The document discusses fetal membranes and twin pregnancies. It describes the development and functions of the major fetal membranes - the amnion, chorion, yolk sac, allantois, and umbilical cord.
The amnion forms a fluid-filled sac that surrounds and protects the embryo. The chorion forms the outer wall of the chorionic sac and supports the growth of chorionic villi which facilitate nutrient exchange. The yolk sac provides early nutrition and plays a role in blood cell and germ cell formation. The allantois contributes to the development of the umbilical vessels. The umbilical cord develops from the connecting stalk and transports nutrients and waste between the fetus and placent
1. The document discusses the structure and classification of placentas. It describes the different types of placentas found across mammals based on their gross shape, layers between maternal and fetal blood, and histological structure.
2. The major placenta types discussed are epithelio-chorial (found in marsupials and some ungulates), syndesmo-chorial (ruminant ungulates), endothelio-chorial (carnivores), haemochorial (primates and bats), and haemo-endothelial (rodents). Each type involves a different number of layers separating maternal and fetal blood and tissues.
3. Placentas are also classified
The document discusses the fetal membranes and placenta. It describes the origin and functions of the amnion, yolk sac, allantois, chorion and decidua. The amnion forms the amniotic sac that surrounds and cushions the embryo. The yolk sac provides early nutrition but shrinks by the 10th week. The allantois forms the umbilical vessels. The chorion forms the walls of the chorionic sac and develops chorionic villi to increase its surface area. The decidua is the endometrium that supports implantation and pregnancy. The placenta develops from the chorion and decidua and acts as the interface between mother and fetus, facilitating gas and
The document discusses fetal membranes including the amnion, chorion, yolk sac, allantois, and umbilical cord. It describes their development, structure, and functions. The amniotic fluid is mainly composed of water and plays various roles in fetal growth. The chorion develops from the trophoblast and contains villi that contribute to placental formation. The placenta forms from the chorionic villi and decidua basalis and functions to exchange gases, nutrients, and waste between the maternal and fetal blood without mixing.
The document discusses the placenta, fetal membranes, decidua, trophoblast, and amnion. It describes their structure, development, functions, and roles in implantation, fetal-maternal circulation and immunological acceptance of pregnancy. Key points include how the decidua and trophoblast interact for implantation, trophoblast invasion of maternal spiral arteries, establishment of maternal blood flow, and the metabolic and protective roles of the amnion and fetal membranes.
Implantation of the blastocyst in the uterine lining leads to formation of the placenta and fetal membranes. The ovarian cycle results in follicular development and ovulation. The decidua forms from secretory endometrium under the influence of estrogen and progesterone. Implantation involves apposition, adhesion and invasion of the trophoblast into the decidua. The placenta develops from chorionic villi and undergoes remodeling of the maternal spiral arteries to establish maternal blood flow to the intervillous space. The fetal membranes, including the amnion and chorion, develop and enclose the developing embryo.
This document summarizes various sites of embryo implantation and placental abnormalities in pregnancy. It describes normal implantation in the uterus and discusses abnormal locations including placenta praevia where the placenta is close to or covers the cervix. Rare sites of ectopic pregnancy outside the uterus are also outlined. The document then examines placental abnormalities categorized by shape, implantation site and degenerative lesions. Specific conditions like placenta accreta where the placenta invades the uterus are defined. In summary, the key sites of abnormal embryo implantation and classifications of placental anomalies are concisely presented.
The document discusses the fetal membranes, placenta, and twinning. It describes the structures and functions of the fetal membranes including the chorion, amnion, yolk sac, and allantois. It then explains the anatomy and functions of the placenta as the interface between mother and fetus, allowing for nutrient/gas exchange and hormone production. Finally, it briefly covers the two types of twins - monozygotic (identical) twins from one zygote and dizygotic (non-identical) twins from two separate zygotes.
The placenta is an organ that develops in mammals during pregnancy to connect the developing fetus to the uterine wall. It allows for nutrient uptake, waste elimination, and gas exchange from the mother's blood supply to nourish the fetus. The placenta has both a fetal component from the chorionic sac and a maternal component from the endometrium. It begins developing upon implantation and grows throughout pregnancy, reaching full development by the end of the first trimester. The placenta plays a vital role in sustaining the fetus during intrauterine development.
1. The document discusses the structure and classification of placentas. It describes the different types of placentas found across mammals based on their gross shape, layers between maternal and fetal blood, and histological structure.
2. The major placenta types discussed are epithelio-chorial (found in marsupials and some ungulates), syndesmo-chorial (ruminant ungulates), endothelio-chorial (carnivores), haemochorial (primates and bats), and haemo-endothelial (rodents). Each type involves a different number of layers separating maternal and fetal blood and tissues.
3. Placentas are also classified
The document discusses the fetal membranes and placenta. It describes the origin and functions of the amnion, yolk sac, allantois, chorion and decidua. The amnion forms the amniotic sac that surrounds and cushions the embryo. The yolk sac provides early nutrition but shrinks by the 10th week. The allantois forms the umbilical vessels. The chorion forms the walls of the chorionic sac and develops chorionic villi to increase its surface area. The decidua is the endometrium that supports implantation and pregnancy. The placenta develops from the chorion and decidua and acts as the interface between mother and fetus, facilitating gas and
The document discusses fetal membranes including the amnion, chorion, yolk sac, allantois, and umbilical cord. It describes their development, structure, and functions. The amniotic fluid is mainly composed of water and plays various roles in fetal growth. The chorion develops from the trophoblast and contains villi that contribute to placental formation. The placenta forms from the chorionic villi and decidua basalis and functions to exchange gases, nutrients, and waste between the maternal and fetal blood without mixing.
The document discusses the placenta, fetal membranes, decidua, trophoblast, and amnion. It describes their structure, development, functions, and roles in implantation, fetal-maternal circulation and immunological acceptance of pregnancy. Key points include how the decidua and trophoblast interact for implantation, trophoblast invasion of maternal spiral arteries, establishment of maternal blood flow, and the metabolic and protective roles of the amnion and fetal membranes.
Implantation of the blastocyst in the uterine lining leads to formation of the placenta and fetal membranes. The ovarian cycle results in follicular development and ovulation. The decidua forms from secretory endometrium under the influence of estrogen and progesterone. Implantation involves apposition, adhesion and invasion of the trophoblast into the decidua. The placenta develops from chorionic villi and undergoes remodeling of the maternal spiral arteries to establish maternal blood flow to the intervillous space. The fetal membranes, including the amnion and chorion, develop and enclose the developing embryo.
