Development and aging of cell topography in the human retinal pigment epithelium

Purpose. To determine how regional cell density of this tissue changes with age, the authors examined the topography of the human retinal pigment epithelium (RPE) in wholemounted tissue obtained from eyes aged 12 to 89 years, donated for corneas. Methods. The RYE, with choroid attached, was wholemounted and stained with cresyl violet. From these preparations, the authors analyzed retinal area, RYE cell number, and cell density. Results. Retinal pigment epithelial cell number is highly variable between persons but does not appear to be age related. Retinal area increases until approximately 30 years of age, but beyond this age individual variation masks further enlargement. The distinctive topography of the RPE changes markedly with age. There is a modification from the relatively homogeneous cell density distribution in the youngest retinas examined toward a more heterogeneous pattern in older retinas. From mid-adolescence, a hand of larger cells appears at the extreme periphery, adjacent to the ora serrata, which gradually widens so that by 90 years of age, it occupies the outermost 30% of the retinal area. Cell density is highest in the central temporal retina, adjacent to the macula in the neural retina, throughout life. Cell density values in this region increase slightly with age, and the difference between this and surrounding regions becomes more marked with age. Conclusions. With no marked change in total cell number, peripheral RPE in humans enlarges in area throughout life, but the RPE in more central regions decreases in area

Fulfilling the 'cultural mission': popular genre and public remit

Over the last three decades, public broadcasting in Europe, like other public institutions, has been under sustained pressure in various forms, including attacks on public provision from positions within, neoclassical economics and new right politics; left critique of public broadcast institutions and texts as reproductive of power formations; and development of new flexible media delivery systems and technologies. Public broadcasting has been required to justify itself under circumstances where conmmercial free-to-air broadcasting has been progressively challenged by pay TV in the broadcasting environment and where its necessarily national framework has been threatened by globalizing processes and. the flow of audiovisual technologies and content across national borders. One key site where these tensions are being played out is in the popular television genre of sport. Television sport is probably the most spectacular and regular vehicle for conveying and communicating both global and national culture. however these concepts might be critiqued and contested. Ini Europc, public broadcasters have played a foundational role in the development and nurturing of broadcast sport as national culture. Sport, therefore, is an especially important subject for debates about the state and future of the popular in public broadcasting. This article uses television sport as a case study in the exploration and analysis of the dilemrmrras of public broadcasting in Europe arid seeks to propose a tenable normrative framework for both its maintenance and development

Muddy Shore to Modern Port: Redimensioning the Montréal Waterfront Time-space

For Montréal in the nineteenth century, as for most port cities, the waterfront served as the primary interface between the city and the markets of the world. This paper examines how and why the primitive waterfront of Montréal as of 1830 was repeatedly adapted and transformed into a modern port district by 1914. Beyond a detailed examination of the set of physical changes on the waterfront, this paper draws theoretical insights from geographical interpretations of the rhythm of capital accumulation to explore the formative and adaptive processes underlying waterfront redevelopment. Global innovations in transport and cargo-handling technology are recognised as the preconditions for the periodic redimensioning of the port of Montréal, and it is established that these changes were driven by the perennial demands of local investors to accelerate circulation and thus reduce the turnover time of capital. This paper offers a new perspective on waterfront development by conceptualising the entire port as a comprehensive circulatory system and then exploring the redevelopment of various components in relation to others. The findings indicate that massive increases in traffic—the number and size of ships—through the port were correlated with the redimensioning of all of the connected components of the circulatory system; that is, the major arteries such as the St Lawrence River ship channel, as well as the smaller capillaries like finger piers