Embryology (Part 1) Flashcards Preview

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Flashcards in Embryology (Part 1) Deck (171)
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1
Q

During embryonic development, what event occurs on day six?

A

Implantation in the uterine wall

2
Q

What is the gene that is expressed at the base of limbs in a zone of polarizing activity?

A

Sonic hedgehog (SHH) gene

3
Q

The sonic hedgehog gene regulates patterning along the _____ (anterior-posterior or cranial-caudal) axis.

A

anterior-posterior

4
Q

Name 2 genes expressed at the apical ectodermal ridge (the thickened ectoderm at the distal end of each developing limb).

A

Wnt-7 and FGF

5
Q

What is the gene responsible for proper organization along the dorsal-ventral axis?

A

Wnt-7

6
Q

What gene is responsible for the lengthening of limbs?

A

FGF

7
Q

Which embryonic layer responds to products of the FGF gene?

A

The mesoderm

8
Q

How does the FGF gene cause limbs to lengthen?

A

It stimulates mitosis of the underlying mesoderm

9
Q

What phenotype would be seen if there was a mutation in the homeobox gene?

A

There would be defects in segmental organization

10
Q

Day 0 of fetal life is marked by the _____ of an ovum by a sperm.

A

Fertilization

11
Q

What is formed when a sperm fertilizes an ovum?

A

The zygote

12
Q

At what stage of fetal development does implantation occur?

A

The blastocyst stage

13
Q

The embryo exists as a _____ disk during the second week of development.

A

Bilaminar

14
Q

What two layers make up the bilaminar disk?

A

The epiblast and the hypoblast

15
Q

During fetal development, the process of _____ occurs during the third week, which gives rise to a trilaminar disk.

A

Gastrulation

16
Q

If an embryo has a notochord and the neural plate is beginning to form, how many weeks old is the embryo?

A

3 weeks old

17
Q

If an embryo has a primitive streak, how many weeks old is the embryo?

A

3 weeks old

18
Q

During what part of embryonic development does organogenesis occur?

A

Weeks 3-8

19
Q

In an embryo, the neural tube forms from a neural plate between which days?

A

Days 18-21

20
Q

The embryo is most susceptible to teratogens during what time period?

A

Weeks 3-8

21
Q

During what week of development does the heart of an embryo begin to beat?

A

Week 4

22
Q

During what week of embryonic development do the upper and lower limb buds begin to form?

A

Week 4

23
Q

When is the first time the fetus begins to move and looks like a baby?

A

Week 8

24
Q

During what week of development do embryos first have genitalia with either male or female characteristics?

A

Week 10

25
Q

During embryonic development, what stage begins on day 2?

A

The zygote stage (2 haploid cells form a single diploid cell)

26
Q

During embryonic development, what stage begins on day 3?

A

The morula stage (morula is latin for mulberry and occurs after the 16-cell stage)

27
Q

During embryonic development, what stage begins on day 5?

A

The blastocyst stage (containing an outer layer of cells and an inner cell mass)

28
Q

During embryonic development, what event occurs on day 6?

A

Implantation

29
Q

What embryonic structure implants itself into the uterine wall on day 6?

A

The blastocyst

30
Q

After the primitive streak, name three structures formed by neural precursor tissue.

A

Neural plate, neural crest, and neural tube

31
Q

The alar plate is on the _____ side of the neural tube, while the basal plate is on the _____ side.

A

dorsal; ventral

32
Q

What is the function of the neurons derived from the alar plate?

A

Sensory

33
Q

What is the function of the neurons derived from the basal plate?

A

Motor

34
Q

What are the two cell layers that are present during the second week of embryonic development?

A

The epiblast and the hypoblast (remember: 2 germ layers at 2 weeks)

35
Q

What are the two cavities that are present during the second week of embryonic development?

A

The amniotic sac and the yolk sac (remember: 2 cavities at 2 weeks)

36
Q

What are the two components of the placenta that are present during the second week of development?

A

The cytotrophoblast and the syncytiotrophoblast (remember: 2 components of the placenta at 2 weeks)

37
Q

What three cell layers are present during the third week of embryonic development?

A

Ectoderm, mesoderm, and endoderm (remember: 3 germ layers at 3 weeks)

38
Q

When is the earliest you expect to see four heart chambers?

A

At 4 weeks (remember: 4 heart chambers at 4 weeks)

39
Q

When do the four limb buds appear?

