The primordial germ cells of the chick I. the effect on the gonad of complete and partial removal of the ‘germinal crescent’ and of removal of other parts of the blastodisc

✍ Scribed by Joseph B. Goldsmith

• Publisher: John Wiley and Sons
• Year: 1935
• Tongue: English
• Weight: 959 KB
• Volume: 58
• Category: Article
• ISSN: 0362-2525
• DOI: 10.1002/jmor.1050580208

✦ Synopsis

Abstract

The ‘germinal crescent’ of the primitive streak stage chick embryo is located in the zone of junction anterior and lateral to the proamnion. The primordial germ cells supposedly arise from this area.

The following experiments were carried out. 1. Complete removal of the germinal crescent. 2. Partial removal of the germinal crescent. 3. Removal of areas of corresponding size of the blastodisc other than the germinal crescent.

The results are as follows: In experiment 1, a careful search of the entire specimen failed to reveal any primordial germ cells. Such embryos invariably died during or before the fifth day of incubation.

In experiments 2 and 3, the presence of the primordial germ cells was quite obvious. Such embryos did not invariably die. Some from each group was brought through to hatching, with the exception of that group in which the piece was taken from the lateral region of the blastodisc. In this case the injury to the circulation was too great to overcome.

As was to be expected, in those specimens in which the circulatory system was injured rather severely death always ensued and occurred before the third day of incubation regardless of the type of experiment.

Both cauterization and removal with scissors were tried. Mechanical removal gave superior results and was used exclusively in the latter part of the experiment.