Week 8: Difference between revisions
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[[Head Development|Head]] scalp vascular plexus visible | [[Head Development|Head]] scalp vascular plexus visible | ||
[ | [[Musculoskeletal_System_-_Limb_Development|Limb]] upper limbs begin to rotate ventrally | ||
[[Neural_System_Development|Neural]] - amygdaloid body has at least four individual nuclei<ref><pubmed>2268071</pubmed></ref> | [[Neural_System_Development|Neural]] - amygdaloid body has at least four individual nuclei<ref><pubmed>2268071</pubmed></ref> | ||
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| <center>51</center> | | <center>51</center> | ||
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| [ | | [[Gastrointestinal Tract Development|Gastrointestinal Tract] ] anal membrane perforates | ||
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[[Neural_System_Development|Neural]] - cortical plate appears in the area of future insula<ref name="PMID2252222"><pubmed>2252222</pubmed></ref> | [[Neural_System_Development|Neural]] - cortical plate appears in the area of future insula<ref name="PMID2252222"><pubmed>2252222</pubmed></ref> | ||
[ | [[Musculoskeletal_System_-_Limb_Development|Limb]] upper and lower limbs rotate | ||
[ | [[Coelomic Development|Intraembryonic Coelom]] pericardioperitoneal canals close | ||
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| [[File:Stage22_bf1c.jpg|200px|link=Carnegie stage 22]][[Neural_System_Development|Neural]] - neocortical fibres project to epithalamus, to dorsal thalamus, and to mesencephalon<ref name="PMID2252222" /> | | [[File:Stage22_bf1c.jpg|200px|link=Carnegie stage 22]][[Neural_System_Development|Neural]] - neocortical fibres project to epithalamus, to dorsal thalamus, and to mesencephalon<ref name="PMID2252222" /> | ||
[ | [[Musculoskeletal_System_-_Limb_Development|Limb]] fingers and toes lengthen | ||
[ | [[Sensory_-_Smell_Development|Sense - Smell]] Stage 22 to early fetal period - migratory streams of neurons from the subventricular zone of the olfactory bulb towards the future claustrum<ref name="PMID15604533"><pubmed>15604533</pubmed></ref> | ||
|- | |- | ||
| <center>55</center> | | <center>55</center> | ||
| | | | ||
| [ | | [[Genital System Development|Genital]] 8 Weeks Testis - mesenchyme, interstitial cells (of Leydig) secrete testosterone, androstenedione | ||
[ | [[Genital System Development|Genital]] 8 to 12 Weeks - hCG stimulates testosterone production | ||
[ | [[Tongue_Development|Tongue]] Week 8 - nerves penetrate epitheilai basal lamina and synapse with undifferentiated, elongated, epithelial cells (taste bud progenitor cell) | ||
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'''Mesoderm ''' heart prominence, ossification continues | '''Mesoderm ''' heart prominence, ossification continues | ||
[ | [[Head Development|Head]] nose, eye, external acoustic meatus, eyelids, external ears, rounded head | ||
'''Body '''- straightening of trunk, heart, liver, umbilical cord, intestines herniated at umbilicus | '''Body '''- straightening of trunk, heart, liver, umbilical cord, intestines herniated at umbilicus | ||
[ | [[Musculoskeletal_System_-_Limb_Development|Limb]] upper limbs longer and bent at elbow, hands and feet turned inward, foot with separated digits, wrist, hand with separated digits | ||
'''Extraembryonic Coelom''' chorionic cavity is now lost by fusion with the expanding amniotic cavity | '''Extraembryonic Coelom''' chorionic cavity is now lost by fusion with the expanding amniotic cavity | ||
| Line 86: | Line 86: | ||
[[Neural_System_Development|Neural]] - rhombencephalon, pyramidal decussation present, nuclei and tracts similar to those present in the newborn cerebellum present as only a plate connected to midbrain and hindbrain through fibre bundles<ref name="PMID2244584"><pubmed>2244584</pubmed></ref> | [[Neural_System_Development|Neural]] - rhombencephalon, pyramidal decussation present, nuclei and tracts similar to those present in the newborn cerebellum present as only a plate connected to midbrain and hindbrain through fibre bundles<ref name="PMID2244584"><pubmed>2244584</pubmed></ref> | ||
[ | [[Musculoskeletal_System_-_Axial_Skeleton_Development|Axial Skeleton]] vertebral column 33 or 34 cartilaginous vertebrae (20-33 mm in total length), vertebral pedicles, articular and transverse processes identifiable (no spinous processes)<ref name="PMID7216919"><pubmed>7216919</pubmed></ref> | ||
|- | |- | ||
| <center> </center> | | <center> </center> | ||
| Week 8 | | Week 8 | ||
| [ | | [[Gastrointestinal_Tract_-_Stomach_Development|Stomach]] - Week 8 - Gastrin containing cells in stomach antrum. Somatostatin cells in both the antrum and the fundus. | ||
|} | |} | ||
Revision as of 22:19, 15 May 2011
Key Events of Human Development during the eighth week (week 8) following fertilization or Clinical week 10 (LMP).
