Anatomy Block 2: Embryonic Period, Fetus And Placenta

Front 1

The embryonic period is weeks __________ of human development.

Back 1

3-8

Front 2

The 3 germ layers (ecto, meso and endoderm) become recognizably human in the _________________ period of development.

Back 2

embryonic

Front 3

The period during which the conceptus is most likely to develop a major congenital malformation is the _______________ period.

Back 3

embryonic

Front 4

Name the 6 things the ectodermal germ layer gives rise to.

Back 4

1. nervous system (central and peripheral)
2. sensory epithelium
3. epidermis
4. subcutaneous glands
5. pituitary gland
6. tooth enamel

Front 5

The formation of the CNS begins with the development of a pear-shaped thickening of the ectoderm called the ________________.

Back 5

neural plate

Front 6

The lateral edges of the neural plate, the __________, fuse to form the neural tube.

Back 6

neural folds

Front 7

The cranial and caudal neuropores finally fuse at days _____ and _____, respectively.

Back 7

25 and 27

Front 8

spinal (posterior root) ganglia and sensory ganglia of cranial nerves V, VII, IX, and X; automonic ganglia; the adrenal medulla; Schwann cells; connective tissues of the anterior part of the skull and meninges; melanocytes; C cells of the thyroid gland; and the conotruncal septum of the heart are all derivatives of the ___________.

Back 8

neural crest

Front 9

As part of the formation of the face and anterior neck, neural crest cells migrate into ______________ and form connective tissues

Back 9

pharyngeal arches

Front 10

The 3 sections of the mesodermal germ layer, medial to lateral, are:

Back 10

1. paraxial
2. intermediate
3. lateral plate

Front 11

The paraxial mesoderm becomes segmented into 42-44 blocks of tissue called __________.

Back 11

somites

Front 12

The age of the embryo is expressed by the number of ________.

Back 12

somites (20 days is 1 to 4 somites, 25 days is 17 to 20 somites, 30 days is 34-35 somites)

Front 13

Cartilage, bones of the axial skeleton (including vertebral column) are formed by the ________________ division of the somite.

Back 13

ventromedial sclerotome

Front 14

Dorsomedial muscle forming region of the somite is also called the (epimeric/hypomeric) region.

Back 14

epimeric

Front 15

Dorsolateral muscle forming region of the somite is also called the (epimeric/hypomeric) region.

Back 15

hypomeric

Front 16

Each somite has a _______________, which forms the dermis of the skin for its segment of the body.

Back 16

dorsal dermatome

Front 17

The intermediate mesoderm differentiates into the ___________.

Back 17

urogenital structures (kidney, gonads)

Front 18

The lateral plate mesoderm divides into 2 layers separated by the _____________ cavity.

Back 18

somatic/parietal layer

Front 19

The _________________ division of the lateral plate mesoderm joins the overlying ectoderm to form the ventral and lateral body walls.

Back 19

somatic/parietal

Front 20

The _________________ division of the lateral plate mesoderm joins the underlying endoderm to form the wall of the gut.

Back 20

splanchnic/visceral

Front 21

The intraembryonic cavity is lined with ___________________ for the _________, __________, and _________ cavities of the adult.

Back 21

the serous membranes that will later secrete serous fluid

pericardial, pleural, peritoneal

Front 22

Blood vessel formation first occurs in the _______________ and later in the ___________.

Back 22

-extraembryonic mesoderm surrounding yolk sac

-lateral plate mesoderm (**later--lateral mesoderm)

Front 23

The ____________ becomes the major hematopoietic organ of the fetus by week 6.

Back 23

liver

Front 24

The liver sends stem cells to colonize the ____________, the definitive blood-forming organ after the seventh month of gestation.

Back 24

bone marrow

Front 25

The main organ system derivative of the endoderm is the...

Back 25

GI tract

Front 26

The GI tract forms as a result of ___________ and ___________ folding of the trilaminar germ disc.

Back 26

-cephalocaudal

-lateral

Front 27

Cephalocaudal folding causes the formation of a ____________ and _______ fold in the embryo, causing the "fetal position."

Back 27

-head fold
-tail fold

Front 28

The endoderm-derived gastrointestinal tract is comprised of the __________, the _________, and the ___________ between the first two.

Back 28

foregut, hindgut, and midgut between the foregut and hindgut

Front 29

The midgut is temporarily connected to the yolk sac by the _____________.

