Embryology Flashcards
1
Q
What are the main events during Weeks 1-2 of fetal development
A
Fertilization
Implantation in endometrium of uterus
Formation of two layers
Development of primitive streak
2
Q
What are the main events during Weeks 3-8 (Embryonic Period) of fetal development
A
Formation of three layers
Beginning of development of all organs and body parts (Organogenesis)
3
Q
What are the main events during weeks 9-38 (Fetal Period) of fetal development
A
Growth and maturation of organs and body parts
4
Q
One cell divides and gives
rise to two genetically
identical daughter cells,
each with the same 46
chromosomes as the
mother cell
A
Mitosis
5
Q
____ only occurs in the germ
cells and gametes are
formed through this
process, which results in
four genetically different
haploid cells ensuring
genetic diversity.
A
Meiosis
6
Q
Spermatogenesis Diagram
A
7
Q
Oogenesis Diagram
A
8
Q
What is the most likely location of abnormal implantation?
A
Ampulla of the fallopian tube
9
Q
The egg is released from where before it enters the fallopian tube?
A
Ovarian Follicle
10
Q
What propels the ova down the fallopian tube toward the uterus?
A
The movement of cilia
11
Q
Process in which a sperm combines with an ovum to produce a zygote
A
Fertilization
12
Q
What is the glycoprotein later; defense against multiple sperm penetration
A
Zona Pellucida
13
Q
biochemical change in outer layer of sperm that allows it to be successfully fertilized in the egg
A
Sperm Capacitation
14
Q
After Fertilization, a _ develops on day 4, a _ on day 5, and the Blastocyst implants on day _
A
After Fertilization, a **Morula develops on day 4, a *Blastocyst on day 5, and the Blastocyst implants on day *6-10
15
Q
The _ is the dorsal layer of the Bilaminar disc and forms the _
A
The Epiblast is the dorsal layer of the Bilaminar disc and forms the Entire Embryo
16
Q
The _ is the ventral layer of the Bilaminar disc and forms the _
A
The Hypoblast is the ventral layer of the Bilaminar disc and forms the yolk sac lining
17
Q
During which prenatal period would exposure to a
teratogenic drug, such as the antiepileptic
phenytoin, have the most profound effect on
development?
A
Weeks 3-8
18
Q
When does Gastrulation occur and what occurs?
A
Week 3
Bilaminar disc trnasforms into a tilaminar disc
Organogenesis
19
Q
What are the three layers in the Trilaminar disc?
A
Ectoderm
Mesoderm
Endoderm
20
Q
What are the Surface Ectoderm Derivatives
A
- Epidermis and epidermal appendages
- Mammary Glands
- Adenohypophysis
- Parotid Gland
- Olfactory Epithelium
- Sensory organs of the inner ear
- Lens of the eye
- Anal canal below Pectinate Line
- Ameloblasts and tooth enamel
21
Q
What are some Neuroectoderm Derivatives?
A
- Brain and Spinal Cord
- Somatic Motor Nerves
- Preganglionic Autonomic Nerves
- Neuroglia
- Neurohypophysis
- Retina
22
Q
What are some Neural Crest Derivatives?
A
- Somatic Sensory Nerves
- Somatic and Autonomic Ganglia
- Postganglionic Autonomic Nerves
- Schwan Cells and Satellite Cells
- Pia Mater and Arachnoid Mater
- Adrenal Medulla
- Melanocytes of Skin
- Some head and neck connective tissue, dermism and bones
- Aorticopulmonary Septum
- Odontoblasts and Dentin
23
Q
_ is composed of epiblast cells that migrate up and sandwiched between overlying ectoderm and underlying endoderm
A
Mesoderm is composed of epiblast cells that migrate up and sandwiched between overlying ectoderm and underlying endoderm
24
Q
The _ forms muscle, blood cells, most connective tissue, dermis, cartilage, bone, and notochord
A
The mesoderm forms muscle, blood cells, most connective tissue, dermis, cartilage, bone, and notochord
25
Mesoderm defects can be remembered as
VACTERL
Vertebral defects
Anal atresia
Cardiac defects
Tracheo-Esophageal fistula
Renal defects
Limb defects
26
A premature infant has trouble breathing. The
clinician has found that the lining of the infant’s
alveoli does not produce enough surfactant to
allow for normal breathing. Which of the following
structures is derived from the same germ layer as
the respiratory lining cells that produce surfactant?
