Structures in a 24-hr chick embryo

Question 1

Paired longitudinal mass of cells which started to fuse in the region of the future midbrain.

Answer 1

Neural folds

Question 2

The anterior region of the developing neural tube which remained open for a time.

Answer 2

Anterior neuropore

Question 3

Space which appeared like a letter V flanked by neural folds.

Answer 3

Neural groove

Question 4

A clear region above the head fold delineated by the lateral horn of the mesoderm.

Answer 4

Proamnion

Question 5

A broad but short light “veil” on the anterior portion of the open neural tube. It is defined by a thick dark concave layer of a head ectoderm.

Answer 5

Head fold

Question 6

An external bay beneath the head of embryo. It resulted from the folding of somatopleure.

Answer 6

Subcephalic pocket

Question 7

Unevenly thickened recurved lines above the margin of anterior intestinal portal.

Answer 7

Thickened splanchnic mesoderm

Question 8

Thin line on each side of the head region. It appears like translucent veil beneath the head fold and continuous with the tip of the margin of splanchnic mesoderm.

Answer 8

Margin of foregut

Question 9

Paired blocks of cells between the neural folds and neural plate.

Answer 9

Somites

Question 10

Vertical mass of undifferentiated cells below the last formed somites.

Answer 10

Unsegmented mesoderm

Question 11

Elongated tube flanked by the neural folds. It is larger at the posterior end than the anterior.

Answer 11

Notochord

Question 12

Dark mass of cells below the notochord.

Answer 12

Hensen’s node

Question 13

Short thin line below the Hensen’s node.

Answer 13

Primitive streak

Question 14

A narrow elliptical cavity surrounded by a thick dense layer of cells below the neural folds.

Answer 14

Foregut

Question 15

Median portion of the ectoderm that is in contact with the floor of the foregut.

Answer 15

Oral plate

Question 16

Rounded structure in which the neural folds unite enclosing a central cavity, the neural cell. This is the region of the future midbrain.

Answer 16

Neural tube

Question 17

Lighter-staining cells scattered around the neural tube and other structures. The nuclei are the only ones visible. There are is a space around these cells.

Answer 17

Head mesenchyme

Question 18

Paired space ventrolateral to the foregut.

Answer 18

Amnio-cardiac vesicle

Question 19

Double layers of cells below the subcephalic pocket.

Answer 19

Splanchnopleure

Question 20

A large median space lined with endoderm. It leads the pharyngeal pouches on both sides.

Answer 20

Anterior intestinal portal

Question 21

Fingerlike spaces dorsolateral to the anterior intestinal portal. These are formed by the evagination of the pharyngeal wall.

Answer 21

Pharyngeal pouches

Question 22

A wide chamber continuous with the foregut. It is a floorless gut, appearing as a large space diverging on the upper sides of the embryo.

Answer 22

Midgut

Question 23

Layer of cells parallel to the ectoderm. This fused with the splanchnic mesoderm to enclose the future pericardial coelom.

Answer 23

Somatic mesoderm

Question 24

Thickened splanchnic mesoderm ventrolateral to the anterior intestinal portal. Level of somite.

Answer 24

Cardiac primordia

Question 25

A thin and short strip of cells connected to the somites. They are also called nephrotome.

Answer 25

Intermediate mesoderm

Question 26

Paired layers of cells connected to the nephrotome. They split into two layers: somatic and splanchnic.

Answer 26

Lateral plate mesoderm

Question 27

A narrow cavity inside the lateral plate mesoderm.

Answer 27

Coelom

Question 28

A shallow v-shaped cavity in the median region bounded by the primitive folds.

Answer 28

Primitive pit

Question 29

Region surrounding the embryo where yolk and blood islands are found.

Answer 29

Area opaca vasculosa

Question 30

Large cord of cells lateral to the mesenchyme. Thee appear as coarse, dense granules scattered around the area pellucida.

Answer 30

Blood islands

Question 31

Clear region lateral to the area opaca vasculosa. It is free of mesoderm and blood islands.

Answer 31

Area opaca vitellina