What Happens to the Wall Between the Shelves: Seam Removal, EMT versus Apoptosis
Developmental domain · Lesson 9 of 20 · Principles of Biomedical Science (PBS)
Today's goal: Explain that the midline epithelial seam must be removed for the palate to become one continuous tissue, and compare the candidate mechanisms (EMT, apoptosis, cell migration, and live-cell extrusion) as a genuine, still-evolving scientific question.
What a finished product looks like
This is a model of the work you should turn in. Use it to check your own: match the structure and the level of detail, do not copy it. Your wording should be your own.
1. Settled: for the palate to be one continuous tissue, the midline epithelial seam must be removed so the left and right mesenchyme join.
2. Competing mechanisms: EMT (seam cells convert to mesenchyme), apoptosis (orderly cell death), migration (cells slide away), and live-cell extrusion (cells squeezed out, with apoptosis as a partner).
3. Currently favored and why: contraction-driven extrusion plus apoptosis, because lineage labeling showed little EMT and live imaging let scientists watch individual cells over time.
4. Honest note: the exact mechanism is not fully closed; better imaging keeps refining it.
For Mateo: seam-removal failure stays a possible upstream cause, not something we can see on a newborn exam.
How this was built, step by step
The finished product above did not appear all at once. Here is the path from the question to the turned-in work, so you can follow the same steps.
- 1Start from today's question: What happens to the wall of seam cells so the becomes one continuous , and how sure are scientists about the answer?
- 2Work the Model and the Explore questions to reason it out before writing anything.
- 3Pull the specific evidence the product needs from the reading and any database you used.
- 4Write it up in the required format: Write the "open questions" box for Mateo's case file: (1) state what is settled (the seam must be removed for one continuous ), (2) name the competing mechanisms, (3) say which is currently favored and why (better imaging), and (4) note honestly that the question is not fully closed. Add one line that seam-removal failure stays a possible cause, not something visible on .
- 5Check it against the rubric, then submit.
| Criterion | Proficient | Developing | Beginning |
|---|---|---|---|
| Complete | Every required part of the artifact is present and filled in. | Most parts are present, but one is missing or left blank. | Several parts are missing. |
| Accurate | The science and data are correct and match the evidence. | Mostly correct, with a small factual slip. | Key science or data is wrong. |
| Scientific reasoning (CER) | States a claim, backs it with specific evidence, and explains the reasoning. | Has a claim and evidence, but the reasoning is thin or missing. | Gives an answer with no evidence or reasoning. |
| Professional communication | Clear, organized, and labeled the way a clinician or scientist would write it. | Readable but disorganized or missing labels. | Hard to follow. |
| Submitted | Turned in the right way (Schoology for routine work) and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
- CompleteProficient: Nothing is left blank: the model fills every part of "Write the "open questions" box for Mateo's case file: (1) state what is settled (the seam must be removed for one continuous palate), (2) name the competing mechanisms, (3) say which is currently favored and why (better imaging), and (4) note honestly that the question is not fully closed. Add one line that seam-removal failure stays a possible upstream cause, not something visible on newborn exam.".
- AccurateProficient: Every number and claim matches the case evidence.
- Scientific reasoning (CER)Proficient: It names a claim, cites the specific evidence, and explains the reasoning, not just the answer.
- Professional communicationProficient: It is organized and labeled like a real chart note.
- SubmittedProficient: It would be turned in on Schoology and confirmed.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.