Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Human Development > Anatomy Practical - basic embryology 3 > Flashcards

Anatomy Practical - basic embryology 3 Flashcards

(103 cards)

Start Studying
1
Q

What are the main events in week 1

A
  • Fertilization
  • Cleavage
  • Blastocyst formation
  • Implantation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how much of the sperm deposited in the vagina enter the cervix

A

Only around 1% of sperm deposited in the vagina enter the cervix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how does the movement of the sperm take place

A
  • sperms own propulsion

- movement of fluid in the uterus by cilia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the time taken for the sperm to travel

A
  • from the cervix to the oviduct takes a minimum of 2-7 hours - they become less motile
  • at ovulation the sperm speed up agains and swim down the uterine tube where they meet the egg
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

when must the sperm and oocyte fuse by

A

The oocyte must meet and fuse with the sperm within 24 hours after ovulation or it will degenerate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe the process of fertilisation

A

A. Fertilization occurs in the ampulla of the uterine tube.
B. The sperm bind to the zona pellucida of the secondary oocyte arrested in metaphase of meiosis II and triggers the acrosomal reaction, causing the release of acrosomal enzymes (e.g. acrosin)
C. Aided by the acrosomal enzymes, the sperm penetrates the zona pellucida. Penetration of the zona pellucida elicits the cortical reaction, rendering the secondary oocyte impermeable to other sperm.
D. The sperm and secondary oocyte cell membranes fuse, and the content of the sperm enters the cytoplasm of the oocyte. The male genetic material forms the male pronucleus.
E. The secondary oocyte completes meiosis II, forming a mature ovum. The nucleus of the ovum is the female pronucleus.
F. The male and female pronuclei fuse to form a zygote.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is cleavage

A

this is a series of mitotic division in the zygote

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe how cleaner takes place

A

A. Cleavage is a series of mitotic divisions of the zygote.
B. The zygote cytoplasm is successively cleaved to form a blastula consisting of increasingly smaller blastomeres
C. At the 16 to 32 cells stage, the blastomeres form a morula (mulberry) consisting of an inner cells mass and an outer cell mass.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does blastocyte formation occur

A

Blastocyst formation occus when fluid secreted within the morula forms the blastocyst cavity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe how blastocyte formation takes place

A

A. Blastocyst formation occus when fluid secreted within the morula forms the blastocyst cavity.
B. The inner cell mass, which becomes the embryo, is now called the embryoblast or embryo proper.
C. The outer cell mass, which becomes part of the placenta, is now called the trophoblast.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe the process of implantation

A

A. The zona pellucida must degenerate for implantation to occur.
B. The blastocyst implants within the posterior superior wall of the uterus.
C. The blastocyst implants within the functional layer of the endometrium during the secretory phase of the menstrual cycle.
D. The trophoblast differentiates into cytotrophoblast and syncytiotrophoblast.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what must degrade in order for implantation to happen

A

The zona pellucida must degenerate for implantation to occur.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what does the trophoblast differentiate into

A

cytotrophoblast and syncytiotrophoblast.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what happens in week 2

A
  • embryoblast differentiation
  • trophoblast differentiation
  • the blastocyst gets more deeply embedded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what happens by day 13

A
  • By day 13 the surface defect in the endometrium is healed as the embryo has now become fully embedded.
  • There may be a little bleeding/spotting at this time, which can be confused with the menstrual cycle.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what does the embryo blast differentiate into

A

the dorsal epiblast and the ventral hypoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe what happens during embyroblast differentiation

A

A. The embryoblast differentiates into 2 distinct cell layers: the dorsal epiblast and the ventral hypoblast. Both layers together from a flat, ovoid-shaped disk known as the bilaminar embryonic disk.
B. Within the epiblast, clefts develop and eventually coalesce to from the amniotic cavity.
C. Hypoblast cells migrate and line the inner surface of the cytotrophoblast and eventually delimit the space called the definite yolk sac.
D. The epiblast and the hypoblast fuse to from the prochordal plate, which mark the future site of the mout

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what do the dorsal epiblast and ventral hypoblast form

