2010 Lab 3

From Embryology

Trilaminar Embryo


This laboratory will look at the third to fourth week of human development (stage 7 onward). We will be using a range of online materials and resources to explore these topics. The laboratory will also allow time for work on the group online project.

The best way of beginning to understand the sequence is by considering the "stages" of development in relation to age (in days or weeks). Stages are based on the external and/or internal morphological development of the vertebrate embryo, and are not directly dependent on either age or size. Historically, the human embryonic period proper is divided into 23 Carnegie stages and criteria beyond morphological features include age in days, number of somites present, and embryonic length have sometimes been included in the stage descriptions. These stages are also shown in the movie "Carnegie stage human growth through embryonic period"


  1. Understand the conceptus changes during week 3 following implantation.
  2. Understand the process of gastrulation and the trilaminar embryo
  3. Understand the development of mesoderm
  4. Understand the development of ectoderm
  5. Identify the early stages of embryonic development