Developmental Mechanisms

Introduction

Mechanism - "a process, technique, or system for achieving a result".

These notes are intended to introduce a number of different mechanisms at the all levels that form structures within the embryo. These are general notes about these mechanisms giving only a few examples. For specific tissues and organs read the system notes.

What is remarkable, given our biological diversity, is the strong evolutionary conservation of developmental mechanisms.

--Mark Hill 08:45, 15 May 2010 (EST) Currently template page only.

Axes

All embryos occupy 3 D space and appear differently externally and internally within this space. This gives us 3 different axes which need to be determined: Head/Tail (rostro/caudal), Front/Back (anterior/posterior), and Left/Right. The left/right axis appears at first mirror symetrical, and looks very similar externally, but clearly many internal organs are not duplicated (heart, liver, brain etc).

Cellular Mechanisms

These notes are intended to introduce a number of mechanisms at the cellular level that form structures within the embryo. These cellular dynamic and physical interactions form basic tissue structures of epithelia, connective tissues and features such as tubes.

Cell Migration

Molecular Mechanisms

This page is a link to many different resources related to Molecular Development. In current years we have turned from wanting to merely describe the events of embryogenesis, to a desire to understand the mechanisms of development. This has been a boon in allowing the use of many (easier) model systems such as the genetist's tool the fruitfly, and the worm, frog, chicken, zebrafish and mouse (see other embryos page).

A continuing theme also seems to be the reuse of signals at different times and places within the embryo, for diiferent jobs. This has given rise to the concept of "switches" which by themselves may contain no "information" but to activate other genes or switches. Finally, you can imagine that of our 20,000-25,000 protein-coding genes, a large number of these may only be expressed during development or if reused, have a completely different role in the mature animal.

Sex Determination

Epigenetics

In terms of molecular mechanisms, the field of epigenetics has begun to florish with some recent important findings.

Glossary Links

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Cite this page: Hill, M.A. (2026, September 11) Embryology Developmental Mechanisms. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Developmental_Mechanisms

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