A

Both layers together from a flat, ovoid-shaped disk known as the bilaminar embryonic disk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

describe what happens in trophoblast differentiation

A

A. The syncytiotrophoblast continues its growth into the endometrium to make contact with endometrial blood vessels and glands.
B. The syncytiotrophoblast produces human chorionic gonadotrophin (hCG).
C. Primary chorionic villi formed by the cytotrophoblast protrude into the syncytiotrophoblast.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what produces hCG

A

The syncytiotrophoblast produces human chorionic gonadotrophin (hCG)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the extra embryonic mesoderm

A

Extraembryonic mesoderm is a new layer of cells derived from the epiblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what does the extra embryonicmesoderm line

A
  • Extraembryonic mesoderm lines the cytotrophoblast, forms the connecting stalk, covers the amnion and the yolk sac.
  • The extraembryonic mesoderm lines the chorionic cavity, and its wall is called the chorion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

describe development of the extra embryonic mesoderm

A

A. Extraembryonic mesoderm is a new layer of cells derived from the epiblast.
B. Extraembryonic mesoderm lines the cytotrophoblast, forms the connecting stalk, covers the amnion and the yolk sac.
C. The extraembryonic mesoderm lines the chorionic cavity, and its wall is called the chorion.
D. The chorion is formed of extraembryonic mesoderm, cytotrophoblast and syncytiotrophoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the chorion formed from

