[Subretinal microphotodiode array as replacement for degenerated photoreceptors?]. / Subretinales Mikrophotodioden-Array als Ersatz für degenerierte Photorezeptoren?

A survey is given on the status of developments, concerning a subretinal electronic microphotodiode array that aims at replacing degenerated photoreceptors. Various prototypes have been developed, tested, and implanted in various experimental animals up to 18 months. The fact that electrical responses were recorded from the visual cortex of pigs after electrical stimulation by subretinal electrodes and the fact that responses are also recorded in-vitro in degenerated rat retinae, shows the feasibility of this approach. However, there are a number of open questions concerning the biocompatibility, the long-time stability, and the type of transmitted image to be solved before application in patients can be considered.

The development of subretinal microphotodiodes for replacement of degenerated photoreceptors.

There are presently several concepts to restore vision in blind or highly visually handicapped persons by implanting electronic devices into the eye in order to partially restore vision. Here, the approach to replace retinal photoreceptors by a subretinally implanted microphotodiode array (MPDA) is summarized. A survey is given on the present state of the development of MPDAs, the possibility of in vitro and in vivo tests as well as first results on biocompatibility and histology. Additionally, electrophysiological recordings in rabbits and rats are presented which have received such subretinal implants.

[Histogenesis of nevus cell nevi. Implications of a case report]. / Zur Histogenese der Naevuszellnaevi. Implikationen einer Fallbeobachtung.

A case of multiple lesions of junctional melanocytic hyperplasia arising in a skin graft after excision of a congenital melanocytic naevus is reported. This observation is shown to support the concept of the histogenesis of acquired melanocytic naevi proposed by Cramer [2], i.e. that acquired melanocytic naevi are derived from melanocyte precursors located in nerve sheaths, whereas it is inconsistent with notions of the origin of naevogenesis in the epidermal melanocyte.

[Pachydermodactyly. Sequela of obsessive-compulsive neurosis]. / Pachydermodaktylie. Folge einer Zwangsneurose.

Pachydermodactyly is an acquired, asymptomatic swelling of the lateral sides of the fingers and is seen mainly in young men. The formal pathogenesis is a benign fibromatosis. The casual pathogenesis was until now unclear, although we believe, that exogenic factors are the main reason. Consequently Pachydermodactyly has to be considered as a result of compulsion neurosis.