Embrology

Question 1

Kidney development types

Answer 1

Pronephros (non functional)
Mesonephros (transient and functional)
Metonephros (permanent kidney)

Rudimentary, transient kidneys (nephrotomes) have cavities (nephrocoeles) developing craniocaudally

Question 2

Mesonephros

Answer 2

Appears at 3 weeks, drains into mesonephric duct. Communication breaks down at 8 weeks

Question 3

Urine formation begins?

Answer 3

Weeks 11-12

Question 4

XY development

Answer 4

Week 7 - > Testis determining factor stimulates sex cord (coelomic epithelium)/sertoli.
Week 8 - leydig cells (intermediate mesenchyme) make T.
Tunica albuingea formed (int. meso)
Cord breadk down - >rete testis
Anti-mullarian hormone (sertoli cells) causes paramesonephric to degrade (utriculus prostaticus) and mesonephric duct - > ductus deferens, epidiymus, ejaculatory duct and seminal vesicles.
Week 10 - > phallus elongates, UG folds approach to cover urethra

Question 5

XX development

Answer 5

Week 6, paraseonephric duct appears and pinches off.
In absence of AMH, forms uterine tubes, uterus, upper 1/3 of vagina.

Week 8: No TFD then sec cords regress, vascular stroma in medulla (further development in 4th month)
Week 9: mesonephric degrade, but can remain as cysts (Garter’s ducts)
Week 10: genitalial develop (but UG folds never fuse)

Question 6

Undifferentiated gonads

Answer 6

Week 3 v- > yolk sac to genital ridge (medial on coelomic epithelium)
Undifferentiated until week 6.

Question 7

Gonadal descent

Answer 7

3rd month
Testes goes through inguinal canal. Testes have anteriro double payer of peritoneum (tunica vaginalis).
Ovaries remain intraperitoneal.
Gubernaculum becomes round ligament in XX

Question 8

Renal agenesis

Answer 8

Ureteric bud fails/regresses. Incompatible with life

Question 9

Horseshoe kidney

Answer 9

Inferior poles fuse together

Question 10

UG/rectum separation

Answer 10

Week 8, but still membrane covered.

Question 11

Median umbilical ligament

Answer 11

Remnant of alantois, fibrous cord. Can be patent (urachal fistula) with urine leaking out of umbilicus

Question 12

Medial umbilical ligament

Answer 12

Remnant of umbilical vein

Question 13

ureteric bud gives

Answer 13

Ureter, renal pelvic, major/minor calyx and collecting duct

Question 14

Metanephros gives

Answer 14

Nephron 9other than CD)

Question 15

Neural groove driver

Answer 15

Notocord secretes chordin (morphogen inhibits BMP/TGF beta, they drive epidermal development)

Question 16

Somites make

Answer 16

Skeletal muscle, vertebrae, cartilage

Question 17

Date of gastrulation

Answer 17

15

Question 18

Timing of differentiation of neuro ectoderm and ectoderm

Answer 18

4th week

Question 19

Neural crest cell migration

Answer 19

Week 5

Question 20

PNS neural crest cells

Answer 20

Neurons, sensory/sympathetic/parasympathetic ganglia, plexi, neuroglial cells, scwann cells

Question 21

Endocrine neural crest

Answer 21

Adrenal medulla

Question 22

Pigment neural crest cells

Answer 22

melanocytes

Question 23

Facial bone/cartilage neral crest

Answer 23

Anterior and facial skull cartilage and bone

Question 24

Connective tissue neural crest

Answer 24

Cornea, tooth paillae, dermis, smooth muscle adopse tissue of skin/head/neck
Gland connective tissue
Connective tissue/smooth muscle of aortic arch arteries

Question 25

Trunk cells

Answer 25

Can remain in somite - DRG | If through somite then sympathetic/adrenal medulla

Question 26

Vagal/sacral NC

Answer 26

Enteric ganglia

Question 27

MElanocytes

Answer 27

Dosrolateral neural crests between ectoderm and somites

Question 28

Cardial NC

Answer 28

Form endothelial lining of aortic arches, endocardial cushion, aorticopulmonary septum

Question 29

Cranial NC influenced by

Answer 29

Rhombomeres. | Forms craniofacial mesenchyme, cranial neurons, glia.

Question 30

Middle ear/jaw bone formed from

Answer 30

Pharyngeal arches

Question 31

Viscerocranium

Answer 31

NC cell derived. Makes frontal, nasal, lacrimal, zygomatic, maxilla, incisive, mandible, sphenoid and SQUAMOUS temporal

Question 32

Neurocranium

Answer 32

Paraxial mesoderm (somites). Has parietal, petrous temporal and occipital

Question 33

Laryngeal cartilages

Answer 33

MEsenchyme from lateral plate mesoderm

Question 34

Neuropore closure

Answer 34

Anterior at day 25, posterior at day 28

Question 35

Brain veiscles form

Answer 35

Weeks 3-4

Question 36

Rhombencephalon

Answer 36

Hindbrain - becomes metencephalon (pons/cerebellum, 4th ventricle) and myeloncephalon (medulla/4th ventricle)

Question 37

Metencephalon

Answer 37

Pons/ cerebellum/ 4th ventricle)

Question 38

Myeloncephalon

Answer 38

Medulla/4th ventricle

Question 39

Mesencephalon

Answer 39

Midbrain

Question 40

Procsencephalon

Answer 40

Becomes telencephalon (cerebrum, basal nuclei, lateral ventricles) and diencephalon (dicenephalon, retina, 3rd ventricle)

Question 41

Telencephalon

Answer 41

cerebrum, basal nuclei, lateral ventricles)

Question 42

Dicencephalon

Answer 42

Diencephalon, retina, 3rd ventricle)

Question 43

Brain flexures

Answer 43

Cerical flexure is between hindbrain and spinal cord (transient) Cephalic flexure is at midbrain - remains in adults

Question 44

Stem cell source for spinal cord neurons?

Answer 44

Ependymal layer (neuroepthelial layer/neuroblast layer)

Question 45

Spinal cord development

Answer 45

Marginal layer (white matter) with mantle layer (cell bodies)

Question 46

Mantle layer

Answer 46

Alar plate (sensory reception from NC DRG) and basilar plate (motor cell bodies from mantle)

Question 47

Neuroblasts and glioblasts

Answer 47

Neuroblasts give neurons, glioblasts give astrocytes and olgiodendrocytes

Question 48

Oligodendrocytes come from

Answer 48

Neuroepithelium (ependymal layer)

Question 49

Sulcus limitans

Answer 49

Groove preventing cell bodies migrating accross

Question 50

Spinal cord development complete by

Answer 50

Week 6

Question 51

Neural tube defects seen

Answer 51

Weeks 3-4

Question 52

Spina bifida is

Answer 52

Failure of vertebral arch fusion

Question 53

Spina bifida grading

Answer 53

Minor is occulta, exposed cauda equina but fat pad protects | Spina bifida cystica can be meningocoele (meninges protrude) or myelomeningocoele (meninges plus cauda equina)

Question 54

SB diagnosis

Answer 54

MS-AFP and U/S

Question 55

Encephalocele, anencephaly, hydrocephalus

Answer 55

Encephalocoele is failure of posterior skull fusion Anencephaly is failure for anterior to fuse Hydrocephalus is fluid accumulation in brain - associated with spina bifida