General Embryology

Question 1

Fertilisation occurs in the.

Answer 1

Ampulla of the Fallopian tube.

Question 2

What happens when the morula enters the uterine cavity.

Answer 2

Fluid from the uterine cavity enters the morula an divides it into

1. Outer cell mass - trophoblast
2. Inner cell mass - embryoblast

Question 3

Outer cell mass differentiates into.

Answer 3

1. Syncitiotrophoblast- cell walls absent/ scattered nucleus

2. Cytotrophoblast - cell walls are distinct/ 1 nucleus in each cell

Question 4

Inner cell mass differentiates into.

Answer 4

1. Epiblast - tall columnar cells

2. Hypoblast - cuboidal cells

Question 5

Rounded anterior end of primitive streak.

Answer 5

Primitive knot / node.

Question 6

Depression in the primitive node.

Answer 6

Blastopore/ primitive pit.

Question 7

Persistent primitive streak leads to.

Answer 7

Sacrococcygeal teratomas.

Question 8

Formation of notochord.

Answer 8

Formed in the mesoderm.

Extends from primitive knot to the prochordal plate.

Question 9

Remnants of notochord are seen in.

Answer 9

1. Nucleus pulposus of the inter-vertebral disc.

Question 10

Sites where ectoderm and endoderm are fused.

Answer 10

Prochordal plate and cloacal membrane.

Question 11

Intra-embryonic mesoderm is divided into.

Answer 11

1. Par-axial mesoderm.
2. Intermediate plate mesoderm.
3. Lateral plate mesoderm.

Question 12

Par-axial mesoderm forms.

Answer 12

Somites which further differentiate into dermomyotomes and sclerotome.

Dermomyotomes - forms dermis and skeletal muscle.
Sclerotomes - forms vertebral column and ribs.

Question 13

Intermediate plate mesoderm forms.

Answer 13

Genito-urinary system.

Question 14

Lateral plate mesoderm forms.

Answer 14

Encloses a cavity - Intra-embryonic coelom

Which forms pleural, peritoneal and pericardial cavities.

Question 15

Anterior neuropore closes by ? Failure of closure ?

Answer 15

25th day of IU life.

Anencephaly.

Question 16

Posterior neuropore closes by ? Failure of closure ?

Answer 16

28th day of IU life.

Spina bifida.

Question 17

Derivatives of neural crest cells. (13 structures)

Answer 17

Adrenal medulla.
Leptomeninges - arachnoid and Pia mater.
Odontoblasts
Melanocytes.
Schwann cells.
Dorsal root ganglia.
Autonomic ganglia.
Skeleton of the face.
Nerves of the pharyngeal arches.
Endocardial cushions of the heart.
Aortico-pulmonary septum.
Corneal stroma.
Parafollicular C-cells of thyroid.