Chick Organogenesis

Question 1

The process of “organ formation,” where the three embryonic germ layers (ectoderm, mesoderm, endoderm) differentiate into specialized tissues and organs.

Answer 1

Organogenesis (Definition)

Question 2

Occurs during gestation (pregnancy in mammals, incubation in birds).

Answer 2

Timing of Organogenesis

Question 3

Ectoderm, mesoderm, and endoderm; the three primary layers from which all tissues and organs develop.

Answer 3

Germ Layers

Question 4

Gives rise to the epidermis, nervous system, and sensory organs.

Answer 4

Ectoderm (General)

Question 5

Develops into connective tissue, muscle, bone, circulatory system, reproductive organs, and excretory system.

Answer 5

Mesoderm (General)

Question 6

Forms the lining of the digestive and respiratory tracts, liver, pancreas, and other glands.

Answer 6

Endoderm (General)

Question 7

Organs are formed from groups of cells from one or more germ layers. Cells communicate and tissues differentiate into specialized tissues and then organs.

Answer 7

Process of Organ Formation

Question 8

The size and shape of organs are precisely controlled; requires proper cell communication and tissue differentiation.

Answer 8

Factors Affecting Organogenesis

Question 9

Epidermis, skin glands, hair, nails.

Answer 9

Ectoderm Derivatives: Surface Ectoderm

Question 10

Central nervous system (brain, spinal cord).

Answer 10

Ectoderm Derivatives: Neural Tube

Question 11

Peripheral nervous system, sensory ganglia, facial skeleton, pigment cells.

Answer 11

Ectoderm Derivatives: Neural Crest

Question 12

Notochord.

Answer 12

Mesoderm Derivatives: Chordamesoderm

Question 13

Urinary system, gonads.

Answer 13

Mesoderm Derivatives: Intermediate Mesoderm

Question 14

Somatic mesoderm: parietal pleura, peritoneum, pericardium (lining of body cavities); Splanchnic mesoderm: heart, blood vessels, visceral pleura, peritoneum, pericardium, connective tissue of gut, yolk sac mesoderm.

Answer 14

Mesoderm Derivatives: Lateral Plate Mesoderm

Question 15

Somites (dermatomyotome, sclerotome): dermis, skeleton, body muscles.

Answer 15

Mesoderm Derivatives: Paraxial Mesoderm

Question 16

Digestive system, respiratory system.

Answer 16

Endoderm Derivatives: Primitive Gut

Question 17

Endoderm of yolk sac.

Answer 17

Endoderm Derivatives: Extraembryonic Endoderm

Question 18

Primordial germ cells (oocytes, sperm).

Answer 18

Germ Cells

Question 19

Early development of brain vesicles, optic cup, heart, somites, limb buds; key structures: prosencephalon, mesencephalon, rhombencephalon, optic vesicle, auditory vesicle, heart, somites, foregut.

Answer 19

48-hour Chick Embryo

Question 20

Further development of body shape and organs; wing bud, leg bud, allantois, cranial nerves more defined.

Answer 20

72-hour Chick Embryo

Question 21

Continued growth and differentiation; visible eye, ear, brain regions, heart, limb buds.

Answer 21

6-day Chick Embryo

Question 22

Development of facial features, limbs, body form; upper/lower beak, eye, external auditory meatus, knee joint apparent.

Answer 22

9-day Chick Embryo

Question 23

Significant development of feathers and body size; refined limb structure and facial features.

Answer 23

12-day Chick Embryo

Question 24

Near hatching; embryo is largely developed, fills the egg, prominent features.

Answer 24

18-day Chick Embryo

Question 25

Incubate fertilized eggs for 48, 72 hours, 6, 9, 12, 18 days; observe, photograph, label, describe, and compare embryos.

Answer 25

Incubation Procedure

Question 26

"Organ formation."

Answer 26

Literal meaning of "organogenesis"

Question 27

Ectoderm, mesoderm, endoderm.

Answer 27

Three primary embryonic germ layers

Question 28

Ectoderm (specifically neural ectoderm).

Answer 28

Germ layer for central nervous system

Question 29

Endoderm.

Answer 29

Germ layer for lining of digestive tract

Question 30

Somites: dermis, skeleton, body muscles.

Answer 30

Structures from paraxial mesoderm

Question 31

Chordamesoderm (a subdivision of mesoderm).

Answer 31

Notochord is derived from

Question 32

Give rise to peripheral nervous system and sensory ganglia.

Answer 32

Primary function of neural crest cells

Question 33

48 hours.

Answer 33

Incubation time for 48-hour chick embryo

Question 34

Eye, ear, brain regions, heart, limb buds.

Answer 34

Structures visible in a 6-day chick embryo

Question 35

Embryo is largely developed, fills the egg, prominent features visible.

Answer 35

Prominent feature by 18 days incubation

Question 36

Cells become specialized via gene expression and signaling; tissues organize into organs through communication and positional cues.

Answer 36

Cellular differentiation and tissue formation

Question 37

Ectoderm: skin, nervous system; Mesoderm: muscle, bone, heart; Endoderm: gut lining, liver, pancreas.

Answer 37

Compare/contrast germ layer derivatives

Question 38

48h: brain/heart/somites; 72h: limb buds, cranial nerves; 6d: eyes/ears/limbs; 9d: facial/limb features; 12d: feathers/body size; 18d: nearly hatched, filled egg.

Answer 38

Major chick embryo milestones (48h–18d)

Question 39

Migrates from neural tube; forms PNS, facial skeleton, pigment cells, adrenal medulla, etc.

Answer 39

Role of neural crest in vertebrates

Question 40

Paraxial: somites (muscle, bone); Intermediate: urinary/gonads; Lateral plate: body cavity linings, heart, blood vessels.

Answer 40

Importance of mesoderm regions

Question 41

Process of organ formation during embryonic development.

Answer 41

Organogenesis

Question 42

Three primary layers (ectoderm, mesoderm, endoderm) in the early embryo from which all tissues and organs develop.

Answer 42

Germ Layers

Question 43

Outermost germ layer; forms epidermis, nervous system, sensory organs.

Answer 43

Ectoderm

Question 44

Middle germ layer; forms connective tissue, muscle, bone, circulatory system, internal organs.

Answer 44

Mesoderm

Question 45

Innermost germ layer; forms lining of digestive/respiratory tracts, glands.

Answer 45

Endoderm

Question 46

Process by which less specialized cells become more specialized cell types.

Answer 46

Differentiation

Question 47

Flexible rod from chordamesoderm; provides support and signaling in embryo.

Answer 47

Notochord

Question 48

Dorsal tube from neural ectoderm; develops into brain and spinal cord.

Answer 48

Neural Tube

Question 49

Migratory cells from dorsal neural tube; form PNS, facial skeleton, pigment cells, etc.

Answer 49

Neural Crest

Question 50

Paired blocks of paraxial mesoderm; give rise to dermis, skeletal muscle, vertebrae.

Answer 50

Somites

Question 51

Extraembryonic membrane for waste disposal/gas exchange in birds/reptiles; umbilical cord in mammals.

Answer 51

Allantois

Question 52

Extraembryonic membrane for nutrition in birds/reptiles; blood cell formation/nutrient transfer in mammals.

Answer 52

Yolk Sac