This document summarizes various sites of embryo implantation and placental abnormalities in pregnancy. It describes normal implantation in the uterus and discusses abnormal locations including placenta praevia where the placenta is close to or covers the cervix. Rare sites of ectopic pregnancy outside the uterus are also outlined. The document then examines placental abnormalities categorized by shape, implantation site and degenerative lesions. Specific conditions like placenta accreta where the placenta invades the uterus are defined. In summary, the key sites of abnormal embryo implantation and classifications of placental anomalies are concisely presented.
The document discusses the fetal membranes, placenta, and twinning. It describes the structures and functions of the fetal membranes including the chorion, amnion, yolk sac, and allantois. It then explains the anatomy and functions of the placenta as the interface between mother and fetus, allowing for nutrient/gas exchange and hormone production. Finally, it briefly covers the two types of twins - monozygotic (identical) twins from one zygote and dizygotic (non-identical) twins from two separate zygotes.
The placenta is an organ that develops in mammals during pregnancy to connect the developing fetus to the uterine wall. It allows for nutrient uptake, waste elimination, and gas exchange from the mother's blood supply to nourish the fetus. The placenta has both a fetal component from the chorionic sac and a maternal component from the endometrium. It begins developing upon implantation and grows throughout pregnancy, reaching full development by the end of the first trimester. The placenta plays a vital role in sustaining the fetus during intrauterine development.
The document describes the development of the placenta and umbilical cord from fertilization through gestation. It discusses the stages of embryogenesis including cleavage, morula, blastula, and gastrula. It then describes the formation and differentiation of the chorionic villi and decidua, and the roles they play in nutrient and gas exchange between mother and fetus. Finally, it summarizes the key functions of the mature placenta including breathing, nutrition, waste removal, and establishing an immunological barrier between mother and fetus.
The placenta forms from the fusion of fetal and maternal tissues to nourish the developing embryo. It is composed of the chorion, which contains villi from the fetus, and the decidua, which are tissues from the maternal uterus. The placenta allows nutrients, waste, and gases to pass between mother and fetus. It is found in nearly all mammals and some other viviparous species, and plays a vital role in sustaining pregnancy.
The placenta arises from trophoblast tissue and serves as the fetal lungs, kidneys, and gastrointestinal tract throughout pregnancy. It grows equally with the fetus. At term, the placenta is 15-20cm in diameter, 2-3cm thick, and covers half the internal uterus. The placenta establishes circulation between mother and fetus by the 12th day of pregnancy through chorionic villi, allowing nutrients to pass selectively between the maternal and fetal blood while preventing direct exchange. It produces hormones and facilitates gas and nutrient exchange until birth.
The document discusses implantation, placenta formation, and the role of the placenta. It describes how the blastocyst implants in the endometrium, leading to formation of the trophoblast and decidua. This allows establishment of the uteroplacental circulation. It then details the development of the primary, secondary, and tertiary villi to form the chorionic frondosum and definitive placental villi. The placenta connects the fetus to the uterine wall, allowing for nutrient/gas exchange without mixing of maternal and fetal blood. After birth, the placenta separates from the uterine wall as the afterbirth.
The placenta is a fetomaternal organ with fetal and maternal components that functions to protect the fetus, provide nutrition, aid respiration, perform excretion, and produce hormones. It develops from the chorionic sac and endometrium. In early development, chorionic villi form and connect to the embryo's circulatory system. Later, the villous chorion develops into the fetal part of the placenta while the decidua basalis forms the maternal part. At term, the placenta has a discoid shape and cotyledons, and the umbilical cord connects it to the fetus for nutrient/waste exchange across the placental membrane.
The document discusses the morphology, development, and abnormalities of the umbilical cord. It begins by describing the umbilical cord's typical length, diameter, shape, and contents. It then explains the development of the primitive, then definitive umbilical cord. The document concludes by listing some abnormalities that can occur, such as short or long cords, umbilical hernias, or abnormal attachments.
The human placenta is discoid, haemochorial, deciduate, and larynthine. It attaches to the uterine wall and connects the mother and fetus through the umbilical cord. The placenta undergoes development from implantation through the third trimester, forming the chorionic and basal plates separated by the intervillous space containing branching villi. The placenta acts as the site of nutrient, waste, and gas exchange between mother and fetus as well as producing important hormones. Various abnormalities can occur in placental shape, implantation, circulation or development that impact clinical outcomes.
Placenta development and its abnormalitiesbhoomikasingh8
The document describes the anatomy and development of the placenta and discusses some common abnormalities. It notes that the placenta establishes a connection between the mother and fetus to allow for nutrient/waste exchange. During development, trophoblast cells form villi that invade the uterine wall. The three layers of the placenta each have specific functions in nutrient exchange and hormone production. Some abnormalities can cause issues like abnormal bleeding, fetal growth restriction, or stillbirth if not properly managed. Ultrasound is used to diagnose many placental abnormalities prenatally.
The document summarizes the development, functions, and abnormalities of the placenta. It discusses how the placenta develops from implantation through formation of chorionic villi and circulation. It describes the placenta's main functions of transferring nutrients and waste between mother and fetus, as well as endocrine and barrier functions. It also covers placental hormones, mechanisms of substance transfer, and diagnostic uses and immunological role of the placenta.
The amniotic fluid cushions the fetus, protects it from infection and trauma, and allows freedom of movement. It maintains a stable temperature and permits lung development. Amniotic fluid volume is normally 500-1000cc at term. It is produced by the amniotic membranes and passes across the fetal skin and through fetal urination, swallowing, and respiratory secretions. Abnormal volumes can indicate fetal problems and complications in pregnancy.
Placenta yolk sac and amniotic_fluid_structure_functionJitendra Kumar
The human placenta develops from fetal and maternal tissues and is completed by 12 weeks of gestation. At term, the placenta is a fleshy, 500g organ that is 15-20cm in diameter and occupies 30% of the uterine wall. It has both maternal and fetal surfaces and facilitates gas, nutrient, and waste transfer between the mother and fetus through specialized cellular layers and transport mechanisms. The amniotic sac contains fluid that protects and cushions the fetus.
The document discusses the development of various fetal membranes over 13 days, including the formation of the chorion, amnion, chorionic villi, and placenta. It notes that the chorion forms by day 12 from extra-embryonic mesoderm and contains syncytiotrophoblast and cytotrophoblast layers. The amnion forms as a cavity lined by amnioblasts and epiblast cells by day 8. The placenta develops from chorionic villi that invade the decidua basalis and form the intervillous spaces filled with maternal blood. Exchange of gases, nutrients and waste occurs across the placental barrier layers.
The document summarizes the development and anatomy of the human placenta. It begins by defining the placenta and outlining its objectives. It then describes the development of the placenta from the chorion and decidua, the structures of the mature placenta including the chorionic plate, basal plate, intervillous space and villi, and the maternal and fetal circulations that occur through it. Finally, it discusses placental aging and the degenerative changes that occur over the course of a pregnancy.
