Vogel 1 Flashcards
development of body form; requires cell movements, divisions, and shape changes
morphogenesis
the embryonic rudiment or primordium of a tissue or organ (plural = anlage; primordia) e.g. primordial mouth, _____ of the thyroid gland
anlagen
joining or fusion of an egg (ovum) and a sperm
fertilization
cell that results from union of sperm and egg (ovum) during fertilization
zygote
embryo + its associated membranes (the embryo becomes the baby, and the embryonic membranes are discarded after birth)
conceptus
extends from fertilization to end of 8th week; primordia (anlage) of all major organs are present by day 56
Embryonic Period
beginning of ninth week of development to birth; growth & differentiation of tissues and organs occur (growth of fetus from week 11 through full term shown below)
Fetal Period
abnormal development; development of congenital anomalies (Gr. teratos = monster)
Teratogenesis
any agent that can produce a congenital anomaly Examples: CMV, alcohol, thalidomide, methylmercury
Teratogen
The human embryo is most sensitive to teratogens from _________ of development (embryonic period). Teratogens may cause functional defects and minor congenital anomalies during the fetal period.
the third through the eighth week
Fertilization usually occurs in the _____ of uterine tube
ampulla
The diploid zygote nucleus duplicates its DNA to prepare for first mitotic (_____) division
cleavage
Rapid cleavage divisions of the zygote result in production of embryonic cells called ______.
blastomeres
When the embryo consists of 12-32 blastomeres, it is called a ______, which enters the uterus about 3-4 days after fertilization.
morula
By day 4-5, a _________ appears within the morula, and the embryo is now called a _______.
- blastocystic cavity
- blastocyst
Two groups of cells can be distinguished in the blastocyst: outer cells form the ______, and inner cells form the ______ (inner cell mass).
- trophoblast
- embryoblast
Layer of flattened cells, around entire periphery of blastocyst The trophoblast will form part of the placenta (nutrition function).
Trophoblast
Ball of cells (blastomeres) internal to trophoblast The embryoblast will form the embryo proper (i.e. the baby!).
Embryoblast
Zona pellucida degenerates day ____ (blastocyst “hatches”) ; now the trophoblast is exposed to uterine wall and can begin the implantation process
6 or 7
On day 7 after fertilization, the embryoblast also differentiates. A layer of cells adjacent to the blastocystic cavity splits off to form the ______.
hypoblast
The hypoblast (primary endoderm) has an important role in providing molecular signals for development of the _________ of the embryo, and contributes to ____ cells in the embryo.
- cranial – caudal axis
- no
All of the cells in a newborn baby originate from the embryoblast, which will become a disc-like layer called the ______, during the second week of development.
epiblast
The region where epiblast and hypoblast are in contact is called the _________ (week ____)
- bilaminar embryonic disc
- 2
The ________ is a thickened area of hypoblast.
prechordal plate
- indicates the future site of
the mouth (i.e. you can now distinguish cranial and caudal ends) - produces molecular signals that instruct development of the head from the cranial end of the epiblast
- as part of the hypoblast, will not contribute any cells that would be found in a newborn baby
Prechordal plate
The _____ gives rise to the three germ layers (embryonic ectoderm, embryonic mesoderm, embryonic endoderm) that will form all the organs and tissues of the baby. _____ is a subset of the embryonic mesoderm.
- epiblast
- Notochord
During the third week of development, the _______ of the embryo are established.
three germ layers
______ converts the bilaminar embryonic disc into a trilaminar embryonic disc. This is the beginning of morphogenesis (development of body form), and includes formation of the three germ layers and establishment of body axes.
Gastrulation
The groove or indentation in the caudal midline of the epiblast is the _____; it first appears at the caudal end of the epiblast, and extends towards the cranial end
primitive streak
At the bottom of the primitive streak is the ______, where some cells of the epiblast are actively migrating ventrally (_______).
- primitive groove
- invagination
Some epiblast cells will displace the hypoblast cells, and become _______.
embryonic endoderm
Some epiblast cells do not invaginate at the primitive groove, and instead remain on the surface (facing the amniotic cavity); these cells are the _________.
embryonic ectoderm
Other epiblast cells that invaginate at the primitive groove migrate between the embryonic ectoderm and embryonic endoderm; these cells are the ________.
embryonic mesoderm
When gastrulation is complete, the embryo is a ________.
trilaminar disc
The mesoderm cells that migrate towards the prechordal plate, through the cranial end of the primitive streak (called the primitive node) form a rodlike structure, called the _______, in the midline of the embryo.
notochord
The cranial extension of the notochord is blocked by the prechordal plate. The prechordal plate marks the site of the _________, which indicates the future position of the mouth of the embryo.
oropharyngeal membrane
At the caudal end of the embryo, you can
see the ________, which indicates the future position of the anus of the embryo.
cloacal membrane
Notochord instructs overlying ectoderm to form an elongated _______.
neural plate
Neural folds move towards midline and fuse to form a _______, which is the primordium of the CNS (brain and spinal cord).
neural tube
A special population of neuroectodermal cells, the _______, undergoes an epithelial-mesenchymal transition, and separates from the neural folds and surface ectoderm.
neural crest
- neurons of the dorsal root ganglia
- neurons of autonomic and enteric ganglia
- Schwann cells and other support cells of peripheral nerves and ganglia
- chromaffin cells of the adrenal medulla
- melanocytes
In the trunk of the embryo, neural crest cells migrate along two different pathways, and give rise to…
• neurons and support cells of cranial sensory and sympathetic ganglia • Schwann cells of cranial nerves • odontoblasts • skeletal and connective tissue structures
In the head of the embryo, cranial neural crest cells give rise to…
On either side of the notochord, _______ cells organize into paired cubes called _____.
- paraxial mesodermal
- somites
Somites give rise to the axial skeleton, skeletal muscles, and dermis of the skin:
• ______: vertebrae, ribs
• ______: skeletal muscle of trunk and limbs
• ______: dermis of skin
- sclerotome
- myotome
- dermatome
Lateral to the paraxial mesoderm is the _________, which gives rise to the kidneys and gonads.
intermediate mesoderm
Lateral mesoderm splits into two layers:
- somatic mesoderm
* splanchnic mesoderm
The two layers of lateral mesoderm surround a space called the ________, which is the primordial body cavity.
intraembryonic coelom
The primordial heart also develops from ______ – in particular from the cardiogenic area.
lateral mesoderm
Future pharynx and esophagus develop from _______.
foregut endoderm
At the caudal end of the embryo, endoderm folds into a _______.
hindgut
The _____ is the terminal part of the hindgut that develops into the rectum and urinary bladder.
cloaca
Right and left ______ are produced by growth of the somites and developing spinal cord.
lateral folds
Primordia of the abdominal wall fold toward the midline, and the ______ forms from endoderm
midgut
