---
title: "Gastrulation and Laying Down the Body Axes"
description: "Gastrulation is where a ball of cells becomes an animal with an inside, an outside and three germ layers, by cells moving rather than dividing. The axes are set at the same time, and grafting experime"
canonical: https://lightmysky.com/learn/science/gastrulation-and-laying-down-the-body-axes-mt_PABfw_4RPs
source: https://lightmysky.com/learn/science/gastrulation-and-laying-down-the-body-axes-mt_PABfw_4RPs.md
retrieved: 2026-09-12
---

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# Gastrulation and Laying Down the Body Axes

Gastrulation is where a ball of cells becomes an animal with an inside, an outside and three germ layers, by cells moving rather than dividing. The axes are set at the same time, and grafting experiments showed that one small region can organise a whole second axis.

Subject: Science · Area: Organisms & Life Processes · Ages 19 to 20
Page: https://lightmysky.com/learn/science/gastrulation-and-laying-down-the-body-axes-mt_PABfw_4RPs

## Ready when they can

- Name the three germ layers and one adult tissue derived from each
- Describe the cell movements of gastrulation as distinct from cell division
- Explain what an organiser graft demonstrated and why the control mattered

## Lesson: Folding a ball into a body

Gastrulation turns a ball of cells into an animal with an inside, an outside, and three germ layers. Cells crawl, fold, and squeeze past each other to get there. Division takes a back seat: this step is about movement, not making more cells.

The three layers are ectoderm outside, mesoderm in the middle, and endoderm inside. Ectoderm makes skin and the nervous system, mesoderm makes muscle, bone, blood, and kidneys, and endoderm lines the gut and builds the liver and lungs.

At the same time the embryo lays down its map axes: head to tail, back to belly, and left from right. That early map is why your heart sits left and your liver right. Grafting experiments showed one small region can organise a whole second axis, and the ungrafted controls proved the graft did the work. Like the layers, the axes are mapped by moving cells, not by extra division.

**Tip.** If a question asks what gastrulation adds, answer three layers plus axes: an inside, an outside, and a map, all made by moving cells.

**Recap.** Movement folds one ball into three layers with axes, ready for organs.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Fertilisation and the First Cleavages](https://lightmysky.com/learn/science/fertilisation-and-the-first-cleavages-mt_9BXQsdP8fI)
- [Animal Body Plans: Symmetry, Cavities and the Deep Splits](https://lightmysky.com/learn/science/animal-body-plans-symmetry-cavities-and-the-deep-splits-mt_hEC72cvFQF)
- [Junctions, Adhesion and the Extracellular Matrix](https://lightmysky.com/learn/science/junctions-adhesion-and-the-extracellular-matrix-mt_Sjcd3kQUmw)

## Opens up

- [Morphogen Gradients and Positional Information](https://lightmysky.com/learn/science/morphogen-gradients-and-positional-information-mt_EbOK5M7V6Y)