The document discusses the fetal membranes, which include the umbilical cord, amnion, amniotic fluid, yolk sac, and allantois. It describes the development, structure, function and abnormalities of each membrane. The umbilical cord connects the fetus to the placenta and transports nutrients. The amnion surrounds the fetus and amniotic fluid, protecting the fetus and allowing movement. The yolk sac provides early nutrition but later degenerates. The allantois contributes to blood and urinary system development. Abnormalities can impact fetal health.
The human placenta is a discoid, haemochorial organ that develops during pregnancy to connect the developing fetus to the uterine wall for nutrient/waste exchange. At term, the placenta is a circular disc about 15-20cm in diameter and 2.5cm thick that weighs around 500g. It has both a fetal side covered by amnion/umbilical cord and a rough, spongy maternal side with lobes. The placenta facilitates gas/nutrient exchange between maternal and fetal blood supplied by the umbilical cord and establishes a connection between the mother and developing fetus.
The document discusses the development and types of placentas. It begins by describing the early development of the placenta from the trophoblast cells. It then discusses the stages of placental development including the prelacunar, lacunar, villous, and maturity stages. The document concludes by describing some abnormal placenta shapes including bilobed, circumvallate, succenturiate, membranacea, and ring-shaped placentas. Ultrasound appearance of normal and some abnormal placentas is also presented.
This document provides an overview of the umbilical cord, including its structure, development, functions, measurements, and abnormalities. The umbilical cord connects the fetus to the placenta, containing two arteries and a vein enclosed in Wharton's jelly. It normally measures 50cm in length and 1-2cm in diameter. Various abnormalities are discussed such as battledore cord insertion, velamentous insertion, short and long cord, single umbilical artery, true and false knots, and nuchal cord.
The amnion is a membrane that encloses the amniotic cavity and develops from amnioblast cells at 8 days of pregnancy. It separates from the cytotrophoblasts by 12 days. During the 4th week, expansion of the amniotic cavity leads to folding of the embryonic disc. By the 3rd month, the amnion comes into contact with the chorion. The amnion surrounds the fetus and forms a sheath around the umbilical cord by the end of the 3rd month.
The document summarizes various placental and umbilical cord abnormalities. It describes the typical shapes of most placentae as round or oval but notes that variations are common, including multiple placentae or bilobed placentae. It also discusses abnormalities in placental structure, cord insertion sites, umbilical cord vessels, and other variations that can occur in the placenta and umbilical cord. Many of these abnormalities are associated with risks like abnormal fetal growth, preterm delivery, fetal distress, or hemorrhage. The document provides details on the incidence, risk factors, pathogenesis, and clinical implications of numerous placental and umbilical cord variations.
The document discusses the fetal membranes including the chorion, placenta, amnion, and umbilical cord. It describes their formation, structure, development, functions, and some abnormalities. The chorion forms early in development and differentiates into chorionic villi. The placenta develops from the chorion and facilitates gas/nutrient exchange between mother and fetus. The amnion forms a sac surrounding the fetus filled with amniotic fluid. The umbilical cord contains blood vessels connecting the fetus to the placenta.
The document summarizes fetal development from the 9th week of gestation through birth. It describes how the fetus grows in length and weight each month. It also discusses the development of organs and tissues like the brain, lungs, skin, and muscles. The document then covers the fetal membranes - the amnion, chorion, yolk sac, allantois, and umbilical cord. It explains their roles in protecting the fetus and transporting nutrients. The placenta forms from the chorion and develops branched villi to facilitate nutrient exchange between mother and fetus.
The document describes the development of the placenta and umbilical cord from fertilization through gestation. It discusses the stages of embryogenesis including cleavage, morula, blastula, and gastrula. It then describes the formation and differentiation of the chorionic villi and decidua, and the roles they play in nutrient and gas exchange between mother and fetus. Finally, it summarizes the key functions of the mature placenta including breathing, nutrition, waste removal, and establishing an immunological barrier between mother and fetus.
The placenta forms from the fusion of fetal and maternal tissues to nourish the developing embryo. It is composed of the chorion, which contains villi from the fetus, and the decidua, which are tissues from the maternal uterus. The placenta allows nutrients, waste, and gases to pass between mother and fetus. It is found in nearly all mammals and some other viviparous species, and plays a vital role in sustaining pregnancy.
The placenta arises from trophoblast tissue and serves as the fetal lungs, kidneys, and gastrointestinal tract throughout pregnancy. It grows equally with the fetus. At term, the placenta is 15-20cm in diameter, 2-3cm thick, and covers half the internal uterus. The placenta establishes circulation between mother and fetus by the 12th day of pregnancy through chorionic villi, allowing nutrients to pass selectively between the maternal and fetal blood while preventing direct exchange. It produces hormones and facilitates gas and nutrient exchange until birth.
The document discusses implantation, placenta formation, and the role of the placenta. It describes how the blastocyst implants in the endometrium, leading to formation of the trophoblast and decidua. This allows establishment of the uteroplacental circulation. It then details the development of the primary, secondary, and tertiary villi to form the chorionic frondosum and definitive placental villi. The placenta connects the fetus to the uterine wall, allowing for nutrient/gas exchange without mixing of maternal and fetal blood. After birth, the placenta separates from the uterine wall as the afterbirth.
The placenta is a fetomaternal organ with fetal and maternal components that functions to protect the fetus, provide nutrition, aid respiration, perform excretion, and produce hormones. It develops from the chorionic sac and endometrium. In early development, chorionic villi form and connect to the embryo's circulatory system. Later, the villous chorion develops into the fetal part of the placenta while the decidua basalis forms the maternal part. At term, the placenta has a discoid shape and cotyledons, and the umbilical cord connects it to the fetus for nutrient/waste exchange across the placental membrane.
The document discusses the morphology, development, and abnormalities of the umbilical cord. It begins by describing the umbilical cord's typical length, diameter, shape, and contents. It then explains the development of the primitive, then definitive umbilical cord. The document concludes by listing some abnormalities that can occur, such as short or long cords, umbilical hernias, or abnormal attachments.
The human placenta is discoid, haemochorial, deciduate, and larynthine. It attaches to the uterine wall and connects the mother and fetus through the umbilical cord. The placenta undergoes development from implantation through the third trimester, forming the chorionic and basal plates separated by the intervillous space containing branching villi. The placenta acts as the site of nutrient, waste, and gas exchange between mother and fetus as well as producing important hormones. Various abnormalities can occur in placental shape, implantation, circulation or development that impact clinical outcomes.
