Early Human Embryo Development

Match the following programming languages with their primary usage:

What is the primary reason why the study of embryonic development lends itself to the use of model organisms?

What is the function of the gene that specifies where eyes form in a vertebrate embryo?

What is a common feature of early stages of embryonic development across different species?

What is the benefit of using Drosophila melanogaster as a model organism?

What is the significance of the fact that the gene from a mouse can direct eye formation when experimentally introduced into a fly embryo?

What is the primary feature of the 5-week-old human embryo in Figure 46.1?

What is the common feature of embryonic development across different species that allows lessons learned from one species to be applied to others?

What is the significance of the fact that the gene that specifies where eyes form in a vertebrate embryo has a close counterpart with a nearly identical function in the fruit fly Drosophila melanogaster?

Development in Animals

A 5-week-old human embryo has already achieved several milestones, including a beating heart, a digestive tract, and a forming brain.

Common Features of Early Development

Biologists have observed common features in early stages of embryonic development across different species.
Experiments have shown that specific patterns of gene expression in an embryo direct cells to adopt distinct functions during development.

Shared Mechanisms of Development

Many animals share basic mechanisms of development and often use a common set of regulatory genes.
The gene that specifies where eyes form in a vertebrate embryo has a close counterpart with a nearly identical function in the fruit fly Drosophila melanogaster.
When the gene from a mouse is introduced into a fly embryo, the mouse gene directs eye formation wherever it is expressed.

Model Organisms

The study of development lends itself well to the use of model organisms, species chosen for the ease with which they can be studied in the laboratory.
Examples of model organisms include Drosophila melanogaster, sea urchin, frog, chick, and nematode (roundworm).

Stages of Embryonic Development

Development occurs at multiple points in the life cycle, including embryonic development, metamorphosis, and adult development.
The stages of embryonic development include:
- Fertilization: the fusion of sperm and egg
- Cleavage: a series of cell divisions that divide the embryo into many cells
- Gastrulation: the folding of the blastula into a multilayered embryo, the gastrula
- Organogenesis: the generation of rudimentary organs from which adult structures grow

This quiz explores the milestones achieved by a 5-week-old human embryo, including the formation of its heart, digestive tract, brain, and vertebrae. It also touches on the common features of early stages in embryos from different species.