Primers start with the sequence pppAG positioned opposite the sequence 3 '-GTC-5' in the template.

TLS Online TPP Program

#Id: 1605

#Unit 5. Developmental Biology

Cells passing through the more anterior portions of the primitive streak give rise to the endoderm, head mesoderm, and notochord.

TLS Online TPP Program

#Id: 1606

#Unit 5. Developmental Biology

Cells passing through the more posterior portions of the primitive streak give rise to the majority of mesodermal tissues.

TLS Online TPP Program

#Id: 2350

#Unit 5. Developmental Biology

Planarian flatworms can reproduce asexually by binary fission, during which they split themselves in half.

TLS Online TPP Program

#Id: 2351

#Unit 5. Developmental Biology

If the planarian is cut in half, the anterior portion of the lower half regenerates a head while the posterior of the upper half regenerates a tail. 

TLS Online TPP Program

#Id: 2352

#Unit 5. Developmental Biology

If a flatworm is cut into three pieces, the middle piece will regenerate a head from its anterior end and a tail from its posterior end.

TLS Online TPP Program

#Id: 2353

#Unit 5. Developmental Biology

If the middle slice is too narrow, there is no discernible morphogen gradient within it, and regeneration is abnormal.