Placenta development and its abnormalitiesbhoomikasingh8
The document describes the anatomy and development of the placenta and discusses some common abnormalities. It notes that the placenta establishes a connection between the mother and fetus to allow for nutrient/waste exchange. During development, trophoblast cells form villi that invade the uterine wall. The three layers of the placenta each have specific functions in nutrient exchange and hormone production. Some abnormalities can cause issues like abnormal bleeding, fetal growth restriction, or stillbirth if not properly managed. Ultrasound is used to diagnose many placental abnormalities prenatally.
The document summarizes the development, functions, and abnormalities of the placenta. It discusses how the placenta develops from implantation through formation of chorionic villi and circulation. It describes the placenta's main functions of transferring nutrients and waste between mother and fetus, as well as endocrine and barrier functions. It also covers placental hormones, mechanisms of substance transfer, and diagnostic uses and immunological role of the placenta.
The amniotic fluid cushions the fetus, protects it from infection and trauma, and allows freedom of movement. It maintains a stable temperature and permits lung development. Amniotic fluid volume is normally 500-1000cc at term. It is produced by the amniotic membranes and passes across the fetal skin and through fetal urination, swallowing, and respiratory secretions. Abnormal volumes can indicate fetal problems and complications in pregnancy.
Placenta yolk sac and amniotic_fluid_structure_functionJitendra Kumar
The human placenta develops from fetal and maternal tissues and is completed by 12 weeks of gestation. At term, the placenta is a fleshy, 500g organ that is 15-20cm in diameter and occupies 30% of the uterine wall. It has both maternal and fetal surfaces and facilitates gas, nutrient, and waste transfer between the mother and fetus through specialized cellular layers and transport mechanisms. The amniotic sac contains fluid that protects and cushions the fetus.
The document discusses the development of various fetal membranes over 13 days, including the formation of the chorion, amnion, chorionic villi, and placenta. It notes that the chorion forms by day 12 from extra-embryonic mesoderm and contains syncytiotrophoblast and cytotrophoblast layers. The amnion forms as a cavity lined by amnioblasts and epiblast cells by day 8. The placenta develops from chorionic villi that invade the decidua basalis and form the intervillous spaces filled with maternal blood. Exchange of gases, nutrients and waste occurs across the placental barrier layers.
The document summarizes the development and anatomy of the human placenta. It begins by defining the placenta and outlining its objectives. It then describes the development of the placenta from the chorion and decidua, the structures of the mature placenta including the chorionic plate, basal plate, intervillous space and villi, and the maternal and fetal circulations that occur through it. Finally, it discusses placental aging and the degenerative changes that occur over the course of a pregnancy.
The document discusses the fetal membranes, which include the umbilical cord, amnion, amniotic fluid, yolk sac, and allantois. It describes the development, structure, function and abnormalities of each membrane. The umbilical cord connects the fetus to the placenta and transports nutrients. The amnion surrounds the fetus and amniotic fluid, protecting the fetus and allowing movement. The yolk sac provides early nutrition but later degenerates. The allantois contributes to blood and urinary system development. Abnormalities can impact fetal health.
The human placenta is a discoid, haemochorial organ that develops during pregnancy to connect the developing fetus to the uterine wall for nutrient/waste exchange. At term, the placenta is a circular disc about 15-20cm in diameter and 2.5cm thick that weighs around 500g. It has both a fetal side covered by amnion/umbilical cord and a rough, spongy maternal side with lobes. The placenta facilitates gas/nutrient exchange between maternal and fetal blood supplied by the umbilical cord and establishes a connection between the mother and developing fetus.
The document discusses the development and types of placentas. It begins by describing the early development of the placenta from the trophoblast cells. It then discusses the stages of placental development including the prelacunar, lacunar, villous, and maturity stages. The document concludes by describing some abnormal placenta shapes including bilobed, circumvallate, succenturiate, membranacea, and ring-shaped placentas. Ultrasound appearance of normal and some abnormal placentas is also presented.
This document provides an overview of the umbilical cord, including its structure, development, functions, measurements, and abnormalities. The umbilical cord connects the fetus to the placenta, containing two arteries and a vein enclosed in Wharton's jelly. It normally measures 50cm in length and 1-2cm in diameter. Various abnormalities are discussed such as battledore cord insertion, velamentous insertion, short and long cord, single umbilical artery, true and false knots, and nuchal cord.
The amnion is a membrane that encloses the amniotic cavity and develops from amnioblast cells at 8 days of pregnancy. It separates from the cytotrophoblasts by 12 days. During the 4th week, expansion of the amniotic cavity leads to folding of the embryonic disc. By the 3rd month, the amnion comes into contact with the chorion. The amnion surrounds the fetus and forms a sheath around the umbilical cord by the end of the 3rd month.
The document summarizes various placental and umbilical cord abnormalities. It describes the typical shapes of most placentae as round or oval but notes that variations are common, including multiple placentae or bilobed placentae. It also discusses abnormalities in placental structure, cord insertion sites, umbilical cord vessels, and other variations that can occur in the placenta and umbilical cord. Many of these abnormalities are associated with risks like abnormal fetal growth, preterm delivery, fetal distress, or hemorrhage. The document provides details on the incidence, risk factors, pathogenesis, and clinical implications of numerous placental and umbilical cord variations.
The document discusses the fetal membranes including the chorion, placenta, amnion, and umbilical cord. It describes their formation, structure, development, functions, and some abnormalities. The chorion forms early in development and differentiates into chorionic villi. The placenta develops from the chorion and facilitates gas/nutrient exchange between mother and fetus. The amnion forms a sac surrounding the fetus filled with amniotic fluid. The umbilical cord contains blood vessels connecting the fetus to the placenta.
The document summarizes fetal development from the 9th week of gestation through birth. It describes how the fetus grows in length and weight each month. It also discusses the development of organs and tissues like the brain, lungs, skin, and muscles. The document then covers the fetal membranes - the amnion, chorion, yolk sac, allantois, and umbilical cord. It explains their roles in protecting the fetus and transporting nutrients. The placenta forms from the chorion and develops branched villi to facilitate nutrient exchange between mother and fetus.
The topic discussed here is the Process of fertilization, different stages of fertilization, Implantation, Gastrulation, Formation of foetal membranes, Development of Embryo, Labor & Parturition
USMLE GENERAL EMBRYOLOGY 010 Second week of development embryo .pdfAHMED ASHOUR
During the second week of embryonic development, important events occur as the blastocyst undergoes further differentiation and begins the process of implantation into the uterine lining.
