Embryo Flashcards
1
Q
Spermatogonia and oogonia (gametes) are derived from populations of _ cells
A
Spermatogonia and oogonia (gametes) are derived from populations of primordial germ cells
2
Q
Primordial germ cells are produced during week _ of the embryo’s life
A
Primordial germ cells are produced during week 3 of the embryo’s life
* They initially migrate outside of the embryo into the yolk sac
3
Q
During week 4, primordial germ cells return to the embryo and follow a path along the gut tube to the _ where the ovary/testis develops
A
During week 4, primordial germ cells return to the embryo and follow a path along the gut tube to the gonadal ridge where the ovary/testis develops
4
Q
Primordial germ cells reach the gonadal ridge at about 6 weeks gestation and continue to proliferate via _
A
Primordial germ cells reach the gonadal ridge at about 6 weeks gestation and continue to proliferate via mitosis
5
Q
Oogonia multiply by mitosis before beginning meiosis 1 and arresting in _
A
Oogonia multiply by mitosis before beginning meiosis 1 and arresting in prophase (2N, 4C)
6
Q
(True/False) Oogonia continue to proliferate and differentiate into primary oocytes
A
False; by the 7th month of gestation nearly all of the eggs are in the primary oocyte stage and the fetus will stop producing oogonia
* Atresia is the process of cell death of remaining oocytes and some primary oocytes as we age until menopause
7
Q
What is the sequence of oogenesis?
A
Primordial germ cell –> oogonia –> primary oocyte –> secondary oocyte –> mature oocyte
8
Q
Oogenesis occurs during the (follicular/luteal) phase of the ovarian cycle
A
Oogenesis occurs during the follicular phase of the ovarian cycle –> culminates in ovulation
9
Q
During the follicular phase, _ is secreted from the pituitary gland and stimulates _ cells surrounding the primary oocyte to enlarge, transform into cuboidal cells and begin secreting estrogens
A
During the follicular phase, FSH is secreted from the pituitary gland and stimulates granulosa cells surrounding the primary oocyte to enlarge, transform into cuboidal cells and begin secreting estrogens
* About 15-20 primordial follicles in each ovary will begin this but only 1-2 will ovulate
10
Q
Once activated, primordial follicles transform into primary follicles with the development of _
A
Once activated, primordial follicles transform into primary follicles with the development of zona pellucida (glycoprotein layer)
11
Q
Between the granulosa cells and the primary oocyte is the _ layer
A
Between the granulosa cells and the primary oocyte is the zona pellucida
* Glycoprotein layer that contains receptors and components needed for fertilization
12
Q
_ cells eventually form the corona radiata
A
Granulosa cells eventually form the corona radiata
13
Q
The granulosa cells of the _ will accompany the mature oocyte when it exits the follicle at ovulation
A
The granulosa cells of the corona radiata will accompany the mature oocyte when it exits the follicle at ovulation
14
Q
When there is sufficient estrogen in circulation, a surge of _ is released from the pituitary and a _ is released from its meiotic inhibition
A
When there is sufficient estrogen in circulation, a surge of LH is released from the pituitary and a primary oocyte is released from its meiotic inhibition
15
Q
This first meiotic division (at ovulation) produces _ + _
A
This first meiotic division (at ovulation) produces one large secondary oocyte + polar body
16
Q
The secondary oocyte (formed with ovulation) will be arrested in _
A
The secondary oocyte (formed with ovulation) will be arrested in metaphase II
17
Q
The secondary oocyte ruptures through the cells of the mature follicle and gets drawn into the _
A
The secondary oocyte ruptures through the cells of the mature follicle and gets drawn into the fallopian tube (leaving ovary)
18
Q
Following ovulation, the ruptured follicle transforms into the _
A
Following ovulation, the ruptured follicle transforms into the corpus luteum
19
Q
Unlike the ovary with a finite number of oogonia, the testis maintains a stem cell population of mitotically active _ throughout life
