ANAT2341 Lab 10 - Early Embryo
ANAT2341 Lab 10: Introduction | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment |
Week 4
During week 4 a number of features appear visible on the embryo surface:
- At the level of the body heart, liver, somite bulges and limb buds appear.
- At the level of the head sensory placodes and pharyngeal arches appear.
Carnegie Stage 12 to 14
Week 4
This is a scanning EM of the embryo superior dorsal view showing the paired otic placodes sinking into the surface at the level of the hindbrain between day 24 and day 25
Vision - Week 4
(data based upon[1] and other sources).
- Stage 10 - optic primordia appear.
- Stage 11 - right and left optic primordia meet at the optic chiasma forming a U-shaped rim.
- Stage 12 - optic neural crest reaches its maximum extent and the optic vesicle becomes covered by a complete sheath,
Week 5
Sensory Placodes
Stage 13
Identify the structure and position of the otic vesicle (otocyst) relative to other head structures.
Vision - Week 4 to 5
(data based upon[2] and other sources).
- Week 4 - Stage 13 - By the end of the fourth week the optic vesicle lies close to the surface ectoderm. Optic evagination differentiation allows identification of optic part of retina, future pigmented layer of retina, and optic stalk. The surface ectoderm overlying the optic vesicle, in response to this contact, has thickened to form the lense placode.
- Week 5 - Stage 14 - (about 32 days) the lens placode is indented by the lens pit, cup-shaped and still communicates with the surface by a narrowing pore. Stage 15 - (about 33 days) the lens pit is closed. The lens vesicle and optic cup lie close to the surface ectoderm and appear to press against the surface.
Pharyngeal Arches
Stage 13 Pharyngeal Arches
A6L A7L B1L B2L B3L B4L B5L B6L
Look through the above cross-sections of the stage 13 embryo observing and identifying structures of the face and ear visible at this stage.
Structures derived from Arches
Arch |
Nerve |
Muscles |
Skeletal |
Artery |
(maxillary/mandibular) |
|
mastication |
Meckel's cartilage |
maxillary(terminal branches) |
(hyoid) |
|
facial expression |
Reichert's cartilage |
stapedial (embryonic) |
|
|
stylopharyngeus |
greater cornu of hyoid, lower part of body of hyoid bone |
common carotid, internal carotid (root) |
|
|
intrinsic muscles of larynx, pharynx; levator palati |
thyroid, cricoid, arytenoid, corniculate and cuneform cartilages |
4 - aortic arch, right subclavian |
Structures derived from Pouches
Pouch |
Overall Structure |
Specific Structures |
|
tubotympanic recess |
tympanic membrane, tympanic cavity, mastoid antrum, auditory tube |
|
intratonsillar cleft |
crypts of palatine tonsil, lymphatic nodules of palatine tonsil |
|
inferior parathyroid gland, thymus gland |
|
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superior parathyroid gland, ultimobranchial body |
|
|
becomes part of 4th pouch |
Additional Information
Additional Information - Content shown under this heading is not part of the material covered in this class. It is provided for those students who would like to know about some concepts or current research in topics related to the current class page. |
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Review article[3]
References
- ↑ <pubmed>7364662</pubmed>
- ↑ <pubmed>7364662</pubmed>
- ↑ <pubmed>14523380</pubmed>| Nat Rev Neurosci.
ANAT2341 Lab 10: Introduction | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment |
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Cite this page: Hill, M.A. (2024, April 25) Embryology ANAT2341 Lab 10 - Early Embryo. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/ANAT2341_Lab_10_-_Early_Embryo
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G