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Carnegie Stage 14 Introduction

Stage 14 embryos have a greatest length of 5 to 7 mm and an estimated postfertilization age of 33 days. The optic cup and lens pit are present and the endolymphatic duct begins. The stage is represented by Carnegie embryo #6502 that has a grade of excellent. It has an estimated greatest length of 6.7 mm (after fixation) and is on the borderline of the next stage.

The embryo was prepared for microscopic examination in 1931. It is uncertain what fixative was used for this specimen but it is thought to have been Souza's. It was embedded in celloidin and paraffin and serially sectioned transverse to the long axis at 10 microns. The sections were mounted on 45 large glass slides and stained with hematoxylin and eosin. Silver was added later to sides 1 to 25. There are 1109 sections through the embryo.

The Browse part of the database contains 111 of the 1109 section images. Approximately every tenth section was digitally restored and labeled, and can be viewed at four magnifications (only 3 zoom levels are available on the CD version). Several 3D reconstructions were produced from the aligned sections. Animations of the 3D-reconstructions of the embryo surface and fly-through animations of the aligned sections are included on the disks.

Little has been published on the details of embryo 6502's morphology. Included on the disk are some photographs of the embryo before it was sectioned and a few figures from published accounts of stage 14 structure.

Source: The Virtual Human Embryo.