A
Unlike the ovary with a finite number of oogonia, the testis maintains a stem cell population of mitotically active spermatogonia throughout life
20
Q
Sequence of spermatogenesis
A
Spermatogonia –> primary spermatocyte –> secondary spermatocyte –> spermatid –> spermatozoa
21
Q
Spermatogenesis begins at _
A
Spermatogenesis begins at puberty
* When spermatogonia start meiosis
22
Q
Spermatogenesis takes place in the _ and requires supporting cells called _
A
Spermatogenesis takes place in the seminiferous tubules and requires supporting cells called sertoli cells
23
Q
The haploid cells (male germ cells) that are produced after meiosis II are called _
A
The haploid cells (male germ cells) that are produced after meiosis II are called spermatids
24
Q
The process of transforming spermatids into specialized spermatozoa is called _
A
The process of transforming spermatids into specialized spermatozoa is called spermiogenesis
25
Three important features in spermiogenesis that mature the spermatozoa:
Three important features in spermiogenesis that mature the spermatozoa:
1. **Acrosome** added to head of sperm (enzyme rich)
2. **Flagellum** powered by mitochondria
3. **Pronucleus** from condensation of haploid genome
26
After spermatozoa leave the seminiferous tubules, they enter the _ where they will fully mature
After spermatozoa leave the seminiferous tubules, they enter the **epididymus** where they will fully mature
27
During emission, sperm exit the epididymus, travel via the vas deferens to gain access to the urethra; on their way they join secretions from the _ and _
During emission, sperm exit the epididymus, travel via the vas deferens to gain access to the urethra; on their way they join secretions from the **seminal vesicles** and **prostate gland**
28
As the sperm passes through the uterine cavity they undergo _ in which the glycoproteins on the plasma membrane of the sperm head are removed and the acrosome is exposed
As the sperm passes through the uterine cavity they undergo **capacitation** in which the glycoproteins on the plasma membrane of the sperm head are removed and the acrosome is exposed
29
(3) steps of fertilization
1. Sperm penetrate corona radiata
2. Penetration of the zona pellucida; release of contents of the acrosome (acrosomal reaction)
3. Fusion of the oocyte and sperm cell membranes
30
How does the egg respond to the fusion of sperm fushion?
1. **Cortical reaction**: release of cortical granules and lysosomal enzymes that harden the zona pellucida and hydrolyze the sperm receptors; block polyspermy
2. **Resumption of meiosis II**: second asymmetrical cell division occurs
3. **Egg activation**: increase in metabolism in preparation
31
Fertilization is complete with the first mitotic division of the _
Fertilization is complete with the first mitotic division of the **zygote**
32
Fertilization is followed by a series of mitotic divisions inside the hardened _ ; this proliferation is called _ since cytoplasm does not growth and dividing cells get smaller and smaller; these cells are called _
Fertilization is followed by a series of mitotic divisions inside the hardened **zona pellucida** ; this proliferation is called **cleavage** since cytoplasm does not growth and dividing cells get smaller and smaller; these cells are called **blastomeres**
33
Compaction is the process of packaging the blastomeres into a tightly-packed ball and is mediated by _
**Compaction** is the process of packaging the blastomeres into a tightly-packed ball and is mediated by **E-cadherin**
* We get inner and outer cells
34
Once the embryo consists of 16 cells we call it the _
Once the embryo consists of 16 cells we call it the **morula**
* Will form the inner cell mass or embryoblast (future embryo proper)
35
The cells surroundig the morula cells will form the outer cell mass, or _
The cells surroundig the morula cells will form the outer cell mass, or **trophoblast**
* Trophoblast will contribute to the placenta
36
Prior to compaction, blastomeres are (totipotent/pluripotent)
Prior to compaction, blastomeres are **totipotent**
