Chapter 5 & 6

Question 1

Greek for the little stomach

Answer 1

Grastula

Question 2

Caudal migration of epiblasts forms the ______ at the caudal midline of the blastocyst.

Answer 2

primitive streak

Question 3

Composition of Primitive Streak

Answer 3

Hensen’s node (primitive node or primitive knot)
Primitive groove (central depression)
Primitive folds (lateral elevations)

Question 4

What are the 3 primary germ layers?

Answer 4

Ectoderm, Mesoderm, Endoderm

Question 5

What happens to the remaining epiblasts of the primitive streak?

Answer 5

Give rise to ectoderm

Question 6

Migrating cells from primitive streak entering the coelom will become ______

Answer 6

Mesoderm

Question 7

Which germ layer forms the epidermis of skin, epithelium of oral and nasal cavities, nervous system and sense organs?

Answer 7

Ectoderm

Question 8

Which germ layer forms the muscles, connective tissues including bones and components of circulatory, urinary and genital systems?

Answer 8

Mesoderm

Question 9

Which germ layer forms the mucosal epithelium and glands of respiratory and digestive systems?

Answer 9

Endoderm

Question 10

When does the primitive streak in avian embryo reach its maximum length?

Answer 10

18 hours of incubation

Question 11

Continuous migration of epiblast from the primitive streak and non-addition of new epiblasts to the primitive streaks results to ________

Answer 11

regression of primitive streak

Question 12

Primitive streak of avian embryo disappears by _________ of incubation

Answer 12

60 hrs (2.5 days)

Question 13

True or false in most primitive vertebrates the notochord is the chief axial supporting structure of the body.

Answer 13

True

Question 14

True or false the formation of notochord induces the formation of the head, nervous system and somite.

Answer 14

True

Question 15

True or false the formation of notochord does not indicate the future location of vertebral column in higher vertebrates.

Answer 15

False

Question 16

What is the ultimate fate of the notochord?

Answer 16

Nucleus pulposus of intervertebral disc.

Question 17

What is the Morphogenic process that gives rise to the 3 primary germ layers: ectoderm, mesoderm and endoderm?

Answer 17

Gastrulation

Question 18

What is the stage of early embryonic development characterized by early development of CNS, formation of the head process and foregut, formation of somites and formation of cardiac tube?

Answer 18

Neurulation

Question 19

The depressed midregion of the neural plate is called

Answer 19

neural groove

Question 20

The raised edges at the neural plate

Answer 20

neural folds

Question 21

Cavity of neural tube

Answer 21

neural canal

Question 22

Bilaterally some cells from neuroectoderm excluded during fusion of neural folds lie dorsolateral to the neural tube and constitute the ________

Answer 22

neural crest

Question 23

The neural tube give rise to _______

Answer 23

CNS, brain and spinal cord

Question 24

development of 2 or more embryos in a dam that normally gives birth to
one offspring per gestation.

Answer 24

embryonic Duplication or Twinning

Question 25

result from fertilization of separate ova.

Answer 25

Free separate symmetrical dizygotic or polyzygotic twins

Question 26

from two separate zygotes.

Answer 26

Dizygotic twins

Question 27

similar to dizygotic twins except that the number of zygotes is more than two. Ex: triplets

Answer 27

Polyzygotic twins

Question 28

derived from a single zygote

Answer 28

Free or conjoined, symmetrical, monozygotic twins

Question 29

the zygote duplicates itself and the twins separate completely.

Answer 29

Free symmetrical monozygotic twins or identical twins -

Question 30

– the zygote incompletely divides.

Answer 30

Conjoined or fused symmetrical monozygotic twins

Question 31

are identified according to the site of attachment

Answer 31

Diplopagus or Siamese twins

Question 32

twins are attached at the sternal region facing each other with partially fused hearts.

Answer 32

Thoracopagus

Question 33

twins are attached at the abdomen, often with partially fused intestines

Answer 33

Abdominopagus

Question 34

twins are attached at the pelvis or sacrum back-to-back

Answer 34

Pygopagus

Question 35

twins are attached in the head region.

Answer 35

Cephalopagus

Question 36

abnormally fused symmetrical monozygotic twins where the axial structures are duplicated

Answer 36

Monster

Question 37

two heads

Answer 37

Dicephalus

Question 38

two faces

Answer 38

Diprosopus

Question 39

two tails

Answer 39

Dicaudatus

Question 40

four thoracic limbs

Answer 40

Tetrabrachius

Question 41

four pelvic limbs

Answer 41

Tetrascelus

Question 42

originate from monozygotic or dizygotic twins. Has one normal and one rudimentary twin

Answer 42

Free asymmetrical twins

Question 43

Fused twins with one normal individual called autosite and an extra body part, the parasite attached to it

Answer 43

Conjoined asymmetrical twins

Question 44

where an extra pelvic limb is attached to the back of the normal twin

Answer 44

Notomelus

Question 45

elliptical region of specialized thickened ectoderm is referred to as

Answer 45

neural plate

Question 46

neural folds continue to elevate, appose in the midline, and, eventually, fuse to create the

Answer 46

neural tube