A

At 4 weeks (remember: 4 limb buds at 4 weeks)

40
Q

An embryo with three germ cell layers is known as a _____.

A

Gastrula

41
Q

During fetal development, what cell layer of the bilaminar disk gives rise to the ectoderm?

A

The epiblast

42
Q

During fetal development, the _____ of the bilaminar disc invaginates during the process of gastrulation to form the _____ _____.

A

Epiblast; primitive streak

43
Q

Name two germ layers that arise from cells of the primitive streak.

A

Endoderm and mesoderm

44
Q

During fetal development, the adenohypophysis is derived from the _____ _____, and the neurohypophysis is derived from the _____.

A

Surface ectoderm; neuroectoderm

45
Q

During fetal development, what germ layer gives rise to the lens of the eye?

A

The surface ectoderm

46
Q

What germ cell layer gives rise to the cells in the retina?

A

The neuroectoderm

47
Q

During fetal development, _____ typically forms the CNS and brain, while _____ typically forms the PNS and non-neural structures nearby.

A

neuroectoderm; neural crest cells

48
Q

During fetal development, what germ layer gives rise to the epithelial linings of the oral cavity, eye, ear and nose, and to the epidermis?

A

The surface ectoderm

49
Q

What germ cell layer gives rise to salivary, sweat, and mammary glands?

A

The surface ectoderm

50
Q

During fetal development, what germ layer gives rise to central nervous system neurons?

A

The neuroectoderm

51
Q

During fetal development, the supporting cells of the central nervous system (the oligodendrocytes, the astrocytes, and the ependymal cells) are all derived from the _____, except for the microglia, which arise from the _____.

A

Neuroectoderm; mesoderm

52
Q

During fetal development, what germ cell layer gives rise to the pineal gland?

A

The neuroectoderm

53
Q

What cell type ultimately gives rise to the autonomic nervous system?

A

The neural crest cells

54
Q

During fetal development, the dorsal root ganglia are derived from _____.

A

Neural crest cells

55
Q

During fetal development, central nervous system neurons are derived from the _____, whereas the cranial nerves are derived from _____.

A

neuroectoderm; neural crest cells

56
Q

During fetal development, central nervous system neurons arise from the _____, whereas autonomic nervous system neurons arise from _____.

A

neuroectoderm; neural crest cells

57
Q

During fetal development, epidermal cells are derived from the _____, whereas melanocytes are derived from _____.

A

ectoderm; neural crest cells

58
Q

During fetal development, the chromaffin cells of the adrenal medulla are derived from the _____, and the adrenal cortex is derived from the _____.

A

neural crest cells; mesoderm

59
Q

During fetal development, the pia and arachnoid are derived from the _____, whereas the dura mater is derived from the _____.

A

neural crest cells; mesoderm

60
Q

During fetal development, the celiac ganglia are derived from the _____.

A

neural crest cells

61
Q

During fetal development, Schwann cells are derived from the _____, whereas oligodendrocytes are derived from the _____.

A

neural crest cells; neuroectoderm

62
Q

During fetal development, odontoblasts are derived from the _____.

A

Neural crest cells (remember: odonto = teeth; think Crest toothpaste)

63
Q

During fetal development, the follicular cells of the thyroid are derived from _____, whereas the parafollicular cells (C cells) are derived from the _____.

A

endoderm; neural crest cells

64
Q

During fetal development, cartilage is generally derived from the _____, except for the laryngeal cartilage, which arises from the _____.

A

mesoderm; neural crest cells

65
Q

During fetal development, bones are generally derived from the _____, except for the bones of the skull, which arise from the _____.

A

mesoderm; neural crest cells

66
Q

During fetal development, what germ layer gives rise to the muscle?

A

The mesoderm

67
Q

During fetal development, what germ cell layer gives rise to the heart?

A

The mesoderm

68
Q

During fetal development, what germ cell layer gives rise to the blood vessels?

A

The mesoderm

69
Q

During fetal development, what germ cell layer gives rise to the lymphatics?

A

The mesoderm

70
Q

During fetal development, what germ cell layer gives rise to the cellular elements of the blood?

A

The mesoderm

71
Q

During fetal development, what germ cell layer gives rise to the urogenital structures?

A

The mesoderm

72
Q

During fetal development, what germ cell layer gives rise to the serous linings of body cavities, such as the peritoneal membranes?

