QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Saxén, L. Search for Related Content PubMed Articles by Saxén, L. Social Bookmarking                         What's this?

The Initial Formation and Subsequent Development of the Double Visual Cells in Amphibia

Zoological Laboratory of the University of Helsinki

¹ Author's address: Zoological Laboratory, University of Helsinki, Helsinki, Finland.

Received for publication 31 May 1955.

SUMMARY

In 1867 Schultze described the main types of visual cell in the vertebrates, the rod and the cone, and one year later a third type, the double cone. The two first-mentioned types have subsequently been the objects of a large number of investigations; hence their structure, development, and function are largely understood. On the other hand, the double cells have attracted surprisingly little interest. Many writers apparently do not know of their existence, whilst others mention them only as a rarity, not deserving of particular study. Physiologists, too, speak only of rods and cones, without crediting the double cells with any specific function. The very fact, however, that double cells are extremely common in the vertebrates and compose, as a rule, a considerable proportion of the retinal receptors, should be sufficient evidence that they are not an insignificant rarity, and still less artefacts, as has sometimes been alleged.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?