The Fetus And Placenta Flashcards
The period from the 💡beginning of the ninth week to 💡birth is known as the
It is characterized by 💡maturation of tissues and organs and 💡rapid growth of the body.
Fetal period.
The 💡length of the fetus is usually indicated as the?
Crown-rump length (CRL) (sitting height)
The measurement from the 💡vertex of the skull to the 💡heel (standing height).
Crown-heel length (CHL)
💡Growth in length is particularly striking during the?
Third, fourth, and fifth months
Increase in weight is most striking during the?
Last 2 months of gestation
The length of pregnancy is considered to be __ after the onset of the last normal menstrual period (LNMP) or, more accurately, __ after fertilization.
280 days, or 40 weeks
266 days or 38 weeks
One of the 💡most striking changes taking place during fetal life is the?
Relative slowdown in growth of the head
During the __, the face becomes more human looking
Third month
💡Primary ossifícation centers are present in the long bones and skull by the __.
Also, 💡external genitalia develop to such a degree that the sex of the fetus can be determined by external examination (ultrasound)
12th week
By __ intestinal loops cause a large swelling (herniation) in the umbilical cord, but by the __, the loops have withdrawn into the abdominal cavity.
Sixth week
12th week
During the __, the fetus lengthens rapidly, and at the end of the first half of intrauterine life, its CRL is approximately 15 cm, about half the total length of the newborn.
Fourth and fifth months
The fetus is covered with fine hair, called?
Lanugo hair
During the __, 💡movements of the fetus can be felt by the mother.
Fifth month
During the __,weight increases considerably, particularly during the last 2.5 months, when 50% of the full term weight (approximately 3,200 g) is added.
Second half of intrauterine life
During the __, the skin of the fetus is 💡reddish and has a 💡wrinkled appearance because of the 💡lack of underlying connective tissue.
Sixth month
At what month the fetus has a CRL of about 💡25 cm and weighs approximately 💡1,100 g. If born at this time, the infant has a 90% chance of surviving.
7 months
At what month the fetus is 💡well-rounded contours as the result of 💡deposition of subcutaneous fat
By the end of intrauterine life, the skin is covered by a whitish, fatty substance (vernix caseosa) composed of secretory products from sebaceous glands.
8th month
It is a 💡whitish, fatty substance which is composed of secretory products from 💡sebaceous glands.
vernix caseosa
At what month where the 💡skull has the largest circumference of all parts of the body, an important fact with regard to its passage through the birth canal.
The weight of a normal fetus is 💡3,000 to 3,400 g, its CRL is about 💡36 cm, and its CHL is about 💡50 cm. 💡Sexual characteristics are pronounced, and the 💡testes should be in the scrotum.
Ninth month
It is the action of giving birth to young
Parturation
The date of birth is most accurately indicated as __, after fertilization.
266 days, or 38 weeks
The obstetrician calculates the date of birth as __ from the first day of the LNMP.
This method is accurate among women with regular 28-day menstrual periods
280 days or 40 weeks
Most fetuses are born within __ of the calculated delivery date.
10 to 14 days
If the fetuses are born much earlier, they are categorized as
Premature
If the fetuses are born later, they are categorized as
Postmature
It is a valuable tool which can provide an accurate (1 to 2 days) measurement of CRL during the 7th to 14th weeks.
Ultrasound
Measurements commonly used in the 💡16th to 30th weeks are:
Biparietal diameter (BPD), Head and abdominal circumference Femur length.
It is the 💡organ that facilitates nutrient and gas exchange between the maternal and fetal compartments.
Placenta
FUNCTIONS OF PLACENTA
- Exchange of metabolic and gaseous products between maternal and fetal bloodstreams.
- Transmission of Maternal Antibodies (IgG)
- Hormone Production (Progesterone)
The fetal component of the placenta is derived from the __ and __ (the chorionic plate); the maternal component is derived from the __.
