What Happens to the Wall Between the Shelves: Seam Removal, EMT versus Apoptosis
Take the reading one piece at a time. For each piece: read it once, underline the sentence that says what happens, then look up any word in the list. Tap a word to see its definition.
Piece 1 of 2
Picture the joined roof in cross section: running down the middle is the midline epithelial seam (MES), a thin column of epithelial cells where the two edges met, with mesenchyme on both sides still separated by that wall. For the palate to work as one tissue, the left mesenchyme must become continuous with the right, which can only happen if the seam is removed. Lab records show the MES thins, breaks into islands, and is gone, leaving uninterrupted mesenchyme across the midline. So the seam does disappear; the question is HOW its cells leave.
Piece 2 of 2
Researchers proposed several mechanisms, and the favored answer changed as imaging improved. Idea A, EMT: the seam cells convert into mesenchyme and blend in (cells switch teams, not lost). Idea B, apoptosis: the cells get a self-destruct signal and die in an orderly way. Idea C, migration: the cells slide away from the midline without dying or changing identity. Idea D, live-cell extrusion: the seam cells pull on each other, gather into rosettes, and get physically squeezed out of the sheet while still alive, with apoptosis as a partner. Early work leaned toward EMT; then lineage labeling found little evidence for conversion and pointed to apoptosis plus migration; the most recent live imaging favors contraction-driven extrusion working with apoptosis.
Reading the Research
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Now put it together: In one or two sentences, say what this whole reading is telling you about Mateo. Then go back to the lesson and fill in the guided notes.