File:Early zygote labelled.jpg

From Embryology

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Early Zygote

This is described as an early human zygote due to the presence of the 2 pronuclei (male and female) in the centre of the cytoplasm.

The haploid pronuclei of the male (spermatozoa) and female (oocyte) have not yet combined to form a single nucleus.

The polar bodies can be seen at the edge of the cytoplasm (at 3 o'clock position). These exclusion bodies contain the additional oocyte DNA produced in meiosis.

The zona pellucida forms the thick clear layer that surrounds the cell. This specialised extracellular matrix has nay roles in early development.

At this stage in vivo:

  • there would still be granulosa cells and spermatozoa attached to the zone pellucida.
  • the zygote floats freely within the uterine tube.
  • The cell is preparing for the first mitotic division.

Zygote Image Links: Image - Early zygote | Image - Early zygote labelled | Image - zygote 1 | Image - zygote 2 | Image - zygote 3 | Image - zygote 2 labeled | Fertilization | Zygote | Carnegie stage 1 | Category:Zygote

About Carnegie Stage 1

Facts: Week 1, size 0.1 - 0.15 mm (100 - 150 microns)

Features: zygote, fertilized oocyte, pronuclei, polar bodies, zona pellucida

Cite this page: Hill, M.A. (2024, June 23) Embryology Early zygote labelled.jpg. Retrieved from

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

File history

Yi efo/eka'e gwa ebo wo le nyangagi wuncin ye kamina wunga tinya nan

current11:47, 10 March 2012Thumbnail for version as of 11:47, 10 March 2012500 × 441 (29 KB)Z8600021 (talk | contribs)increase image size
13:28, 20 July 2010Thumbnail for version as of 13:28, 20 July 2010216 × 191 (8 KB)S8600021 (talk | contribs)==Early Zygote (labelled)== About Carnegie Stages 1 Facts: Week 1, size 0.1-0.15 mm Features: zygote, fertilized oocyte, pronuclei, polar bodies, zona pellucida Related Images: Early zygote | Image Source: UNSW Embryology ht