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==Placenta Anchoring Villi==
==Placenta Anchoring Villi==


Histological image showing the junctional region between the trophoblast shell of the conceptus and the maternal decidua.
Histological image showing the junctional region between the maternal decidua (left) and the embryonic placental villi (right).
   
   
In week 2, the trophoblast shell cells proliferate and form a syncitiotrophoblast and cytotrophoblast layer around he conceptus. Syncitiotrophoblast cells migrate into the uterine wall, forming maternal blood-filled spaces (lacunae).
* In week 2, the trophoblast shell cells proliferate and form a syncitiotrophoblast and cytotrophoblast layer around he conceptus.  
* Syncitiotrophoblast cells migrate into the uterine wall, forming maternal blood-filled spaces (lacunae).


Placentation begins once the conceptus begins to implant in the uterine wall and the placenta will have both a fetal and a maternal component. The fetal component begins as villi form. The fetal chorion will form two regions: smooth chorion (chorion laeve) and villous chorion (chorion frondosum).
Placentation begins once the conceptus begins to implant in the uterine wall and the placenta will have both a fetal and a maternal component. The fetal component begins as villi form. The fetal chorion will form two regions: smooth chorion (chorion laeve) and villous chorion (chorion frondosum).

Revision as of 19:01, 23 May 2011

Placenta Anchoring Villi

Histological image showing the junctional region between the maternal decidua (left) and the embryonic placental villi (right).

  • In week 2, the trophoblast shell cells proliferate and form a syncitiotrophoblast and cytotrophoblast layer around he conceptus.
  • Syncitiotrophoblast cells migrate into the uterine wall, forming maternal blood-filled spaces (lacunae).

Placentation begins once the conceptus begins to implant in the uterine wall and the placenta will have both a fetal and a maternal component. The fetal component begins as villi form. The fetal chorion will form two regions: smooth chorion (chorion laeve) and villous chorion (chorion frondosum).

The maternal component is formed by the decidualization of the endometrium.

  • Fibrinoid layer (Nitabuch's layer) is formed at maternal/fetal interface during placentation and is thought to act to prevent excessively deep conceptus implantation.
    • Fibrin-type fibrinoid - maternal blood-clot product)
    • Matrix-type fibrinoid - secreted by invasive extravillous trophoblast cells


Placenta Links: placenta | Lecture - Placenta | Lecture Movie | Practical - Placenta | implantation | placental villi | trophoblast | maternal decidua | uterus | endocrine placenta | placental cord | placental membranes | placenta abnormalities | ectopic pregnancy | Stage 13 | Stage 22 | placenta histology | placenta vascular | blood vessel | cord stem cells | 2013 Meeting Presentation | Placenta Terms | Category:Placenta
Historic Embryology - Placenta 
1883 Embryonic Membranes | 1907 Development Atlas | 1909 | 1910 Textbook | 1917 Textbook | 1921 Textbook | 1921 Foetal Membranes |1921 human | 1921 Pig implantation | 1922 Single placental artery | 1923 Placenta Review | 1939 umbilical cord | 1943 human and monkey | 1944 chorionic villus and decidua parietalis | 1946 placenta ageing | 1960 first trimester placenta | 1960 monkey | 1972 Placental circulation | Historic Disclaimer

| Implantation


Image Source: UNSW Embryology, no reproduction without permission.

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current15:37, 3 August 2009Thumbnail for version as of 15:37, 3 August 2009600 × 450 (167 KB)MarkHill (talk | contribs)Placenta anchoring villi Histological image showing the junctional region between the trophoblast shell of the conceptus and the maternal decidua. In week 2, the trophoblast shell cells proliferate and form a syncitiotrophoblast and cytotrophoblast lay