Carnegie stage 1

From Embryology

Introduction

Early zygote.jpg

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

References

  1. 1.0 1.1 1.2 1.3 <pubmed>20579351</pubmed>| Reprod Biol Endocrinol.
  2. <pubmed>19924284</pubmed>
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

Cite this page: Hill, M.A. (2020, November 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 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G