* Capable of developing into all tissues necessary for development (embryonic or placental)
37
Inner mass cells are (totipotent/pluripotent)
Inner mass cells are **pluripotent**
38
Trophoblast cells secrete fluid into the interior of the morula, sequestering the embryoblasts at one pole; the embryo is now called the _
Trophoblast cells secrete fluid into the interior of the morula, sequestering the embryoblasts at one pole; the embryo is now called the **blastocyst**
39
Once the embryo reaches the uterine cavity, a molecule on the blastocyst cell membrane lyses a small hole in the zona through which it hatches; this is called _
Once the embryo reaches the uterine cavity, a molecule on the blastocyst cell membrane lyses a small hole in the zona through which it hatches; this is called **implantation**
40
Once the embryo adheres to the uterine endometrium, the trophoblast differentiates into the _ (inner layer) and _ (outer layer)
Once the embryo adheres to the uterine endometrium, the trophoblast differentiates into the **cytotrophoblast** (inner layer) and **syncytiotrophoblast** (outer layer)
41
Syncytiotrophoblast provides the mechanism for _ and also begins to secrete _
Syncytiotrophoblast provides the mechanism for **endometrial penetration** and also begins to secrete **beta-hCG**
* Invasive tissue; making endometrial penetration possible
* hCG rescues the corpus luteum
42
Menstrual age of the fetus is usually _ than the fertilization age
Menstrual age of the fetus is usually **two weeks greater** than the fertilization age
43
Parturition is usually _ weeks menstrual age and _ weeks fertilization age
Parturition is usually **40 weeks** menstrual age and **38 weeks** fertilization age
44
During the second week of development, the embryoblast cells become organized into _
During the second week of development, the embryoblast cells become organized into **bilaminar disc**
45
(Hypoblast/Epiblast) is the thin sheet of cells of the bilaminar disc that is adjacent to the blastocyst cavity
**Hypoblast** is the thin sheet of cells of the bilaminar disc that is adjacent to the blastocyst cavity
46
(Hypoblast/Epiblast) is the thin sheet of cells of the bilaminar disc that is not in contact with the blastocyst cavity
**Epiblast** is the thin sheet of cells of the bilaminar disc that is not in contact with the blastocyst cavity
47
(Hypoblast/Epiblast) is the thin sheet of cells of the bilaminar disc that is *ventral*
**Hypoblast** is the thin sheet of cells of the bilaminar disc that is *ventral*
48
(Hypoblast/Epiblast) is the thin sheet of cells of the bilaminar disc that is *dorsal*
**Epiblast** is the thin sheet of cells of the bilaminar disc that is *dorsal*
49
Fluid begins to fill the cavity in the bilaminar disc, called the _
Fluid begins to fill the cavity in the bilaminar disc, called the **amnion (amnionic cavity)**
50
The internal, fluid-filled space defined by the hypoblast derived cells is the _
The internal, fluid-filled space defined by the hypoblast derived cells is the **primary yolk sac**
51
Cells of the hypoblast also give rise to an additional population of cells, the _
Cells of the hypoblast also give rise to an additional population of cells, the **extraembryonic mesoderm**
* These will surround primary yolk sac and amnionic cavity
* Eventually cavities get formed and become chorionic cavity
52
Once the chorionic cavity forms, we get degeneration of the primary yolk sac while the _ becomes the definitive yolk sac of the embryo
Once the chorionic cavity forms, we get degeneration of the primary yolk sac while the **secondary yolk sac** becomes the definitive yolk sac of the embryo
53
At the end of week 2 of development, the only attachment between the embryo and the cytotrophoblast is via the _
At the end of week 2 of development, the only attachment between the embryo and the cytotrophoblast is via the **connecting stalk**
54
The bilaminar embryonic disc is converted into the trilaminar embryo during week _
The bilaminar embryonic disc is converted into the trilaminar embryo during **week 3**
55
What are the three layers of the trilaminar embryo?
