Tracking cell movement in developing chick embryo using carbon markers

Chicken Lab

Chicken Embryo Lab Report

A fate map can be used to track the progression of cell movements during chick embryo development. There are several potential uses for the information gathered and recorded on fate maps; the movement of cells and organs during development can yield a great deal of information regarding specifics of the species or genetic line as well as more general evolutionary information. In this technique, pioneered by N. Spratt and H. Haas (Journal of Experimental Zoology 103: 259-304 1946; 144: 139-158, 1960), the fate map is created by placing carbon markers in the blastoderm after it has been transferred to a petri dish. It is expected that significant movement of the carbon markers will occur during the experiment.

Results

Following two days of continuing incubation, the blastoderm appeared to have undergone significant development. Several bubble-like structures of rather minute size had formed within the cellular material, the primitive streak was no longer visible at al,, and there was a clear circular definition of a darker area within the larger blastoderm. The carbon (charcoal) that had been added to the blastoderm had also undergone fairly significant changes, having been spread out over a wider area of the blastoderm. The three initial points of carbon deposit were still clearly visible and provided the highest concentration of carbon in the blastoderm, but these points had more regular edges and shapes more closely approaching true circles than they had following the initial deposit of the material. Specks of carbon, including some spots of fairly sizable, extended in the same line on which the initial deposits had been placed though spread much further towards the edges of the blastoderm.

Discussion

The hypoblast is formed from the inner cell mass, which concentrates and solidified into the hypoblast as one part of several in cell development that occur at the same stage. The spread of the carbon throughout the blastoderm occurred in a more regular and predictable pattern than had been initially predicted, in keeping the form of a relatively straight line as it spread out. Though the results did not exactly match the hypothesis, there was still agreement in the distance of spread that was achieved. Growth also seems to occur on a linear rather than a circular basis as had been predicted, which is a very useful result obtain from such a "failure."