growth -- Periodicals; 574.3
• DOI: 10.1111/dgd.12599
• Languages: English
• ISSNs: 0012-1592

Abstract

Abstract: The forebrain develops into the telencephalon, diencephalon, and optic vesicle (OV). The OV further develops into the optic cup, the inner and outer layers of which develop into the neural retina and retinal pigmented epithelium (RPE), respectively. We studied the change in fate of the OV by using embryonic transplantation and explant culture methods. OVs excised from 10‐somite stage chick embryos were freed from surrounding tissues (the surface ectoderm and mesenchyme) and were transplanted back to their original position in host embryos. Expression of neural retina‐specific genes, such as Rax and Vsx2 ( Chx10 ), was downregulated in the transplants. Instead, expression of the telencephalon‐specific gene Emx1 emerged in the proximal region of the transplants, and in the distal part of the transplants close to the epidermis, expression of an RPE‐specific gene Mitf was observed. Explant culture studies showed that when OVs were cultured alone, Rax was continuously expressed regardless of surrounding tissues (mesenchyme and epidermis). When OVs without surrounding tissues were cultured in close contact with the anterior forebrain, Rax expression became downregulated in the explants, and Emx1 expression became upregulated. These findings indicate that chick OVs at stage 10 are bi‐potential with respect to their developmental fates, either for the neural retina or for the telencephalon, and that the surrounding tissues have a pivotal role in their actual fates. An in vitro tissue culture model suggests that under the influence of the anterior forebrain and/or its surrounding tissues, the OV changes its fate from the retina to the telencephalon. Abstract : Optic vesicles from chick embryos without the surrounding tissues were spliced to the anterior brain vesicle of host embryos from which the OVs had been removed previously. Expression of the neural retina specific genes, Rax and Vsx2 (Chx10), were soon downregulated in the transplants. Instead, expression of the telencephalon specific gene, Emx1, emerged in the proximal region of the transplants, while in the distal part of the transplants, the RPE specific gene, Mitf, was expressed.