6. Each of the following statements concerning the blastocyst is true, EXCEPT:
A
– contains the outer layer called the trophoblast, from which the chorion arises; B – is
surrounded by the zona pellucida before implantation; C
– lacks its own cavity; D –
contains the inner cell mass called the embryoblast, from which the embryo proper arises;
E
– lies in the uterine secretions until it is attached to the endometrium.
7. Each of the following statements concerning the first stage of gastrulation is true,
EXCEPT:
A
– embryoblast is transformed into the bilaminar disk; B – delamination is a mechanism of
this stage; C
– epiblast will give rise to three germ layers; D – hypoblast will be displaced
to extraembryonic regions; E
– occurs during the first week of development.
8. Each of the following statements concerning the second stage of gastrulation is
true, EXCEPT:
A
– occurs on the 7th day of development; B – morphological changes take place only in
epiblast; C
– proliferation and migration of epiblastic cells give rise to the primitive streak
with a primitive groove; D
– the primitive streak cells migrate through the primitive groove
inwardly between epiblast and hypoblast to form endoderm and mesoderm; E
– the cells
that remain in epiblast after migration are refered to as ectoderm.
9. Each of the following statements concerning the notochord is true, EXCEPT:
A
– is formed by cell migration through the primitive knot; B – looks like a cellular rod that
grows between ectoderm and endoderm from the primitive knot towards the cranial end; C
– forms the midline axis of the embryo; D – gives rise to the embryo skeleton; E –
degenerates, but persists as the nucleus pulposus of intervertabral disks.
10. Each of the following statements concerning the mesoderm differentiation is
true, EXCEPT:
A
– somites divide into the myotome, dermotome, and sclerotome; B – the somite cord
differentiates into the nephrogonadotome; C
– coelom appears in the paraxial mesoderm;
D
– the somatopleure and splanchnopleure surround the coelom; E – some cells leave the
mesoderm and become the mesenchyme.
11. Each of the following statements concerning the mesoderm differentiation is
true, EXCEPT:
A
– myotome gives rise to skeletal muscles; B – dermotome gives rise to the skin dermis;
C
– sclerotome gives rise to the skeleton; D – nephrogonadotome gives rise to the kidney
and gonads; E
– coelom will become the abdominal cavity.
12. Each of the following statements concerning the mesoderm and mesenchyme
differentiation is true, EXCEPT:
A
– somatopleure and splanchnopleure give rise to the mesothelium lining serous cavities;
B
– mesenchyme develops into blood, lymph, and blood vessels; C – endocardium is
derived from mesenchyme; D
– myocardium and epicardium arise from mesenchyme; E –
splanchnopleure takes part in the adrenal cortex development.
13. Each of the following statements concerning the cell determination and
differential genome activity is true, EXCEPT:
A
– include changes in cell structure, biochemistry, and functions; B – they determine the
pathway of cell differentiation; C
– each cell nucleus contains a complete genome
established in the zygote during fertilization; D
– as cells develop, some genes are
expressed and others repressed; E
– only a small percentage of genome is expressed in
each cell, and RNA portion is specific for a given cell type.
Directions
: one or more of the given statements or completions is/are correct. Choose the
answer: A
– if only 1,2, and 3 are correct; B – if only 1 and 3 are correct; C – if only 2 and
4 are correct; D
– if only 4 is correct; E – if all are correct.
14. The following statements regarding the ovum transport along the uterine tube
are true: