Embryology Flashcards
(143 cards)
1
Q
the heart and great vessels come from what cell line?
A
the mesenchymal cells in the cardiogenic area
2
Q
at what point do vasculogenesis and angiogenesis, blood vessel development begin?
A
at the beginning of the 3rd week
3
Q
where does vasculogenesis and angiogenesis happen?
A
in the extraembryonic mesoderm of the yolk sac, allantosis and chorion
4
Q
how does the heart tube form?
A
2 endothelial-lined channels, known as the endocardial heart tubes, fused together to form the heart tube
5
Q
by the end of the 3rd week what does the primoridal CVS look like?
A
the heart is represented by the heart tubes and is joined by blood vessels from the embryo and extraembryonic membrane
6
Q
What 4 main segments compose the inferior vena cava?
A
- hepatic segment; from the hepatic vein and sinusoids. 2. prerenal segment; from the right subcardinal veins. 3. renal segment; from the subcardinal supra anastomosis 4. post-renal; from the right supracardinal vein.
7
Q
what germ layer forms the excretory organs?
A
mesoderm
8
Q
what germ layer forms the glands opening into the GI tract?
A
endoderm
9
Q
what germ layer forms the glandular cells o the liver and and pancreas?
A
endoderm
10
Q
what germ layer forms the lining of the GI tract?
A
endoderm
11
Q
what remnants persist after the joining of the embryonic palantine processes and is located in the soft palate>
A
the palantine raphe
12
Q
the embryonic ductus venosus become what after birth?
A
ligamentum venosum
13
Q
the embryonic umbilical vein become what after birth?
A
ligamentum teres
14
Q
the embryonic umbilical arteries become what after birth?
A
umbilical ligament
15
Q
from what does the aorta and pulmonary trunk develop?
A
a. bulbar ridges fuse and become an aorti-copulmonary septum. b. this then divides the bulbus cordis and the truncus arteriosis into two arterial channels. c. these two channels become the aorta and the pulmonary tree.
16
Q
The aorta and the pulmonary truck are formed when in gestation
A
between week 5 and 6
17
Q
At what point can a fetal heart beat be detected by a doppler heart monitor?
A
7 weeks after the last known menstrual period, aka 5 weeks in fertilization terms.
18
Q
Fetal circulation happens in what order?
A
The umbilical vein delivers oxygenated blood. After bypassing the liver, the blood moves from the ductus venosus into the IVC and the right atrium. It enters the left atrium and ventricle through the foramen ovale. It enters the pulmonary trunk at the same time via the ductus arteriosis. After it enters the lung and the peripheral body through the aorta, it is passed back to the placenta thanks to the umbilical arteries.
19
Q
The embryonic foramen ovale become what after birth?
A
fossa ovalis
20
Q
the embryonic ductus arteriosis becomes what after birth?
A
ligamentum arteriosum
21
Q
what forms the atria?
A
the separation into the right and left of the primitive sinuatrium or septum primum.
22
Q
the fusion of the endocardial and atroventricular cushions posteriorly and anteriorly forms what?
A
the tricuspid and mitral inlets which become the AV valves.
23
Q
what does the interventricular foramen result in?
A
by the end of week 7 it closes resulting in the interventricular septum.
24
Q
from what tissue does the hypothalamus develop?
A
ectodermal tissue (on day 32 the hypothalamic sulcus develops from the diencephalon)
25
what tissue invaginates to form the anterior lobe of the pituitary gland? what is this known as?
Ectodermal tissue of the oropharynx, Known as: Rathke's pouch (which eventually extends down to the HTH and becomes the pituitary stalk)
26
from what does the posterior lobe of the pituitary gland arise ?
neural crest
27
what does the pancreas form from?
two diverticular buds of the foregut
28
by what week have the first islet of the pancreas appeared?
around week 10, they first appear at the tail of pancreas
29
from what tissue does the thyroid develop?
its starts developing in the primitive ailmentary tract and consists of endodermal cells.
30
where does the thyroid first develop?
in the buccal cavity
31
what structure does the thyroid gland help to develop as it matures?
the tongue
32
what embryonic connection do the thyroid and tongue share?
the thyroglossal duct
33
where on the tongue does the thyroglossal duct open?
the foramen cecum
34
from which pouches do the parathyroid glands develop?
the superior glands descend from the 4th pharyngeal pouch and the inferior glands from the 3rd pharyngeal pouch.
35
True or false; the adrenal cortex and medulla develop from the same embryonic line?
false, the cortex develops from the coelomic mesodermal tissue and the medulla arises from the ectodermal tissue of the neural crest.
36
Between the adrenal cortex and the medulla, which develops parallel with the sympathetic nervous system?
the adrenal medulla
37
angioblasts from from what?
mesoderm
38
angioblasts form what as they cluster?
blood islands
39
the blood islands fuse together to form what?
a primordial vascular network
40
hemocytoblasts arise from what?
core cells within blood islands
41
blood formation occurs at what week?
week 5
42
what is the allantosis?
it is the part of the yolk sac that extends outward into the connecting stalk
43
what is the role of the allantosis?
it is involved in early blood formation, plays a role in bladder development, and its blood vessels become umbilical arteries and veins.