1. **Ectoderm**
2. **Mesoderm**
3. **Endoderm**
56
The central nervous system and the sensory organs are derived from _
The central nervous system and the sensory organs are derived from **ectoderm**
57
The epidermis of the skin and its appendages (nails, sweat glands, mammary glands, tooth enamel) is derived from _
The epidermis of the skin and its appendages (nails, sweat glands, mammary glands, tooth enamel) is derived from **ectoderm**
58
Neural crest cells are derived from _
Neural crest cells are derived from **ectoderm**
59
The neural crest cells give rise to _
The neural crest cells give rise to **PNS, melanocytes, endocrine tissues, connective tissues in head and heart**
60
Mesoderm gives rise to mainly _ and _
Mesoderm gives rise to mainly **muscle** and **connective tissues** (including blood)
* Therefore most organs come from mesoderm
61
_ layer derives the epithelial linings of respiratory, gastrointestinal, and urinary tracts
**Endoderm** layer derives the epithelial linings of respiratory, gastrointestinal, and urinary tracts
62
The epithelial portions of many glands and organs gets derived from _
The epithelial portions of many glands and organs gets derived from **endoderm**
63
Most of the body organs are formed from _ layer
Most of the body organs are formed from **mesoderm**
64
Gastrulation begins with the formation of the _ in the epiblast which eventually becomes the caudal end of embryo
Gastrulation begins with the formation of the **primitive streak** in the epiblast which eventually becomes the caudal end of embryo
65
The primitive streak of the epiblast eventually becomes the (caudal/cranial) end
The primitive streak of the epiblast eventually becomes the **caudal end**
66
The primitive node is at the (caudal/cranial) end of the embryo
The primitive node is at the **cranial** end of the embryo
67
In the three layered embryo, mesoderm is absent in only two locations _ and _
In the three layered embryo, mesoderm is absent in only two locations **buccopharyngeal membrane** and **cloacal membrane**
68
The _ membrane of the trilaminar disc represents the future oral cavity
The **buccopharyngeal membrane** of the trilaminar disc represents the future oral cavity
69
The _ membrane of the trilaminar disc represents the future GI/GU tracts
The **cloacal membrane** of the trilaminar disc represents the future GI/GU tracts
70
The axial mesoderm --> _ + _
The axial mesoderm --> **prechordal plate** (forebrain) + **notochord**
71
Paraxial mesoderm will give rise to tissue blocks termined _ which give rise to dermis layer, skeletal muscle, etc
Paraxial mesoderm will give rise to tissue blocks termined **somites** which give rise to dermis layer, skeletal muscle, etc
* These form the "body wall" (dermis, skeletal muscle, bone, cartilage)
72
Dermis is derived from _
Epidermis is derived from _
Dermis is derived from **mesoderm**
Epidermis is derived from **ectoderm**
73
Intermediate mesoderm gives rise to most of the tissues of the _ organs
Intermediate mesoderm gives rise to most of the tissues of the **genitourinary organs**
74
The precardiac mesoderm which gives rise to the heart primoridum is derived from _ mesoderm
The precardiac mesoderm which gives rise to the heart primoridum is derived from **splanchnic mesoderm** (lateral plate)
75
The differentiation of neural tissue from the ectoderm is dependent on induction signal received from the _
The differentiation of neural tissue from the ectoderm is dependent on induction signal received from the **notochord**
76
The cells immediately adjacent to the notochord become columnar and form a distinctive neural plate which will become the _ and _
The cells immediately adjacent to the notochord become columnar and form a distinctive neural plate which will become the **brain** and **spinal cord**
77
Soon after neural plate formation, the neural folds approach one another in the midline and fuse to form the _
Soon after neural plate formation, the neural folds approach one another in the midline and fuse to form the **neural tube**