A

The mesoderm

73
Q

During fetal development, the kidney arises from what germ cell layer?

A

The mesoderm

74
Q

During fetal development, the spleen arises from what germ cell layer?

A

The mesoderm, from the foregut mesentery

75
Q

During fetal development, what germ cell layer gives rise to the gastrointestinal tract epithelium?

A

The endoderm

76
Q

During fetal development, what germ cell layer gives rise to the lung epithelium?

A

The endoderm

77
Q

During fetal development, what germ cell layer gives rise to the pancreas?

A

The endoderm

78
Q

During fetal development, what germ cell layer gives rise to the thymus?

A

The endoderm

79
Q

During fetal development, the follicular cells of the thyroid are derived from the _____, the parafollicular (C) cells are derived from the _____, and the cells of the parathyroid are derived from the _____.

A

endoderm; neural crest cells, endoderm

80
Q

During fetal development, the notochord induces the formation of what other germ cell layer?

A

The neuroectoderm

81
Q

What germ cell layer is the notochord derived from?

A

The mesoderm

82
Q

What structure in the adult body is derived from the notochord?

A

The nucleus pulposus of the intervertebral disk

83
Q

An infant is born with a truncus arteriosus malformation; what germ layer is normally responsible for the aorticopulmonary septum?

A

Neural crest cells

84
Q

An infant is born with vertebral defects, anal atresia, and limb defects; what internal organ systems are you concerned about?

A

Cardiac, renal, and tracheoesophageal defects (remember VACTERL: Vertebral defects, Anal atresia, Cardiac defects, Tracheo-Esophageal fistula, Renal defects, Limb defects)

85
Q

What are common abnormalities seen in a neonate with defects in embryogenesis involving the mesodermal germ layer?

A

VACTERL: Vertebral defects, Anal atresia, Cardiac defects, Tracheo-Esophageal fistula, Renal defects, Limb defects

86
Q

A 2-week-old embryo is exposed to a teratogen; what is the likely effect on development?

A

Before week 3 there is usually an all-or-none effect: either embryonal demise or no abnormalities

87
Q

What embryonic process is occuring when the fetus is most susceptible to teratogens?

A

Organogenesis, between the 3rd and 8th weeks of pregnancy

88
Q

A fetus is exposed to a teratogen after 8 weeks of pregnancy; will organogenesis be affected?

A

No; typically after 8 weeks, growth and function are affected but not organogenesis

89
Q

What teratogen is the leading cause of mental retardation in children?

A

Alcohol

90
Q

True or False: Alcohol can cause birth defects and mental retardation in children, and it produces fetal alcohol syndrome.

A

TRUE

91
Q

Angiotensin-converting enzyme inhibitors can lead to damage of what organ in the fetus?

A

The kidney

92
Q

True or False: Maternal cocaine use can result in fetal addiction.

A

TRUE

93
Q

What placental pathology are cocaine-using mothers susceptible to?

A

Placental abruption

94
Q

Exposure to diethylstilbestrol in utero leads to an increased incidence of what type of cancer?

A

Vaginal clear cell adenocarcinoma

95
Q

A young woman is diagnosed with clear cell carcinoma of the vagina. This cancer is associated with exposure to what teratogen in utero?

A

Diethylstilbestrol

96
Q

Name 2 teratogenic effects of iodine deficiency or excess in utero.

A

Congenital goiter or hypothyroidism

97
Q

What birth defects might result if the acne treatment 13-cis-retinoic acid is taken during pregnancy?

A

Spontaneous abortions, cleft palate, cardiac abnormalities

98
Q

What teratogen is known for causing limb defects that are known as "flipper" limbs?

A

Thalidomide; the defect is known as phocomelia

99
Q

True or False: Tobacco use during pregnancy is associated with preterm labor.

A

TRUE

100
Q

True or False: Tobacco use during pregnancy has no effect on the placenta during development.

A

False; tobacco is associated with placental problems such as IUGR

101
Q

True or False: Tobacco use during pregnancy is associated with attention-deficit/hyperactivity disorder in children.

A

TRUE

102
Q

Which is a better choice for a woman who needs anticoagulation during pregnancy: heparin or warfarin?

A

Heparin; warfarin use during pregnancy is associated with bone deformities, fetal hemorrhage, and abortion

103
Q

True or False: X-rays can cause multiple anomalies in the offspring of women who are irradiated during pregnancy.

