Embryology Flashcards
_____ is the study of structural changes that embryos undergo.
____ is the division of embryology and pathology that deals with abnormal development
Embryology
Teratology
Causes of congenital disorders:
Genetic factors
Environmental factors
Multifactorial inheritance (genetic and environmental factors acting together)
During 5 weeks of gestation, the risk of birth defects is the ____.
Highest
____ life is before birth and involves zygote, embryo, fetus. ____ is after birth
Prenatal
Postnatal
____ is the formation of gametes (egg and sperm
Gametogenesis
____ is the joining of gametes to form a zygote
Fertilization
_____ Is a series of rapid cell divisions, forming morula and later blastocyst
Cleavage
_____ is the rearrangement of cells into three primary germ layers
Gastrulation
Formation of the tube within a tube body plan is formed by the outer _____ tube and the inner ____ tube
Ectodermal
Endodermal
_____ is the formation of organ, rudiments and organ systems
Organogenesis
Fertilization, zygote, morula, blastocyst, and the start of implantation all occurs with the first ____ of development
Week
Diagram:
Fertilization takes place in the ____ of the oviduct (fallopian tube)
Ampulla
Formation of a zygote:
Cleavage is a series of mitotic divisions of the ____, resulting in a rapid increase in the number of cells (_____). There is no increase in the size of the embryo.
Zygote
Blastomeres
When there are 12 to 32 blastomeres it is called a ____.
Morula
Morula undergoes, re-organization of cells that results in an ___ ___ ___ (embryoblast) and an ___ ___ ___ (trophoblast). This is still part of the cleavage stage.
Inner cell mass
Outer cell mass
A ______ forms when embryo blast cells compact at one side of the cavity. Trophoblasts organize into a thin, single layered epithelium on the outside of the cavity.
Blastocyst
Early stages of implantation:
Implantation stages:
The trophoblast differentiate into two layers. The ____ is the inner layer of cells. The ____ is the outer layer.
The syncytiotrophoblast extends through the Endometrial, epithelium and invades the endometrial tissue.
Cytotrophoblast
Syncytiotrophoblast
By the end of the first week, the blastocyst is superficially implanted in the compact layer of the ____ and is deriving it’s nourishment from the eroded ____ tissues
Endometrium
Maternal
Ectopic pregnancy occurs if the blastocyst implants in the _____ cavity on the surface of the ovary within the fallopian tube. Or any other abnormal site.
Peritoneal
Implantation diagram:
Full implantation via continued ____ of the endometrium caused by syncytiotrophoblast. The hormone ____ ___ ____ (hCG) maintains vessel formation in myometrium
Erosion
Human chorionic gonadotropin
The Embryoblast, undergoes reorganization into two layers:
____ is the external/upper layer of columnar cells. ____ is the internal/lower layer of cuboidal cells adjacent to the blastocyst cavity.
Epiblast
Hypoblast
The Epiblast will give rise to the actual ___ of the embryo.
Body
Epiblast and hypoblast give rise to ____ ___ ___.
Bilaminar embryonic disc
With the formation of the bilaminar embryonic disc, formation of other structures including ___ ___, __ __, and ___ ___ will arise
Amniotic cavity
Yolk sac
Chorionic cavity
Formation of the amniotic cavity:
Fluid collects between ___ and ___. Layer of epiblast cells differentiate into a thin membrane called an ____, separating the new cavity from the cytotrophoblast (delamination)
Epiblast
Trophoblast
Amnion
The amniotic cavity expands, and by the ____ week, it encloses the entire embryo
8th
Formation of umbilical vesicle:
____ cells form the umbilical vesicle on the other side of the bilaminar embryo.
Hydroblasts
Formation of the chorionic cavity:
The outer layer of cells from the umbilical vesicle forms the ____ ___, which splits into two layers forming the ___ cavity.
Extraembryonic mesoderm
Chorionic
The chorionic cavity separates the embryo from the outer wall of the blastocyst, now called the _____.
Chorion
By the end of the second week, the embryonic disc and it’s accessory cavities are suspended in the chorionic cavity solely by thick stalk of extra embryonic mesoderm called the ____ ____.
Connecting (body) stalk
Uteroplacental circulation:
As the embryonic disc and cavities form, isolated cavities called ____ appear in the syncytiotrophoblast.
Adjacent lacunae fuse to form ___ ___.
Lacunae
Lacunar networks
Uteroplacental circulation:
As lucinar networks form, the ____ proliferates locally to form extensions that grow into the blood filled lacunae of the overlying syncytiotrophoblast. This is the beginning of a circulatory exchange between ___ and ____ tissues.