The second week is characterized by the differentiation of cell types within the blastocyst and the initiation of implantation into the uterine lining. These processes set the stage for the subsequent stages of embryonic development, including gastrulation and the formation of the three germ layers. The establishment of early extraembryonic structures is crucial for supporting the developing embryo during its early stages of growth.
an overview of placenta and membranes. Whether you're a medical professional, researcher, student, or simply intrigued by the wonders of human biology, this presentation promises to provide valuable insights into the marvels of the placenta and membranes.
The physiological processes that regulate parturition and the onset of labor continue to be defined. It is clear, however, that labor onset represents the culmination of a series of biochemical changes in the uterus and cervix. These result from endocrine and paracrine signals emanating from both mother and fetus.
The document summarizes the processes of fertilization, gametogenesis, implantation, and early embryonic development. It begins by describing fertilization as the union of an egg and sperm in the fallopian tube, forming a zygote. It then discusses gametogenesis, the formation of male and female gametes, including oogenesis and spermatogenesis. The next stages covered are implantation of the blastocyst in the uterus and formation of the placenta and fetal membranes. The document concludes by outlining the differentiation of the inner cell mass into the three germ layers and the formation of the amniotic cavity and yolk sac in early embryonic development.
This document discusses the development of the placenta, umbilical cord, and membranes. It describes how the placenta forms from the decidua basalis of the endometrium and chorion frondosum of the fetus, which combine to form the placenta. It also discusses the development of chorionic villi and differentiation of trophoblast cells, invasion of spiral arteries by trophoblasts, and establishment of the placental circulation by the 17th day of development. The morphology of the mature placenta is also described, including its discoid shape, surfaces, weight, and potential abnormalities.
During the second week of intrauterine life (days 8-13):
1. The blastocyst implants and differentiates into the trophoblast (outer layer) and inner cell mass. The inner cell mass then forms two layers - the hypoblast and epiblast. Together these layers form a flat disc called the bilaminar germ disc.
2. Within the disc, a cavity (the amniotic cavity) forms within the epiblast. Between the trophoblast and yolk sac, extraembryonic mesoderm starts to form and an extraembryonic cavity (the chorionic cavity) develops.
3. By the end of the second week, the formation of
Fertilization, implantaion and embryologyobgymgmcri
1. The document summarizes key stages in human development from fertilization through embryonic and fetal development. It describes fertilization, cleavage, implantation, and the formation of the three germ layers and extraembryonic membranes.
2. Implantation of the blastocyst in the endometrium occurs around 7 days after fertilization. The trophoblast erodes into the endometrium and connections are made between embryonic and maternal blood vessels in the placenta.
3. The embryonic phase lasts until 8 weeks when major organ systems have begun to form and it is then called a fetus. By the end of the third month the placenta is functioning to exchange gases, nutrients, and waste
Histololgy of Female Reproductive System.pptxAyeshaZaid1
Dive into an in-depth exploration of the histological structure of female reproductive system with this comprehensive lecture. Presented by Dr. Ayesha Irfan, Assistant Professor of Anatomy, this presentation covers the Gross anatomy and functional histology of the female reproductive organs. Ideal for students, educators, and anyone interested in medical science, this lecture provides clear explanations, detailed diagrams, and valuable insights into female reproductive system. Enhance your knowledge and understanding of this essential aspect of human biology.
This document provides information about placental pathology. It describes the structure, development, functions and examination of the placenta. It discusses various anomalies and non-neoplastic lesions seen in placenta such as twin pregnancy, succenturiate lobes, membranacea and infarcts. It also covers tumors and tumor-like conditions including chorioangioma and gestational trophoblastic disease. Complete hydatidiform mole is described as a condition caused by abnormal gametogenesis resulting in trophoblastic hyperplasia and cistern formation.
The document summarizes key events during the first and second weeks of human embryonic development:
- In the first week, the fertilized egg undergoes cleavage and compaction to form a morula, which then develops into a blastocyst as it travels through the fallopian tube. The blastocyst implants in the uterine wall around day 6.
- In the second week, the blastocyst becomes fully embedded. The outer cell mass differentiates into trophoblast layers, while the inner cell mass forms the hypoblast and epiblast. Primary villi and the chorionic cavity develop as the embryo becomes established.
- By the end of the second week, the main cavities and cell layers
This document provides information about conception and implantation. It discusses the reproductive phases in women including the ovarian and menstrual cycles. It describes gametogenesis and oogenesis, noting that the maximum number of oogonia a woman is born with is around 2 million. The document then discusses ovulation, fertilization, embryo development, implantation, and the products of conception including the fetus, placenta and fetal membranes. It provides details on placental development and establishment of the fetomaternal circulation. The functions and abnormalities of the placenta and umbilical cord are summarized. The document concludes with information about the liquor amnii and its indications for amniocentesis.
Breast - Anatomy and Phsiology with Congenital anomalies - Dr. Vijayandra.pptxJhansi897032
This document provides an overview of the anatomy, physiology, and congenital anomalies of the breast. It begins with the embryological development of the breast from mammary ridges. The anatomy sections describe the structure, blood supply, lymphatic drainage and microscopic anatomy. Physiology sections cover development during puberty, the menstrual cycle, pregnancy, lactation and involution. The document concludes with descriptions of common congenital anomalies such as accessory nipples, hypoplasia, amastia and Poland's syndrome.
During the first two weeks of development, the fertilized egg undergoes cell division through cleavage to form a blastocyst. The blastocyst implants in the uterine wall and begins to develop two cell layers - the outer trophoblast and inner cell mass. The trophoblast layer further separates into cytotrophoblast and syncytiotrophoblast. The syncytiotrophoblast starts to invade the maternal tissues and establish placenta. Meanwhile, the cell mass develops into the amniotic cavity and the yolk sac to support the growing embryo. Primary villi also begin to form on the trophoblast as the basis for later placenta development.
The female reproductive system consists of two ovaries, two oviducts, the uterus, the vagina, and external genitalia. The ovaries contain primordial follicles which develop into mature follicles that may ovulate an oocyte. The oviducts contain ciliated cells that help transport the oocyte. The uterus has an endometrium, myometrium, and epimetrium. The endometrium contains glands and changes throughout the menstrual cycle. The myometrium is a thick muscular layer important for pregnancy and birth.
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6. Fetal membrane
• The term fetal membrane is applied to those structures
derived from the blastocyst which do not contribute to
the embryo.
The amnion,
the chorion,
the yolk sac
Allantois
Umbilical cord
7. AMNION It is a thin, transparent &tough fluid-
filled, membranoussac surrounding the
embryo
form by--- amniotic epi. +extraembryonic
mesoderm
At term amnion is a tough, tenacious &
pliable membrane.
Inner most ,avescular,&provide tensile
strength.
