2011 Lab 10 - Early Embryo

From Embryology
2011 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

Stage 11

Stage11 sem13c.jpg Stage11 sem20c.jpg

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

Stage 12

Stage12 sem1c.jpg Stage12 bf2c.jpgStage12 bf1c.jpg

Stage12 sem4.jpg Stage12 sem5.jpg

Week 5

Stage 13

Stage13 sem1c.jpg Stage13 bf1c.jpg Stage13 sem2c.jpg

Sensory Placodes

Stage14 sem2l.jpg

Stage 14

Sensory placodes develop as small patches of ectodermal thickenings.

The placodes are laterally paired and contribute key components to sensory structures of the ear, eye and nose.

Named by the sensory system and components they will form: otic placode, lens placode and nasal placode.

The links below are to additional information providing background about each of the sensory systems. Only hearing is covered in today's class.

Hearing Links: Introduction | inner ear | middle ear | outer ear | balance | placode | hearing neural | Science Lecture | Lecture Movie | Medicine Lecture | Stage 22 | hearing abnormalities | hearing test | sensory | Student project

  Categories: Hearing | Outer Ear | Middle Ear | Inner Ear | Balance

Historic Hearing Embryology 
Historic Embryology: 1880 Platypus cochlea | 1902 Development of Hearing | 1906 Membranous Labyrinth | 1910 Auditory Nerve | 1913 Tectorial Membrane | 1918 Human Embryo Otic Capsule | 1918 Cochlea | 1918 Grays Anatomy | 1922 Human Auricle | 1922 Otic Primordia | 1931 Internal Ear Scalae | 1932 Otic Capsule 1 | 1933 Otic Capsule 2 | 1936 Otic Capsule 3 | 1933 Endolymphatic Sac | 1934 Otic Vesicle | 1934 Membranous Labyrinth | 1938 Stapes - 7 to 21 weeks | 1938 Stapes - Term to Adult | 1940 Stapes | 1942 Stapes - Embryo 6.7 to 50 mm | 1943 Stapes - Fetus 75 to 150 mm | 1948 Stapes - Fetus 160 mm to term | 1959 Auditory Ossicles | 1963 Human Otocyst | Historic Disclaimer
Vision Links: vision | lens | retina | placode | extraocular muscle | cornea | eyelid | vision abnormalities | Student project 1 | Student project 2 | Category:Vision | sensory
Historic Embryology  
1906 Eye Embryology | 1907 Development Atlas | 1912 Eye Development | 1912 Nasolacrimal Duct | 1918 Grays Anatomy | 1921 Eye Development | 1922 Optic Primordia | 1925 Iris | 1927 Oculomotor | 1928 Human Retina | 1928 Retina | 1928 Hyaloid Canal | Historic Disclaimer
Smell Links: Introduction | placode | Rhinencephalon | head | respiratory | Student project | taste | sensory | Category:Smell
Historic Embryology  
Historic Embryology: 1902 Olfactory Structures | 1910 cavum nasi | 1940 Olfactory and Accessory Olfactory Formations | 1941 Olfactory nerve | 1980 Staged embryos
Taste Links: Introduction

Stage 13

Identify the structure and position of the otic vesicle (otocyst) relative to other head structures.

Stage 13 image 051.jpg

Stage 13 image 052.jpg

Stage 13 image 053.jpg

Stage 13 image 054.jpg

Stage 13 image 055.jpg

Pharyngeal Arches

Head arches cartoon.jpg Pharyngeal arch structure cartoon.gif

Stage 13 Pharyngeal Arches

Stage13 pharyngeal arch excerpts.gif

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.


Pharyngeal arch cartilages.jpg

Structures derived from Arches

Arch

Nerve

Muscles

Skeletal

Artery

1
(maxillary/mandibular)
trigeminal (V)

mastication
(temporalis, masseter, medial pterygoid, lateral pterygoid)

Meckel's cartilage
mandible modelmalleus, incus

maxillary(terminal branches)

2
(hyoid)
facial (VII)

facial expression
(buccinator, platysma, stapedius, stylohyoid, digastric posterior belly)

Reichert's cartilage
stapes, styloid process, lesser cornu of hyoid, upper part of body of hyoid bone

stapedial (embryonic)
corticotympanic (adult)

3
glossopharyngeal (IX)

stylopharyngeus

greater cornu of hyoid, lower part of body of hyoid bone

common carotid, internal carotid (root)

4 and 6
superior laryngeal and recurrent laryngeal branch of vagus (X)

intrinsic muscles of larynx, pharynx; levator palati

thyroid, cricoid, arytenoid, corniculate and cuneform cartilages

4 - aortic arch, right subclavian
6 - ductus arteriosus, pulmonary (roots)

Structures derived from Pouches

Pouch

Overall Structure

Specific Structures

1

tubotympanic recess

tympanic membrane, tympanic cavity, mastoid antrum, auditory tube

2

intratonsillar cleft

crypts of palatine tonsil, lymphatic nodules of palatine tonsil

3

inferior parathyroid gland, thymus gland

4

superior parathyroid gland, ultimobranchial body

5

becomes part of 4th pouch

Additional Information

Cranial neural crest skeletal fate 01.jpg Cranial neural crest contribution to skeletal structures

The embryo figure shows colonization of the head and pharyngeal arches by diencephalic, anterior and posterior mesencephalic, and rhombencephalic neural crest cells (NCCs), as indicated by the colour code. The diagram is representative human embryos, although the NCC migratory pathways might differ slightly in different species. The skull drawings show contributions of NCC populations to cranial skeletal elements of humans, based on NCC fate-mapping studies and on extrapolation of avian and mouse data to known homologues in the human.

Some bones, including the squamosal (SQ), alisphenoid (AS), and pterygoid (PT), are shown with mixed contribution from different NCC populations. Note that in mammals the frontal (FR) and parietal (PA) bones have been reported to be of neural crest and mesodermal origin, respectively.

(text modified from original figure legend)

  • BA1-BA3 - pharyngeal arches 1 - 3
  • di - diencephalon
  • FNP - frontonasal process
  • HY - hyoid bone
  • IN - incus
  • MA - malleus
  • mes - mesencephalon
  • MX - maxillary bone
  • NA - nasal bone
  • R1–R7 - rhombomeres 1 – 7
  • ST - stapes
  • ZY - zygomatic bone

Review article[1]

References

  1. <pubmed>14523380</pubmed>| Nat Rev Neurosci.
2011 Lab 10: Introduction | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment

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Cite this page: Hill, M.A. (2019, January 19) Embryology 2011 Lab 10 - Early Embryo. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2011_Lab_10_-_Early_Embryo

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G