Second Week Of Development Flashcards
Implantation occurs on
6th -7th day of fertilisation
Implantation is completed on
2nd week
Hypoblast is also called
Primitive endoderm
Hypoblast contributes to formation of
Roof of primary yolk sac
Epiblast / primitive ectoderm consists of ——- cells
Columnar
The first germ layer to be formed is
Hypoblast
Amniotic cavity is a space between ————- below and ————- above
Epiblast
Trophoblast
Roof of amniotic cavity has ———- cells derived from the trophoblast while it’s floor is formed by epiblast
Amniogenic cells
Flattened cells of ——— spread and line the inside of blastocystic cavity ( lining of cells- heusers membrane)
Cavity —- primary yolk sac
Hypoblast
The cells of ———— give origin to extraembryonic mesoderm
Trophoblast
The cells of extra embryonic mesoderm separate the walls of ——— from ——-
Amniotic cavity ; trophoblast
Small cavities in extraembryonic mesoderm—fuse— one large cavity called —
Extraembryonic coelom
The part lining the inside of the trophoblast and the outside of the amniotic cavity is called
Parietal/somatopleuric mesoderm
Chorionic plate
The part lining the outside of yolk sac is called
Visceral or splanchnopleuric extra embryonic mesoderm
The extraembryonic coelom does not extend into that part of the extraembryonic mesoderm which attaches the wall of the amniotic cavity to the ———
Trophoblast
The unsplit part of mesoderm forms a structure known as
Connecting stalk
Chorion is formed by
Parietal/ somatopleuric extraembryonic mesoderm on Inside
Trophoblast on outside
Yolk sac becomes much smaller so it is called
Secondary yolk sac
The cells of yolk sac are no longer flattened but become ———-
Cubical
The wall of the yolk sac is first site for formation of
Blood
Yolk sac forms endodermal lining of
GI tract and respiratory tract
Epiblast has ———- cells
Hypoblast has ——— cells
Columnar
Cuboidal
Cubical cells of hypoblast become columnar. This area is called
Prochordal plate
The first embryonic membrane is
Trophoblast
Trophoblast are precursor cells of ———-
Human placenta
Differentiation of trophoblast is essential for the formation of
Chorionic villi
Cells nearest to decidua lose their cell boundaries and form a continuous sheet of cytoplasm with many nuclei (syncytium)
This layer of trophoblast is called
Syncytiotrophoblast / plasmodiotrophoblast
Cells of the trophoblast deep to syncytium retain their walls and form a layer called
Cytotrophoblast / langerhans layer
Langerhans layer (cuboidal cells) with a clear outline rests on
Extraembryonic mesoderm
Chorionic villi is formed by
Syncytiotrophoblast
Cytotrophoblast
Somatopleuric layer of extraembryonic mesoderm
What is chorion
The cellular outermost extraembryonic membrane composed of trophoblast lined with extra embryonic somatopleuric mesoderm