78
The fusion of the neural tube begins at somite _ in the cervical region and proceeds cranially and caudally
The fusion of the neural tube begins at **fifth somite** in the cervical region and proceeds cranially and caudally
79
If failure of the neural tube closure occurs in the cranial region the the defect is called _
If failure of the neural tube closure occurs in the cranial region the the defect is called **anencephaly** (most of the brain fails to form)
80
Neural crest cells are formed from _
Neural crest cells are formed from **neurulation**
* As the neural folds fuse, cells at their lateral borders lose adhesion and dissociate --> neural crest cells
81
Neural crest cells give rise to _
Neural crest cells give rise to:
* Sensory neurons
* Autonomic neurons (SNS, PNS)
* Neurological cells of PNS
* Melanocytes
* Adrenal medulla cells
* Connective tissues and bone of face/skull
82
Failure of the neural crest cells to migrate into the wall of the developing large intestine results in megacolon, called _
Failure of the neural crest cells to migrate into the wall of the developing large intestine results in megacolon, called **Hirschsprung disease**
83
The _ layer of the embryo forms the ventral surface of the embryo and the roof of the yolk sac
The **endoderm** layer of the embryo forms the ventral surface of the embryo and the roof of the yolk sac
84
The epithelial lining of the GI tract/ "gut tube" comes from _
The epithelial lining of the GI tract/ "gut tube" comes from **endoderm**
85
Development of the head fold incorporates part of the yolk sac into the embryo as the foregut which will give rise to _
Development of the head fold incorporates part of the yolk sac into the embryo as the *foregut* which will give rise to **upper GI; pharynx, esophagus, stomach, proximal duodenum**
86
Prior to caudal folding, the yolk sac extends a small diverticulum into the connecting stalk, called the _
Prior to caudal folding, the yolk sac extends a small diverticulum into the connecting stalk, called the **allantois**
87
The vitelline duct, connecting stalk, and allantois form the bulk of the tissues in the _
The vitelline duct, connecting stalk, and allantois form the bulk of the tissues in the **umbilical cord**
88
_ folding of the embryo incorporates the midgut into the abdominal cavity and closes the body wall
**Lateral folding** of the embryo incorporates the midgut into the abdominal cavity and closes the body wall
* Lateral folding also causes amniotic sac to wrap around embryo and enclose it in amniotic cavity
89
An example of a ventral body wall defect is _ , a condition in which a portion of the gut tube fails to return to the abdominal cavity following its normal herniation into the umbilical cord
An example of a ventral body wall defect is **omphalocele** , a condition in which a portion of the gut tube fails to return to the abdominal cavity following its normal herniation into the umbilical cord
90
The morula is the structure that forms _ days after fertilization
The morula is the structure that forms **4 days** after fertilization
91
Blastocyst implants in the uterus on day _
Blastocyst implants in the uterus on **day 6**
92
What week does the primitive streak form?
What week does the primitive streak form? **week 3**
93
The nucleus pulposus comes from the _ structure
The nucleus pulposus comes from the **notochord**
94
The brain and spinal cord are derived from the _
The brain and spinal cord are derived from the **neural plate**
95
Organogenesis occurs during _ weeks
Organogenesis occurs during **week 3-8 (embryonic period)**
* This is when teratogen exposure leads to embryonic malformations
96
Fetal movement occurs at week _ of development
Fetal movement occurs at **week 8** of development
* "Eight = gait"
97
Fetal sex is recognizable at week _ of development
Fetal sex is recognizable at **week 10** of development
* "Ten = Gen for gender"
98
The ectoderm divides into two components the _ and _
