Week 2 Embryology 2 Flashcards

Question

The Streak organizes embryo

Answer 1

along a craniocaudal axis

Answer 2

Hypoblast | frontal

Answer 3

In embryo | anus

Answer 4

Two primitive streaks

Answer 5

Forms from a proliferation of epiblast cells Cells migrate to center of embryo Streak elongates with cells added to the caudal end

Answer 6

Towards the middle of the cell

Answer 7

(groove) | Functions like a sieve, allows them to get underneath

Answer 8

Starts as a hat, above brain, during folding, moves to correct place

Answer 9

Epiblast NOT hyphoblast

Answer 10

Teratoma Can have teeth, hair, bone, etc. Since it comes from all 3 germ layers, can contain anything. Removed after birth, can present some issues Ex. can put strain on heart

Answer 11

``` Remnants of primitive streak Derivatives of all 3 germ layers 'Common' tumor type in newborn (1:35000) Bizarre mixture of tissue types (all layers) Like spina bifida can do fetal surgery ```

Answer 12

Germ layer problem. Usually fetus is not viable *Mesoderm problem Total or parial failure of development of the lower vertebrae including sacrum. Also known as sacral agenesis, sacral regression, caudal aplasia, caudal regression sequence, sirenomelia - once thought to be all of these.

Answer 13

Caused by abnormal gastrulation Mesoderm migration is disturbed In about 16% of cases (relative risk for a child of a diabetic mother: about 1%)

Answer 14

1. complete absence of the sacrum and lower vertebrae, multiple congenital anomalies and association with maternal diabetes 2. agenesis of distal sacral or coccygeal segments 3. hemisacral dysgenesis with presacral teratoma 4. hemisacral dysgenesis with anterior meningocele

Answer 15

Herniation of spinal cord cover

Answer 16

replaces the primitive streak | Forms in middle layer - Mesoderm

Answer 17

Migrating cells also form a median column of cells, posterior to head region Originally called the notochordal process Will become the notochord Also called the chordamesoderm (British)

Answer 18

Structure - acts as a rigid axis around which the embryo develops Skeletal - foundation upon which the vertebral column will form Forms part of the intervetrebal discs Induction - will bring about formation of the neural tube (future nervous system)

Answer 19

The disk part of the spinal cord

Answer 20

Primary malignant bone cancer, usually at base of skull or in sacrum Develops from remnants of embryonic notochord Avg age of diagnosis - 49 for skull, 69 for spine Avg survival - 7 years Affects men more frequently than women

Answer 21

Benign but invasive skull base tumors arise from bone and often grow through dura. Most can be debulked through an endonasal approach. Because of their invasivness, many require radiotherapy to control further growth.

Answer 22

Overlying ectoderm to form neural plate --> neural tube. | Tells ectoderm to become the nervous system

Answer 23

Specific signaling molecules are produced by cells of the notochord that elicit a response in the overlying ectoderm to begin the process of neurulation

Answer 24

Organisms are formed by interactions between cells and tissues When one group of cells/tissues causes another set of cells/tissues to change their fate is called this.

Answer 25

Group of cells or tissues that send signal in induction

Answer 26

Group of cells or tissues that receive signal in induction

Answer 27

During Induction when the Inducer and Responder 'talk' tack and forth

Answer 28

Most signaling molecules are proteins synthesized by one cell that diffuses over short distances to contact other cells Growth and differentiation factors (GDFs)

Answer 29

Growth and Differentiation Factors

Answer 30

Specific molecules are produced by cells of the notochord that elicit a response in the overlying extoderm to begin the process of neurulation Separates the ectoderm into two parts * Epithelial (surface) ectoderm * Neural ectoderm

Answer 31

formation of the neural tube

Answer 32

* Epithelial (surface) ectoderm | * Neural ectoderm

Answer 33

1. Thickening of the neural plate 2. Formation of the neural folds and groove 3. Convergence of the lateral margins of the neural plate - Neural crest begins to 'pinch off' of the neural folds and form other structures 4. Fusion of the neural plate to form the neural plate

Answer 34

Migrates extensively to form a variety of structures throughout the body

Answer 35

(Surface) Epidermis, hair, nails, tooth enamel, cutaneous glands (sweat, oil, ceruminous), mammary glands, anterior pituitary, lens of eye, inner ear, sensory nasal epithelium

Answer 36

Derived from neural plate and neural folds

Answer 37

CNS (brian, spinal cord), retina, pineal body, posterior pituatary

Answer 38

Sensory ganglia and nerves of PNS, Schwann cells, adrenal medulla, pigment cells, pharyngeal arch cartilages. Components of the eye, skull, teeth and skin. **Some argue this is the fourth germ layer

Answer 39

Neuroectoderm Neural crest

Answer 40

Problems with surface ectoderm Group of about 150 heritable disorders that affect the ectoderm, outer layer of tissue in a developing baby. When child has at least two types of abnormal extodermal features, the child is identified as being affected by an 'ED' syndrome

Answer 41

Neural crest disorders Diseases of melanocyte development, function and survival Ex. Piebaldism, Albinism, Vitiligo

Answer 42

``` Pigmentary Disorder (from neural crest issue) characterized by a congenital white forelock and multiple symmetrical hypopigmented and depigmented areas ```

Answer 43

Most are autosomal recessive Global reduction or absence of pigment in skin, hiar and eyes or eyes only (ocular) Eye conditions often include: nystagmus, strabismus, light sensitivity due to lack of pigment

Answer 44

Affects only eyes

Answer 45

Affects skin, hair and eye

Answer 46

Need melanin for muscle, so this causes problem | Ex. nystagmus, strabismus

Answer 47

Pigmentary Disorder Loss of melanocytes Autoimmune disorder Other support for autosomal dominant iheritance with variable expression and incomplete penetrance

Answer 48

Prosencephalon

Answer 49

Mesencephalon

Answer 50

Rhombencephalon

Answer 51

Cerebellum

Answer 52

Important for position and movement in space

Answer 53

Autonomic control of nervous system and heart beating

Answer 54

(NTDs) | When there is a connection from neural and ectoderm

Answer 55

Cranial day 24 | Caudal day 27

Answer 56

aka Craniorachischisis | Cranial doesn't close, can be born alive and live for awhile

Answer 57

Folding of head goes wrong so spine is hyperextended Extreme retroflexion of head, short/absent neck Facial skin connected directly to the skin of the chest Do not survive.

Answer 58

``` Bones don't fuse so that some of the contents can herniate Cranium bifida Most common in occipital region *Meningoenephalocele *meningohydroencephalocele ```

Answer 59

herniation contains meninges and brain

Answer 60

Herniation contains meninges, brain and ventricular system

Answer 61

Herniation of cerebellar vermis or tonsils through the foramen magnum blocking the flow of CSF *can be associated with neural tube defect, isn't one on it's own

Answer 62

Failure of closure of Caudal Neuropore

Answer 63

1. Spina Bifida 2. S.B. Occulta 3. S.B. Meningocele 4. S.B. Meningomyelocele

Answer 64

Failure of neural arches to form Spectrum disorder. The lower the defect, the better the outcome Usually: urinary/bowel dysfunction, range of locomotor difficulties and reduced sensation

Answer 65

Arches absent, tube is normal

Answer 66

Dura and arachnoid also protrude

Answer 67

Neural tissue also protrudes

Answer 68

Daily intake of 0.4mg of folic acid (folate) will decrease 70% of neural tube defects

Answer 69

AFP Is produced in the fetal liver. In a fetus with open NTD, AFP leaks across the defect into the amniotic fluid and across placenta into the maternal serum.