A

TRUE

104
Q

An infant is born with discolored teeth; what was the fetus exposed to in utero?

A

Tetracyclines

105
Q

A woman undergoes chemotherapy with alkylating agents during her pregnancy; what fetal abnormalities are you concerned about?

A

Multiple anomalies, including absence of digits

106
Q

What should you be sure to test for in an infant exposed to aminoglycosides in utero?

A

Deafness; aminoglycosides can cause CN VIII toxicity

107
Q

What birth defect might result if the mother is taking valproic acid?

A

Valproic acid is a folate antagonist, which may cause neural tube defects

108
Q

True or False: Infection and certain antibiotics during pregnancy can produce congenital malformations.

A

TRUE

109
Q

What is the leading cause of congenital malformations in the United States?

A

Fetal alcohol syndrome

110
Q

True or False: Newborns of mothers who consumed significant amounts of alcohol during pregnancy have an increased incidence of congenital abnormalities.

A

TRUE

111
Q

What teratogen is commonly associated with microcephaly, facial abnormalities, limb dislocation, and heart and lung fistulas?

A

Fetal alcohol syndrome

112
Q

True or False: Fetal alcohol syndrome is associated with an increased incidence of deafness.

A

False; fetal alcohol syndrome is associated with developmental retardation, microcephaly, holoprosencephaly, facial abnormalities, limb dislocations, and heart and lung fistulas

113
Q

What is a possible mechanism of congenital malformation in fetal alcohol syndrome?

A

There may be an inhibition of cell migration

114
Q

On what day of fetal development is the amnion formed?

A

Day 8

115
Q

On what day of fetal development is the chorion formed?

A

Day 3

116
Q

If twinning occurs before 3 days, what is the amniotic and chorionic status of the gestation?

A

The twins will be dichorionic and diamniotic

117
Q

If twinning occurs between day 3 and day 8, what is the amniotic and chorionic status of the gestation?

A

The twins will be monochorionic and diamniotic

118
Q

If twinning occurs after day 8, what is the amniotic and chorionic status of the gestation?

A

The twins will be monochorionic and monoamniotic

119
Q

At which point is the risk greatest for conjoined twins: if twinning occurs before 3 days, between 3 and 8 days, or after 8 days?

A

After day 8 there is an increased risk for conjoined twins

120
Q

How many chorions and amniotic sacs do conjoined twins have?

A

1 chorion and 1 amniotic sac

121
Q

True or False: Twins who are born with two amniotic sacs but a single common chorion and placenta are always monozygotic twins.

A

True; one zygote split evenly and formed all of the structures listed

122
Q

True or False: Twins who are born with two placentas (which may or may not be fused), separate chorions, and separate amniotic sacs are always dizygotic twins.

A

False; monozygotic twins may also form two placentas, two chorions, and two amniotic sacs

123
Q

True or False: The placenta is the primary site of nutrient and gas exchange between mother and fetus.

A

TRUE

124
Q

The fetal component of the placenta consists of which two cell types?

A

Cytotrophoblast; syncytiotrophoblast

125
Q

The cytotrophoblast composes what layer of the chorionic villi?

A

Inner

126
Q

The syncytiotrophoblast composes what layer of the chorionic villi?

A

Outer

127
Q

Which layer of the chorionic villi secretes human chorionic gonadotropin?

A

Outer layer (the syncytiotrophoblast)

128
Q

What placental cell type secrete hCG?

A

Syncytiotrophoblast

129
Q

Is the decidua basalis derived from the maternal or fetal component of the placenta?

A

Maternal

130
Q

True or False: The decidua basalis is derived from the endometrium.

A

TRUE

131
Q

True or False: Blood from fetal capillaries in the branch villus is oxygenated directly by maternal capillaries.

A

False; the fetal branch villus is oxygenated by pooled maternal blood within lacunae of the decidua basalis

132
Q

The umbilical cord contains how many umbilical arteries and umbilical veins?

A

Two arteries and one vein

133
Q

Do the umbilical arteries carry oxygenated or deoxygenated blood?

A

Deoxygenated blood

134
Q

The umbilical arteries return blood to the placenta via which fetal vessels?

A

The fetal internal iliac arteries

135
Q

Does the umbilical vein carry oxygenated or deoxygenated blood?

A

Oxygenated blood

136
Q

The _____ functions to remove nitrogenous waste from the fetal bladder.

