BGDA Practical 7 - Week 6: Difference between revisions
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==Limb Development== | |||
==Endocrine Development== | ==Endocrine Development== |
Revision as of 11:30, 18 May 2011
Introduction
Practical 6: Week 3 | Week 4 | Week 5 | Week 6 | Week 7 | Week 8 |
Key Events of Human Development during the sixth week (week 6) following fertilization or Clinical week 8 (LMP).
Limb Development
Endocrine Development
These organs mainly develop in the embryonic period and function in the fetal period. (Covered in next practical)
- Thyroid - develops from thyroid median endodermal thickening in the floor of pharynx outpouch – thyroid diverticulum (day 24), functions from week 10
- Pituitary - develops from surface (anterior) and neural tube (posterior) ectoderm, connecting stalk between pouch and oral cavity degenerates
- Parathyroid - develop from endoderm of pharyngeal pouches, diverticulum elongate, hollow then solid, dorsal cell proliferation
- Thymus - develops from 2 origins for lymphoid thymocytes and thymic epithelial cells, diverticulum elongate, hollow then solid, ventral cell proliferation
- Adrenal - develops from 2 origins adrenal medulla (neural crest) and fetal cortex (surrounding mesenchyme), fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia
- Gonad - develops from 2 origins, germ cells migrate into the genital ridge (mesothelium and underlying mesenchyme)
- Links: Endocrine System Development
Sex Determination
At an earlier stage during week 4, the primordial germ cells began their migration into the region where the gonads will eventually form, the genital ridge, see this migration in the mouse.
- Humans (week 5-6), these germ cells do not determine sex, it is the support cells regulated by the presence of an X or Y chromosome.
- germ cells migrate into gonadal ridge
- Gonads (male - testis, female - ovary) identical at this stage, termed "indifferent"
Note - Sex determination and development will be covered in detail in BGDB.
Practical 6: Week 3 | Week 4 | Week 5 | Week 6 | Week 7 | Week 8 |
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. |
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.
Endocrine Development
Embryo Stages and Events
Day | Stage | Event |
Pituitary Week 6 - connecting stalk between pouch and oral cavity degenerates
Parathyroid Week 6 - diverticulum elongate, hollow then solid, dorsal cell proliferation Thymus Week 6 - diverticulum elongate, hollow then solid, ventral cell proliferation Adrenal Week 6 - fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia Respire Week 6 - descent of heart and lungs into thorax. Pleuroperitoneal foramen closes Tongue Week 6 - gustatory papilla, caudal midline near the foramen caecum (week 6 to 7 - nerve fibers approach the lingual epithelium) | ||
Stage 16 | Neural first parasympathetic ganglia, submandibular and ciliary, are identifiable PMID: 2751117
Limbs upper limb bud nerves median nerve, radial nerve and ulnar nerve entered into hand plate, myoblasts spindle shaped and oriented parallel to limb bud axis. Heart outflow tract elliptical configuration with four cushions, the two larger fusing at this stage. Semilunar valve leaflets form at the downstream end of the cushions Head lip and palate components of the upper lip, medial nasal prominence and maxillary process present, median palatine process appears. | |
Stage 17 |
Neural telencephalon areas of the future archicortex, paleocortex, and neocortex, visible. Beginning of future choroid plexus PMID: 2802187 Sense - Smell olfactory nerve fibres enter the brain PMID: 15604533 Neural primordium of the epidural space appears first on the ventral part of the vertebral canal and develops rostro-caudally PMID: 15478101 | |
Heart separation of common cardiac outflow (aortic arch and pulmonary aorta) |
BGDA: Lecture 1 | Lecture 2 | Practical 3 | Practical 6 | Practical 12 | Lecture Neural | Practical 14 | Histology Support - Female | Male | Tutorial
Glossary Links
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Cite this page: Hill, M.A. (2024, May 6) Embryology BGDA Practical 7 - Week 6. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDA_Practical_7_-_Week_6
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G