This is the final week of embryonic development, after this we describe development as fetal.
Timeline
| Event | ||
| Stage 20 | 
Head scalp vascular plexus visible Limb upper limbs begin to rotate ventrally Neural - amygdaloid body has at least four individual nuclei[1] oculomotor nerve shows a dorsolateral and a ventromedial portion rhombic lip (rhombencephalon) formation of the cerebellum (intermediate layer) and of the cochlear nuclei cerebellum cell layer (future Purkinje cells) develops choroid plexuses of the fourth and lateral ventricles | |
| [[Gastrointestinal Tract Development|Gastrointestinal Tract] ] anal membrane perforates | ||
| Stage 21 | 
Neural - cortical plate appears in the area of future insula[2] Limb upper and lower limbs rotate Intraembryonic Coelom pericardioperitoneal canals close | |
| Stage 22 |  Neural - neocortical fibres project to epithalamus, to dorsal thalamus, and to mesencephalon[2]
Limb fingers and toes lengthen Sense - Smell Stage 22 to early fetal period - migratory streams of neurons from the subventricular zone of the olfactory bulb towards the future claustrum[3] | |
| Genital 8 Weeks Testis - mesenchyme, interstitial cells (of Leydig) secrete testosterone, androstenedione
Genital 8 to 12 Weeks - hCG stimulates testosterone production Tongue Week 8 - nerves penetrate epitheilai basal lamina and synapse with undifferentiated, elongated, epithelial cells (taste bud progenitor cell) | ||
| Stage 23 |  Stage 23 defines the end of the embryonic (organogenesis) period
Mesoderm heart prominence, ossification continues Head nose, eye, external acoustic meatus, eyelids, external ears, rounded head Body - straightening of trunk, heart, liver, umbilical cord, intestines herniated at umbilicus Limb upper limbs longer and bent at elbow, hands and feet turned inward, foot with separated digits, wrist, hand with separated digits Extraembryonic Coelom chorionic cavity is now lost by fusion with the expanding amniotic cavity Neural - rhombencephalon, pyramidal decussation present, nuclei and tracts similar to those present in the newborn cerebellum present as only a plate connected to midbrain and hindbrain through fibre bundles[4] Axial Skeleton vertebral column 33 or 34 cartilaginous vertebrae (20-33 mm in total length), vertebral pedicles, articular and transverse processes identifiable (no spinous processes)[5] | |
| Week 8 | Stomach - Week 8 - Gastrin containing cells in stomach antrum. Somatostatin cells in both the antrum and the fundus. |
References
Embryo Week: Week 1 | Week 2 | Week 3 | Week 4 | Week 5 | Week 6 | Week 7 | Week 8 | Week 9
- 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
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. (2024, April 16) Embryology Week 8. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Week_8
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
