In vitro induction and transplantation of eye during early Xenopus development

Abstract

A vertebrate eye was induced via a series of coordinated inductive interactions. Here, we describe a novel in vitro system to induce eye formation at high frequency using Xenopus early gastrulae. The eye formed in vitro is morphologically similar to the normal eye. When the in vitro eye was transplanted into a stage-33 tadpole, the optic nerve was seen extending from the grafted eye to the tectum of the host brain and the in vitro eye graft was retained after metamorphosis. In addition, we transplanted the eye formed in vitro into a tadpole with both eyes removed. The resultant juvenile frogs could perceive brightness using the grafted eye and thereby control their skin color, suggesting that the eye formed in vitro could function normally.

Comparison of induction during development between Xenopus tropicalis and Xenopus laevis

“…In summary, we described that animal cap cells of Xenopus tropicalis and Xenopus laevis display comparable competence for activin induction. This indicates the likelihood that the same method reported previously in Xenopus laevis can be used for tissue induction in Xenopus tropicalis (Ariizumi and Asashima, 1995, Ariizumi et al, 2003, Asashima et al, 2000a, Chan et al, 1999, Furue et al, 2002, Moriya et al, 2000, Osafune et al, 2002, Sedohara et al, 2003. This new information will further advance both tissue induction research and our understanding of the molecular mechanisms of organ differentiation through genetic approaches that are possible by using Xenopus tropicalis.…”

“…These cells show competency in response to certain growth factors to differentiate into several different cell lineages. Many in vitro inductive systems using animal cap cells have been developed and various cell and tissue types have been induced using animal caps from Xenopus laevis, including heart, pronephros, pancreas, cartilage and eye (Ariizumi et al, 2003, Asashima et al, 2000a, Chan et al, 1999, Furue et al, 2002, Moriya et al, 2000, Osafune et al, 2002, Sedohara et al, 2003. In addition, animal cap assays have been used to investigate mechanisms of cell differentiation by treating the cells with various growth factors and to analyze gene function by injecting with various mRNAs.…”

Ectopic eyes outside the head inXenopustadpoles provide sensory data for light-mediated learning

“…Prior work showed that ectopic eyes induced in the cranial region of tadpoles extended cellular bridges and axons towards the optic tecta and were maintained through metamorphosis (Harris, 1986;Koo and Graziadei, 1995;Sedohara et al, 2003). When ectopic eyes were transplanted just behind the head along the dorsal midline, axons from transplanted eyes appeared to enter the spinal cord (Giorgi and Van der Loos, 1978;Katz and Lasek, 1978).…”

“…In particular, Xenopus has been successfully used to analyze eye development, with well-documented pathways for eye induction, lens formation, retinal pathfinding and vascularization (Holt, 1984;Henry and Grainger, 1990;Chien et al, 1993;Hirsch and Harris, 1997;Kenyon et al, 1999;Lupo et al, 2005). In addition, studies have reported the generation of ectopic eyes in tadpoles through surgical techniques, and more recently through embryonic microinjection of a number of 'eye control genes' including Pax6, Rx1, Otx2 and Six3 (Koo and Graziadei, 1995;Chow et al, 1999;Ohuchi et al, 1999;Ashery-Padan and Gruss, 2001;Kenyon et al, 2001;Sedohara et al, 2003;Bailey et al, 2004), as well as through modulation of bioelectrical determinants of organ identity (Pai et al, 2012). Ectopic eyes induced in the cranial region of tadpoles appear to extend 'cellular bridges' and axons towards the optic tecta of the host and these structures are maintained across metamorphosis into adulthood (Harris, 1986;Koo and Graziadei, 1995;Sedohara et al, 2003).…”

“…In addition, studies have reported the generation of ectopic eyes in tadpoles through surgical techniques, and more recently through embryonic microinjection of a number of 'eye control genes' including Pax6, Rx1, Otx2 and Six3 (Koo and Graziadei, 1995;Chow et al, 1999;Ohuchi et al, 1999;Ashery-Padan and Gruss, 2001;Kenyon et al, 2001;Sedohara et al, 2003;Bailey et al, 2004), as well as through modulation of bioelectrical determinants of organ identity (Pai et al, 2012). Ectopic eyes induced in the cranial region of tadpoles appear to extend 'cellular bridges' and axons towards the optic tecta of the host and these structures are maintained across metamorphosis into adulthood (Harris, 1986;Koo and Graziadei, 1995;Sedohara et al, 2003). When ectopic eyes were transplanted just behind the head along the dorsal midline, axons from transplanted eyes appear to enter the spinal cord of the host, perhaps following the pathways of native Rohon-Beard neurons (Giorgi and Van der Loos, 1978;Katz and Lasek, 1978).…”