2010 BGD Practical 6 - Week 8
Key Events of Human Development during the eighth week (week 8) following fertilization or Clinical week 10 (LMP).
BGD Cycle A 2010 Audio - Dr Mark Hill Monday 17th May 2010 3-5pm G2G4.
This page will give an overview of limb and neural development and look at other system organization compared with the earlier stages.
- Limb upper and lower limbs rotate in different directions (upper limb dorsally, lower limb ventrally)
- see also Adult dermatomes
Other Embryo Systems
Movies - Embryo Carnegie stage 22 - These are rotating animations based upon reconstruction of a human embryo (stage 22) serial slice images.
|Conceptus||Embryonic development (weeks)||Fetal period (weeks)|
|Loss||Major abnormalities||Functional and Minor abnormalities|
|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.|
Detailed Week by Week
The following information is a detailed timeline of embryonic development between week 3 to 8 and content does not form part of the current practical class.
Embryo Stages and Events
Head scalp vascular plexus visible
Limb upper limbs begin to rotate ventrally
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 anal membrane perforates|
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 PMID: 2252222
Limb fingers and toes lengthen
|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 PMID: 2244584
|Week 8||GIT - Stomach - Week 8 - Gastrin containing cells in stomach antrum. Somatostatin cells in both the antrum and the fundus.|
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- 2010 BGD: Lecture 1 | Lecture 2 | Practical 3 | Practical 6 | Practical 12
Cite this page: Hill, M.A. (2020, January 28) Embryology 2010 BGD Practical 6 - Week 8. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2010_BGD_Practical_6_-_Week_8
- © Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G