A

urachus

137
Q

True or False: A single umbilical artery is associated with congenital and chromosomal anomalies.

A

TRUE

138
Q

What connects the fetal bladder with the allantois?

A

The urachus

139
Q

What fetal structure removes nitrogenous waste, like a urethra?

A

The urachus

140
Q

From what fetal structure are the umbilical arteries and veins derived?

A

The allantois

141
Q

What is the term for a fistula between the umbilicus and terminal ileum?

A

Vitelline fistula

142
Q

What is the term for a fistula between the umbilicus and the bladder?

A

Urachal fistula

143
Q

A ______ (vitelline/urachal) fistula results in fecal discharge.

A

vitelline

144
Q

A ______ (vitelline/urachal) fistula results in urinary discharge.

A

urachal

145
Q

In the embryonic heart, the truncus arteriosus gives rise to what two vessels?

A

Ascending aorta and pulmonary trunk

146
Q

What embryonic structure gives rise to the ascending aorta?

A

The truncus arteriosus

147
Q

What embryonic structure gives rise to the pulmonary trunk?

A

The truncus arteriosus

148
Q

In the embryonic heart, the bulbus cordis gives rise to the _____ (smooth/trabeculated) part of ______ (right/left/both) ventricle(s).

A

Smooth; both

149
Q

In the embryonic heart, the primitive ventricle gives rise to the _____ (smooth/trabeculated) part of ______ (right/left/both) ventricle(s).

A

Trabeculated; both

150
Q

In the embryonic heart, the smooth part of the ventricles is derived from the ______, whereas the trabeculated part is derived from the _____.

A

Bulbus cordis; primitive ventricle

151
Q

In the embryonic heart, the primitive atria give rise to the _____ (smooth/trabeculated) part of the ______ (right/left/both) atrium(a).

A

Trabeculated; both

152
Q

In the embryonic heart, the left horn of the sinus venosus gives rise to what structure?

A

The coronary sinus

153
Q

In the embryonic heart, the coronary sinus is derived from what structure?

A

The left horn of the sinus venosus

154
Q

In the embryonic heart, the right horn of the sinus venosus gives rise to what structure?

A

The smooth part of the right atrium

155
Q

In the embryonic heart, the smooth part of the right atrium is derived from what structure?

A

The right horn of the sinus venosus

156
Q

In the embryonic heart, the trabeculated part of the right atrium is derived from the _____, and the smooth part of the right atrium is derived from the _____.

A

primitive atria; right horn of the sinus venosus

157
Q

In the embryonic heart, the right common cardinal vein and the right anterior cardinal vein jointly give rise to what vein in the adult?

A

The superior vena cava

158
Q

What is the opening called in the early muscular ventricular septum?

A

The interventricular foramen

159
Q

_____ divides the truncus arteriosus into the aortic and pulmonary trunks.

A

The aorticopulmonary septum

160
Q

The aorticopulmonary septum meets and fuses with the muscular ventricular septum to form the _____.

A

membranous interventricular septum

161
Q

______ forms to close the interventricular foramen and separate the two ventricles.

A

The membranous interventricular septum

162
Q

What two components make up the interventricular septum?

A

The muscular septum and the membranous septum

163
Q

During development of the interatrial septum, the _____ narrows as the septum primum grows toward the endocardial cushion.

A

Foramen primum

164
Q

During development of the interatrial septum, perforations in the septum primum form the ______ as the foramen primum disappears.

A

Foramen secundum

165
Q

During development of the interatrial septum, the _____ maintains the right-to-left shunt as the septum secundum begins to grow.

A

Foramen secundum

166
Q

What is the direction of the shunt maintained by the foramen secundum?

A

Right-to-left

167
Q

During development of the interatrial septum, what is the name of the opening in the septum secundum that is patent throughout fetal life?

A

Foramen ovale

168
Q

During development of the interatrial septum, as the ______ enlarges, the upper part of the septum primum degenerates.

A

Foramen secundum

169
Q

Near the end of fetal heart development, the remaining portion of the septum primum is called the valve of the ______.

A

Foramen ovale

170
Q

Near the end of fetal heart development, what composes the valve of the foramen ovale?

A

The remaining portion of the septum primum

171
Q

In the diagram, identify the three types of spinal neural tube defects: (A), (B), and (C).

A

(A) spina bifida occulta; (B) meningocele; (C) myelomeningocele