44
the liver starts hematopoesis during which week?
week 6
45
the fetal spleen takes over hematopoesis when?
week 26 to 28
46
from what does the thymus arise?
the 3rd pharyngeal pouch
47
what tissue forms the cortex and medulla of the thymus?
the cortex is formed from the ectoderm and the medulla is formed from the endoderm
48
the spleen arises from which germ line?
mesoderm
49
what are present in the spleen by the first trimester?
macrophages
50
True or false: the spleen is capable of hematopoiesis during fetal life
True, as well as after birth
51
what germ layer forms the bone marrow?
mesoderm
52
before bone marrow develops where are blood cells formed?
they start being produced in the yolk sac, then the liver takes over, and lastly the spleen handles the responsibility till the bone marrow matures.
53
what germ layer forms the connective tissue?
mesoderm
54
what germ layer forms the epidermis?
ectoderm
55
from what do the dermis and hypodermis arise?
mesoderm
56
how does the periderm develop?
ectodermal cells proliferate and forma layer of epithelium called periderm and a basal layer at the same time.
57
what happens to the peridermal cells?
the cells undergo kertinization and desquamation and are slowly replaced by other cells arising from the basale layer.
58
what germ layer forms the retina of the eye?
ectoderm
59
what is the lanugo?
a downy coat of delicate hairs that cover a 5-6 mo old fetus
60
sweat and sebacous glands develop from what?
sebacous glands develop from epithelial root sheaths of hair follicles and eccrine sweat glands develop from down growths in the mesenchyme
61
What germs layer forms smooth ms coat?
mesoderm
62
what germ layer forms smooth ms?
mesoerm
63
what germ layer forms the skeleton ?
mesoderm
64
what germs layer form striated ms?
mesoderm
65
These pair blocks of mesoderm give rise to skeletal ms?
somites
66
what are the 3 layers that the somite splits into?
myotome, dermatome, and sclerotome layers
67
what are the 4 support cells (fibroblasts, chondrocytes, osteoblasts, and myofibroblasts) derived from?
mesenchyme
68
what activates the transcription of ms specific genes and mygoenic cell diffentiation?
MyoD
69
how do limb muscles develop?
cells migrate from the ventral dermomyotomes of somites and form limb buds.
70
what happens to cells that move into limb buds?
they undergo epitheliomesenchyma transformation
71
what germ layer forms the central and peripheral NS?
ectoderm
72
what happens after anteroposterior invagination of the neural placode?
the lateral ends fold to form the neural tube
73
once the neural tube has formed, what happens next?
neuroepithelial cells proliferate resulting into neuroblasts
74
after proliferation (resulting in neuroblasts) what do the cells do?
they migrate to mature sites in order to establish synaptic connection and extend axons to the target tissues
75
what doe the neural crest and neural tube eventually become?
the neural crest differentiates into the majority of the PNS and ANS (consisting of cranial, spinal, and autonomic ganglia). The neural tube differentiates into the CNS, consisting of the brain and spinal cord.
76
what are astrocytes and ependymal cells formed from?
Radial glial cells
77
what cells differentiate into microglial cells?
mesenchymal cells
78
the primordial meninx eventually become what structure?
the spinal meninges
79
what germ layer forms the epithelial lining of the resp tract?
endoderm
80
what is the sulcus larngotrachialis?
the groove in the ventral lower pharynx that will develop into the lungs
81
what is the next step in lung development?
the true lung primordium buds from the lower portion.
82
After the true lung primordium forms, what happens next?
it divides into 2 main bronchi and the endodermal branches into the lobes
83
when can the lung primordium first be observed?
28 days
84
the epiglottis develops from what structure?
the hypopharyngeal eminence
85
what cell is the precursor of ciliated epithelium and secretory cells in the pulmonary system?
cubic epithelium
86
a premature fetus born after 26 weeks has better odds of survival due to what?
capillaries have bulged into developing alveoli thus establishing a blood-air barrier and allowing for adequate gas exchange
87
at what point in development are the terminal sacules lined with type 1 alveolar cells?
by week 26
88
when do type II alveolar cell start producing surfactant?
by week 20 small amounts are produced, but adequate levels for survival are only produced around week 26-28.
89
what days on the menstrual cycle form the menstrual phase?
days 1-4
90
the secretory or luteal phase occurs on what days of the menstrual cycle?
days 15-28
91
the proliferative or follicular phase occurs on what days of the menstrual cycle?
day 4-14
92
what hormone is released to promote the development of the follicle?
FSH
93
what causes a surge of LH?
Estrogen
94
what is the zygote?
diploid cells resulting from union of sperm and ovum
95
what structure consists of 12-15 blastomeres?
morula
96
what contains are fluid-filled cavity that separates teh blastomere into two parts?
