2009 Lecture 3
From Embryology
Week 1 and 2
Introduction
Following fertilization the first week is a series of rapid cell divisions still contained within the zona pellucida.
Lecture Overview
- Week 1-2 of human development
- Fertilization options - In vitro fertilization
- Zygote, Morula, Blastocyst
- Cell layers - Trophoblast, Syncytiotrophoblast, Cytotrophoblast, Embryoblast
- Implantation - Normal, Ectopic, Uterine changes, Blastocyst implantation changes
Fertilization Options
- Natural sex
- Artificial insemination of mother with father's sperm, with mother with donor sperm, with egg and sperm donors, using surrogate mother
- In vitro fertilization (IVF) using egg and sperm of parents
- Intra-Cytoplasmic Sperm Injection (ICSI), frozen embryos, pre-implantation Genetic Diagnosis (PGD), egg donor, sperm donor, egg and sperm donor, surrogate using parents' egg and sperm, surrogate and egg donor, surrogate and sperm donor, surrogate using her egg and sperm from baby's father, surrogate using egg and sperm donors
Formation of Zygote
- 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
Cleavage of Zygote
- cleavage of zygote forms 2 blastomeres and is cleavage with no cytoplasm synthesis (special "embryonic" cell cycle MSMSMSMS, adult MG1SG2) therefore individual cell volume decreases
- cell division is initially synchronous, then asynchronously
- slow- centre cells, larger fast- peripheral cells
Morula - solid ball of cells with peripheral cells flattened against zona pellucida
UNSW Embryology Links
Glossary Links
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- Dr Mark Hill 2009 UNSW CRICOS Provider Code No. 00098G