Clue 1: Orient yourself
What must match before docking begins?
Use the labels and the picture's left-to-right, near-to-far, or before-and-after order. Name only what you can point to.
The question
What must match before docking begins?
Why it matters: The face forms through a timed sequence of growth, movement, and joining. Locating the missed step helps researchers ask a testable question instead of treating every cleft as the same process. Today you practice the professional reasoning behind that work: After elevation, the medial edges must recognize, adhere to, and align with one another before fusion can continue.
On your WebXam
Explaining why the non-stick periderm must be removed before shelf adhesion
For life
To find the cause, change one thing and watch what changes.
Principle: Same look, different cause
Five principles we return to
Having it is not using it
Same instructions, different switches
Same look, different cause
Change one thing and watch
Boss or doorman?
Decides the result or only allows it
Held down, not gone
Remove the brake and it returns
Many roads, one ending
One result can begin many ways
Try the everyday version first
A docking spacecraft needs matching ports
Two spacecraft dock only when their ports approach, align, touch, and lock. Reaching the same area is not enough if the ports face the wrong way.
Do not jump to the biology yet. Treat the picture as a small system. Track its parts, follow one change at a time, and keep more than one explanation open until the picture supplies a way to separate them.
Clue 2: Trace one change
How is touching different from locking?
Follow one object, stage, or path. Point to the first place where the situation changes instead of jumping to the ending.
Clue 3: Keep the cause open
What prevents the wrong surfaces from attaching?
List more than one explanation that still fits. Name the extra observation that would help you separate those possibilities.
Now inspect the illustration
Work from the visible evidence. A useful answer names the part of the picture that supports it and leaves unknown causes open.
- 1What must match before docking begins?
- 2How is touching different from locking?
- 3What prevents the wrong surfaces from attaching?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: What must match before docking begins?
You can complete today's required check without opening the technical details below.
Ready for the real names? Optional tier 2
Technical rules and limits
Rule 1: Contact requires the correct surfaces.
Rule 2: Alignment must come before stable adhesion.
Rule 3: Surface identity can permit or prevent sticking.
Where the analogy stops: Cells use changing proteins and behaviors, not metal docking latches.
Carry the previous idea forward
Palatal shelves must rapidly elevate above the tongue, and jaw-tongue geometry can block that movement.
Today's technical takeaway
After elevation, the medial edges must recognize, adhere to, and align with one another before fusion can continue.
Now map the same rules onto biology
Zoom in on the medial edge epithelium
Matching docking ports
Opposing medial edge epithelia
Initial contact
Shelf apposition at the midline
Docking lock
Adhesion and midline epithelial seam formation
Educational illustration, not a clinical photograph. Use the labels and evidence cards to make the biological claim.
Mateo's case file: evidence supplied in this lesson
DEV08-E1
Elevated shelves grow toward one another at the midline.
Why it matters: Correct position creates the opportunity for contact.
DEV08-E2
The medial edge epithelia make contact and adhere.
Why it matters: A specific surface interaction begins fusion.
DEV08-E3
Contact creates a midline epithelial seam.
Why it matters: The first joined state still contains an epithelial wall.
Make the clinical decision
You are scoring palate explants after 24 hours in culture.
One pair touches but separates with gentle handling. Another pair forms a stable midline seam.
AScore the first as contact without stable adhesion and the second as adhesion.
BScore both as complete fusion.
CIgnore the seam because touching is always enough.
Choose the scoring rule and cite the evidence that separates contact from adhesion.
Evidence required
DEV08-E1 + DEV08-E2 Claim ceiling
You may score contact and adhesion. You may not call mesenchymal fusion complete while the seam remains.Go deeper Optional tier 3
Everything required for today is above. Open these only if you want the explainer, source trail, or download files.
The everyday model and Tier 1 check are the complete required path for this lesson.
Use these checks to keep your place. They are not turned in through the portal.
Check off as you finish
- Worked through the everyday picture and answered its three questions.
- Completed the Tier 1 check in plain words.
Turn in: Developmental lesson 8: Two Shelves Become One Roof: Adhesion, the Medial Edge Epithelium, and the Seam
Go to Schoology to turn this in.
Submit one PDF. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf.
Open Schoology PDF upload helpIf you cannot get in, see Mr. Mendoza. Do not skip the work.