A. Epithelial lining of the stomach
B. Melanocytes
C. Retina
D. Spinal cord
E. Sternum
A. Epithelial lining of the stomach
27
_ is composed of epiblast cells that migrate and completely displace the hypoblast
**Endoderm** is composed of epiblast cells that migrate and completely displace the hypoblast
28
What linings, glands, and structures are formed by the endoderm?
29
What occurs during the Embryonic Period?
Organs and body parts continue to develop; Near complettion of the exterior body and early stages of all organ systems
30
Folding occurs during week 4, what does that look like?
The cranial end folds ventrally, the caudal end folds ventrally, and the lateral sides fold ventrally -> 3D trunk -> Limb buds
Gastrointestinal, respiratory, genitourinary, and cardiovascular system start to develop; **heart starts to beat**
31
What occurs during the Fetal Period
Organs and body parts continue to develop -> Near completion of theexterior body and early stages of all organ systems
32
What are four iimportant genes of Embryogenesis
* Sonic Hedghog (SHH)
* Wnt-7
* Fibroblast Growth Factor
* Homeobox (Hox)
33
Sonic Hedgehog gene location and function
Location: Zone of polarizing activity at base of limb buds
Function: Anterior-posterior axis patterning, CNS development
34
Wnt-7 Gene location and Function
Location: Apical ectodermal ridge at the distal end of end limb
Function: Dosral-ventral axis patterning limb development
35
Fibroblast growth factor gene location and function
Location: Apical ectodermal ridge
Function: Limb lengthening (via mitosis of mesoderm)
36
Homeobox gene location and function
Location: Multiple places
Function: Segmental organization in cranial-caudal direction, transcription factor coding
37
What do Transcription factors do in embryogenesis
Regulate which genes are activated or repressed
38
What does intracellular communcation do during embryogenesis
Interaction of a cell with a neighbor cell
39
What do diffuse signals do during embryogenesis
* Help direct migration of cells
* Determine differentiation of a cell at a specific location
40
What do cell receptors do during embryogenesis
Groth factors bind to these and regulate mitosis, apoptosis, migration, etc.
41
The failure of what pharyngeal structure to develop
results in T-cell deficiency?
Pharyngeal pouch 3
42
What is the Pharyngeal Apparatus
Embryonic structures that give rise to the lower 2/3rds of the face, ears, neck, and some lymphoid and endocrine structures
43
What does the pharyngeal apparatus consist of?
* Five pharyngeal arches
* Four pharyngeal clefts
* Four pharyngeal pouches
* Four pharyngeal membranes
44
When do the pharyngeal arches begin to develop?
Week 4
45
What are the components that make up the pharyngeal arches?
* Neural Crest
* Mesoderm
* Cranial Nerves
* Artery
46
1st pharyngeal arch nerve, skeletal elements, and muscles
Nerve: CN V
Skeletal Elements:
* Maxilla
* Zygomatic
* Squamous portion of temporal bone
* Mandible
* Meckel cartilage:
* Malleus
* Incus
* Anterior ligament of malleus
* Sphenomandibular ligament
Muscles:
* Muscles of mastication
* (temporalis, masseter, lateral and medial pterygoids)
* Mylohyoid
* Anterior belly of digastric
* Tensor tympani
* Tensor veli palatini
47
2nd pharyngeal arch nerve, skeletal elements, and muscles
Nerve: CN VII
Skeletal Elements:
* Reichert cartilage:
* Stapes
* Styloid process
* Stylohyoid ligament
* Lesser horn and upper body of hyoid
Muscles:
* Muscles of facial expression (buccinator, auricularis, frontalis, platysma, orbicularis oris, orbicularis oculi, etc)
* Stapedius
* Stylohyoid
* Posterior belly of digastric
48
3rd pharyngeal arch nerve, skeletal elements, and muscles
Nerve: CN IX
Skeletal Elements: Greater horn and lower body of hyoid
Muscle: Stylopharyngeus
49
4th pharyngeal arch nerve, skeletal elements, and muscles
Nerve: CN X (superior laryngeal nerve)
Skeletal Elements:
* Thyroid cartilage
* Cricoid
* Corniculate
* Cuneiform
* Arytenoids
Muscles:
* Pharyngeal constrictors
* Cricothyroid
* Levator veli palatine
50
6th pharyngeal arch nerve, skeletal elements, and muscles
Nerve: CN X (recurrent laryngeal nerve)
Skeletal Elements:
* Thyroid cartilage
* Cricoid
* Corniculate
* Cuneiform
* Arytenoids
Muscles: All intrinsic muscles of larynx (except cricothyroid)
51
Ear Derivation from Pharyngeal Arches
52
A mobile circumscribed mass is felt at the angle of
the mandible of an 8-year-old girl. The mass is
less than 1 cm and nontender. All laboratory
workups are normal, and the patient does not
have any other symptoms. The mass is most likely
to be which of the following?
