Embrionic period

Question 1

Somites

Answer 1

derived from paraxial mesoderm, divide into ventromedial sclerotome, dorsomedialo epimeric, hypomeric dorsolateral, and dorsal dermatome.

Question 2

ventromedial sclerotome

Answer 2

forms cartilage, bone of axial skeleton including vertebral colulmn.

Question 3

hypomeric somite

Answer 3

dorsolateral, skeletal muscle-forming

Question 4

epimeric somite

Answer 4

dorsomedial,skeletal muscle forming

Question 5

dermatome

Answer 5

forms the dermis of the skin for it’s segment of the body.

Question 6

intermediate mesoderm

Answer 6

temporarily connects the paraxial and lateral plate mesoderms, also becomes urogenital structures like kidney and gonads.

Question 7

lateral plate mesoderm

Answer 7

divides into somatic/parietal layer, and splanchnic/visceral layer, which form the intraembryonic cavity.

Question 8

somatic/parietal layer

Answer 8

joins the ectoderm and forms the ventral and lateral body walls

Question 9

splanchnic layer

Answer 9

joins the endoderm and forms the wall of the gut

Question 10

blood vessel formation

Answer 10

occurs in the mesoderm, first in the meso surrounding the yolk sac and later in the lateral plate meso.

Question 11

liver

Answer 11

colonized by hematopoietic stem cells, is the major hematopoietic organ by week 6,

Question 12

definitive blood-forming organ

Answer 12

bone marrow, liver sends stem cells to colonize the bone marrow, by seventh month of gestation bone marrow is major hematopoietic organ.

Question 13

GI tract

Answer 13

forms from the endodermal germ layer, forms due to cephalocaudal folding, which incorporates part of the yolk sac into the body.

Question 14

lateral folding

Answer 14

occurs from growth of the somites, ensures that the amniotic sac encloses the fetus.

Question 15

cephalocaudal folding

Answer 15

caused by growth of the brain vesicles, causes a head fold and a tail fold and cuases curved fetal position.

Question 16

Respiratory diverticulum

Answer 16

begining of the respiratory system, it is the lung bud that forms as a projection from the ventral wall of the foregut that will become the lung.

Question 17

morula and blastocyst constist of:

Answer 17

inner cell mass called embryoblast that form the embryo proper and an outer cell mass called trophoblast that form the fetal placenta.

Question 18

trophoblast

Answer 18

at second week cells split into syncitiotrophoblast (outer) and cytotrophoblast (inner)

Question 19

decidua rxn

Answer 19

endometrial cells become loaded with glycogen and lipids and become edematous.

Question 20

secondary yolk sac

Answer 20

pinched off from the primary yolk sac during formation of the the chorionic cavity

Question 21

chorionic cavity

Answer 21

develops w/ in extraembryonic mesoderm, between cytotrophoblast and the primitive yolk sac.

Question 22

outer cytotrophoblast shell

Answer 22

when cytotroph cells penetrate syncitioblast layer and form a firm attachment to the endometrium.

Question 23

chorion frondosum

Answer 23

fetal portion of the placenta where villi remain

Question 24

decidua basalis

Answer 24

maternal component of the placenta overlying the ch. frondosum.

Question 25

hormones released from placenta

Answer 25

human chorionic gonadotropin hCG to maintain corpus leutium, progesterone, and estrogen to stimulate uterine growh and mam. gland development.

Question 26

amniotic bands

Answer 26

when amnion tears away. these may encircle a part of the body of the fetus which may cause loss of a limb.

Question 27

amnioti fluid

Answer 27

fills amniotic cavity, derived from maternal blood, may be collected for lab tests.

Question 28

polyhydramnios

Answer 28

too much amniotic fluid, in anencephaly or intestinal atresia which prevent swalloing and absorption respectively.

Question 29

oligohydramnios

Answer 29

deficiency in amniotic fluid, may be due to renal agenesis or amnion rupture, resulting in club foot or hypoplasia