Embryology Flashcards by Lily Nunvar

_____ is the study of structural changes that embryos undergo.
____ is the division of embryology and pathology that deals with abnormal development

Embryology
Teratology

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Causes of congenital disorders:

Genetic factors
Environmental factors
Multifactorial inheritance (genetic and environmental factors acting together)

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During 5 weeks of gestation, the risk of birth defects is the ____.

Highest

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____ life is before birth and involves zygote, embryo, fetus. ____ is after birth

Prenatal
Postnatal

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____ is the formation of gametes (egg and sperm

Gametogenesis

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____ is the joining of gametes to form a zygote

Fertilization

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_____ Is a series of rapid cell divisions, forming morula and later blastocyst

Cleavage

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_____ is the rearrangement of cells into three primary germ layers

Gastrulation

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Formation of the tube within a tube body plan is formed by the outer _____ tube and the inner ____ tube

Ectodermal
Endodermal

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_____ is the formation of organ, rudiments and organ systems

Organogenesis

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Fertilization, zygote, morula, blastocyst, and the start of implantation all occurs with the first ____ of development

Week

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Diagram:

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Fertilization takes place in the ____ of the oviduct (fallopian tube)

Ampulla

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Formation of a zygote:

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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

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When there are 12 to 32 blastomeres it is called a ____.

Morula

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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

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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

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Early stages of implantation:

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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

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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

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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

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Implantation diagram:

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Full implantation via continued ____ of the endometrium caused by syncytiotrophoblast. The hormone ____ ___ ____ (hCG) maintains vessel formation in myometrium

Erosion
Human chorionic gonadotropin

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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