A. Branchial (pharyngeal) cleft cyst
B. Thymus
C. Thyroglossal duct
D. Thyroglossal duct cyst
E. Thyroid gland
A. Branchial (pharyngeal) cleft cyst
53
What are the pharyngeal clefts?
Four, ectoderm-covered exterior recesses between neighboring arches
54
Where is the 1st pharyngeal cleft?
External auditory meatus
55
Where are the 2-4th pharyngeal clefts?
Temporary cervical sinuses
56
What are Pharyngeal pouches?
Four, endoderm-lined invaginations of the pharyna between neighboring arches
57
The _ pharyngeal puch derivative are the middle ear (tympanic) cavity, eustachian tube, mastoid air cells
The **1st** pharyngeal puch derivative are the middle ear (tympanic) cavity, eustachian tube, mastoid air cells
58
The _ pharyngeal pouch derivative is palantine tonsils
The **2nd** pharyngeal pouch derivative is palantine tonsils
59
The _ pharyngeal pouch derivatives are inferior parathyroids and Thymus
The **3rd** pharyngeal pouch derivatives are inferior parathyroids and Thymus
60
The _ pharyngeal pouch derivatives are superior parathyroids and ultimobranchial body --> parafollicular (C) cells of thyroid
The **4th** pharyngeal pouch derivatives are superior parathyroids and ultimobranchial body --> parafollicular (C) cells of thyroid
61
What are the pharyngeal membranes?
Sites in the clefts and pouches where the cleft ectoderm and pouch endoderm meet
62
Which pharyngeal membrane develops?
1st; Develops tympanic membrane
63
What happens to the remaining three pharyngeal membranes?
2-4 pharyngeal membranes are obliterated when the second arch overgrows thr more caudal pharyngeal clefts
64
What is a thyroid duct cyst?
A thyroglossal duct cyst is a common congenita anomaly that arises when the thyroglossal duct does not completely atrophy. It is an anterior, midline, painless, mobile neck
mass, often near the hyoid bone, and it elevates with
tongue protrusion
65
Which Aortic arch is responsible for the formation of the ductus arteriosus?
sixth
66
On the left or right side of the aorta is there a branchiocephalic trunk
Right
67
The _ loops around the right subclavian artery
The **right recurrent laryngeal nerve** loops around the right subclavian artery
68
The _ loops around the aortic arch distal to ductus arteriosus
The **left recurrent laryngeal nerve** loops around the aortic arch distal to ductus arteriosus
69
Aortic Arch _ branches
Right: Maxillary Artery
Left: Maxillary Artery
Aortic Arch **1** branches
Right: Maxillary Artery
Left: Maxillary Artery
70
Aortic Arch _ branches
Right: Stapedial Artery
Left: Stapedial Artery
Aortic Arch **2** branches
Right: Stapedial Artery
Left: Stapedial Artery
71
Aortic Arch _ branches
Right: Common Carotid Artery and first part of the internal carotid artery
Left: Common Carotid Artery and first part of the internal carotid artery
Aortic Arch **3** branches
Right: Common Carotid Artery and first part of the internal carotid artery
Left: Common Carotid Artery and first part of the internal carotid artery
72
Aortic Arch _ branches
Right: Proximal part of the right subclavian artery
Left: Aortic Arch
Aortic Arch **4** branches
Right: Proximal part of the right subclavian artery
Left: Aortic Arch
73
Aortic Arch _ branches
Right: Does not form
Left: Does not form
Aortic Arch **5** branches
Right: Does not form
Left: Does not form
74
Aortic Arch _ branches
Right: Proximal right pulmonary artery
Left: Proximal left pulmonary arty and ductus arteriosus (connection between aorta and pulmonary trunk)
Aortic Arch **6 **branches
Right: Proximal right pulmonary artery
Left: Proximal left pulmonary arty and ductus arteriosus (connection between aorta and pulmonary trunk)
75
A surgeon fails to identify surrounding
structures while operating to correct a
coarctation of the aortic arch in a 10-year-old
child. Which of the following can be
damaged during this procedure?