Trophoblast
Extraembryonic mesoderm
Uterine endometrium
These are formed when 💡syncytium becomes very thin, and large pieces containing several nuclei may break off and drop into the intervillous blood lakes.
They 💡enter the maternal circulation and usually 💡degenerate without causing any symptoms.
Syncytial knots
The 💡villi on the embryonic pole continue to grow and expand, giving rise to the?
It is the 💡only portion of the chorion participating in the 💡exchange process
Chorion frondosum (bushy chorion)
Villi on the abembryonic pole degenerate, and by the third month, this side of the chorion, now known as the known as the?
Chorion laeve
It is the 💡functional layer of the endometrium, which is 💡shed during parturition.
Decidua
The 💡decidua over the chorion frondosum which consists of a compact layer of 💡large cells, 💡decidual cells, with 💡abundant amounts of lipids and glycogen.
Decidua basalis
It is 💡tightly connected to the chorion
Decidual plate
It is the 💡decidual layer over the abembryonic pole.
With growth of the chorionic vesicle, this layer becomes stretched and degenerates.
Decidua capsularis
It is the 💡uterine wall where the chorion laeve comes into contact on the opposite side of the uterus, and the two fuse, obliterating the uterine lumen.
Decidua parietalis
Chorion frondosum + Decidua basalis
placenta
Amnion + Chorion
It is this 💡membrane that ruptures during labor (breaking of the water).
Amniochorionic membrane
By the beginning of the 💡fourth month, the placenta has two components:
Fetal portion
Maternal portion
It is formed by the 💡chorion frondosum
Fetal portion
It is formed by the 💡decidua basalis
Maternal portion
It 💡borders the placenta on the 💡fetal side.
Chorionic plate
It 💡borders the placenta on the 💡maternal side
Decidual basalis
This is where 💡trophoblast and 💡decidual cells 💡intermingle.
This zone is characterized by 💡decidual and syncytial giant cells, is rich in amorphous extracellular material.
Junctional zone
During the fourth and fifth months, the decidua forms a number of __, which project into intervillous spaces but do not reach the chorionic plate
These septa have a 💡core of maternal tissue, but their surface is covered by a layer of 💡syncytial cells, so that at all times, a syncytial layer separates maternal blood in intervillous lakes from fetal tissue of the villi.
Decidual septa
They 💡divide the placenta into a 💡number of compartments as a result of the 💡decidual septum formation
Cotyledons
It is a 💡discoid with a diameter of 💡15 to 25 cm, is approximately 💡3 cm thick, and weighs about 💡500 to 600 g.
Full-Term Placenta
When the placenta is viewed from the maternal side, 15 to 20 slightly bulging areas, the cotyledons, covered by a thin layer of decidua basalis, are clearly recognizable. Grooves between the cotyledons are formed by decidual septa.
True
The __ of the placenta is covered entirely by the 💡chorionic plate.
Fetal surface
It separates maternal and fetal blood, is initially composed of four layers: (1) The endothelial lining of fetal vessels
(2) The connective tissue in the vlllus core
(3) The cytotrophoblastic layer
(4) The syncytium
Placental membrane
Placental barrier
It is the oval line of reflection between the amnion and embryonic ectoderm (amnio-ectodermal junction)
Primitive umbilical ring
At the end of pregnancy, a number of changes that occur in the placenta may indicate reduced exchange between the two circulations. These changes include:
(1) An increase in fibrous tissue in the core of the villus
(2) Thickening of basement membranes in fetal capillaries
(3) Obliterative changes in small capillaries of the villi
(4) Deposition of fibrinoid on the surface of the villi in the junctional zone and in the chorionic plate.
It is a 💡clear, watery fluid that is produced in part by 💡amniotic cells but is 💡derived primarily from 💡maternal blood which filled the 💡amniotic cavity.
