On the surface coat in the amphibian embryo

✍ Scribed by Løvtrup, Søren

• Publisher: John Wiley and Sons
• Year: 1962
• Tongue: English
• Weight: 824 KB
• Volume: 150
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1401500304

✦ Synopsis

cellular cement serve more purposes than merely that of binding cells together." Robert Chambers ('40).

The question about the function of the surface coat covering the amphibian egg was first emphasized in the very comprehensive study of Holtfreter ('43a). Several important functions were attributed to this structure, viz., wound healing, osmoregulation, and a number of different effects which may be grouped together under the heading: Morphogenetic action.

Since the work of Holtfreter, new results have been published concerning the formation, the composition and the action of the surface coat. None of these results disclaim the importance of this part of the cortex, but some of them are in conflict with interpretations given by Holtfreter. It may therefore be warranted to review the whole question, in connection with this presentation of various results bearing principally on the osmoregulatory function of the coat.

EXPERIMENTAL

The biological material was ovarian and unfertilized eggs and embryos of Rana platyrrhina (= R. temporaria). Permeability was determined with the Cartesian diver balance (Pigon and Zeuthen, '51; L~vtrup and Pigon, '51; Prescott and Zeuthen, '53; Lovtrup, '60, '62).

Volume determinations were made by determinations of the egg diameter with an ocular screw micrometer. As emphasized by Holtfreter ('43a) this method is not very accurate. However, when relatively large volume changes occur, the accurracy is satisfactory, as illustrated by the standard deviations shown in figure 1.