Developmental Anatomy
Stage 13: Summary
External: All four limb buds are usually visible; the optic vesicle is closed; the lens disc is generally not yet indented.
Internal: Septum primum and foramen primum appear in the heart; right and left lung buds are recognizable, and the trachea begins its development; retinal and lens discs appear; the endolymphatic appendage becomes distinguishable by the end of the stage.
Lab Manual - Horizon 13 (8066)
- Length: 4 - 6 mm.
- Pore of optic invagination closed.
- Lens vesicle not yet indented.
- Definite arm buds and beginning leg bud.
- Heart chambers distended.
- Ovulation age: 28 - 32 days.
Stage 13: Animation
Developmental Stages in Human Embryos by Ronan O'Rahilly and Fabiola Müller.
Published by Carnegie Institution of Washington, Publication 637. 1987.
Stage 13 (PDF 1 MB)
QUESTION: What are some characteristics of the heart chambers?
