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Embryology > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

The period from the beginning of the ninth week to birth is known as the ___

A

fetal period

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2
Q

Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 13-16

A

Crl: 9-14cm
Weight: 60-200

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3
Q

The length of the fetus is usually indicated as the___ (sitting height) or as the ___, the measurement from the vertex of the skull to the heel (standing height)

A

crown-rump length (CRL) - crown heel length (CHL)

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4
Q

In general, the length of pregnancy is considered to be 280 days, or 40 weeks after the onset of the last normal menstrual period (LNMP) or, more accurately, 266 days or 38 weeks after fertilization. True/ False

A

True

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5
Q

Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 9-12

A

Crl: 5-8cm
Weight: 10-45g

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6
Q

Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 17-20

A

Crl: 15-19cm
Weight: 250-450g

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7
Q

Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 25-28

A

Crl: 24-27cm
Weight: 900-1300g

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8
Q

Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 21-24

A

Crl: 20-23cm
Weight: 500-820g

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9
Q

Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 29-32

A

Crl: 28-30cm
Weight: 1400 - 2100g

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10
Q

Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 33-36

A

Crl: 31-34cm
Weight: 2200-2900g

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11
Q

Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 37-38

A

Crl: 35-36cm
Weight: 3000-3400g

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11
Q

During the ____, the face becomes more human looking . The eyes, initially directed laterally, move to the ventral aspect of the face, and the ears come to lie close to their definitive position at the side of the head. The limbs reach their relative length in comparison with the rest of the body, although the lower limbs are still a little shorter and less well developed than the upper extremities

A

third month

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12
Q

___ are present in the long bones and skull by the 12th week. Also, by the 12th week, external genitalia develop to such a degree that the sex of the fetus can be determined by external examination (ultrasound)

A

Primary ossification centers

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12
Q

During the ___ and ___, the fetus lengthens rapidly, and at the end of the first half of intrauterine life, its CR is approximately 15 cm, about half the total length of the newborn

A

fourth and fifth months

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13
Q

During the 6th week, ____, but by the 12th week, the loops have withdrawn into the abdominal cavity.

A

intestinal loops cause a large swelling (herniation) in the umbilical cord

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14
Q

The fetus is covered with fine hair, called __; eyebrows and head hair are also visible

A

lanugo hair

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15
Q

During the ____, movements of the fetus can be felt by the mother

A

fifth month

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16
Q

During the ___, the skin of the fetus is reddish and has a wrinkled appearance because of the lack of underlying connective tissue

A

sixth month

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17
Q

During the ___, weight increases considerably, particularly during the last 2.5 months, when 50% of the full-term weight (approximately 3,200g) is added

A

second half of intrauterine life

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18
Q

Development of taste buds appear at what wk?

A

7

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19
Q

Development of some sounds can be heard at what wk?

A

24-26

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19
Q

Development of swallowing at what wk?

A

10

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19
Q

Development of eyes sensitive to light at what wk?

A

28

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19
Q

A valuable tool for assisting in this determination is __, which can provide an accurate (1 to 2 days) measurement of CRL during the 7th to 14th weeks.

A

ultrasound

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20
Q

Development of respiratory movements appear at what wk?

A

14-16

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20
Q

At the end of the ___, the skull has the largest circumference of all parts of the body, an important fact with regard to its passage through the birth canal. At the time of birth, 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.

A

ninth month

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21
Q

Development of sucking movements at what wk?

A

24

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22
Q

During the last 2 months, the fetus obtains 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 (____) composed of secretory products from sebaceous glands

A

vernix caseosa

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23
Q

Most fetuses are born within 10 to 14 days of the calculated delivery date. If they are
born much earlier, they are categorized as ___; if born later, they are considered ___

A

premature - postmature

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23
Q

Measurements commonly used in the 16th to 30th weeks are ____, ____ and ___, and ____

A

biparietal diameter (BPD), head and abdominal circumference, and femur length

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24
Q

In contrast, the terms ___ and ___ take into account gestational age

A

intrauterine growth restriction [IUGR] - small for gestational age [SGA]

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24
Q

The average size of a newborn is 2,500 to
4,000 g [6 to 9 lb] with a length of 51 cm [20 in]. The term ___ refers to a weight <2,500 g, regardless of gestational age

A

low birth weight [LBW]

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25
Q

Many infants weigh <2,500 g because they are ____ [born before 37 weeks of
gestation]

A

Preterm

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26
Q

___ 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

A

IUGR

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27
Q

Infants who are ___ have a birth weight that is below the 10th percentile for their gestational age. These babies may be pathologically small [they may have IUGR]
or they may be constitutionally small [healthy but smaller in size]

A

SGA

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28
Q

For example, babies with IUGR 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 [called
the ____].

