77 yo

77 years ago, Wetzel nicely described and depicted cell movements at the chick embryo epiblast. And this is from his 1929 paper¹

Almost 3 years ago, overwhelmed by such a complex pattern, somebody² considered that dealing with a small part of it should be sufficient. And described the cell movements as follows (red lines over Wetzel’s view.

Oversimplifying already quite simple problems may lead you to lose sight of quite important things, say, that the region you are looking in particular isn’t teared apart, as you may think, but rather compressed³!

1.   Wetzel, R. Untersuchungen am Hu ̈hnchen. Die Entwicklung des Keims wa ̈hrend der ersten beiden Bruttage. Arch. EntwMech. Org. 119, 188–321 (1929).

2.   Fleury, V An Elasto-Plastic Model of Avian Gastrulation. Organogenesis 1, 2 6-16 (2005)

3.   Voiculescu 0, Bertocchini F, WolpertL., Keller RE, Claudio D. Stern CD The amniote primitive streak is defined by epithelial cell intercalation before gastrulation Nature 449, 1049 – 1052 (25 Oct 2007) Letters to Editor