A. Cricothyroid muscle
B. Left recurrent laryngeal nerve
C. Left vagus nerve
D. Right recurrent laryngeal nerve
E. Right vagus nerve
B. Left recurrent laryngeal nerve
76
_ nerves travel superiorly, on either side of the trachea, to supply the intrinsic muscles of the larynx, exept the cricothyroid muscle
Left and Right Recurrent laryngeal nerves travel superiorly, on either side of the trachea, to supply the intrinsic muscles of the larynx, exept the cricothyroid muscle
77
A 1-year-old boy is brought to the emergency
department, and a condition that requires
abdominal surgery is diagnosed. During surgery, an
abdominal cyst connected to both the ileum and
umbilicus by fibrous bands is found incidentally.
Which of the following is the embryonic origin of
this abnormality?
A. Allantois
B. Cloaca
C. Urachus
D. Vitelline duct
E. Yolk sac
D. Vitelline duct
78
What is the Vitelline duct (yolk sac , omphalomesenteric duct, omphalocentric duct)
connects the tolk sac to the midgut (ileum) in the embryo
79
The vitelline duct is _ -lined
The vitelline duct is **Endoderm-lined**
80
Vitelline Duct Anomalies
81
Rules of 2s in Meckel Diverticulum
2 times more likely in males
2 inches long
2 feet from the ileocecal valve
2% of the population
2 years old (presents)
2 types of ectopic epithelia (gastric and pancreatic)
82
The Urcahus develops from the narrow, sausage-shaped _
The Urcahus develops from the narrow, sausage-shaped **allantosis**
83
After birth, the urachus becomes the _
After birth, the urachus becomes the **median umbilical ligament**
84
Urachus Anomalies
85
The _ develop in the posterior (retroperitoneal) lumbar abdominal wall from the intermediate mesoderm
The reproductive systems develop in the posterior (retroperitoneal) lumbar abdominal wall from the intermediate mesoderm
86
_ early period of development when the female and
male reproductive structures (primordia) are the same
**Indifferent stage:** early period of development when the female and
87
Which statement accurately describes the
paramesonephric ducts?
A. They are retained in the female fetus by
antimullerian hormone.
B. They are the source of cells that form the
lower vagina.
C. They give rise to the internal and external
female reproductive structures.
D. They give rise to the uterus, uterine tubes, and
upper vagina.
E. They secrete estrogen.
D. They give rise to the uterus, uterine tubes, and
upper vagina.
88
_ is the precursor to the repoductive duct in the male
**Mesonephric Duct (aka Wolffian duct)** is the precursor to the repoductive duct in the male
89
_ is the precursor to the repoductive duct in the female
**Paramesonephric Duct (aka Mullerian duct)** is the precursor to the repoductive duct in the female
90
_ gene (on the Y chromosome) produces testis determining factor (TDF) aka SRY protein --> testes development
**SRY** gene (on the Y chromosome) produces testis determining factor (TDF) aka SRY protein --> testes development
91
_ secrete Mullerian inhibitory factor (MIF, aka antimullerian hormone) --> suppresses development of paramesonephric ducts
**Sertoli cells** secrete Mullerian inhibitory factor (MIF, aka antimullerian hormone) --> suppresses development of paramesonephric ducts
92
_ secrete androgens --> stimulate development of mesonephric ducts
**Leydig cells **secrete androgens --> stimulate development of mesonephric ducts
93
Which weeks does embryo secually indifferent stage take place
Weeks 5-6
94
_ form due to the absence
of SRY gene and SRY protein
**Ovaries** form due to the absence
of SRY gene and SRY protein
95
**Paramesonephric (Mullerian) **ducts form the fallopian tubes, uterus, cervix, upper vagina
**Paramesonephric (Mullerian) **ducts form the fallopian tubes, uterus, cervix, upper vagina
96
Male and Female Development Diagram
97
Male and Female Reproductive Homologs Diagram