Cytotrophoblast
Maternal
Fetal
Uteroplacental circulation:
Further development of these structures now called ___ ____ ___ give rise to blood vessels that connect with the vessels forming in the embryo
Tertiary chorionic villi
____ ____ is abnormal placenta due to enlargement of chorionic villi. Partial versus complete mole: generalized edema, forming grape-like trophoblastic cells, and absence of an embryo.
Hydatidiform mole
A complete mole shows clinical signs of ___, ___ ___ levels, and enlarged ____ with bleeding. It can also become malignant. Must be surgically removed.
Preeclampsia
elevated hCG
Uterus
Hydatidiform moles are thought to arise from an imbalance of ___ and ___ genomes. The more skewed, the imbalance is toward a male genome, the more invasive, and problematic the placenta becomes.
Maternal
Paternal
Gastrulation occurs around day ___. A thickening containing a midline group forms along the surface of the epiblast called a ___ ___
15
Primitive streak
Gastrulation:
The primitive streak elongates by addition of cells at its ____ end. The cranial end proliferates to form the ___ ___. Simultaneously a ___ ___ develops. The depression in the node is called called the ___ ___.
Caudal
Primitive node
Primitive groove
Primitive pit
The ___ ___ defines the embryos craniocaudal axis, dorsal/ventral surfaces, and right and left sides
Primitive streak
Gastrulation:
As the cells of the epiblast reach the primitive streak, they change shape, and passed through it on their way to forming a new layers beneath the epiblast. This process is called:
____/____
Ingression/invagination
Invagination:
Epiblast cells travel into the primitive streak, where they undergo ____to____ ____ (EMT). The ___ is a sheet of regularly shaped cuboidal cells that are tightly interconnected. The ____ is embryonic connective tissue with more irregularly shaped cells and loosely connected.
Epithelial-to-mesenchymal transformation
Epithelium
Mesenchyme
Formation of endoderm:
First, invaginating epiblast cells invade the hypoblast and displace its cells, so that the hypoblast is eventually completely replaced by a new layer of cells, called the ___ ____. This gives rise to the lining of the future gut.
Definitive endoderm
Formation of mesoderm:
Other epiblast cells migrate through the primitive streak into the space between epiblast and the forming endoderm to form a new germ layer called ____ ____.
Intraembryonic mesoderm
Formation of ectoderm:
Once the mesoderm is formed, epiblast cells no longer ingress through the primitive streak. The remaining epiblast now constitutes the ___ ___.
Embryonic ectoderm
The embryonic ectoderm differentiates into the central ___ ___ and the peripheral ___ ___.
Neural plate
Surface ectoderm
Two faint depressions form in the ectoderm:
At the cranial end the ____ ____ forms which eventually forms the oral cavity.
At the caudal end the ____ ___ forms which eventually forms openings of anus and urogenital tract.
Oropharyngeal membrane
Cloacal membrane
Germ layers and derivatives:
Formation of notochord:
Mesodermal cells, migrating cranially form the primitive node in the midline and form a thick walled midline cord called the ____ ___. Several transformations take place to convert it from a hollow tube to a flattened plate to a solid rod, called the ____.
Notochordal process
Notochord
As the notochordal process ____, the primitive streak ____ and eventually becomes insignificant
Elongates
Shortens
The notochord gives the embryo ____. It serves as the basis for the development of the axial skeleton. It degenerates and disappears, almost completely as the bodies of the ____ form (but it remains as nucleus pulposus)
Rigidity
Vertebrae
Surrounding the notochord, there are a series of developing tissues:
Paraxial mesoderm
Intermediate mesoderm
Lateral plate mesoderm
Remnants of the notochord may persist and give rise to a slowly growing malignant tumor called a ____. They often infiltrate bone and muscle and are challenged to resect.
Chordoma
During cleavage, ____ divisions are occurring.
Mitotic
Blastomeres during cleavage are ____ meaning they can give rise to everything required for development
Totipotent
The first point of cell differentiation is the distinction between ____ ___ ___ and ___ ___ ___.
Inner cell mass
Outer cell mass
The ____ cavity is fluid filled. Throphoblasts begin to have a more _____ cell type.
Blastocystic
Epithelial
Embryoblasts and trophoblasts are no longer ____. Trophoblast gives rise to the ____. Embryoblast gives rise to the ____.
Totipotent
Placenta
Body
Chronological order:
Syncytiotrophoblast produces ____ hormone which signals to the uterus.
hCG
Review:
The connecting stalk becomes the ___ ___.
Umbilical cord
A hydatidiform mole is basically a ____ without an embryo.
Placenta
Review
Gastrulation starts at week ___.
3
Gastrulation is driven by cell ____, not division.
Migration
Notochord picture:
Review
Review
