Embryology/Development Flashcards
1
Q
Timeframe for zygote to get into uterus and implant?
A
- 5 days to get into uterus and begin impantation
- 11 days to fully inplant into endometrium
2
Q
Zygote (2)
A
- Egg that’s been fetrilized
- Fertilization occurs in uterine tube’s ampulla
3
Q
Morula (3)
A
- Blastomeres at 16 cell stage
- Inner cell mass (embryoblast) that forms embryo and components of fetal membranes
- Outter cell mass (trophoblast) contribute to fetal membranes and placenta
4
Q
Zona Pellucida Functions (5)
A
- Barrier that prevents multiple fertilizations
- Filter to allow uterine secretions to reach embryo
- Immunological barrier between mother and embyro
- Prevents blastomeres from dissociating
- Prevents premature implantation (before embryo reaches uterine wall)
5
Q
Lacuna (2)
A
- Blood filled spaces in embryotic pole of syncytiotrophoblast
- Form primative uteroplacenta circulation
6
Q
Connecting Stalk (3)
A
- Portion of extraembryonic mesoderm that connects embryo to chorion (becomes fetal portion of placenta)
- Fills space left over from chorionic cavity formation
- Eventaully become umbilical
7
Q
Buccopharyngeal and Cloacal Membranes
A
- Buccopharyngeal becomes mouth
- Cloacal becomes anus
- 2 layers so they’ll rupture
8
Q
Gastrulation (3)
A
- Bilayer becomes 3 germ layers (enod, meso, & ectoderm) once epiblast cells invaginate in the midline
- Primitive streak and primitive pit/primitive node form
- Week 3
9
Q
Endoderm Cells
A
- Develop into: lining of digestive, respiratory, urogenital systems, and pharyngeal pouches of head and neck region
10
Q
Mesoderm Cells
A
- Develops into: skeletal, smooth, & cardiac muscle, most cartilage & bone, dermis of skin, and portion of kidneys & gonads
11
Q
Ectoderm Cells
A
- Develop into: nervous system and epidermis of skin
12
Q
Notochord (3)
A
- Specialized rod of mesoderm cells that migrated rostrally from primitive node/pit
- Forms basis of vertebral column and ends up in nucleus pulposis of discs
- Signals formation of: neural plate, groove, & fold, CNS from endoderm
13
Q
2 vs 3 layered membranes
A
- 2 layered membranes rupture
- 3 layered membranes don’t rupture
14
Q
Cells Migrating from Primitive Streak
A
- Rostral cells of primitive streak form more midline structures (axial muscles & skeleton, and notochord
- Caudal cells form more lateral structures
15
Q
Prechordal Plate
A
- “Head organizer” that forms parts of head and brain
16
Q
Neurulation (3)
A
- Formation of primitive nervous system
- Facilitated by notochord secreting inducing factors
- Ectoderm proliferates and thickens into neural plate
17
Q
Neural Crest Cells Derivatives (9)
A
Derive into:
- spinal, autonomic, and cranial nerve ganglia
- Schwann cells
- Medulla of adrenal gland
- Meninges
- Pigment cells of skin
- Glial cells
- C cells of thyroid
- Conotruncal regions of heart
- Connective tissue, some bones, and dermis of back & head
18
Q
Anterior & Posterior Neuropores
A
- Anterior closes day 25 and causes Exencephaly if done incorrectly
- Posterior closes day 27 and causes Spina Bifidia (on a spectrum) if done incorrectly
19
Q
Paraxial Mesoderm (3)
A
- Most axial
- Form longitudinal columns on each side of notochord/neural tube
- Differentiate into 44 pairs of somites
20
Q
Intermediate Mesoderm (2)
A
- Not extensively developed
- Differentiates into parts of urogenital and reproductive systems
21
Q
Lateral Plate Mesoderm
A
- Most lateral portion of mesoderm
- Somatic (parietal) portion is in contact with ectoderm
- Splanchnic (visceral) portion is in contact with endoderm
22
Q
Somatic (parietal) Mesoderm Contributions (2)
A
- Contributes to:
1. Serosa of body cavities & long bones (appendicular skeleton)
2. Connective tissue of the body wall
23
Q