A

Barker hypothesis

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29
Q

The major growth-promoting factor during
development before and after birth is ___, which has ___ and ____.

A

insulin-like growth factor 1 [lGF-1]
mitogenic and anabolic effects

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30
Q

Mutations in the IGF-1 gene result in IUGR, and this growth retardation is continued after birth. In contrast to the prenatal
period, postnatal growth depends on ___

A

growth hormone [GH]

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31
Q

Mutations in the GHR result in ___, which is characterized by marked short stature, and sometimes blue sclera

A

Laron dwarfism

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32
Q

Maternal blood is delivered to the placenta by spiral arteries in the uterus. Erosion ofthese maternal vessels to release blood into intervillous spaces is accomplished by ___ by cytotrophoblast cells

A

endovascular invasion

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33
Q

During the following months, numerous small extensions grow out from existing stem villi and extend as free villi into the surrounding ___ or ___

A

lacunar or intervillous spaces

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34
Q

These pieces, known as ___, enter the maternal circulation and usually degenerate without causing any
symptoms

A

syncytial knots

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35
Q

___ is a condition characterized by maternal hypertension and proteinuria due to reduced organ perfusion and occurs in approximately 5% of pregnancies

A

Preeclampsia

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36
Q

In the early weeks of development, villi cover the entire surface of the chorion. As
pregnancy advances, villi on the embryonic pole continue to grow and expand, giving rise to the ___ (bushy chorion)

A

chorion frondosum

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37
Q

Villi on the abembryonic pole degenerate, and by the third month, this side of the chorion, now known as the ___, is smooth

A

chorion laeve

38
Q

The difference between the embryonic and abembryonic poles of the chorion is also reflected in the structure of the __, the functional layer of the endometrium, which is shed during parturition

A

decidua

39
Q

The decidua over the chorion frondosum, the ____, consists of a compact layer of large cells, decidual cells, with abundant amounts of lipids and glycogen

A

decidua basalis

40
Q

The decidua over the chorion frondosum, the decidua basalis, consists of a compact layer of large cells, ___, with abundant amounts of lipids and glycogen

A

decidual cells

41
Q

This layer, the ___, is tightly connected to the chorion

A

decidual plate

42
Q

The decidual layer over the abembryonic pole is the ____

A

decidua capsularis

43
Q

Subsequently, the chorion laeve comes into contact with the uterine wall (____) on the opposite side of the uterus, and the two fuse, obliterating the uterine lumen

A

decidua parietalis

44
Q

Hence, the only portion of the chorion participating in the exchange process is the chorion frondosum, which, together with the decidua basalis, makes up the ___

A

placenta

45
Q

Similarly, fusion of the amnion and chorion to form the ___ obliterates the chorionic cavity

A

amniochorionic membrane

46
Q

On the fetal side, the placenta is bordered by the ____; on its maternal side, it is bordered by the decidua basalis, of which the ___ is most intimately incorporated into the placenta

A

chorionic plate - decidual plate

46
Q

By the beginning of the fourth month, the placenta has two components:
(1) a ___, formed by the chorion frondosum
(2) a ___, formed by the decidua basalis

A

fetal portion - maternal portion

47
Q

In the ___, trophoblast and decidual cells intermingle. This zone, characterized by decidual and syncytial giant cells, is rich in amorphous extracellular material. By this time, most cytotrophoblast cells have degenerated

A

junctional zone

48
Q

When the placenta is viewed from the ___, 15 to 20 slightly bulging areas, the ___, covered by a thin layer of decidua basalis, are clearly recognizable

A

maternal side - cotyledons

48
Q

During the fourth and fifth months, the decidua forms a number of ___, which project into intervillous spaces but do not reach the chorionic plate

A

decidual septa

49
Q

As a result of this septum formation, the placenta is divided into a number of compartments, or ___

A

cotyledons

50
Q

The ____ of the placenta is covered entirely by the chorionic plate. A number of large arteries and veins, the ___, converge toward the umbilical cord

A

fetal surface - chorionic vessels

50
Q

Rarely, however, does it insert into the chorionic membranes outside the placenta (_____)