Optional legacy technical materials Open only if you want the original notes, vocabulary, artifact, and CER work
Before this page, you should know
- Elevation is the step where each vertical rotates to above the tongue at about human week 8.
- Elevation depends on internal remodeling of the shelf, including the water-holding matrix molecule , plus external room as the tongue descends and the head grows wider.
Today's new idea is only
Two shelves can only join if a non-stick layer () is removed on schedule so the two medial edge epithelia can adhere into one seam.
Goal: Describe how the two elevated shelves adhere at their medial edge and form a single seam, and explain why a non-stick surface layer must be removed first.
Know by the end
- The -facing edge of each elevated shelf is covered by the , and the very outside is capped by the .
- The is a non-stick protective layer whose normal job is to keep embryonic surfaces from sticking.
- For , the over the MEE must be cleared at the right moment, then the two bare MEE layers adhere and intercalate into a single .
- The gene program (IRF6 and partners) controls whether the clears on cue; if it is faulty, fails.
1
The shelf edge, layer by layer
Model start: The -facing edge of each shelf is the , and the caps it on the outside.
- The is a flat protective surface layer that normally keeps embryonic surfaces from ____.
- For , the over the MEE must first be ____ (cleared / shed) at the right time and place.
2
From two edges to one seam
- Once the is gone, the two bare MEE layers adhere at the ____ () and intercalate into one layer.
- That single shared layer is the ____ (MES).
3
The non-stick then must-stick switch
- The switch is controlled by the gene program (____ and partners) that differentiates the .
- If that program is off or faulty, surfaces stick where they should not or fail to adhere where they should, and the ____.
Everything you need for today is on this page. These links are optional.
What to read
Read the short plain-language explanation written for this lesson. Plain-language explainer for this lesson
Why this source matters
This explanation gives you the background for today's idea without making you decode a research paper: Two shelves can only join if a non-stick layer () is removed on schedule so the two medial edge epithelia can adhere into one seam.
Words to unlock first
Reading moves
- 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.
Stop point
Stop after the final 'Use it now' section. The research citations are available separately for advanced readers.
Your output
Write one claim-evidence sentence: state the main idea, then name the example or evidence that supports it.
Where this fits
Tested on (Ohio WebXam)
Genetics of Disease · 072130
PLTW lesson
MI · Developmental domain · Tissues and epithelia at the cell level (adhesion and seam formation)
WebXam domain
Molecular and Genetic Technology
Evidence to produce
Annotate a labeled tissue diagram of the shelf edge: label, in order from outside in at the moment of touching, periderm (being shed), MEE, the forming MES at the midline, and mesenchyme. Then write one sentence explaining why the periderm has to go first, and add to Mateo's chart: "Act 3 begins, shelves adhere into a seam."
Lab / skill
Principles of Biomedical Science (PBS) · Medical Interventions (MI)
Everything required for today's decision is already in the case file and plain-language explainer. The links below are original papers and database records for teachers and advanced readers, not assigned student reading.
- Claim: Two palatal shelves join when their ____ adhere into a single ____.
- Evidence: Before they can adhere, the ____ must be cleared away, because its normal job is to keep surfaces from sticking.
- Reasoning: This matters for Mateo because if the non-stick layer does not clear on time, the shelves ____ and a can result, which adds a possible cause to our list.
How this is graded (rubric)
For: Annotate a labeled tissue diagram of the shelf edge: label, in order from outside in at the moment of touching, periderm (being shed), MEE, the forming MES at the midline, and mesenchyme. Then write one sentence explaining why the periderm has to go first, and add to Mateo's chart: "Act 3 begins, shelves adhere into a seam."
| 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. |
How the model answer scores against this rubric
- CompleteProficient: Nothing is left blank: the model fills every part of "Annotate a labeled tissue diagram of the shelf edge: label, in order from outside in at the moment of touching, periderm (being shed), MEE, the forming MES at the midline, and mesenchyme. Then write one sentence explaining why the periderm has to go first, and add to Mateo's chart: "Act 3 begins, shelves adhere into a seam."".
- 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.
What's next: The shelves adhere at their medial edges and form one seam down the . But the roof is not truly finished: a wall of cells, the seam, still runs through it. If that wall stays, the two sides are not really one piece. What happens to that wall of cells? We chase that next time, and the answer turns out to be a real scientific argument.