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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 ...
After hatching, the embryonic pole of the blastocyst faces the uterine endometrium. Once they make contact the trophoblast begins to rapidly proliferate. 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.
The chorion consists of two layers: an outer formed by the trophoblast, and an inner formed by the extra-embryonic mesoderm. The trophoblast is made up of an internal layer of cubical or prismatic cells, the cytotrophoblast or layer of Langhans, and an external multinucleated layer, the syncytiotrophoblast .
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 ...
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 inner cell mass (ICM) or embryoblast (known as the pluriblast in marsupials) is a structure in the early development of an embryo.It is the mass of cells inside the blastocyst that will eventually give rise to the definitive structures of the fetus.
Fluid collects between the trophoblast and the greater part of the inner cell-mass, and thus the morula is converted into a vesicle, called the blastodermic vesicle. The inner cell mass remains in contact, however, with the trophoblast at one pole of the ovum; this is named the embryonic pole, since it indicates the location where the future ...