• It lacks smooth muscles,lymphatics,nervs&
bld vesscles.
Bourne (1962) described five separate layers of
amnion –
1)innermost single layer of cuboidal epithelium
derived from embryonic ectoderm.basement
membrane
2)acellular compact layer, which is composed
primarily of interstitial collagens
3)fibroblast-like mesenchymal cells, derived from
embryonic
4)disc mesoderm
5)acellular zona spongiosa, contiguous with second
fetal membrane, the chorion laeve
• a
8. Devlopment
Early during implantation:- a space develops between the embryonic cell mass and
adjacent trophoblasts.
Small cells that line this inner surface of trophoblasts have been called amniogenic
cells—precursors of amnionic epithelium.
At First : It is seen as a small cavity lying dorsal to the embryonic plate.
At Stage of Chorionic Vesicle: The amnion becomes separated from the
chorion by chorionic cavity or extra embryonic coelom.
After Folding: the amnion expands greatly and is becomes on the ventral
surface of the embryo.
As a result of expansion of the amnion, the extra embryonic coelom is
gradually obliterated and amnion forms the epithelial covering of umbilical
cord & Reflected amnion is fused to the chorion laeve.
• Placental amnion covers placental surface & thereby is in contact with adventitial
surface of chorionic vessels.
• Umbilical amnion covers the umbilical cord.
• Diamniotic- dichorionic the conjoined portion of membranes of twin placenta, fused
amnions are separated by fused chorion laeve.
• Diamniotic-monochorionic placenta, there is no intervening tissue between the
fused amnions.
9. Amniotic Fluid
Produce by: 1)amniotic cells
2)infusion of fluid from maternal blood
3)urine output from the fetus
4)pulmonary secretions
Output: 1) absorbed by amniotic cells
• 2) fetus swallow
• Plays a major role in fetal growth and development.
• Daily contribution of fluid from respiratory tract is 300-400 ml.
• 500 ml of urine is added daily during the late pregnancy.
• Amniotic fluid volume is 30 ml at 10 weeks, 350 ml at 20 weeks, 700-1000 ml
at 37 weeks.
• Composition:99 % is water
• Desquamated fetal epithelial cells
• Organic & inorganic salts
• Protein, carbohydrates, fats, enzymes, hormones
• Meconium & urine in the late stage
10. function
• Helps maintain the body temperatureEnables the fetus to move freelyProvides
symmetrical external growth of the embryo.
• During labor it help dilatation of the cervix of the uterus and It wash birth
canal and protect the fetus against infections.
• Cushions & protects the embryo and fetus
Acts as a barrier to infection (it is an aseptic medium)
Permits normal fetal lung development
Prevents adherence of embryo to amnion
It protects embryo against external injuries.
Allows the embryo to move freely, aiding muscular development
in the limbs
It is involved in maintaining homeostasis of fluids & electrolytes
It permits studies on fetal enzymes, hormones and diagnosis of fetal sex and
chromosomal abnormalities
11. ABNORMALATIES OF AMNIOTIC FLUID VOLUME
: Oligo-hydramnios:The
volume is less than ½ liters
Causes :
Placental insufficiency
with low placental blood
flow
Preterm rupture of amnio-
chorionic membrane occurs
in 10% of pregnancies
Renal Agenesis (failure of
kidney
• development)
Obstructive Uropathy (urinary
tract obstruction) lead to
absence of fetal urine (the main
source)
Complications :
Fetal abnormalities
(pulmonary,
• facial & limb defects)
Polyhydra
mnios:(Hy
dramnios):
The volume is
more than 2liters,
it is diagnosed by
Ultrasonography.
Causes
Fetal ( 1-20% ) :
Esophageal atresia.
Maternal
(2-20%) :
defects in
maternal
circulation.
Idiopathic (3-
60%)
12. Abnormility Definition & causes Clinical significance
Lined by typical amnionic
epithelium
Fusion of amnionic folds with
subsequent fluid retention
Amnion nodosum Tiny, creamy nodules in the
amnion made up of vernix
caseosa with hair, degenerated
squames and sebum
Oligohydramnios
Found in
fetuses with renal agenesis
Prolonged preterm ruptured
Membranes
The placenta of the donor
fetus with twin-to-twin
transfusion syndrome
Amnionic band Caused when disruption of the
amnion
leads to formation of bands or
strings
Intrauterine amputation
Amnionic
cyst
13. YOLK SAC
• It is essential in the transfer of
nutrients to the embryo during 2nd
& 3rd weeks, when the
uteroplacental circulation is not
established.
• It is large at 32 days
• Shrinks to 5mm pear shaped
remnant by 10th week & connected
to the midgut by a narrow yolk stalk
• Becomes very small at 20 weeks
Usually not visible thereafter
• It does not contain any yolk.
Its development passes
through three stages:
Primary yolk sac.
Secondary yolk sac.
Definitive yolk sac.
• a
14. Primary yolk sac
• a
Appears in the
Blastocyst stage at 10-
days, it lies ventral to
the embryonic
plate.
Its roof is formed by
hypoblast (primary
endoderm),
Its wall is formed by
exocoelomic membrane,
it lines the inner surface of
the cytotrophoblast, and
separated from it by the
extraembryonic
mesoderm
15. Secondary yolk sac
• a
Appears in the chorionic
vesicle stage
Its roof is formed by
hypoblast (embryonic
endoderm), its wall is
formed by exocoelomic
membrane + inner layer
(splanchnic layer) of the
extraembryonic
mesoderm.
At day 16: a diverticulum
appears from its
dorsocaudal
end (Allantois) into the
substance of the connecting
stalk
16. Definitive yolk sac
• a
After folding, part of
Yolk Sac is enclosed
within the embryo to
form the Gut (Foregut,
Midgut & Hindgut).
The remainder of Yolk
Sac that remains outside
the embryo becomes the
Definitive Yolk Sac
The midgut is
temporarily connected to
Definitive Yolk Sac by a
narrow duct Vitello-
intestinal duct (Yolk
stalk), which is
incorporated inside the
umbilical cord.
This is fibrosed and
degenerated by
• the end of (6th week)
17. Function of yolk sac
a
3rd week:
(a) Blood formationt
• First formed in the extra-
embryonic mesoderm covering the
wall of the
yolk sac, until hemopoietic activity
begins in the liver during 6th week
4th week: endoderm of yolk
sac is incorporated into the
embryo to form primordial gut
Epithelium of Respiratory system
&G.I.T
b)Primordial germ cells:- in the endodermal lining of the wall of caudal end of the
yolk sac migrate into the developing sex glands to differentiate into germ cells
(spermatogonia or oogonia)
18. Fate of yolk sac
• a
Yolk stalk detached from
midgutby the end of 6th
week. In (2%) of adults, its
proximal intra-abdominal
part persists as ileal
diverticulum (Meckel
diverticulum).
