Decidua
Decidua means gravid endometrium.
Decidualization / Decidua reaction
·
Stromal cells of the endometrium become polyhedral
and loaded with glycogenand lipids
·
Stromal cells begin to secrete cytokines,
growth factors, and proteins like IGFBP1 and prolactin along with extracellular matrix (ECM) proteins such as fibronectin and laminin.
The increased production of these ECM proteins turns the endometrium into the
dense structure known as the decidua,
·
Presence of decidual white blood cells (leukocytes),
·
intercellular spaces are filled with extravasate
·
the tissues is edematous
At first
it occur at the site of implantation but soon spread throughout the endometrium.
Parts of deciduas:it is divided into three parts
1.
Decidua basalis :parts
of decidua deep to the developing embryo which contributes to the development
of placenta
2.
Decidua capsularis :part
of decidua which surround the embryo and it is separated from the uterine
cavity
3.
Decidua parietalis :rest
of the decidua excluding decidua basalis and decidua capsularis
Chorion
It is a highly specialized extra-embryonic membrane that
participates in the formation of the placenta.
Formation :it is formed by
1.
Somatopleuric
layer of extraembryonic mesoderm
2.
Cytotrophoblast
3.
Syncytotrophoblast
Parts of chorion:
It has two parts
·
Chorion frondosum:the part of chorion where chorionic
villi are well developed and it form the fetal parts of placenta.
·
Chorion leave:the part of chorion where chorionic
villi are less developed.
Chorionic villi
Numerous small finger-like projections arise from the surface
of the chorion is known as chorionic
villi.
Types of chorionic villi:
Primary, Secondary, Tertiary
1. Fertilization
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