Blastula
97
how soon after fertilization does implantation in the endometrial epithelium of the uterus take place?
6 days
98
what forms the wall of the gestational or chorionic sac?
chorion membranes
99
what forms the floor of the amniotic cavity?
epiblast
100
what forms the roof of the exocoelomic cavity?
hypoblast
101
what is the process of bilaminar embryonic disc development into trilaminar embryonic disc called?
Gastrulation
102
What are the 3 trilaminar layers called?
Ectoderm, mesoderm, endoderm
103
what germ layer forms the reproductive organs?
mesoderm
104
what fetal organs are developed at 4 weeks gestation?
Heart, forebrane, upper and lower limbs, ears, lens of the eye.
105
at what stage does the external auditory canal develop?
6 weeks
106
at what stage do the digits and external genitalia develop?
8 weeks
107
at what stage do do the intestines develop?
7 weeks
108
at what stage does the ossification of bone begin?
7 weeks
109
True or false: fibrocartilage forms the temporary fetal skeleton, which eventually is replaced by bone?
False, it is Hyaline cartilage
110
Describe the schema for fetal circulation.
oxygenated blood from placenta via umbilical vein; through ductus venosis (bypasses the liver), into the IVC and right atrium; through the foramen ovale to the left atrium and left ventricle, or into right ventricle and pulmonary trunk to ductus arteriosus (bypasses lungs); from aorta to internal iliac and umbilical arteries, to the capillaries in the chorionic villi of the placenta
111
the kidneys and ureter arise from what germ layer?
intermediate mesoderm
112
the kidney develop from what entity?
urogenital ridge
113
of the 3 subsets of the urogenital ridge, which matures into the actual kidneys?
the metanephros
114
from which part of the metanephros does the renal pelvices, calyces, and collecting duct develop?
the ureteric buds
115
the ureters develop from which portion of the metanephros?
the proximal part known as the ureteric ducts
116
what are the other 2 primitive kidney structures called?
the pronephros (formed in the begining of week 4), and the mesonephros (formed at the end of week 4)
117
the metanephros forms when?
its is formed in week 5, but it does not actually function till week 9.
118
from what germ line do the bladder and urethra develop?
urogenital sinus
119
What is the primordium of the central tendon of the diaphragm in the adult?
the septum transversum
120
What do the pair pleuroperitoneal membranes later become?
the fibrous pericardium surrounding the heart
121
what is the primordium of the crura of the diaphragm?
dorsal mesentery of the esophagus
122
when does the diaphragm become innervated by the phrenic nerves (originate C3, 4, 5)?
week 4
123
what is congenital diaphragmatic hernia?
herniation of the abdominal contents into the pleural cavity. Bochdalek's hernia- most common and L posterior lateral
124
which pharyngeal arch makes the aorta?
4th arch
125
What fold is responsible for creating the trachea and esophagus (i.e. separating the two structures) and what major pathology would it cause if this did not occur properly?
Tracheoesophageal. Trachea and TE fistula can result with the failure to fuse to create the tracheoesophageal septum. (weeks 5-6)
126
what type of esophageal fistula is the most common?
"type c", esophageal atressia w/TE fistula at the distal 1/3rd end of the trachea.
127
what do type 2 pneumocytes make?
surfactant (decreases surface tension in alveoli)-- decrease seen in premies
128
function of type 1 pneumocytes?
provide a barrier of minimal thickness that is readily permeable to gases such as oxygen and carbon dioxide.
129
When do the lung buds form-- into main (primary) bronchi?
week 5
130
what is the sequence of lung development?
main/primary bronchi -->lobar/secondary -->segmental /tertiary --> segmental bronchi
131
What are the periods of lung development?
Pseudoglandular: W 7-16, Canalicaular: W16-24, Terminal sac: W24-birth, Alveolar: W32-8 yrs
132
what other defect is seen with pulmonary hypoplasia (PH)?
Classically involves the right lung in association with right sided obstructive congenital heart defect and congenital diaphragmatic hernia. (no heart defects if occurs on Left side)
133
What disease is caused by the deficiency or absence of surfactant?
Hyaline membrane disease
134
Hyaline membrane disease is associated with what type of hemorrhage?
Germinal matrix hemorrhage(GMH)
135
What condition is associated with Bronchiectasis?
cystic fibrosis
136
What is the classic Xray finding of bronchiectasis?
honeycombing
137
the Ligamentum arteriosum used to be?
ductus arteriosusm (fetus)
138
the fossa ovale used to be...
foramen ovale (fetus)
139
the ligamentum venosum used to be...
ductus venosus (fetus)
140
the ligamentum teres used to be...
the left umbilical vein (fetus)
141
the medial umbilical ligament used to be...
right and left umbilical arteries (fetus)
142
what system does the intermediate mesoderm create?
GU : kidneys and gonads
143
the paraxial mesoderm is responsible for...
the head and somites (scleroderm, myotome, dermatome)