A
  • extraembryonic mesoderm,
  • cytotrophoblast
  • syncytiotrophoblast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what develops in embryonic period
- major organ systems begin to develop during the embryonic period, causing a craniocaudal and lateral body folding of the embryo
26
what happens by the end of the embryonic period
- the embryo has a distinct human appearance
27
what is gastrulation
Gastrulation is a process that establishes the three primary germ layer (ectoderm, mesoderm and endoderm), thereby forming a trilaminar embryonic disk
28
what are the three primary germ layer
ectoderm, mesoderm and endoderm
29
what first indicates gastrulation
- the formation of a primitive streak within the epiblast
30
describe the process of gastrulation
A. Gastrulation is a process that establishes the three primary germ layer (ectoderm, mesoderm and endoderm), thereby forming a trilaminar embryonic disk. B. This process is first indicated by the formation of a primitive streak within the epiblast. C. The cells of the epiblast migrate, detach and slip underneath the epiblast in a process called invagination.These invaginating cells displace the hypoblast and create the endoderm, the epiblast cells that do not invaginate become the ectoderm and the cells that lie between the ectoderm and the endoderm become the mesoderm.
31
what can all adult cells and tissue trace there embryonic origin back to
All adult cells and tissues can trace their embryonic origin back to the three primary germ layers
32
the epiblast that invaginate becomes...
these invaginating cells displace the hypoblast and create the endoderm
33
the epiblast that does not invaginate becomes..
the epiblast cells that do not invaginate become the ectoderm
34
they layer that lies between the ectoderm and endoderm is...
the mesoderm
35
what is neurulation
- this refers to the formation and closure of the neural tube
36
describe the process of neurulation
A. The notochord induces the overlying ectoderm to differentiate into neuroectoderm and form the neural plate. (The notochord forms the nucleus pulposus of the intervertebral disk in adults.) B. The neural plate folds to give rise to the neural tube, which is open at both ends at the anterior and posterior neuropores. The anterior and posterior neuropores connect the lumen of the neural tube with the amniotic cavity. C. The anterior neuropore closes day 25. D. The posterior neuropore closes day 27. E. As the neural plate folds, some cells differentiate into neural crest cells and from a column of cells along both sides of the neural tube. F. The rostal/cephalic part of the neural tube becomes the adult brain. G. The caudal part of the neural tube becomes the adult spinal cord. H. The lumen of the neural tube gives rise to the ventricular system of the brain and central canal of the spinal cord.
37
what do cranial neural crest cells differentiate into
- a variety of cells such as bones of neurocranium, Pia and arachnoid and several components of cranial nerves
38
what do trunk region neural crest cell differentiate into
into a variety of cells such as melanocytes, Schwann cells, dorsal root ganglia and parasympathetic nerves of the gut, abdomen and pelvis.
39
when do the 3 primary Brian vesicles develop
- during week 4
40
where do the 5 secondary brain vesicles develop
The 5 secondary brain vesicles develop during week 6 and form various adult brain derivatives
41
when is the placenta formed
The placenta is formed when the embryo invades the endometrium of the uterus and when the trophoblast forms the villous chorion
42
what are the 3 stages of villous chorion formation
primary, secondary and tertiary chorionic villi.
43
what is the predominant part of the maternal contribution of the placenta
deciduas basalis
44
what is the maternal part of the placenta deviated from
deciduas basalis derided from the endometrium of the uterus located between the blastocyst and the myometrium
45
describe the structure of the maternal placenta
- dark red in colour | - oozes blood due to torn maternal blood vessels
46
what are the components of the foetal placenta
tertiary chorionic villi and then villous chorion
47
what is the tertiary chorionic vili derived from
derived from both the trophoblast and extraembryonic mesoderm
48
where does the villous chorion mostly proliferate
The villous chorion mostly proliferates at the site of the deciduas basalis
49
what is the villous chorion in contrast to
the villous chorion is in contrast to an area of non villus development known as the smooth chorion, surrounded by the deciduas capsularis
50
describe the structure of the foetal surface of the placenta
- characterised by a well vascularised chorionic plate containing the chorion foetal blood vessels - smooth, shiny, light blue and blue pink appearance - 5-8 chorionic foetal blood vessels should be appareant
51
describe the placental membrane in early and late pregnancy
1. In early pregnancy, the placental membrane consists of the syncytiotrophoblast, cytotrophoblast, connective tissue and endothelium of the foetal capillaries. 2. In late pregnancy, the cytotrophoblast and the connective tissue are displaced, leaving the syncytiotrophoblast and foetal capillary endothelium.
52
what does the placental membrane do
The placental membrane separates maternal and foetal blood
53
what does amniotic fluid contain
