Carnegie stage 1

Introduction

Human early zygote showing male and female pronuclei

The early human zygote where the male and female pronuclei (centre of image) have not yet combined to form the single zygote nucleus. These pronuclei are the nuclei from the spermatozoa (sperm) and oocyte (egg) and contain all the nuclear genetic material (chromosomes, DNA, genes). Two of the egg's polar bodies (right, 3 o'clock position of image) are shown at the edge of the egg cytoplasm. These polar bodies contain the excess DNA from the meiotic divisions of the egg. The zona pellucida (edge of image) forms a specialised thick extracellular matrix layer around both the egg and the developing conceptus for the first week. Mitochondria in the cytoplasm contain additional genes and in humans these mitochondrial genes are entirely derived from the oocyte. Facts: Week 1, size 0.1-0.15 mm Features: zygote, fertilized oocyte, pronuclei, polar bodies, zona pellucida Links: Week 1 | Zygote | Zona pellucida | Mitosis | Genetics | Human Genome | Mitochondrial Genome | Lecture | Medicine Practical | Science Practical | Stage 2

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

Carnegie stage 1

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  Early zygote

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  Early zygote labeled

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  Stage 1 size with ruler

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  Human zygote two pronuclei PMID 20579351

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  Human zygote two pronuclei PMID 20579351

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  Human zygote two pronuclei PMID 20579351

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  Human zygote two pronuclei (labelled) PMID 20579351

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  Human oocyte to blastocyst PMID 19924284

Electron Micrographs

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  Human pronuclei EM PMID 6008199

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  Human pronuclei EM PMID 6008199

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  Spermatozoon Components

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  Golgi complex

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  First Polar Body

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  First Polar Body

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  First Polar Body

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  Second Polar Body

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  Second Polar Body

Historic Images

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  Fig. 15. Diagram of fertilization of the ovum

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  Fig. 16. Fertilization of the eggs of the star-fish and sea-urchin

References

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

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Cite this page: Hill, M.A. (2024, April 25) Embryology Carnegie stage 1. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Carnegie_stage_1

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G