At 10 week, small definitive
yolk sac lies in the chorionic
cavity between amniotic &
chorionic sacs
At 20 weeks, as pregnancy
advances, definitive yolk sac
atrophies and becomes a very
small cyst.
In unusual cases, it
persists under the amnion
near the attachment of
Umbilical cord, on the fetal
surface of the placenta. Its
persistence is of no
significance
19.
20. ALLANTOIS
3rd week:Appears as a
diverticulum from caudal wall of Y.S.
that extends into connecting stalk.
2nd month: Its extra- embryonic part
degenerates.
3rd month: Its intra-
embryonicpart extends from UB to
UC as thick tube , ‘(urachus) ’
After birth: the urachus is
obliterated and fibrosed to form
median umbilical ligament, that
extendsfrom apex of UB to
umbilicus.
Function:Blood formation in its
wall during 3rd to 5th week.
Its blood vessels persist as the
umbilical vein & arteries.
• a
21. CHORION
• The extraembryonic somatic mesoderm and the two
layers of trophoblast form the chorion
• Chorion forms the wall of chorionic sac
• Embryo and its amniotic and yolk sacs are suspended into
it by connecting stalk
• Growth of these extensions are caused by underlying
extraembryonic somatic mesoderm
• The cellular projections form primary chorionic villi.
Chorionic villi
• As this sac grows, the villi associated with decidua
capsularis are compressed, reducing the blood supply to
them
• These villi soon degenerates producing an avascular bare
area smooth chorion (chorion laeve).
22.
23. Primary chorionic vilii
• At the end of 2nd
week, finger-like
processes formed
of outer
syncytiotrophoblast
& inner
cytotrophoblast
appear & cover the
entire chorionic sac
until the beginning
of 8th week
25. Tertiary Chorionic villi
• During 3rd week,
arterioles, venules
& capillaries
develop in the
mesenchyme of
villi & join
umbilical vessels
• By the end of 3rd
week, embryonic
blood begins to
flow slowly
through capillaries
in chorionic villi
• a
26. UMBILICAL CORD/ funis
Extends from fetal umbilicus to fetal surface of placenta or
chorionic plate.
• Exterior is dull white, moist, & covered with amnion, through
which three umbilical vessels may be seen.
• Origin :-It develops from the connecting stalk.
• Length:--At term, it measures about 50 cm.
• Diameter:--2 cm.
DEVELOPMENT:--Cord develops in yolk sac & umbilical vesicle
which are prominent early in pregnancy.
Embryo, at first, is a flattened disc interposed between amnion &
yolk sac.
Its dorsal surface grows faster than the ventral surface.
Embryo bulges into amnionic sac in association with elongation of
neural tube.
Dorsal part of yolk sac is incorporated into the body of embryo to
form gut.
27. Allantois projects into base of body stalk from the caudal wall of the yolk sac & later, forms
anterior wall of hindgut.
As pregnancy advances, yolk sac becomes smaller & its pedicle relatively longer.
Middle of 3rd month:- expanding amnion obliterates exocoelom, fuses with the chorion
laeve, & covers the bulging placental disc & lateral surface of the body stalk.Latter is then
called the umbilical cord—or funis.
Insertion:
The cord is inserted in the foetal surface of the placenta
near the center "eccentric insertion" (70%) Or
at the center "central insertion" (30%).
Structure: It consists of mesodermal connective tissue called Wharton's jelly, covered by
amnion.
It contains:
1.One umbilical vein carries oxygenated blood from the placenta to the foetus
2.Two umbilical arteries carry deoxygenated blood from the foetus to the placenta,
3.Remnants of the yolk sac and allantois..
28.
29. CORD AT TERM
• It normally has two arteries
and one vein .
• Right umbilical vein
disappears early during fetal
development, leaving only
the left vein.
• Intra-abdominal portion of
duct of umbilical vesicle,
extending from umbilicus to
intestine, usually atrophies
& disappears.
• If patent, it is known as
Meckel’s diverticulum.
• Most common vascular
anomaly - absence of one
umbilical artery which may
be associated with fetal
anomalies.
• A
30. • Length
• Cord Coiling
• Single Umbilical Artery
• Four-vessel cord
• Abnormalities of cord insertion
• Cord Abnormalities capable of impeding blood flow
• Hematoma
• Cysts
31. LENGTH:--Appreciable variation –Average length of 55 cm
range-- of 30 to 100 cm.
No cord---(acordia) ~
lengths up to 300cm
Excessively long cords : ≥ 70cm( ≥2 SD ) Associated with
-maternal systemic disease
-delivery complications -cord prolapse, cord entanglement
-fetal anomalies and respiratory distress Perinatal mortality : ↑ nearly
threefold
Short umbilical cord:-Generally, cord length less than 30 cm is
considered abnormally short.
Adverse perinatal outcomes –
-fetal growth restriction
congenital malformations
intrapartum distress & risk of death (doubled)
32. Umbilical vessels: in a spiraled manner
CORD COILING:--Umbilical vessels: in a spiraled manner
Hypocoiled cords:-↑ in various adverse outcome in fetuses
- meconium staining, preterm birth and fetal distress.
Hypercoiled cords --higher incidence of preterm delivery &
cocaine abuse.
SINGLE UMBLICAL ARTERY:--Umbilical cord –2-arteries & 1
vein
Risk factors –↑ incidence in women with GDM, PIH, APH,
epilepsy, oligohydramnios & hydramnios.
----¼ of all infants with only 1 artery have associated congenital
anomalies.
FOUR VESSCLE CORD:- Venous remnantin 5% & Significance :
unknown
33. ABNORMALITIS IN CORD INSERSATION
rmalities Definition Incidenc Significance
cate insertion
Umbilical vessels separate from
the cord substance before their
insertion into the placenta
RARE Prone to twisting &
thromboses as vessels lose
their cushioning
ginal Inserion Battledore placenta:
Cord insertion at the placental
margin
7% at
term
Cord being pulled off
during delivery of the
placenta
mentous Insertion Umbilical vessels separate in the
membranes at a distance from
the placental margin.
Reach surrounded only by a fold
1.1% More frequently with
twins
28% of triples
34. Vasa pervia
• Associated with velamentous insertion when some of the fetal vessels in the
membranes cross the region of the cervical os below the presenting fetal part
Associated with :
• Velamentous insertion (50%)
• Marginal cord insertion
• Bilobed or Succenturiate-lobed placentas (50%)
Risk factors :
• Bilobed , Succenturiate or low-lying placenta (80%)
• Multifetal pregnancy
• Pregnancy resulting from in vitro fertilization.
