Medullary collecting duct is permeable to urea, and there are special urea transporters that facilitate urea diffusion across the luminal and basolateral membranes

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#Id: 7363

#Unit 5. Developmental Biology

On the right side of the embryo, activin is expressed, along with activin receptor IIa. This activates Fgf8, a protein that blocks expression of the gene for Cerberus.

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#Id: 7364

#Unit 5. Developmental Biology

In the absence of Cerberus, Nodal is not activated and thus Pitx2 is not expressed

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#Id: 7365

#Unit 5. Developmental Biology

Drosophila eggs undergo Superficial cleavage.

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#Id: 7366

#Unit 5. Developmental Biology

In the Drosophila egg, karyokinesis occurs without cytokinesis to create a syncytium.

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#Id: 7367

#Unit 5. Developmental Biology

In Drosophila, during the ninth division cycle- Pole cells determination 

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#Id: 7368

#Unit 5. Developmental Biology

The transition from specification to determination in Drosophila is mediated by Segmentation genes.