Amniotic fluid is maternally derived water that contains: electrolytes, carbohydrates, amino acids, lipids, proteins (e.g. α-fetoprotein), urea, creatinine, lactate, pyruvate, foetal urine, foetal feces, and foetal lung liquid.
54
what is amniotic fluid produced by
i. direct transfer from the maternal circulation in response to osmotic and hydrostatic forces ii. Excretion of foetal urine by the kidneys into the amniotic fluid. Kidney defects result in oligohydramnios.
55
what reabsorps amniotic fluid
i. The foetus swallows amniotic fluid, amniotic fluid is absorbed into the GI tract ii. Excess amniotic fluid is removed via the placenta and passed into the maternal blood. Swallowing defects and absorption defects (oesophageal and duodenal atresia) result in polyhydramios.
56
how does the amount of amniotic fluid change throughout pregnancy
It is gradually increased during pregnancy from 50ml at week 12 to 1000ml at term
57
what is oligohydraminors and what causes it
Oligohydramnios may result in foetal deformities and hypoplastic lungs due to increased pressure on the foetal thorax.
58
what is a-fetoprotein
α-fetoprotein is foetal albumin that is produced by the foetal hepatocyte
59
when is a-fetoprotein assessed
- AFP is routinely assayed in amniotic fluid and maternal serum between week 14 and 18 of gestation. - AFP levels change with gestational age, so that proper interpretation of AFP is dependent on the accurate gestational age
60
what are elevated levels of A-fetoprotein associated with
- neural tube defects | - oesophageal or duodenal atresia
61
what are reduced levels of a-fetoprotein associated with
downs syndrome
62
when does blood cell formation occur and what over takes it at the beginning of week 5
- Blood cell formation first occurs within the extraembryonic mesoderm around the yolk sac during week 3 of development. - Beginning of week 5, haemopoiesis is taken over by a sequence of embryonic organs: liver, spleen, thymus and bone marrow.
63
what does the heart develop from
- The heart develops from areas in the mesoderm called the heart forming regions (HFR) near the cephalic end of the embryo.
64
how does the heart develop
- As the lateral folding of the embryo occurs, the Heart Forming Regions will fuse and meet in the midline to form a single cardiac tube.
65
what are the 5 dilations that become apparent along the cardiac tube
``` Sinus venosus Primitive atrium Primitive ventricle Bulbus cordis Truncus arteriosus ```
66
describe heart looping
- The heart tube undergoes a right-ward looping. - Then the endocardial cushions are established that cause the growth of the atrial septum and ventricular septum towards these cushions - . Failure to grow towards the cushions would lead to septal defects. - The truncal and the bulbar ridges grow and twist around each other in a spiral fashion and eventually fuse to from the aortic-pulmonary septum. - This septum divides the truncus arteriosus and bulbar cordis into aorta and pulmonary trunk
67
what does failure to grow towards cushions in heart looping end up with
- . Failure to grow towards the cushions would lead to septal defects.
68
what are the pharyngeal arches
The pharyngeal arches are structures seen in the development of vertebrates, are recognisable precursors for numerous structures
69
when are the pharyngeal arches first seen
- they are first seen during the fourth week of development
70
what do the phargengeal arches look like in the fourth week of development
- They appear as a series of out pouching of mesoderm on both sides of the developing pharynx.
71
in the vertebrae what are the pharyngeal arches derived from
- In vertebrates, the pharyngeal arches are derived from all three germ layers
72
what do the neural crest cells do in the pharyngeal arches
Neural crest cells enter these arches where they contribute to features of the skull and facial skeleton such as bone and cartilage.
73
describe what happens to the pharyngeal arches during development
- During human and all vertebrate development, a series of pharyngeal arch pairs form in the developing embryo. - These project forward from the back of the embryo toward the front of the face and neck. - Each arch develops its own artery, nerve that controls a distinct muscle group, and skeletal tissue. - These grow and join in the ventral midline
74
what are the pharyngeal arches numbered
- The arches are numbed from 1 to 6, with 1 being the arch closest to the head of the embryo, and arch 5 existing only transiently.
75
what does the first pharyngeal arch form
- the first arch, as the first to form, separates the mouth pit or stomodeum from the pericardium. - By differential growth the neck elongates and new arches form, so the pharynx has six arches ultimately.
76
describe the structure of pharyngeal arches
- Each pharyngeal arch has a cartilaginous stick, a muscle component that differentiates from the cartilaginous tissue, - an artery, - a cranial nerve. - Each of these is surrounded by mesenchyme.
77
how do the pharyngeal arches develop
Arches do not develop simultaneously but instead possess a "staggered" development.
78
what separates the phargenal arches
pharyngeal grooves (or clefts) form from the lateral ectodermal surface of the neck region to separate the arches
79
what are the endoderm and ectoderm layer separated by
mesoderm layer
