File:Human embryo day 18.jpg: Difference between revisions

Latest revision as of 22:48, 8 October 2015

Human Embryo (day 18)

Approximate cross-section of a different, 18 day human conceptus (Carnegie stage 6).

Identify the

3 cavities - yolk sac, amniotic sac and chorionic sac.
3 layers of the trilaminar embryo - ectoderm (columnar cells), intraembryonic mesoderm (mesenchymal cells, endodermal cells (cuboidal single layer).
extraembryonic mesoderm which surrounds the yolk and amniotic sacs, and continues to form the connecting stalk, where it then continues to line the chorionic sac. Extra- and intra-embryonic mesoderm merge along the perimeter of the embryonic disc.
primitive groove with dense cluster of primitive streak cells below it.

At the top right of the micrograph is a secondary chorionic villus, lying in an empty maternal intervillus space. The villous has an outer layer of syncytiotrophoblast (smaller, darker nuclei), an intermediate layer of cytotrophoblast and a core of mesoblast (extra-embryonic mesoderm).

Links: Carnegie stage 6

Reference

Nishimura etal., 1977

Cite this page: Hill, M.A. (2026, October 20) Embryology Human embryo day 18.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Human_embryo_day_18.jpg

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	Gwalagizhi	Nyangagi	Dimensions	User	Comment
current	22:48, 8 October 2015		531 × 800 (80 KB)	Z8600021 (talk \| contribs)
	21:38, 9 Mayıs 2010		398 × 600 (38 KB)	S8600021 (talk \| contribs)	Human embryo day 18 Category:Week 3

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@@ Line 1: / Line 1: @@
-Human embryo day 18
+==Human Embryo (day 18)==
-Approximate cross-section of a different, 18 day human conceptus.
-Identify the 3 cavities: yolk sac, amniotic sac and chorionic sac.
+Approximate cross-section of a different, 18 day human conceptus ([[Carnegie stage 6]]).
-Identify the 3 layers of the trilaminar embryo: ectoderm (columnar cells), intraembryonic mesoderm (mesenchymal cells, endodermal cells (cuboidal single layer).
+Identify the
+* 3 cavities - yolk sac, amniotic sac and chorionic sac.
+* 3 layers of the trilaminar embryo - ectoderm (columnar cells), intraembryonic mesoderm (mesenchymal cells, endodermal cells (cuboidal single layer).
+* extraembryonic mesoderm which surrounds the yolk and amniotic sacs, and continues to form the connecting stalk, where it then continues to line the chorionic sac. Extra- and intra-embryonic mesoderm merge along the perimeter of the embryonic disc.
+* primitive groove with dense cluster of primitive streak cells below it.
-Identify the extraembryonic mesoderm which surrounds the yolk and amniotic sacs, and continues to form the connecting stalk, where it then continues to line the chorionic sac. Extra- and intra-embryonic mesoderm merge along the perimeter of the embryonic disc.
+At the top right of the micrograph is a secondary chorionic villus, lying in an empty maternal intervillus space. The villous has an outer layer of syncytiotrophoblast (smaller, darker nuclei), an intermediate layer of cytotrophoblast and a core of mesoblast (extra-embryonic mesoderm).
-Identify primitive groove with dense cluster of primitive streak cells below it.
-At the top right of the micrograph is a secondary chorionic villus, lying in an empty maternal intervillus space. The villous has an outer layer of syncytiotrophoblast (smaller, darker nuclei), an intermediate layer of cytotrophoblast and a core of mesoblast (extra-embryonic mesoderm).
+:'''Links:''' [[Carnegie stage 6]]
+===Reference===
-(Image: Nishimura etal., 1977)
+Nishimura etal., 1977
+{{Footer}}
-[[Category:Week 3]]
+[[Category:Week 3]][[Category:Carnegie Stage 6]]