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The trophoblast (from Greek trephein: to feed; and blastos: germinator) is the outer layer of cells of the blastocyst. Trophoblasts are present four days after fertilization in humans. [ 1 ] They provide nutrients to the embryo and develop into a large part of the placenta .
Image showing trophoblast differentiated into the two layers of cytotrophoblast and syncytiotrophoblast during implantation. It is the outer layer of the trophoblasts and actively invades the uterine wall, during implantation, rupturing maternal capillaries and thus establishing an interface between maternal blood and embryonic extracellular fluid, facilitating passive exchange of material ...
They are sometimes called intermediate trophoblast. [1] EVTs that derive from CYT cells on the surface of placental chorionic villi that come into contact with the uterine wall - at the placental bed - begin to express the HLA-G antigen. [2] Extravillous trophoblast (EVT) cells migrate from anchoring villi, and invade into the decidua basalis.
The cytotrophoblast secretes proteolytic enzymes to break down the extracellular matrix between the endometrial cells to allow finger-like projections of trophoblast to penetrate through. Projections of cytotrophoblast and syncytiotrophoblast pull the embryo into the endometrium until it is fully covered by endometrial epithelium, save for the ...
The trophoblast then differentiates into an inner layer, the cytotrophoblast, and an outer layer, the syncytiotrophoblast. The cytotrophoblast contains cuboidal epithelial cells and is the source of dividing cells , and the syncytiotrophoblast is a syncytial layer without cell boundaries.
The interior of the eye lacks lymph vessels but is highly vascularized, and many immune cells reside in the uvea, including mostly macrophages, dendritic cells, and mast cells. [1] These cells fight off intraocular infections, and intraocular inflammation can manifest as uveitis (including iritis ) or retinitis .
The epiblast was first discovered by Christian Heinrich Pander (1794-1865), a Baltic German biologist and embryologist. With the help of anatomist Ignaz Döllinger (1770–1841) and draftsman Eduard Joseph d'Alton (1772-1840), Pander observed thousands of chicken eggs under a microscope, and ultimately discovered and described the chicken blastoderm and its structures, including the epiblast. [1]
Implantation site intermediate trophoblast. Low molecular weight cytokeratin stain. Intermediate trophoblast is a distinct subtype of trophoblastic tissue that arises from the cytotrophoblast. [1] It is sub-categorized by location: [1] Villous intermediate trophoblast: at anchoring villi of trophoblastic column; Implantation site intermediate ...