Splanchnic (visceral) Mesoderm Contributions (3)
A
- Contributes to:
1. Smooth muscle of gastrointestinal system
2. Serosa lining on superficial surface of organs
3. Covers yolk sac after it replaces extraembryonic mesoderm
24
Q
Foregut (1) & Contributions (5)
A
- Most rostral
- Contributes:
1. Lower respiratory system
2. Pharynx
3. Esophagus
4. Stomach
5. Parts of duodenum
25
Midgut (1)
- Becomes remainder of small intestine and much of large intestine
26
Hindgut (1) & Contributions (3)
- Most caudal
- Contributes:
1. Rectum
2. Anal canal
3. Parts of urogenital system
27
Transverse Folding (4)
- Yolk sac pinched off
- Lateral plate mesoderm splits
- Intraembryonic coelom is formed
- 3 guts formed
28
Longitudinal Folding (4)
- Future heart is formed
- Future diaphragm is formed
- Both get forced more caudually
- Caused by rapid nervous system growth
29
Primary Chorionic Villi of Placenta (2)
- Formed by pegs of cytoblast cells protruding into syncytiotrophoblast
- Intervillous spaces in syncytiotrophoblast fill with maternal blood
30
Secondary Chorionic Villi of Placenta (3)
- Transformed from primary chorionic villi when extraembryonic mesoderm invades core of cytotrophoblast
- Embryonic vessels from from mesodermal cells within cytotrophoblast's pegs of tissue
- BV's developed in connecting stalk become umbilical vessels
31
Tertiary/Stem Chorionic Villi of Placenta (3)
- Villi with capilary networks
- Capillaries make vascular connections with embryonic heart after week 3
- Cytotrphoblast cells penetrate synctiotrophoblast and come in contact with the maternal endometrium to anchor the placenta
32
Specialized Mesoderm Regions
- Paraxial
- Intermediate
- Lateral
33
Paraxial Region Gives Rise To?
- Axial skeleton
- Skeletal muscles
- Some dermis of skin
34
Lateral Plate Mesoderm Gives Rise To?
- Pectoral girldle
- Pelvis girldle
- Sternum
- Long bones of limbs
35
Somites (4)
- From paraxial mesoderm
- 44 pairs formed
- Occipital somites form occipital bone
- Most caudal occipital somite contributes to C1 vertebrae
36
Somite Regions & What They Contribute To
**Sclerotome** - axial skeleton
**Myotome** - skeletal muscles
**Dermatome** - sermis of skin in back
37
Resegmentaion of Somites (3)
- Splits into rostral and caudal parts around spinal nerves
- Rostral part fuses with Caudal part below it
- C1 nerve is superior to C1 vertebra because the caudal part fuses to occipital bone
38
Rib Development (2)
- From **costal processes** of somites that develop thoracic vertebrae
- Elongate in week 5
39
Sternum Development (3)
- Lateral plate somatic mesoderm differentiates to **mesenchyme** (connective tissue)
- Mesenchyme migrates anteriorly and condenses into **sternal bars**
- Sternal barts fuse cranial to cuadal (like a zipper)
40
Hypomere (3)
- Muscles of body wall and limbs
- Formed from **ventrally** migrating myotome mass
- Innervated by **ventral** primary rami of spinal nerves
41
Epimere (3)
- True back muscles
- Fromed from **dorsally** migrating myotome
- Innervated by **doral** primary rami of spinal nerves
42
Dorsal Muscle Mass of Limbs (3)
- From hypomere split
- Extensors, supinators, abductors
- Innervated by **dorsal branches** of the **ventral** primary rami (posterior divisions of brachial plexus)
43
Ventral Muscle Mass of Limbs (3)
- From hypomere split
- Flexors, pronators, adductors
- Innervated by **ventral branches** of **ventral** primary rami (anterior division of brachial plexus)
44
Limb Rotation During Development
- Upper limbs rotate laterally
- Lower limbs rotate medially
45
Meromelia
- absence of part of the limb
46
Polydactyly
- Extra digit
47
Amelia
- Absence of one or more limbs
48
Syndactyly
- Fusing of digits
- Simple is cutaneous fusing
Complex is bone or cartilaginous union
