ANAT2341 Lab 10 - Late Embryo

From Embryology
ANAT2341 Lab 10: Introduction | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment


Week 6 to 8 - Vision

(data based upon[1] and other sources).

  • Week 6 - Stage 16 - (37 days) Growth of the lens body results in a D-shaped lens cavity. Perilental blood vessels (tunica vasculosa lentis) are visible. Prior to the development of the eyelids, one small sulcus or groove forms above the eye (eyelid groove) and another below it.
  • Week 6 to 7 - Stages 17 - 19 - Retinal pigment is visible and the retinal fissure is largely closed. Eyelids grooves deepen, eyelid folds develop, first below, and then above, the eye.
  • Week 7 - Stages 18 - Mesenchyme invades the region between the lens epithelium and the surface ectoderm.
  • Week 7 to 8 - Stages 19 - 22 - the eyelid folds develop into the eyelids and cover more of the eye as the palpebral fissure takes shape. The upper and the lower eyelids meet at the outer canthus in Stage 19.
  • Week 8 - Stage 20 - The lens cavity is lost and a lens suture begins to form. The inner canthus is established. Stage 23 - The retina comprises the pigmented layer, external limiting membrane, proliferative zone, external neuroblastic layer, transient fiber layer, internal neuroblastic layer, nerve fiber layer, and internal limiting membrane. Eyelids closure is complete.

Week 8

Stage 22 (serial labeled images)
Section Name Description
Stage 22 image 055.jpg A6L Identify - Cornea. Anterior chamber. Lens. Vitreous body. Sensory retina. optic ventricle (artefact). Pigment epithelium.

Conjunctival sac. Primordium of lacrimal glands (near lateral fornix of conjunctival sac).

Interorbital ligament. Nose. upper eyelids.

Stage 22 image 056.jpg A7L Identify - Medial rectus muscle. Primordium of nasolacrimal ducts.

Upper eyelid (lateral). Lower eyelid (medial).

Stage 22 image 057.jpg B1L Identify - Optic nerve. Note extensive temporal region of retina.

Primordium of nasolacrimal ducts.

Stage 22 image 058.jpg B2L Identify - Medial and lateral rectus muscles. Pigment epithelium.

Note relationship of eye to nasal capsule, sphenoid cartilage and trigeminal ganglion.

Primordium of nasolacrimal ducts (cut obliquely).

Stage 22 image 059.jpg B3L Identify - On left course of maxillary division of trigeminal in relation to position of eye (superior to this level).

Hearing and Balance

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 
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 | 1946 Aquaductus cochleae and periotic (perilymphatic) duct | 1946 aquaeductus cochleae | 1948 Fissula ante fenestram | 1948 Stapes - Fetus 160 mm to term | 1959 Auditory Ossicles | 1963 Human Otocyst | Historic Disclaimer
Stage 22 (serial labeled images)
Section Name Description
Stage 22 image 059.jpg B3L Identify - Rhombic lip (developing cerebellum). IVth ventricle. Trigeminal ganglion. Adenohypophysis. Sphenoid cartilage.
Stage 22 image 060.jpg B4L Identify - Cochlear duct and temporal cartilage. Semicircular duct (ampulla on L). precartilage of auricle (pinna). malleus (medial, L). Incus (lateral, L).
Stage 22 image 061.jpg B5L Identify - Extemal auditory meatus. Auricle.

Incus (dorsal). Malleus (ventral). Tubotympanic recess (auditory rube). Tensor tympani m. (L). Utricle.

Semicircular ducts. Intemal auditory meatus (R), containing vestibular and spiral ganglia. Endolymphatic sac (L).

Note proximity of sac to choroid plexus of 4th ventricle.

Stage 22 image 062.jpg B6L Identify - External auditory meatus. Primordium of tympanic membrane (L).

Manubrium of malleus(L). Meckel's cartilage. Stapes (R). Auditory tube.

Basal turn of cochlea duct (L). Endolymphatic sac (R). Common crus (R). Junction of utricle and saccule (R).

Smell

Stage 22 (serial labeled images)
Section Name Description
Stage 22 image 054.jpg A5L Identify - Olfactory bulbs.
Stage 22 image 055.jpg A6L Identify - Interorbital ligament. nasal septum. primitive olfactory epithelium.
Stage 22 image 056.jpg A7L Identify - nasal capsule, nasal conchae, nasal septum, nasolacrimal duct.
Stage 22 image 057.jpg B1L Identify - nasal capsule, nasal conchae, nasal septum, nasolacrimal duct.
Stage 22 image 058.jpg B2L Identify - Vomeronasal organs (dark spots) beside nasal septum.
Stage 22 image 059.jpg B3L Identify - Nasolacrimal ducts
Stage 22 image 060.jpg B4L Identify - Tongue
Stage 22 image 061.jpg B5L Identify - Unfused palatal shelves either side of tongue. Section through mandible (top of image).

Vision and Hearing Selected Sections

Stage 22 selected serial labeled images
Stage 22 image 150.jpg Stage 22 image 151.jpg Stage 22 image 152.jpg Stage 22 image 153.jpg Stage 22 image 154.jpg Stage 22 image 155.jpg Stage 22 image 156.jpg
A1 head and brain A2 cortex A3 eye A4 optic nerve A5 retina A6 lens A7 CN5 and endocrine
Stage 22 image 157.jpg Stage 22 image 158.jpg Stage 22 image 159.jpg Stage 22 image 160.jpg Stage 22 image 161.jpg Stage 22 image 162.jpg Stage 22 image 163.jpg
B1 CN5 trigeminal B2 pituitary B3 auditory B4 choroid plexus B5 membranous labyrinth B6 inner ear B7 neck

Hearing

Stage 22 image 159.jpg


Stage 22 image 159.jpg Selected Head Images: B4 - Choroid Plexus | B5 - Cochlea | B6 - Cochlea

  • A pale cartilagenous region (that later ossifies) encloses the structuctures of the inner ear.
  • Beside this region the middle ear bones are forming.
  • On the righthand side of the head the external ear is visible.
  • The lower half of the image shows the developing brainstem with a large ventricular space occupied in part by an extensive choroid plexus (manufacturer of cerebrospinal fluid).

Embryonic External Ear

Shown below are the changes in external ear development between week 5 to week 8. Development changes from a series of 6 hillocks on arch 1 and arch 2 (week 5) to a structure resembling the adult ear (week 8).

External ear stages-14-23-adult.jpg

Human embryo head week 6 to 8.jpg Movement of the external ear in human embryo (week 6 to 8)[2]
"In all, 171 samples between Carnegie stage (CS) 17 and CS 23 were selected from MR image datasets of human embryos obtained from the Kyoto Collection of Human Embryos. The three-dimensional absolute position of 13 representative anatomical landmarks, including external and internal ears, from MRI data was traced to evaluate the movement between the different stages with identical magnification. Two different sets of reference axes were selected for evaluation and comparison of the movements. ...The results indicate that movement of all anatomical landmarks, including external and internal ears, can be explained by differential growth. Also, when the external ear is recognized as one of the facial landmarks and having a relative position to other landmarks such as the eyes and mouth, the external ears seem to move cranially."

References

  1. <pubmed>7364662</pubmed>
  2. <pubmed>22296782</pubmed>| PMC3286420 | Head Face Med.
ANAT2341 Lab 10: Introduction | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, October 19) Embryology ANAT2341 Lab 10 - Late Embryo. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/ANAT2341_Lab_10_-_Late_Embryo

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