XXV.—The Early Stages in the Development of Cavia

Abstract

At the end of 1926 a paper by Dr Maclaren entitled “Development of Cavia: Implantation” was published in theTransactions of the Royal Society of Edinburgh(2). In this he dealt with the process of implantation of the blastocyst, and incidentally gave a tentative interpretation of the nature of the layers of which it was formed. The paper was to have been followed by a further contribution dealing especially with the earlier stages in the history of the blastocyst. This was held up for various reasons, and was not ready for publication until 1930, when there appeared appaperd on the subject by Professor Hill and Dr Sansom (6). This forestalled to a considerable extent Dr Maclaren's demonstration of the facts of observation, but there remained to him more than a dozen examples of free blasto-cysts at younger stages of development than the earliest figured in their paper, and indeed of any other worker on the development of Cavia. He then thought that it might be more interesting and instructive if the fixed and sectioned material were controlled by observations on the living blastocyst. A technique for this was developed, and apparatus designed by which living blastocysts could be observed and photographed. Eminently successful in the case of mammals with large blastocysts and tardy implantation, the results obtained in Cavia were disappointing owing to the excessive minuteness of the blastocyst, and to its being very early involved in one of the crypt-like recesses in the mucosa.