Carnegie stage 20

Introduction

Facts

Week 8, 51 - 53 days, 18 - 22 mm

Events

Events Ectoderm: sensory placodes, lens pit, otocyst, nasal pits moved ventrally, fourth ventricle of brain

Mesoderm: heart prominence, ossification continues

Head: forebrain, eye, external acoustic meatus

Features

scalp vascular plexus, eylid, eye, nose, external acoustic meatus, auricle of external ear, arm, elbow, wrist, liver prominence, digital rays

Identify: straightening of trunk, pigmented eye, eyelid, nose, external acoustic meatus, scalp vascular plexus, digital rays, liver prominance, thigh, ankle, foot plate, umbilical cord

Carnegie Stages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | About Stages | Timeline

Bright Field

Kyoto Collection

View: This is a dorsolateral view of embryo. Amniotic membrane removed.

Image source: Embryology page Created: 19.03.1999

Image source: The Kyoto Collection images are reproduced with the permission of Prof. Kohei Shiota and Prof. Shigehito Yamada, Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan for educational purposes only and cannot be reproduced electronically or in writing without permission.

Carnegie Collection

Additional Images

Stage 20-23 limbs
Stage 20 Optical Projection Tomography

Historic Images

Skull - Dorsal aspect of base with the basioccipital in horizontal plane.
Skull - Right half base of cartilaginous skull.
Skull - Dorsal aspect of cartilaginous and membranous skull.
Skull - Median sagittal aspect.
Skull - Ventral aspect of base.
Skull - Lateral aspect and cervical vertebrae with brain and cervical cord and hypophysis.
Skull - Lateral aspect and cervical vertebra with brain, cervical cord, and nerves.
Skull - Lateral view and cervical vertebrae with overlying membranous skull and dorsal membrane.
Skull - Dorsal aspect of sphenoid cartilage.
Skull - Dorsal aspect of sphenoid cartilage.
Skull - Lateral view of right otic region.
Skull - Lateral view of right otic region showing relations of facial nerve.
Skull - Lateral view of base with deeper muscles of occipital region, mouth and pharynx.
Skull - Lateral view of part of cartilaginous and membranous skull.
Skull - Dorsal view of temporal and occipital cartilages.
Human embryonic shoulder girdle