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Biomedical subjects

R M Gaze

Publications and source records attributed to R M Gaze.

At least 55 records · Page 3Linked to original sources
PubMed1976

Neurite outgrowth from explanted Xenopus retina: an effect of prior optic nerve section.

Experimental conditions are described for the in vitro study of explanted eyes from embryos of Xenopus laevis and of retinas from older larvae. When eyes are explanted from embryos of stages 25-34, a rapid outgrowth of fibroblast-like and pigment cells is observed, upon which a neuritic outgrowth is eventually superimposed. Outgrowth from the retina of later stage tadpoles (50-54) is not seen until about a week following explantation and resembles the mixed cell outgrowth observed in whole eye explants from early stage embryos. If, however, the optic nerve of an older tadpole is cut 7 days prior to explantation, a purely neuritic outgrowth is seen from the previously denervated retina within 1-3 days.

Age Factors↗
PubMed1975

The development of the retinotectal projection in Xenopus with one compound eye.

Double-nasal and double-temporal compound eyes were constructed in Xenopus embryos at stages 32 and 37/38. A particular half was removed from the host eye anlage and replaced with the opposite half-eye from the contralateral side of a donor embryo. Control operations consisted of removing a half-eye and replacing it with a similar half from the ipsilateral side of the donor embryo. Whereas in control animals, each half-eye projects its fibres to the appropriate half-tectum, in operated animals each half of the compound eye spread its optic terminals across the entire rostrocaudal extent of the dorsal tectal surface. The area of tectal surface covered by ganglion fibre terminals was similar in operated animals mapped at successive stages of development to that previously observed in normal animals at equivalent stages. Therefore the factors responsible for the extended distribution of fibre terminals from each half of a compound eye must exist at least from mid-tadpole life, and thereafter be continuously present throughout development.

Animals↗
PubMed1975

The structural and functional development of the retina in larval Xenopus.

The structural transformations of the larval Xenopus retina at successive stages of development, and concomitant changes in response characteristics of retinal ganglion cells, were studied using histological and electrophysiological techniques. The first sign of visually evoked electrical responses appears at about the time when the ganglion cells spread out into a single layer and shortly after the inner and outer plexiform layers become discernible. Initially giving simple "on" responses, the cells progressively change their response characteristics and become "event" units. Subsequently, "dimming" units can be identified. Throughout larval life, response properties of these two types become more distinct from one another and approximate to those found in the adult. So do the arborization patterns of the dendritic trees of the ganglion cells. Two types of branching patterns are identifiable in Golgi preparations. Around metamorphic climax, a new type of ganglion cell appears, coinciding with the emergence of "sustained" units electrophysiologically. After metamorphosis, the retina still grows both in thickness (mainly in the inner plexiform layer) and diameter. The three unit types change such they they come to show pronounced inhibitory effects from the peripheral visual field on the receptive field and each unit type acquires a distinct pattern of endogenous discharge.

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