Lecture - Week 1 and 2 Development: Difference between revisions
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* about '''day 4''' is a solid ball of 16-20 cells with peripheral cells flattened against zona pellucida | * about '''day 4''' is a solid ball of 16-20 cells with peripheral cells flattened against zona pellucida | ||
* compaction occurs forming a cavity and leading to the next blastocyst stage | * compaction occurs forming a cavity and leading to the next blastocyst stage | ||
:'''Links:''' [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=hmg.figgrp.928 Figure 8.19. Changes in DNA methylation during mammalian development] | :'''Links:''' [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=hmg.figgrp.928 Figure 8.19. Changes in DNA methylation during mammalian development] | ||
==Blastocyst== | |||
[[Image:CSt3.jpg|thumb|300px|Hatching Blastocyst]] | |||
* about '''day 5''' have 2 identifiable cell types and a fluid-filled cavity (blastoceol) | |||
** '''trophoblast layer''' - peripheral flattened cells, forms the placenta and placental membranes | |||
** '''inner cell mass''' - embryoblast, mass of rounder cells located on one wall of the blastocoel, forms entire embryo | |||
===Blastula Cell Communication=== | |||
Two forms of cellular junctions [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=mboc4.figgrp.3927 Figure 21-69. The blastula] | |||
* '''gap junctions''', allow electrically couple cells of epithelium surrounding a fluid-filled cavity | |||
*''' tight junctions''', close to outer surface create a seal, isolates interior of embryo from external medium | |||
'''Blastocyst Hatching''' - zona pellucida lost, ZP has sperm entry site, and entire ZP broken down by uterine secretions and possibly blastula secretions. | |||
'''Uterine Glands''' - secretions required for blastocyst motility and nutrition | |||
:'''Links:''' [[Carnegie stage | :'''Links:''' [[Carnegie stage 3]] | ||
{{2011ANAT2341}} | {{2011ANAT2341}} | ||
[[Category:Week 1]] [[Category:Week 2]] | [[Category:Week 1]] [[Category:Week 2]] |
Revision as of 14:38, 1 August 2011
2010 Lecture | Zygote | Blastocyst | Implantation
Objectives
- Understand the events during week 1 of development (Zygote, Blastomeres, Morula, Blastocyst)
- Understand the events during week 2 of development (Trophoblast, Syncytiotrophoblast, Cytotrophoblast, Embryoblast, Implantation)
- Brief understanding of early placentation
- Brief understanding of maternal changes
Zygote Formation
- zygote is the first diploid cell formed following fertilisation.
- male and female pronuclei, 2 nuclei approach each other and nuclear membranes break down.
- DNA replicates, first mitotic division
- sperm contributes centriole which organizes mitotic spindle
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Movie - Pronuclear Fusion | Movie - Parental Genomes
- Conceptus - the term refers to all material derived from this fertilised zygote, includes both the embryo and the non-embryonic tissues (placenta, fetal membranes).
- Links: Carnegie stage 1
Cleavage of Zygote
- cleavage of zygote forms 2 blastomeres and is also cleavage with no cytoplasm synthesis.
- special "embryonic" cell cycle S phases and M phases alternate without any intervening G1 or G2 phases (MSMSMSMS, adult MG1SG2) therefore individual cell volume decreases.
- cell division is initially synchronous, then asynchronously
- slow- centre cells, larger fast- peripheral cells
- zona pellucid still intact (division occurs within the ZP)
<wikiflv width="414" height="278" autoplay="true">embryo mitosis.flv|Embryo_mitosis_icon.jpg</wikiflv>
Morula
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Human Embryo (day 2) | Human Embryo (day 3) |
- about day 4 is a solid ball of 16-20 cells with peripheral cells flattened against zona pellucida
- compaction occurs forming a cavity and leading to the next blastocyst stage
Blastocyst
- about day 5 have 2 identifiable cell types and a fluid-filled cavity (blastoceol)
- trophoblast layer - peripheral flattened cells, forms the placenta and placental membranes
- inner cell mass - embryoblast, mass of rounder cells located on one wall of the blastocoel, forms entire embryo
Blastula Cell Communication
Two forms of cellular junctions Figure 21-69. The blastula
- gap junctions, allow electrically couple cells of epithelium surrounding a fluid-filled cavity
- tight junctions, close to outer surface create a seal, isolates interior of embryo from external medium
Blastocyst Hatching - zona pellucida lost, ZP has sperm entry site, and entire ZP broken down by uterine secretions and possibly blastula secretions. Uterine Glands - secretions required for blastocyst motility and nutrition
- Links: Carnegie stage 3
Co-ordinator Note
![]() Dr Mark Hill |
ANAT2341 Embryology S2 2011
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Course Content 2011
2011 Timetable: | Embryology Introduction | Fertilization | Cell Division/Fertilization | Week 1 and 2 Development | Week 3 Development | Week 1 to 3 | Mesoderm Development | Ectoderm, Early Neural, Neural Crest | Trilaminar Embryo to Early Embryo | Early Vascular Development | Placenta | Vascular and Placenta | Endoderm, Early Gastrointestinal | Respiratory Development | Endoderm and Respiratory | Head Development | Neural Crest Development | Head and Neural Crest | Musculoskeletal Development | Limb Development | Musculoskeletal | Renal Development | Genital | Kidney and Genital | Sensory | Stem Cells | Stem Cells | Endocrine Development | Endocrine | Heart | Integumentary Development | Heart and Integumentary | Fetal | Birth and Revision | Fetal
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, June 20) Embryology Lecture - Week 1 and 2 Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Lecture_-_Week_1_and_2_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G