Embryonic lens induction: shedding light on vertebrate tissue determination

Grainger, Robert M.

doi:10.1016/0168-9525(92)90280-h

Cited by 180 publications

(121 citation statements)

References 24 publications

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“…The relevant stages during the morphogenesis of the avian eye are summarized schematically in Figure 4 (based on studies described by Romanoff, 1960;Prada et al, 1991). During gastrulation, signals from the presumptive retinal region of the neural plate together with the underlying endo-mesoderm induce competence to lens formation in a region of head ectoderm (reviewed by Grainger, 1992). During neurulation, the ectodermal lens field is determined by a contact-dependant induction from the optic vesicle (Fig.…”

Section: Unequal Distribution Of the Ld Proteins During Eye Inductionmentioning

confidence: 99%

Limb deformity proteins during avian neurulation and sense organ development

Pompa

James

Zeller

1995

Developmental Dynamics

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The nuclear Limb deformity (Ld) proteins (formins) are expressed during the avian primitive streak stages. Initially, they are detected predominantly in cells of the forming notochord, scattered mesodermal precursors and the induced neural plate. No expression is detected in endodermal cells. The subsequent graded distribution of Ld positive cells along the anterior-posterior axis of the neural tube follows the antero-posterior progression of its differentiation. The Ld proteins are also differentially expressed during induction and development of both the inner ear and eye. An unequal distribution of Ld proteins along the dorso-ventral axis of the otic vesicle is observed during its initial patterning. In the eye, the Ld proteins are expressed by the optic vesicle during secondary induction of the lens placode. Following induction, the proteins are also expressed by the newly formed lens placode, a process which is reminiscent of homeogenetic induction. During differentiation of the retina and lens, the Ld domains seem to demarcate territories, giving rise to specific eye structures. A comparative analysis of the Ld distribution and BrdU incorporation in the two sense organs indicates that the proteins are predominantly expressed by committed and/or differentiating (post-mitotic) cells. In general, expression of Ld proteins is induced during determination and remains during differentiation of particular celltypes. This study implies that the nuclear Ld proteins are involved in morphogenesis of both neuro-ectodermal and mesodermal structures.

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Section: Unequal Distribution Of the Ld Proteins During Eye Inductionmentioning

confidence: 99%

Limb deformity proteins during avian neurulation and sense organ development

Pompa

James

Zeller

1995

Developmental Dynamics

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“…Such interactions lead to the formation of the germ layers, the central nervous system, and various organ systems (Grunz, 1997;Kimelman and Griffin, 1998;Baker and Bronner-Fraser, 2001). For over 100 years, the vertebrate lens has served as a model system for studying the nature of embryonic induction (Grainger, 1992(Grainger, , 1996. As a result of numerous tissue transplantation and explant culture experiments, we have developed a firm understanding of the interactions involved in this process.…”

Section: Introductionmentioning

confidence: 99%

“…1). Embryonic lens formation is directed by a series of inductive interactions that take place during two principal phases Grainger, 1987, 1990;Grainger, 1992Grainger, , 1996. Experiments carried out with the frog Xenopus laevis indicate that an "early phase" of lens induction begins during gastrulation (approximately stage 11; all Xenopus stages follow those of Nieuwkoop and Faber, 1956) when the ectoderm is first competent to respond to these signals (see Fig.…”

Section: Introductionmentioning

confidence: 99%

“…After an initial period of "specification," sufficient inductive signals reach the responding tissue such that when it can then be cultured in isolation to produce a lens, the tissue is then considered to be "specified" (stage 19). Ultimately, the tissue becomes "committed" to the lens cell fate, when it can no longer respond to other signals (definitions according to Slack, 1991;Grainger, 1992Grainger, , 1996. Presumably this occurs by stage 26, when the lens undergoes cellular differentiation, after a phase of "commitment."…”

Section: Introductionmentioning

confidence: 99%

“…At some stage the lens is irreversibly "committed," which presumably takes place by stage 26 when the lens placode is forming and lens crystallin proteins are being produced ( Fig. 1C; general definitions according to Slack, 1991;Grainger, 1992Grainger, , 1996. Although we have a firm understanding of the tissue interactions involved in vertebrate lens induction, much less is known about the genes controlling the processes of lens cell determination and differentiation.…”

Section: Introductionmentioning

confidence: 99%

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Characterizing gene expression during lens formation in Xenopus laevis: Evaluating the model for embryonic lens induction

Henry

Carinato

Schaefer

et al. 2002

Developmental Dynamics

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Few directed searches have been undertaken to identify the genes involved in vertebrate lens formation. In the frog Xenopus, the larval cornea can undergo a process of transdifferentiation to form a new lens once the original lens is removed. Based on preliminary evidence, we have shown that this process shares many elements of a common molecular/genetic pathway to that involved in embryonic lens development. A subtracted cDNA library, enriched for genes expressed during cornea-lens transdifferentiation, was prepared. The similarities/identities of specific clones isolated from the subtracted cDNA library define an expression profile of cells undergoing cornea-lens transdifferentiation ("lens regeneration") and corneal wound healing (the latter representing a consequence of the surgery required to trigger transdifferentiation). Screens were undertaken to search for genes expressed during both transdifferentiation and embryonic lens development. Significantly, new genes were recovered that are also expressed during embryonic lens development. The expression of these genes, as well as others known to be expressed during embryonic development in Xenopus, can be correlated with different periods of embryonic lens induction and development, in an attempt to define these events in a molecular context. This information is considered in light of our current working model of embryonic lens induction, in which specific tissue properties and phases of induction have been previously defined in an experimental context. Expression data reveal the existence of further levels of complexity in this process and suggests that individual phases of lens induction and specific tissue properties are not strictly characterized or defined by expression of individual genes.

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