Back 29

vitelline drainage

Front 30

The respiratory system appears as an outgrowth of the ventral wall of the foregut called the _______________.

Back 30

respiratory diverticulum (lung bud)

Front 31

The ________________ germ layer contributes to the urinary system, thyroid/parathyroid, liver/pancreas, tonsils and thymus and inner ear.

Back 31

endodermal

Front 32

The _________ period is from week 9 of gestation until birth.

Back 32

fetal

Front 33

The fetal period begins ____ weeks after fertilization and _____ weeks after the first day of the last normal menstrual period.

Back 33

38

40

Front 34

The __________ period is the time of growth and functional maturation of tissues and organs.

Back 34

fetal

Front 35

Primary ossification centers are present in all long bones and the skull by ________ weeks of gestation.

Back 35

12

Front 36

During the 4th and 5th months of gestation, the head of the fetus grows (more slowly/faster) than the rest of the body.

Back 36

more slowly

Front 37

At birth, the circumference of the baby's ________ is greater than any other part of the body.

Back 37

skull

Front 38

The inner cell mass of the blastocyst, the __________, forms the ___________.

Back 38

embryoblast

forms embryo

Front 39

The outer cell mass of the blastocyst, the __________, forms the __________.

Back 39

trophoblast

fetal portion of the PLACENTA

Front 40

During the 2nd week of development, the trophoblast differentiates into the outer _____________ and the inner ______________.

Back 40

-syncytiotrophoblast

-cytotrophoblast

Front 41

2nd week of development: The endometrium of the uterus undergoes the ___________________, in which endometrial cells around the conceptus become loaded with glycogen and lipids and the tissue becomes edematous.

Back 41

decidua reaction

Front 42

2nd week of development: Large spaces called ___________ appear in the syncytiotrophoblast as it is invaded by dilated capillaries of the endometrium called ____________. This establishes the the _______________ circulation.

Back 42

-lacunae

-sinusoids

-uteroplacental circulation

Front 43

2nd week of development: The ___________ is pinched off from the primary yolk sac during the formation of the _________________ cavity.

Back 43

secondary yolk sac

chorionic

Front 44

2nd week of development: The amnion amnion and yolk sac remain attached to the chorion (extraembryonic mesoderm plus the two layers of trophoblast) across the chorionic cavity by the ______________, which later becomes the umbilical cord.

Back 44

connecting stalk

Front 45

3rd week of development: the ________________ entirely surrounds the trophoblast and attaches it to the endometrium.

Back 45

outer cytotrophoblast shell

Front 46

__________________ can traverse the placental barrier freely.

Back 46

Drugs and viruses

Front 47

The 4 placental functions include:

Back 47

1. exchange of gasses
2. exchange of nutrients/electrolytes
3. transmission of maternal antibodies (maternal immunoglobulin G/IgG)
4. production of hormones

Front 48

During the first two months the syncytiotrophoblast secretes __________________ to maintain the corpus luteum.

Back 48

human chorionic gonadotropin (hCG)

Front 49

Early pregnancy tests test the hormone _________.

Back 49

hCG

Front 50

By the end of the fourth month, the placenta produces enough _________________ to maintain pregnancy if the corpus luteum were removed

Back 50

progesterone

Front 51

By the end of the fourth month, the placenta produces ____________ to stimulate uterine growth and mammary gland development.

Back 51

estrogens

Front 52

The umbilical cord forms from the ___________ and the __________.

Back 52

connecting stalk

vitelline duct

Front 53

The _____________ contains the allantois and umbilical vessels.

Back 53

connecting stalk

Front 54

Amniotic fluid is derived mainly from _____________.

Back 54

maternal blood

Front 55

The four functions of amniotic fluid are:

Back 55

1. shock absorption
2. preventing embryonic adhesion to amnion
3. allowing fetal movements
4. allowing fetal growth

Front 56

In the fifth month, __________ is swallowed by the fetus, contributing to hypotonic urine.

Back 56

amniotic fluid

Front 57

In anencephaly or intestinal atresia, amniotic fluid is present in __________. This is called ___________.

Back 57

-excess

-polyhydramnios

Front 58

Amniotic fluid may be deficient in amount (______________), e.g., due to renal agenesis or amnion rupture, resulting in clubfoot or lung hypoplasia.

Back 58

-oligohydramnios