A

velamentous insertion

51
Q

This process is an example of ____, and if the maternal response is sufficient, the antibodies will attack and hemolyze fetal red blood cells, resulting in hemolytic disease of the fetus and newborn

A

isoimmunization

51
Q

The ___, which separates maternal and fetal blood, is initially composed of four layers:
(1) the endothelial lining of fetal vessels
(2) the connective tissue in the villus core
(3) the cytotrophoblastic layer
(4) the syncytium

A

placental membrane

52
Q

Sometimes called the ___, the placental membrane is not a true barrier, as many substances pass through it freely

A

placental barrier

53
Q

Because the maternal blood in the intervillous spaces is separated from the fetal blood by a chorionic derivative, the human placenta is considered to be of the ____

A

hemochorial type

54
Q

This process is an example of isoimmunization, and if the maternal response is sufficient, the antibodies will attack and hemolyze fetal red blood cells, resulting in ____

A

hemolytic disease of the fetus and newborn

55
Q

Previously, the disease was called ____ because in some cases, severe hemolysis stimulated an increase in production of fetal blood cells called erythroblasts

A

erythroblastosis fetalis

56
Q

Previously, the disease was called erythroblastosis fetalis because in some cases, severe hemolysis stimulated an increase in production of fetal blood cells called ___

A

erythroblasts

57
Q

In rare cases, the anemia becomes so severe that ___ [edema and effusions into the body cavities] occurs, leading to fetal death

A

fetal hydrops

57
Q

Most severe cases are caused by antigens from the ____ blood group system

A

CDE [Rhesus]

58
Q

The D or ___ is the most dangerous because immunization can result from a single exposure and occurs earlier and with greater severity with each succeeding pregnancy. The maternal antibody response occurs in cases when the fetus is D [Rh]—positive and the mother is D [Rh]—negative and is elicited when fetal red blood cells enter the maternal system because of small areas of bleeding at the
surface of placental villi or at birth

A

Rh antigen

59
Q

Main functions of the placenta are
(1) ___ between maternal and fetal bloodstream
(2) ____

A

exchange of metabolic and gaseous products - production of hormones

59
Q

Immunological competence begins to develop late in the first trimester, by which time the fetus makes all of the components of ___

A

complement

60
Q

Immunoglobulins consist almost entirely of ___, which begins to be transported from mother to fetus at approximately 14 weeks

A

maternal immunoglobulin G (IgG)

61
Q

By the end of the fourth month, the placenta produces ___ in sufficient amounts to maintain pregnancy if the corpus luteum is removed or fails to function properly

A

progesterone

62
Q

Even more dangerous was the use of the synthetic estrogen ____, which easily crosses the placenta. 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

A

diethylstilbestrol [DES]

63
Q

In addition to progesterone, the placenta produces increasing amounts of ___, predominantly ___, until just before the end of pregnancy, when a maximum level is reached

A

estrogenic hormones - estriol

64
Q

During the first 2 months of pregnancy, the syncytiotrophoblast also produces ___, which maintains the corpus luteum. This hormone is excreted by the mother in the urine, and in the early stages of gestation, its presence is used as an indicator of pregnancy

A

human chorionic gonadotropin (hCG)

65
Q

Another hormone produced by the placenta is __ (formerly placental lactogen)

A

somatomammotropin

66
Q

Another hormone produced by the placenta is somatomammotropin (formerly ___)

A

placental lactogen

67
Q

The oval line of reflection between the amnion and embryonic ectoderm (___) is the primitive umbilical ring

A

amnio-ectodermal junction

68
Q

The oval line of reflection between the amnion and embryonic ectoderm (amnio-ectodermal junction) is the ____

A

primitive umbilical ring

69
Q

At the fifth week of development, the following structures pass through the ring:
(1) the ____, containing the allantois and the umbilical vessels, consisting of two arteries and one vein
(2) the ___, accompanied by the vitelline
vessels
(3) the ___ and ____

A

connecting stalk - yolk stalk (Vitelline duct) - canal connecting the intraembryonic and extraembryonic

70
Q

The yolk sac proper occupies a space in the ___, that is, the space between the amnion and chorionic plate

A

chorionic cavity

71
Q

The abdominal cavity is temporarily too small for the rapidly developing intestinal loops, and some of them are pushed into the extraembryonic space in the umbilical cord. These extruding intestinal loops form a ____