The ectoderm divides into two components the **surface ectoderm** and **neuroectoderm**
* Ectoderm makes "beauty and brains"
99
The epidermis is derived from _
The epidermis is derived from **surface ectoderm**
* Ectoderm makes "beauty and brains"
100
The CNS and brain is derived from _
The CNS and brain is derived from **neuroectoderm**
101
The adenohypophysis is derived from _
The adenohypophysis is derived from **surface ectoderm**
102
Hair and nails are derived from _
Hair and nails are derived from **surface ectoderm**
103
Salivary glands are derived from _
Salivary glands are derived from **surface ectoderm**
104
Neural crest cells are a subset of _
Neural crest cells are a subset of **ectoderm**
105
PNS neurons, arachnoid mater, and pia mater are derived from _
PNS neurons, arachnoid mater, and pia mater are derived from **neural crest cells (ectoderm)**
106
The bones and connective tissue of the skull is derived from _
The bones and connective tissue of the skull is derived from **neural crest cells (ectoderm)**
107
Melanocytes are derived from _
Melanocytes are derived from **neural crest cells (ectoderm)**
108
Chromaffin cells of the adrenal medulla are derived from _
Chromaffin cells of the adrenal medulla are derived from **neural crest cells (ectoderm)**
109
Endocardial cushions and the aorticopulomary septum are derived from _
Endocardial cushions and the aorticopulomary septum are derived from **neural crest cells (ectoderm)**
110
Name the subcategories of mesoderm:
Name the subcategories of mesoderm:
**Axial mesoderm**
**Paraxial mesoderm**
**Intermediate mesoderm**
**Lateral plate mesoderm**
111
The notochord is derived from _
The notochord is derived from **axial mesoderm**
* Notochord --> nucleus pulposus
112
Vertebrae and ribs are derived from the _
Vertebrae and ribs are derived from the **paraxial mesoderm**
113
Skeletal muscles are derived from _
Skeletal muscles are derived from **paraxial mesoderm**
114
Kidneys and gonads are derived from _
Kidneys and gonads are derived from **intermediate mesoderm**
115
The lateral plate mesoderm later becomes:
The lateral plate mesoderm later becomes:
* **Cardiovascular system**
* **Microglia**
* **Stem cells of hematopoietic origin**
* **Limbs**
116
The GI tract, respiratory tract, and urinary tract is derived from _
The GI tract, respiratory tract, and urinary tract is derived from **endoderm**
117
Structures of the head and neck (eustachian tube, thymus, parathyroid gland, tonsils, pharynx) come from the _
Structures of the head and neck (eustachian tube, thymus, parathyroid gland, tonsils, pharynx) come from the **endoderm**
118
(3) Components of the pharyngeal apparatus
(3) Components of the pharyngeal apparatus
1. **Pharyngeal clefts/grooves**
2. **Pharyngeal pouches**
3. **Pharyngeal arches**
119
Pharyngeal clefts/grooves are derived from _
Pharyngeal clefts/grooves are derived from **ectoderm**
120
Pharyngeal pouches are derived from _
Pharyngeal pouches are derived from **endoderm**
121
Pharyngeal arches are derived from _
Pharyngeal arches are derived from **mesoderm/neural crest cells**
122
The 1st pharyngeal cleft becomes the _
The 1st pharyngeal cleft becomes the **external auditory meatus**
123
The 2nd-4th pharyngeal clefts become _
The 2nd-4th pharyngeal clefts become **temporary cervical sinuses** (obliterate normally)
* Persistance --> branchial cleft sinus (pharyngeal cleft cyst)
124
The thyroid gland is derived from the _
The thyroid gland is derived from the **thyroglossal duct**
* Failure to obliterate leads to thyroglossal duct cyst (painless, mobile neck mass near hyoid)
125
Mneumonic for pharyngeal arch derivatives:
Mneumonic for pharyngeal arch derivatives:
"Medical students party (hard) in Vagas"
126
Derivatives of the 1st pharyngeal arch:
Derivatives of the 1st pharyngeal arch:
* **Mandibular/maxillary process**
* **Muscles of mastication**
* **Anterior 2/3 of tongue**
* **Maleus, incus of ear**
127
The nerve associated with 1st pharyngeal arch:
The nerve associated with 1st pharyngeal arch:
**Mandibular nerve (V3)** which is a branch of trigeminal (V)
128
Derivatives of the 2nd pharyngeal arch:
Derivatives of the 2nd pharyngeal arch:
* **Stapedius**
* **Stylohyoid process**
* **Stapes**
* **Facial muscles** ("smile muscles")
* **Lesser horn of hyoid**
129
The nerve associated with 2nd pharyngeal arch:
The nerve associated with 2nd pharyngeal arch:
**Facial nerve (CN VII)**
130
Derivatives of the 3rd pharyngeal arch:
Derivatives of the 3rd pharyngeal arch:
* **Stylopharyngeus muscle**
* **Greater horn of hyoid**
131
The nerve associated with 3rd pharyngeal arch:
The nerve associated with 3rd pharyngeal arch:
**Glossopharyngeal (CN IX)**
132
Derivatives of the 4th pharyngeal arch:
Derivatives of the 4th pharyngeal arch:
* **Pharyngeal constrictors**
133
The nerve associated with 4th pharyngeal arch:
The nerve associated with 4th pharyngeal arch:
**Superior laryngeal nerve**
134
Derivatives of the 5th pharyngeal arch:
Derivatives of the 5th pharyngeal arch:
* **There is no 5th pharyngeal pouch**
135
The nerve associated with 5th pharyngeal arch:
The nerve associated with 5th pharyngeal arch:
* **There is no 5th pharyngeal pouch**
136
Derivatives of the 6th pharyngeal arch:
Derivatives of the 6th pharyngeal arch:
* **Larynx muscles (except cricothyroid)**
137
The nerve associated with 6th pharyngeal arch:
The nerve associated with 6th pharyngeal arch:
**Recurrent laryngeal nerve**
138
1st pharyngeal pouch derivatives:
1st pharyngeal pouch derivatives:
**cells of the middle ear, mastoid air, estachian tube**
139
2nd pharyngeal pouch derivatives:
2nd pharyngeal pouch derivatives:
**epithelium of palantine tonsils**
140
3rd pharyngeal pouch derivatives:
3rd pharyngeal pouch derivatives:
**inferior parathyroid glands, thymus**
141
4th pharyngeal pouch derivatives:
4th pharyngeal pouch derivatives:
**superior parathyroid, parafollicular cells of the thyroid**
142
The inferior parathyroid gland is derived from _
The inferior parathyroid gland is derived from *dorsal wing* of **3rd pharyngeal pouch**
143
The superior parathyroid gland is derived from _
The superior parathyroid gland is derived from *dorsal wing* of **4th pharyngeal pouch**
144
The thymus is derived from _
The thymus is derived from *ventral wing* of the **3rd pharyngeal pouch**
145
The parafollicular cells of the thyroid are derived from the _
The parafollicular cells of the thyroid are derived from the *ventral wing* of the **4th pharyngeal pouch**
146
The 1st aortic arch gives rise to the _
The 1st aortic arch gives rise to the **maxillary artery**
147
The 2nd aortic arch gives rise to the _
The 2nd aortic arch gives rise to the **stapedius artery**
148
The 3rd aortic arch gives rise to the _
The 3rd aortic arch gives rise to the **common carotid/internal carotid**
149
The 4th aortic arch gives rise to the _
The 4th aortic arch gives rise to the **aortic arch & right subclavian**
150
The 6th aortic arch gives rise to the _
The 6th aortic arch gives rise to the **DA & pulmonary arteries**
151
The recurrent laryngeal nerve is a branch of the _
The recurrent laryngeal nerve is a branch of the **vagus nerve (X)**
152
The *right* recurrent laryngeal nerve loops under the _
The *right* recurrent laryngeal nerve loops under the **right subclavian artery**
153
The *left* recurrent laryngeal nerve loops under the _
The *left* recurrent laryngeal nerve loops under the **aortic arch at the ligamentum arteriosum**
* The left recurrent laryngeal nerve can be damaged during any surgery related to the aortic arch
154
The recurrent laryngeal nerve supplies the _
The recurrent laryngeal nerve supplies the **intrinsic muscles of the larynx (except cricothyroid)**
155
The vitelline duct connects the _ to _ in the embryo
The vitelline duct connects the **yolk sac** to **midgut (ileum)** in the embryo
156
Urination through the belly button is a problem of the _
Urination through the belly button is a problem of the **urachus**
