Repro - Embryology (Embryologic derivatives & Organ morphogenesis)

Question 1

What are 3 major derivatives/aspects of ectoderm?

Answer 1

(1) Surface ectoderm (2) Neuroectoderm (3) Neural crest

Question 2

What are 6 derivatives of surface ectoderm?

Answer 2

(1) Adenohypophysis (from Rathke pouch); (2) lens of eye; (3) epithelial linings of oral cavity, sensory organs of ear, and olfactory epithelium; (4) epidermis; (5) anal canal below the pectinate line; (6) parotid, sweat, and mammary glands

Question 3

What is craniopharyngioma? What are its distinguish features? To what germ layer does it apply?

Answer 3

Benign Rathke pouch tumor with cholesterol crystals, calcifications; (Surface) Ectoderm

Question 4

What are derivates of the neuroectoderm?

Answer 4

(1) Brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), (2) retina and optic nerve, (3) spinal cord.

Question 5

What system results from neuroectoderm?

Answer 5

Neuroectoderm - think CNS

Question 6

What are 7 derivatives of the neural crest?

Answer 6

(1) PNS (dorsal root ganglion, cranial nerves, celiac ganglion, Schwann cells, ANS), (2) melanocytes, (3) chromaffin cells of adrenal medulla, (4) parafollicular (C) cells of thyroid, (5) pia and arachnoid, (6) bones of the skull, (7) odontoblasts, aorticopulmonary septum

Question 7

From what germ layer does neural crest arise? What kinds of structures result from neural crest?

Answer 7

Neural crest - think PNS and non-neural structures nearby

Question 8

What are 15 derivatives of mesoderm?

Answer 8

(1) Muscle, (2) bone, (3) connective tissue, (4) serous linings of body cavities (e.g., peritoneum), (5) spleen (derived from foregut mesentery), (6) cardiovascular structures, (7) lymphatics, (8) blood, (9) wall of gut tube, (10) vagina, (11) kidneys, (12) adrenal cortex, (13) dermis, (14) testes, (15) ovaries

Question 9

What induces ectoderm to form neuroectoderm? What is another name for neuroectoderm?

Answer 9

Notochord induces ectoderm to form neuroectoderm (neural plate)

Question 10

What is the only postnatal derivative of notochord? From which germ layer is notochord derived?

Answer 10

Its only postnatal derivative is the nucleus pulposus of the intervertebral disc; Mesoderm

Question 11

What are mesodermal defects?

Answer 11

(1) Vertebral defects (2) Anal atresia (3) Cardiac defects (4) Tracheo-Esophageal fistula (5) Renal defects (6) Limb defects (bone and muscle); Think: “Mesodermal defects = VACTERL”

Question 12

What are 3 derivatives of the endoderm?

Answer 12

(1) Gut tube epithelium (including anal canal above the pectinate line), (2) most of urethra (derived from urogenital sinus), (3) luminal epithelial derivatives (e.g., lungs, liver, gallbladder, pancreas, eustachian tube, thymus, parathyroid, thyroid follicular cells).

Question 13

Name 7 types of errors in organ morphogenesis.

Answer 13

(1) Agenesis (2) Aplasia (3) Hypoplasia (4) Deformation (5) Disruption (6) Malformation (7) Sequence

Question 14

What is agenesis, and what causes it?

Answer 14

Absent organ due to absent primordial tissue

Question 15

What is aplasia?

Answer 15

Absent organ despite presence of primordial tissue

Question 16

What is hypoplasia?

Answer 16

Incomplete organ development; primordial tissue present

Question 17

What is deformation? When does it occur?

Answer 17

Extrinsic disruption; occurs after the embryonic period.

Question 18

What is disruption? What is an example of this?

Answer 18

Secondary breakdown of a previously normal tissue or structure (e.g., amniotic band syndrome)

Question 19

What is malformation? When does it occur?

Answer 19

Intrinsic disruption; occurs during the embryonic period (weeks 3-8)

Question 20

What is sequence in the context of organ morphogenesis? What is an example of this?

Answer 20

Abnormalities result from a single primary embryological event (e.g., oligohydramnios –> Potter sequence)