80
what does the pharyngeal apparatus consist of
pharyngeal arches, pouches, grooves and membranes
81
describe the.. - pharyngeal arches - pharyngeal pouch - pharyngeal grooves - pharyngeal membranes
Pharyngeal arches (1-4 & 6) contain mesoderm and neural crest cells. In general, the mesoderm differentiates into muscles and arteries, whereas neural crest cells differentiate into bone and connective tissue. In addition, each pharyngeal arch has a cranial nerve associated with it. Pharyngeal pouches are evaginations of endoderm that lines the foregut (e.g. oral cavity and oesophagus)- internal. Pharyngeal grooves (clefts) are invaginations of ectoderm located between each pharyngeal arch – external. Pharyngeal membranes are structures consisting of ecto-, meso- and endoderm and neural crest cells located between each pharyngeal arch.
82
Pharyngeal arch 1 - nerve - adult derivative
- CN V Mesoderm: muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini, tensor tympani Neural Crest: maxilla, mandible, incus, malleus, zygomatic bone, squamous temporal bone, palantine bone, vomer,
83
Pharyngeal arch 2 - nerve - adult derivative
- CNVII Mesoderm: muscles of facial expression, posterior belly of digastric, stylohyoid, stapedius Neural Crest: stapes, styloid process, lesser horn of hyoid
84
Pharyngeal arch 3 - nerve - adult derivative
- CNIX Mesoderm: stylopharyngeus Neural Crest: greater horn of hyoid
85
Pharyngeal arch 4 - nerve - adult derivative
- CN X - superior laryngeal nerve Mesoderm: muscles of soft palate, muscles of pharynx (expt stylopharyngeus), cricothyroid, laryngeal cartilage Neural Crest: none
86
Pharyngeal arch 6 - nerve - adult derivative
- CN X - recurrent laryngeal nerve Mesoderm: intrinsic muscles of larynx (expt cricothyroid), upper muscles of oesophagus, laryngeal cartilages Neural Crest: none
87
``` describe pharyngeal pouch 1 2 3 4 ```
1- Epithelial lining of auditory tube and middle ear cavity 2- Epithelial lining of palatine tonsil 3- Inferior parathyroid gland, thymus 4 - Superior parathyroid gland
88
describe pharyngeal groove - 1 - 2-4
1 Epithelial lining of external auditory meatus 2-4 Obliterated
89
describe pharyngeal membrane - 1 - 2-4
1 Tympanic membrane 2-4 Obliterated
90
how does the thyroid gland develop
1. In the midline of the floor of the pharynx (tongue), the endodermal lining of the foregut forms the thyroid diverticulum. 2. The thyroid diverticulum migrates caudally (downwards), passing anteriorly to the hyoid bone and laryngeal cartilages. 3. During this migration, the thyroid remains connected to the tongue by the thyroglossal duct, which later obliterates.
91
what is the site of the thyroglossal duct indicated by
the foramen cecum of the tongue
92
what does the tongue have contributions from
- it has contributions from all pharyngeal arches which changes with time
93
what does the tongue initially begin as
The tongue initially begins as swelling rostral to foramen cecum, the median tongue bud.
94
what are the contribution of the pharyngeal arch to the tongue
Arch 1 - oral part of tongue (anterior 2/3). Arch 2 - initial contribution to surface is lost. Arch 3 - pharyngeal part of tongue (posterior 1/3). Arch 4 - epiglottis and adjacent regions.
95
what is the anterior 2/3 of the tongue formed by
- it is formed by pharyngeal arch 1
96
what is the posterior 1/3 of the tongue forced by
Formed by pharyngeal arches 2-4.
97
where does the fusion of the tongue take place
The area of fusion between the anterior 2/3 and posterior 1/3 is indicated by the terminal sulcus
98
where do the intrinsic and extrinsic muscles of the tongue migrate form
- occipital myocytes | - they develop from areas that are not associated with the pharyngeal arches
99
what are the 3 swellings that form the face
The frontonasal prominence The maxillary prominence (pharyngeal arch 1) The mandibular prominence (pharyngeal arch 1)
100
describe the develop meant of the face
1. Bilateral ectodermal thickenings called nasal placodes develop on the ventrolateral aspects of the frontonasal prominence. 2. The nasal placodes invaginate into the underlying mesoderm to form the nasal pits, thereby producing rides of tissue that from the medial nasal prominence and the lateral nasal prominence. 3. A deep groove called the nasolacrimal groove forms between the maxillary prominence and the lateral nasal prominence and eventually forms the nasolacrimal duct and lacrimal sac.
101
what does the inter maxillary segment for
philtrum of the lip, four incisor teeth and the primary palate.
102
how does the inter maxillary segment form
Intermaxillary segment forms when the medial growth of the maxillary prominence pushes the two medial nasal prominences together at the midline
103
how does the secondary palate form
1. The secondary palate forms from outgrowth of the maxillary prominences called the palatine shelves. 2. Initially the palatine shelves project downward on either side of the tongue but later attain a horizontal position and fuse along the palatine raphe to form the secondary palate. 3. The primary and secondary palate fuse at the incisive foramen to form the definite palate. Bone develops in both the primary and anterior part of the secondary palate. 4. Bone does not form in the posterior secondary palate.

Human Development (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions