What Tells Tissues When and Where to Grow: The Signaling Centers SHH, BMP, FGF
Developmental domain · Lesson 10 of 20 · Principles of Biomedical Science (PBS)
Today's goal: Explain that palatal shelves grow on schedule because signaling molecules (SHH, BMP, FGF) are released from specific places and act as instructions for when and where tissue grows, and that losing a signal causes a too-small or mis-grown shelf.
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.
Two layers: epithelium on the surface, mesenchyme inside.
- Arrow 1: SHH from epithelium to mesenchyme, labeled "grow" (drives proliferation; central player in shelf growth).
- Arrow 2: FGF10 from mesenchyme back to epithelium, labeled "keep SHH on" (the feedback loop).
- Arrow 3: BMP in the anterior shelf, labeled "front growth, right dose" (dose-sensitive).
Sentence: If any of these instructions is missing or mis-dosed, the shelf can grow too little to reach the midline, and the palate may cleft. Chart note: we cannot read Mateo's embryonic signals from a newborn exam, so this stays an upstream molecular possibility.
This model shows the level of evidence and organization needed to complete: A two-layer shelf diagram with three labeled signal arrows and a clefting-route sentence.
- Date and label the entry.
- Record the procedure, observation, or design decision clearly.
- End with what the evidence means and the next step.
Keep the structure. Replace the question, facts, measurements, and evidence. Then recheck units, vocabulary, and whether the conclusion goes beyond the evidence.
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: How do nearby tissues tell one another where and how much to grow?
- 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: Build a one-page signal map for Mateo's case file: draw the shelf as two layers ( on the surface, inside) and add three labeled arrows: SHH from epithelium to mesenchyme (grow), FGF10 from mesenchyme back to epithelium (keep SHH on), and BMP in the shelf (front growth, right dose). Add one sentence on how a missing or mis-dosed instruction can leave the shelf too small to reach the , and note we cannot read Mateo's embryonic signals from a .
- 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 through the route named under Submit here 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 "Build a one-page signal map for Mateo's case file: draw the shelf as two layers (epithelium on the surface, mesenchyme inside) and add three labeled arrows: SHH from epithelium to mesenchyme (grow), FGF10 from mesenchyme back to epithelium (keep SHH on), and BMP in the anterior shelf (front growth, right dose). Add one sentence on how a missing or mis-dosed instruction can leave the shelf too small to reach the midline, and note we cannot read Mateo's embryonic signals from a 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 attached to your class form or handed in, and confirmed.
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.
It builds this reusable test skill: Reasoning from a Smo knockout that SHH reception drives secondary-palate growth.
- Name the concept or data pattern being tested.
- Cross out choices that violate that rule or the evidence.
- Justify the best remaining choice before checking the answer.