The Control of Cell Division in the Ocular Lens

Reddan, John R.; Unakar, Nalin J.; Bagchi, M.

doi:10.1016/s0074-7696(08)60060-1

Cited by 142 publications

(56 citation statements)

References 160 publications

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“…However, for large wounds in adult skin where a significant number of cells have been lost, cell replacement is clearly required at some stage. There is a synchronised upsurge in the rate of proliferation at the epidermal wound margin by 12-24 hours (Werner et al, 1994), and this can spread from the wound edges centripetally outwards in a wave-like fashion (Harding et al, 1971). exuberant filopodia that appear to bond them together. Possible clues as to the signals regulating assembly of palatal filopodia come from studies of TGFβ3 knockout mice that lack filopodia at the crucial time of contact, thereby failing in palatal fusion such that mice are born with cleft palate (Taya et al, 1999).…”

Section: Box 3 Cell Proliferation In Migrating Tissuesmentioning

confidence: 99%

mentioning

confidence: 99%

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Parallels between tissue repair and embryo morphogenesis

2004

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Review 3022tissue movements as in the adult, although on a much smaller scale, but only at late foetal stages is healing accompanied by an inflammatory response (Hopkinson-Woolley et al., 1994; Cowin et al., 1998). Prior to these stages, inflammation is absent and the embryo is capable of essentially perfect, near regenerative repair, with no resulting scar. Wound healing, even in the embryo (Fig. 2), is a complex process involving the coordination of several cell behaviours from several different cell types, and for each stage of wound repair there are fundamental cell biology issues that still need resolving (see Box 1). Developmental models of wound healingA number of naturally occurring morphogenetic events involve tissue movements similar to those required for wound healing. Two of the clearest of these, both of which involve closure of epithelial holes, are dorsal closure in the Drosophila embryo and C. elegans ventral enclosure. Dorsal closure in DrosophilaNear the end of the complex and intricately orchestrated cell and tissue movements of Drosophila gastrulation, including the extension of the germband over the dorsal surface and its subsequent retraction, a large hole is left behind on the dorsal surface of the embryo. An extra-embryonic membrane consisting of large flat cells -the amnioserosa -covers this dorsal hole (Fig. 3A-D). The process of bringing together the two epithelial edges over the amnioserosa to close the hole and form a seamless dorsal midline is known as dorsal closure. The dorsal hole is elliptical or eye shaped, and closure proceeds from the anterior and posterior ends (or canthi) of the opening towards the middle. The integrated efforts of three groups of cells are required for proper closure: the dorsalmost row of ectodermal cells defining the perimeter of the epithelial sheet, termed the leading edge (LE) cells; the more ventral epithelial (VE) cells; and the exposed amnioserosa (AS). Dorsal closure has been described as taking place in four phases (for detailed descriptions, see Harden, 2002;Jacinto et al., 2002b). The first phase, initiation (Fig. 3A), begins just prior to the completion of germband retraction, with the two opposing epithelial sheets moving slowly towards one another as a consequence of amnioserosal cell contraction. The trigger(s) required to start the dorsal closure process are not known, but probably include a combination of chemical and mechanical cues, including dorsoventral patterning information and mechanical stresses generated by germband retraction.During the second phase, epithelial sweeping ( Fig. 3B), leading edge cells accumulate actin and myosin just beneath the cell membrane at their dorsalmost (apical) edge. This Factin accumulation forms a contractile cable, which pulls the leading edges of the epithelial sheets taut (Jacinto et al., 2002a) Development 131 (13) Fig. 1. The cellular players in the healing of a skin wound. The wound is first 'plugged' with a fibrin clot, which is infiltrated by inflammatory cells, fibroblasts and a dense plexus...

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Section: Box 3 Cell Proliferation In Migrating Tissuesmentioning

confidence: 99%

mentioning

confidence: 99%

Parallels between tissue repair and embryo morphogenesis

2004

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“…From this point on further lens development and growth occurs throughout life, in a manner similar to other stratified epithelia (Harding et al, 1971). The lens epithelium constitutes the basal layer.…”

Section: Secondary Fibersmentioning

confidence: 92%

Development of lens sutures

Kuszak

Zoltoski²,

Tiedemann³

2004

Int. J. Dev. Biol.

114

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Cylindrical map projections (CMPs) have been used for centuries as an effective means of plotting the features of a 3D spheroidal surfaces (e.g. the earth) on a 2D rectangular map. We have used CMPs to plot primate fiber cell organization from selected growth shells as a function of growth, development and aging. Lens structural parameters and features were derived from slitlamp, light and transmission and scanning electron micrographs. This information was then used to create CMPs of lenses that were then correlated with azimuthal map projections (AMPs; projections that are radially symmetric around a central point [the poles] ) to reveal different suture patterns during distinct time periods. In this manner, both lens fiber and suture branch locations are defined by degrees of longitude and latitude. CMPs and AMPs confirm that throughout defined periods of development, growth and ageing, increasingly complex suture patterns are formed by the precise ordering of straight and opposite end curvature fibers. However, the manner in which additional suture branches are formed anteriorly and posteriorly is not identical. Anteriorly, new branches are added between extant branches. Posteriorly, pairs of new branches are formed that progressively overlay extant branches. The advantage of using CMPs is that the shape and organization of every fiber in a growth shell can be observed in a single image. Thus, the use of CMPs to plot primate fiber cell organization has revealed more complex aspects of fiber formation that may explain, at least in part, changes in lens optical quality as a function of age and pathology. In addition, more accurate measurements of fiber length will be possible by incorporating the latitudinal and longitudinal locations of fibers.KEY WORDS: crystalline lens, cylindrical map projection, azimuthal map projection, suture development, fiber cell organization, 3D CAD Int.

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“…1). Epithelium at the lens equatorial region is the normal site of lens cell multipli cation and confluent differentiation into cuboidal anterior epithelial cells and into fiber cells [1,2], If injured or irradiated, the lens anterior epithelial cells proliferate actively. Mature (finally differentiated) lens fiber cells, however, are devoid of cell organoids and di- viding capacity; therefore, they will not be dealt with in this study.…”

Section: Normal Lens Tissuementioning

confidence: 99%

Eye Lens Tumors: An Experimental-Histological and Theoretical Approach

Veromann

1994

Tumor Biol

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The eye lens is the only tissue in the organism where to date no spontaneous tumors have been described. In pathologic (cataractous) lenses, however, several abnormal cell growths have been described. General tissue properties of these cell growths (morphology, proliferation, formation of cell masses, etc.) are in accordance with characteristics of benign tumors in other tissues, and can therefore be considered as benign lens tumors.

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The Control of Cell Division in the Ocular Lens

Cited by 142 publications

References 160 publications

Parallels between tissue repair and embryo morphogenesis

Parallels between tissue repair and embryo morphogenesis

Development of lens sutures

Eye Lens Tumors: An Experimental-Histological and Theoretical Approach

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