A

physiological umbilical hernia

71
Q

During further development, the amniotic cavity enlarges rapidly at the expense of
the chorionic cavity, and the amnion begins to envelop the connecting and yolk sac stalks, crowding them together and giving rise to the ____

A

primitive umbilical cord

72
Q

When the allantois and the vitelline duct and its vessels are also obliterated, all that remains in the cord are the umbilical vessels surrounded by ___

A

Wharton jelly

73
Q

At birth, the umbilical cord is approximately 1 to 2 cm in diameter and 50 to 60 cm long. It is tortuous, causing ___

A

false knots

74
Q

Normally, there are two arteries and one
vein in the umbilical cord. In 1 in 200 newborns, however, only a ___ is present, and these babies have approximately 20% chance of having cardiac and other vascular defects

A

single umbilical artery

75
Q

Occasionally, tears in the amnion result in
____ that may encircle part of the fetus, particularly the limbs and digits. Amputations, ____, and other abnormalities, including craniofacial deformations, may result

A

amniotic bands - ring constrictions

76
Q

____ is the term used to describe an excess of amniotic fluid [1,500 to 2,000 mL], whereas ____ refers to a decreased amount [<400 mL]

A

Hydramnios or polyhydramnios - oligohydramnios

77
Q

_____ refers to rupture of the membranes before uterine contractions begin and occurs in 10% of pregnancies

A

Premature rupture of the membranes [PROM]

78
Q

___ PROM occurs before 37 completed weeks of pregnancy, occurs in 3% of pregnancies, and is a common cause of preterm labor

A

Preterm

79
Q

Approximately 90% of twins are ___ or ___, and their incidence increases with maternal age (doubling at age 35 years) and with fertility procedures, including ART

A

dizygotic, or fraternal

80
Q

____ is produced by uterine contractions that force the amniotic sac against the cervical canal like a wedge, or if the membranes have ruptured, then pressure will be exerted by the presenting part of the fetus, usually the head

A

Stage 1

80
Q

Occasionally, each dizygotic twin possesses red blood cells of two different types (___), indicating that fusion of the two placentas was so intimate that red cells were exchanged

A

erythrocyte mosaicism

81
Q

The second type of twins, which develops from a single fertilized ovum, is ___ or ___ twins

A

monozygotic or identical

82
Q

For the first 34 to 38 weeks of gestation, the uterine myometrium does not respond to signals for ___

A

parturition (birth)

83
Q

During the last 2 to 4 weeks of pregnancy, however, this tissue undergoes a transitional phase in preparation for the onset of ___

A

labor

84
Q

Labor itself is divided into three stages:
(1) ____ (thinning and shortening) and dilatation of the cervix (this stage ends when the cervix is fully dilated)
(2) ____
(3) ____

A

effacement - delivery of the fetus - delivery of the placenta and fetal membranes

85
Q

___ is also assisted by uterine contractions, but the most important force is provided by increased intra-abdominal pressure from contraction of abdominal muscles

A

Stage 2

86
Q

___ requires uterine contractions and is aided by increasing intra-abdominal pressure

A

Stage 3

87
Q

Factors initiating labor are not known and may involve “______,” in which pregnancy-supporting factors [e.g., hormones] are withdrawn, or active induction caused by stimulatory factors targeting the uterus

A

retreat from maintenance of pregnancy

88
Q

The term ___ 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

A

vanishing twin

89
Q

Factors initiating labor are not known and may involve “retreat from maintenance of pregnancy,” in which pregnancy supporting factors [e.g., hormones] are withdrawn, or ____ caused by stimulatory factors targeting the uterus

A

active induction

90
Q

Preterm birth [delivery before 37 completed weeks] of ____ occurs in approximately 12% of births in the United States and is a leading cause of infant mortality and also contributes significantly to morbidity

A

premature infants

90
Q

Unfortunately, a lack of knowledge about these factors has restricted progress in preventing ___

A

preterm birth

91
Q

The umbilical cord, surrounded by the
amnion contains
(1) ____
(2) ____
(3) ___, which serves as a protective cushion for the vessels

A

two umbilical arteries - one umbilical vein -Wharton jelly

92
Q

The placenta consists of two components:
(1) a fetal portion, derived from the ___ or villous chorion
(2) a maternal portion, derived from the ____.
The space between the chorionic and decidual plates is filled with ___ of maternal blood

A

chorion frondosum - decidua basalis - intervillous lakes

93
Q

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
- Which of the ff are false?

A

None. All are true

Embryology (21 decks)

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