AMNIOTIC FLUID
Functions of AMNIOTIC FLUID:
(1) Absorbs jolts
(2) Prevents adherence of the embryo to the amnion
(3) Allows for fetal movements.
The amount of fluid increases from approximately 30 mL at __ of gestation to 450 mL at __ to 800 to 1,000 mL at __.
10 weeks
20 weeks
37 weeks
The volume of amniotic fluid is replaced every __.
3 hours
During 💡5th month, what will happen to the fetus and the amniotic fluid?
- The fetus swallows its own amniotic fluid
2. Fetal urine is added daily to the amniotic fluid
They result from simultaneous shedding of 💡two oocytes and fertilization by 💡different spermatozoa.
Dizygotic (Fraternal) Twins
It develops from a 💡single fertilized ovum
Monozygotic (identical) Twins
Labor itself is divided into three stages:
(1) Effacement (thinning and shortening) and dilatation of the cervix (this stage ends when the cervix is fully dilated)
(2) Delivery of the fetus
(3) Delivery of the placenta and fetal membranes
It is a term applied to infants who 💡do not attain their optimal intrauterine growth.
These infants are 💡pathologically small and at risk for poor outcomes.
Caused by mutations in the 💡IGF-I gene.
Intra-uterine growth restriction (lUGR)
It is a term applid to infant who have a birth weight that is 💡below the l0th percentile for their gestational age.
These babies may be 💡pathologically small (they may have lUGR) or they may be 💡constitutionally small (healthy but smaller in size).
Small for gestational age (SGA)
Babies with lUGR have been shown to have a greater chance as adults to develop a metabolic disorder later in life, such as obesity, hypertension, hypercholesterolemia, cardiovascular disease, and type 2 diabetes
Barker hypothesis
It is the 💡major growth-promoting factor during development before and after birth.
Mitogenic and anabolic effects
Insulin-like growth factor-l (IGF-I)
This hormone binds to its receptor [GHR], activating a signal trans- duction pathway and resulting in 💡synthesis and 💡secretion of IGF-I.
Growth hormone (GH)
Mutations in the 💡GHR
It is characterized by marked 💡short stature, and sometimes 💡blue sclera.
These individuals show 💡little or no lUGR because IGF-I production does not depend on GH during fetal development.
Laron dwarfism
It is a condition characterized by 💡maternal hypertension and 💡proteinuria due to reduced organ perfusion and occurs in approximately 5% of pregnancies.
Preeclampsia
Hemolytic disease of the fetus and newborn
RH incompatibility
Erythroblastosis fetalis
It happens when the anemia is so severe causing edema and effusions into the body cavities
Fetal hydrops
This compound produced 💡clear cell carcinoma of the vagina and abnormalities of the cervix and uterus in females and in the testes of males in individuals who were exposed to the compound during their intrauterine life
Diethyistilbestrol (DES],
Length of a cord reflects the amount of intrauterine movement of the fetus, and shortened cords have been observed in fetal movement disorders and with intrauterine constraint.
True
Tears in the amnion
It may encircle part of the fetus, particularly the limbs and digits causing amputations, ring constrictions, and other abnormalities, including craniofacial deformations.
Amniotic Bands
It is the term used to describe an excess of amniotic fluid (1,500 to
2,000 mL)
Hydramnios or polyhydramnios
It refers to a decreased amount (<400 mL] of amniotic fluid.
Oligohydramnios
It refers to rupture of the membranes before uterine contractions begin.
Premature rupture of the membranes (PROM)
It refers to the 💡death of one fetus.
This disappearance, which occurs in the 💡first trimester or the 💡early second trimester, may result from resorption or formation of a 💡fetus papyraceus
Vanishing twin
One twin is larger, and the other has been compressed and mummified.
Fetus papyraceus
Placental 💡vascular anastomoses produced unbalanced blood flow to the two fetuses.
Twin transfusion syndrome
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Thoracopagus twins
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Pygopagus twins
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Craniopagus twins
