General Embryology and Early Development

What this page covers

The resources here follow the early weeks of human development. Many start with fertilization, the zygote, the morula and the blastocyst, then move through implantation, the bilaminar embryo and gastrulation. Others go on to the germ layers, somites, the heart, the limbs, the eye and the digestive tract. A few look at model organisms, such as the Early Mouse Development mind map and the Xenopus Development flowchart.

Where to start

Begin with an overview. The mind map Embryology sets out the pre-embryonic phase in week 1, from zygote to blastocyst. The mind map Embryological Development adds the embryoblast and trophoblast. Then open the Embryology Flow Chart (Germ Layers), which links the epiblast, primitive streak, ectoderm, mesoderm and endoderm.

If you prefer reading, the note Blastocyst formation and gastrulation explains how mammals reach the blastocyst stage and how cleavage happens inside the zona pellucida.

Using quizzes and maps together

Study a map first, then test yourself. Quizzes such as Embryology Midterm ask where fertilization typically occurs, what the zona pellucida does and where the mesoderm is absent. Each wrong answer points you back to a branch of a map. Redraw that branch from memory, then retry the quiz.

1. Read one mind map on a stage, such as fertilization or gastrulation.
2. Take a quiz on the same stage.
3. Go through a flashcard deck, such as Somitogenesis or Germ Layers & Differentiation.
4. Return to the quiz a few days later.

Who it suits

Most of this material comes from university courses, so it suits students in anatomy, medicine and related programs. The deck MCAT embryogenesis and development review is a handy fit for professional candidates. Teachers can pull in ready-made maps and quizzes for a block on early development.

Where it sits

This unit belongs to the General Embryology strand of Histology and embryology. Choose a map or quiz that matches your lecture this week and see how it goes.