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58 Cards in this Set

  • Front
  • Back
The embryonic period is weeks __________ of human development.
The 3 germ layers (ecto, meso and endoderm) become recognizably human in the _________________ period of development.
The period during which the conceptus is most likely to develop a major congenital malformation is the _______________ period.
Name the 6 things the ectodermal germ layer gives rise to.
1. nervous system (central and peripheral)
2. sensory epithelium
3. epidermis
4. subcutaneous glands
5. pituitary gland
6. tooth enamel
The formation of the CNS begins with the development of a pear-shaped thickening of the ectoderm called the ________________.
neural plate
The lateral edges of the neural plate, the __________, fuse to form the neural tube.
neural folds
The cranial and caudal neuropores finally fuse at days _____ and _____, respectively.
25 and 27
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 ___________.
neural crest
As part of the formation of the face and anterior neck, neural crest cells migrate into ______________ and form connective tissues
pharyngeal arches
The 3 sections of the mesodermal germ layer, medial to lateral, are:
1. paraxial
2. intermediate
3. lateral plate
The paraxial mesoderm becomes segmented into 42-44 blocks of tissue called __________.
The age of the embryo is expressed by the number of ________.
somites (20 days is 1 to 4 somites, 25 days is 17 to 20 somites, 30 days is 34-35 somites)
Cartilage, bones of the axial skeleton (including vertebral column) are formed by the ________________ division of the somite.
ventromedial sclerotome
Dorsomedial muscle forming region of the somite is also called the (epimeric/hypomeric) region.
Dorsolateral muscle forming region of the somite is also called the (epimeric/hypomeric) region.
Each somite has a _______________, which forms the dermis of the skin for its segment of the body.
dorsal dermatome
The intermediate mesoderm differentiates into the ___________.
urogenital structures (kidney, gonads)
The lateral plate mesoderm divides into 2 layers separated by the _____________ cavity.
somatic/parietal layer
The _________________ division of the lateral plate mesoderm joins the overlying ectoderm to form the ventral and lateral body walls.
The _________________ division of the lateral plate mesoderm joins the underlying endoderm to form the wall of the gut.
The intraembryonic cavity is lined with ___________________ for the _________, __________, and _________ cavities of the adult.
the serous membranes that will later secrete serous fluid

pericardial, pleural, peritoneal
Blood vessel formation first occurs in the _______________ and later in the ___________.
-extraembryonic mesoderm surrounding yolk sac

-lateral plate mesoderm (**later--lateral mesoderm)
The ____________ becomes the major hematopoietic organ of the fetus by week 6.
The liver sends stem cells to colonize the ____________, the definitive blood-forming organ after the seventh month of gestation.
bone marrow
The main organ system derivative of the endoderm is the...
GI tract
The GI tract forms as a result of ___________ and ___________ folding of the trilaminar germ disc.

Cephalocaudal folding causes the formation of a ____________ and _______ fold in the embryo, causing the "fetal position."
-head fold
-tail fold
The endoderm-derived gastrointestinal tract is comprised of the __________, the _________, and the ___________ between the first two.
foregut, hindgut, and midgut between the foregut and hindgut
The midgut is temporarily connected to the yolk sac by the _____________.
vitelline drainage
The respiratory system appears as an outgrowth of the ventral wall of the foregut called the _______________.
respiratory diverticulum (lung bud)
The ________________ germ layer contributes to the urinary system, thyroid/parathyroid, liver/pancreas, tonsils and thymus and inner ear.
The _________ period is from week 9 of gestation until birth.
The fetal period begins ____ weeks after fertilization and _____ weeks after the first day of the last normal menstrual period.

The __________ period is the time of growth and functional maturation of tissues and organs.
Primary ossification centers are present in all long bones and the skull by ________ weeks of gestation.
During the 4th and 5th months of gestation, the head of the fetus grows (more slowly/faster) than the rest of the body.
more slowly
At birth, the circumference of the baby's ________ is greater than any other part of the body.
The inner cell mass of the blastocyst, the __________, forms the ___________.

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

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

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.
decidua reaction
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.


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

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.
connecting stalk
3rd week of development: the ________________ entirely surrounds the trophoblast and attaches it to the endometrium.
outer cytotrophoblast shell
__________________ can traverse the placental barrier freely.
Drugs and viruses
The 4 placental functions include:
1. exchange of gasses
2. exchange of nutrients/electrolytes
3. transmission of maternal antibodies (maternal immunoglobulin G/IgG)
4. production of hormones
During the first two months the syncytiotrophoblast secretes __________________ to maintain the corpus luteum.
human chorionic gonadotropin (hCG)
Early pregnancy tests test the hormone _________.
By the end of the fourth month, the placenta produces enough _________________ to maintain pregnancy if the corpus luteum were removed
By the end of the fourth month, the placenta produces ____________ to stimulate uterine growth and mammary gland development.
The umbilical cord forms from the ___________ and the __________.
connecting stalk

vitelline duct
The _____________ contains the allantois and umbilical vessels.
connecting stalk
Amniotic fluid is derived mainly from _____________.
maternal blood
The four functions of amniotic fluid are:
1. shock absorption
2. preventing embryonic adhesion to amnion
3. allowing fetal movements
4. allowing fetal growth
In the fifth month, __________ is swallowed by the fetus, contributing to hypotonic urine.
amniotic fluid
In anencephaly or intestinal atresia, amniotic fluid is present in __________. This is called ___________.

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