Diagnosis
• Color Doppler examination
• Perinatal diagnosis :-- associated with increased survival
• Antenatal diagnosis : --associated with decreased fetal mortality compared with
discovery at delivery
• Antepartum or intrapartum haemorrhage
• Detecting fetal blood ( Apt test)
• Wright stain : smear the blood on glass slides stain the smears with Wright stain
and examine for nucleated RBC normally are present in cord blood but not
maternal blood
35. TWIN/MULTIPILE PREGNANCY
Two or more fertilization events
Single fertilization followed by splitting of zygote
Combination of both
Incidence:-Global incidence: 4/1000 births
Hellin’s Law : Twins: 1/80 singleton births
• Triplets: 1:802
• Quadruplets: 1:803
Conjoined twins: 1 : 60,000
Typesof twins………
1)-DIZYGOTIC
2)-MONOZYGOTIC
36.
37. Dizygotic/ non-identical twins (binovular ,
fraternal, 2 eggtwins)
~ two third of twins.
fertilization of two independently released ova by
two different sperm.
In all polyzygotic multiple pregnancies, each zygote
develops its own amnion, chorion and placental
circulation, and hence will be polychorionic.
not true twins
39. Monozygotic twins
( uniovular, identical orsingle egg twins
One third of twins.
arise from the splitting of a single fertilized egg
within the first 14 days after fertilization.
Always same sex (Identical)
does not necessarily result in equal sharing of
genetic material , so they may be discordant for
genetic mutations , or may have the same genetic
disease but with marked variability in expression.
teratogenic event
40.
41.
42. ETIOLOGY:-Maternal age
Race and heredity : Black race
Parity: Increasing parity (2.7% in 4th pregnancy)
Heredity
Pituitary Gonadotropin
ART: Ovulation induction with FSH and gonadotropin /chlomiphine Greater the number of
embryos transfered, the greater the risk of multiple pregnancy.
Determination of zygosity/chorionicity :--Chorionicity can be identified in
the first trimester with sonography
Before 10 weeks sonographic findings to determine chorionicity.
Number of
1.gestational sacs
2.amniotic sacs within the chorionic cavity
3.yolk sacs.
43. 1. Number of Gestational Sacs
Each gestational sac forms its own placenta and chorion:
2 gestational sacs: DC twin
1 gestational sac with 2 identified heartbeats: MC twin.
2. Number of Amniotic Sacs Within the ChorionicCavity
Diamniotic twins: separate and distinct amnions
before 10w the separate amnions of a diamniotic pregnancy will not have enlarged
sufficiently to contact each other and create the inter-twinseptum.
TAS: Each single amnion is extremely thin and delicate: very difficult to see TVS: often
successful in differentiating separate amnions.
3. Number of YolkSacs
2 yolk sacs are seen in the extra-embryonal coelom: diamniotic
1 yolk sac-in most cases indicate monoamniotic twins
when there are dual embryos: follow-up 1st T scan to definitively assign amnionicitya
44. .After 10 weeks:-These sonographic
signs are no longer present:
gestational sacs are no longer
distinctly separable, and the inter-twin
membrane is formed.
Findings:-
• 1)-Genitalia
• 2)-Placental number
• 3)-Chorionic peak sign( Lambda sign
& T sign)
• 4)-Membranecharacteristics.
Inter-Twin Membrane :Characteristics
1)DC : -2 layers of amnion and 2 layers
of chorion.Thicker > 2 mm more
reflective
2)MC:- ≤ 2mm
In 2nd T: Number of membranes may be
counted, and if there are > 2, then
dichorionicity is strongly suggested
• .
45. Pregnancy complications
2 to3 fold increased than singletons
Threatened and spontaneous abortions (vanishing twin)
7.3 % risk in multiple
• pregnancy versus 0.9 % in singleton (Joo, 2012)
Hyperemesis
Severe anemia
Hypertensive disorders of pregnancy: 3 to 4 fold increase
Gestational diabetes
Antepartum hemorrhage: abruption
Preterm premature rupture of the membranes
Operative delivery
PPH : 3-4 fold increase
Increased maternal mortality
46. Fetal complications
Low birthweight- due to restricted fetal growth and preterm
delivery
Preterm birth
Monochorionic pregnancy complications
Perinatal asphyxia
Fetal death, Cord accidents
Increased perinatal mortality
• Congenital Malformations- 406/10000 in twins versus 238/10000
singletons .
Structural malformations
1)Conjoint twins,2)Acardiac fetus,3)Anencephaly
• 4)Talipes,5)Dislocation of hip etc.
Chromosomal anomalies
Down’ssyndrome
49. External parasitic twins- grossly defective fetus
or merely fetal parts attached externally to a
relatively normal twin
• Believed to result from demise of the defective
twin with its surviving tissues attached to and
vascularized by its normal twin
Fetus in fetu- early in development, one embryo
may be enfolded within its twin
• Classically vertebral or axial bones are found in
these fetiform mases, supported by their host by a
few large parasitic vessels
50. Monochorionic twins withvascular anastomoses
Two amniotic sacs and a common surrounding chorion
anatomical sharing of the two fetal circulations through
anastomoses of placental arteries and veins
Artery to artery anastomoses are most common and are identified on
the chorionic surface of the placenta- 75%
Vein to vein and artery to vein– approx. 50%.
Deep artery to vein connections can extend from capillary bed of a
given villus, creating a common villous compartment or third circulation
Depending on the degree to which they are hemodynamically
balanced, severity occurs
With significant pressure or flow gradients, a shunt will develop
between fetuses
Chorioinic feto fetal transfusion result in several clinical syndromes
51. Twin-Twin Transfusion syndrome
5 – 17 % of monochorionic twin
Mortality irrespective of gestational age is 60-70%
Mechanism: deep A-Vvascular anastomosis. Blood is
transfused from donor twin to its recipient sibling – donor is
anemic and growth may be restricted
Recipient becomes polycythemic, with circulatory overload
and may manifest as hydrops
Classic TTTS results from unidirectional flow through AV
anastomoses
Deoxygenated blood from donor placental artery- pumped into
a cotyledon shared by recipient. Once oxygen exchange is
completed in the chorionic villus, oxygenated blood leaves the
cotyledon via a placental vein of the recipient twin
52. .Clinically important
TTTS is frequently
chronic, results from
significant volume
differences
Presents in mid
pregnancy, donor fetus-
oliguric due to decreased
renal perfusion –
develops
oligohydramnios
Recipient-
polyhydramnios
Stuck twin,
polyhydramnios-
oligohydramnios –
syndrome (poly-oli
• .