File:Stage18 bf10.jpg

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Human Embryo Carnegie Stage 18

  • Embryo Week 7, 44 - 48 days, 13 - 17 mm
  • The image shows the intact gestational sac (25-30 mm diameter) with chorionic villi (white finger-like extensions) covering the chorionic membrane surface.
  • The chorion surface is now divided into 2 halves:

chorion laeve

(laeve = smooth) The smooth chorion found on conceptus away from maternal blood supply (towards uterine epithelium and cavity) with very few villi present.

chorion frondosum

(frondosum = leafy) the chorion found on conceptus oriented towards maternal blood supply where the majority of villi form and proliferate, will contribute the fetal component of the future placenta.


Stage 18 Links: Embryo in gestational sac | Embryo open sac | Embryo 2 and gestational sac | Embryo 2 | Carnegie stage 18

| Week 4 Gestational Sac


Stage 18 Links: Week 7 | System Development | Lecture - Limb | Lecture - Head Development | Lecture - Sensory | Science Practical - Head | Science Practical - Sensory | Science Practical - Urogenital | Carnegie Embryos | Madrid Embryos | Category:Carnegie Stage 18 | Next Stage 19
  Historic Papers: 1911 larynx | 1948 stage 15-18

Image: Dr Steven O'Connor (Houston, Texas) - Other embryo images.



Cite this page: Hill, M.A. (2024, April 15) Embryology Stage18 bf10.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Stage18_bf10.jpg

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

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Date/TimeThumbnailDimensionsUserComment
current11:48, 12 August 2011Thumbnail for version as of 11:48, 12 August 20111,200 × 897 (151 KB)S8600021 (talk | contribs)==Human Embryo Carnegie Stage 18== Facts: Week 7, 44 - 48 days, 13 - 17 mm View: Lateral view. Amniotic membrane intact. Features: pigmented eye, eyelid, nasolacrimal groove, external acoustic meatus, heart, digital rays, liver prominance, thigh, ankle

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