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Title: ANATOMY AND PHYSIOLOGY OF PLACENTA
Description: In this presentation, we delve into the intricate world of the placenta, a remarkable organ that plays a pivotal role in the development of life. We will explore its anatomy, detailing its structure and how it connects the developing fetus to the uterine wall. Understanding the physiology of the placenta is crucial, as it is responsible for facilitating the exchange of nutrients, oxygen, and waste products between the mother and the fetus. We will also examine how the placenta evolves throughout pregnancy, adapting to meet the changing needs of the growing fetus. Furthermore, we will explore the various functions of the placenta, including endocrine functions, immune modulation, and protection of the fetus against external factors. By the end of this presentation, you will have a comprehensive understanding of the anatomy and physiology of the placenta, highlighting its critical role in supporting fetal development and overall pregnancy health.
Description: In this presentation, we delve into the intricate world of the placenta, a remarkable organ that plays a pivotal role in the development of life. We will explore its anatomy, detailing its structure and how it connects the developing fetus to the uterine wall. Understanding the physiology of the placenta is crucial, as it is responsible for facilitating the exchange of nutrients, oxygen, and waste products between the mother and the fetus. We will also examine how the placenta evolves throughout pregnancy, adapting to meet the changing needs of the growing fetus. Furthermore, we will explore the various functions of the placenta, including endocrine functions, immune modulation, and protection of the fetus against external factors. By the end of this presentation, you will have a comprehensive understanding of the anatomy and physiology of the placenta, highlighting its critical role in supporting fetal development and overall pregnancy health.
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ANATOMY AND PHYSIOLOGY OF
THE PLACENTA
PLACENTA
Placenta is a fetomaternal organ
It has 2 components:
- Fetal part – develops from the chorionic sac ( chorion frondosum)
- Maternal part – derived from the endometrium ( functional layer –
decidua basalis)
Development of the placenta
The fetal component of the placenta is derived from the trophoblast and
extraembryonic meso-derm (the chorionic plate)
The maternal component is derived from the uterine endometrium
Development of placenta
Early in the 3rd week, mesenchyme growth into the primary villi
forming a core of the mesenchymal tissue
By the beginning of the second month, the trophoblast is characterized
by a great number of secondary and tertiary villi, which give it a radial
appearance
Development of the placenta
The villous chorion (increase in number, enlarge and branch) will form
the fetal part of the placenta
The decidua basalis will form the maternal part of the placenta
The placenta will grow rapidly , by the end of the 4th month, the
decidua basalis is almost entirely replaced by the fetal part of the
placenta
Decidua
A specialized, highly modified endometrium of pregnancy
Decidualization, that is, transformation of proliferating endometrial
stromal cells into specialized secretory cells
The decidua produces factors that regulate endometrial receptivity and
modulate immune and vascular cell functions within the maternal–fetal
microenvironment
Structures of decidua
It has four parts
Decidua basalis : it forms the maternal part of the placenta
Decidua capsularis: it covers the conceptus
Decidua parietalis : the rest of the endometrium
Decidua reflexa : junction between capsularis and parietalis
The decidua parietalis and basalis are composed of three layers
Zona compacta – upper or surface layer
Zona spongiosa- middle layer (remnants of glands and numerous small
blood vessels)
Zona basalis- basal zone
The zona compacta and spongiosa together form the zona functionalis
The basal zone remains after delivery and gives rise to new
endometrium
Decidual Histology
Early in pregnancy, the zona spongiosa of the decidua consists of large
distended glands, often exhibiting marked hyperplasia and separated by
minimal stroma
The glands are lined by typical cylindrical uterine epithelium with
abundant secretory activity that contributes to blastocyst nourishment
The decidua basalis contributes to formation of placental plate
The decidua basalis is invaded by trophoblastic invasion and trophoblastic
giant cells
The Nitabuch layer is a zone of fibrinoid degeneration in which invading
trophoblasts meet the decidua basalis
...
STRUCTURE OF PLACENTA
STEM ( ANCHORING VILLI)
Arises from the chorionic plate and extend to the basal plate
...
Maternal cotyledon(15- 20) contains 3 to 5 fetal cotyledons
...
Total surface of the villi for exchange varies between 4 to 14 square metres
...
It is lined internally by synctiotrophoblast and it filled with maternal blood
...
Each of these muscular layer is composed of a
network of interlacing smooth muscle bundles
The vein does have an inner elastic lamina
...
Grooves – formerly occupied by
placental septa,
FETAL SURFACE:
o
Smooth and shiny and its is covered
by amnion
o
The umbilical cord is attached
close to the centre of the placenta
o
The umbilical vessel radiate from
the umbilical cord
o
They branch on the featal surface
to form chorionic vessels
o
They enter the chorionic villi to
form arteriocapillary venous
system
PLACENTAL BARRIER
This is a composite structure that separating the fetal blood from the maternal
blood
It has four layers:
Synctiotrophoblast
Cytotrophoblast
Connective tissue of villous
Endothelium of fetal capillaries
After the 20th week, the cytotrophoblastic cells disappear and the placental
membrane consists only of 3 layers
Placental barrier
PLACENTAL CIRCULATION
MEMBRANES
It consist of the amnion and the chorion
AMNION
the amnion which constitutes the innermost aspect of the embryonic cavity,
develops from the margin of the embryonic disk
The amnionic cavity remains filled with amniotic fluid, which by the end of
gestation approx
...
Such vessels only occur in the chorion, the amnion is an
avascular structure
Decidual Prolactin
The decidua is the source of prolactin, which is present in enormous amounts
in amnionic fluid
Prolactin preferentially enters amnionic fluid, and little enters maternal blood
prolactin levels in amnionic fluid are extraordinarily high and may reach
10,000 ng/mL at 20 to 24 weeks’ gestation
This compares with fetal serum levels of 350 ng/mL and maternal serum levels
of 150 to 200 ng/mL
...
Fibrinoid and sialomucin coating of trophoblast may suppress the trophoblastic antigen
2
...
Nitabuch layer which intervenes between decidua basalis and cytotrophoblast probably
inactivates the antigenic property of the tissue
4
Title: ANATOMY AND PHYSIOLOGY OF PLACENTA
Description: In this presentation, we delve into the intricate world of the placenta, a remarkable organ that plays a pivotal role in the development of life. We will explore its anatomy, detailing its structure and how it connects the developing fetus to the uterine wall. Understanding the physiology of the placenta is crucial, as it is responsible for facilitating the exchange of nutrients, oxygen, and waste products between the mother and the fetus. We will also examine how the placenta evolves throughout pregnancy, adapting to meet the changing needs of the growing fetus. Furthermore, we will explore the various functions of the placenta, including endocrine functions, immune modulation, and protection of the fetus against external factors. By the end of this presentation, you will have a comprehensive understanding of the anatomy and physiology of the placenta, highlighting its critical role in supporting fetal development and overall pregnancy health.
Description: In this presentation, we delve into the intricate world of the placenta, a remarkable organ that plays a pivotal role in the development of life. We will explore its anatomy, detailing its structure and how it connects the developing fetus to the uterine wall. Understanding the physiology of the placenta is crucial, as it is responsible for facilitating the exchange of nutrients, oxygen, and waste products between the mother and the fetus. We will also examine how the placenta evolves throughout pregnancy, adapting to meet the changing needs of the growing fetus. Furthermore, we will explore the various functions of the placenta, including endocrine functions, immune modulation, and protection of the fetus against external factors. By the end of this presentation, you will have a comprehensive understanding of the anatomy and physiology of the placenta, highlighting its critical role in supporting fetal development and overall pregnancy health.