Rough draft.This research track is under review with Dr. Atit's lab. Content and sequence may still change.
The Baby Mateo Case
Developmental domainPrinciples of Biomedical Science (PBS)Lesson 15 of 20Your seat: Embryologist (timing specialist)
Critical Timing Windows, When the Door Closes
Discovery question
Is there a moment after which a can no longer be prevented, and the open structure stays open for good?
💡 Each lip and step runs only inside a narrow critical window, and once that window closes the closure machinery shuts off, so a left open becomes irreversible by normal development.
The plan
Prerequisite check
Before this page, you should know
- The normal build order is: week 4 to 6 lip , week 6 shelf growth, week 8 shelf elevation, weeks 8 to 12 shelf and fusion.
- A lip points to a failure of step 1 (medial nasal plus maxillary ); a cleft only points to a failure of palate growth, elevation, or fusion.
Today's new idea is only
Each lip and step runs only inside a narrow critical window, and once that window closes the closure machinery shuts off, so a left open becomes irreversible by normal development.
Learn first
What you will learn
Goal: Explain that each lip and step has a narrow critical window, and that once a window closes the cannot be undone by later development.
Know by the end
- The lip closes (medial nasal plus maxillary ) during human weeks 4 to 6.
- The secondary grows, elevates, and fuses during human weeks 6 to 12, with complete by about week 12.
- After the window, the face keeps growing larger but does NOT run the steps again; the closure tools (MEE, peel-away, ) are only on during the window.
- A left open when its window closes is irreversible by normal development; growth is not .
Learn first
Model: Two embryos, same problem, different timing
Two embryos each have a shelf that is a little slow to elevate.
X: the shelf catches up and reaches by week 9, while the window is still open. The shelves meet and fuse. Result: closed .
Y: the shelf does not reach until week 13, after the window has closed. The machinery has already shut off, so the shelves never get the signal to join. Result: , permanently.
Same delay. Different outcome. The only difference was whether the shelf arrived before or after the door closed (DATA_TABLES.md Table a; PMID:26589921).
Do the work
Explore (work the model before reading on)
- Give the human week range for lip closure and for .
- Which (X or Y) ended with a , and why?
- Y's shelf was only a few weeks late, yet the result was permanent. What does that tell you about how forgiving the window is?
- After week 12 the face keeps growing. Why does growing larger NOT close a that is already there?
- A treatment could nudge a slow shelf to elevate a little faster. Predict during which weeks that treatment would have to be given to make any difference, and why giving it at week 14 would be useless.
The plan
Guided notes
1
The fusion calendar
Model start: Each step has a critical window: a limited stretch of time when that step can happen at all. Miss the window and the step does not run later.
- The is human weeks ____ (4 to 6).
- The is human weeks ____ (6 to 12), with complete by about week ____ (12).
2
Why the deadline is real
- The closure tools (MEE, peel-away, the switch) are active during the window and then ____ (shut off).
- This makes a , once the window closes, ____ (irreversible) by normal development; the face grows bigger, but growth is not .
Explore
Reading the Research
What to read
Read the title and the abstract only, not the whole paper. Lan & Jiang 2015, Cellular and Molecular Mechanisms of Palatogenesis (Curr Top Dev Biol)
Why this source matters
This is the published evidence behind today's idea: Each lip and step runs only inside a narrow critical window, and once that window closes the closure machinery shuts off, so a left open becomes irreversible by normal development.
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
You do not need the methods or statistics yet. If a sentence is about lab technique or math you have not learned, mark it and skip it.
Your output
Write one claim-evidence sentence: what this source claims, and the one piece of evidence that backs it up.
Where this fits
Tested on (Ohio WebXam)
Genetics of Disease · 072130
PLTW lesson
MI · Developmental domain · PLTW PBS 072110
WebXam domain
Bio-Molecular Technology
Evidence to produce
Build a simple timeline for Mateo. Mark the lip window (weeks 4 to 6) and the palate window (weeks 6 to 12). Then write two sentences: (1) the latest week by which his lip-and-palate closure had to succeed or fail, and (2) why a doctor cannot expect his cleft to close on its own after birth, using the word window and the idea that the fusion machinery has shut off. Do not name a diagnosis.
Lab / skill
Principles of Biomedical Science (PBS)
The plan
Track your progress today
Check these off as you work through the lesson, then submit. This tells Mr. Mendoza how you're doing so he can help the class. It does not replace turning in your producible.
Use the code Mr. Mendoza gave you, not your name. Saved on this device.
Check off as you finish
- Read the Model and answered the Explore questions.
- Filled in the guided notes in my own words.
- Defined the new vocabulary with an example.
- Built the producible: Build a simple timeline for Mateo. Mark the lip window (weeks 4 to 6) and the palate window (weeks 6 to 12). Then write two sentences: (1) the latest week by which his lip-and-palate closure had to succeed or fail, and (2) why a doctor cannot expect his cleft to close on its own after birth, using the word window and the idea that the fusion machinery has shut off. Do not name a diagnosis.
- Wrote my Claim, Evidence, and Reasoning exit ticket.
Pick your period and code first.
Check yourself
Exit ticket (Claim, Evidence, Reasoning)
- Claim: A becomes locked in once its critical window closes.
- Evidence: In Model 2, the late clefted because its shelf arrived ____ the window, when the machinery had ____.
- Reasoning: Because the closure tools only run during the window, a structure left open after the window will ____.
How this is graded (rubric)
For: Build a simple timeline for Mateo. Mark the lip window (weeks 4 to 6) and the palate window (weeks 6 to 12). Then write two sentences: (1) the latest week by which his lip-and-palate closure had to succeed or fail, and (2) why a doctor cannot expect his cleft to close on its own after birth, using the word window and the idea that the fusion machinery has shut off. Do not name a diagnosis.
| 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. |
How the model answer scores against this rubric
- CompleteProficient: Nothing is left blank: the model fills every part of "Build a simple timeline for Mateo. Mark the lip window (weeks 4 to 6) and the palate window (weeks 6 to 12). Then write two sentences: (1) the latest week by which his lip-and-palate closure had to succeed or fail, and (2) why a doctor cannot expect his cleft to close on its own after birth, using the word window and the idea that the fusion machinery has shut off. Do not name a diagnosis.".
- 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.
Explore
Where this leads: careers
Embryologist Developmental biologist
What's next: We now know the face has narrow closure windows, and those windows are when it is most fragile. If the is most vulnerable during these weeks, can something from outside the embryo reach in during the window and change whether the face forms correctly?
Mapping the Failure, Which Step Breaks for a Cleft Lip Versus a Cleft PalateWhen the Outside World Reaches the Embryo