Embryology Flashcards
The name given to the Embryonic components of the placenta
Chorion Frondosum
The name give to the maternal components of the placenta
Decidua Basalis
Define Decidua:
Endometrial lining of uterine cavity.
Define Decidua Basalis:
Portion of endometrium underlying the implantation site.
Define Decidua Capsularis:
Portion overlying the implanted embryo
Decidua Parietalis:
The remainder of the endometrium
What does DB stand for?
Decidua Basalis (part of the placenta)
What does DP stand for?
Decidua parietalis
What does DC stand for?
Decidua Capularis
Decidua Capsularis
Portion overlying the implanted embryo and separating it from the uterine cavity. It is eventually lost as the amniotic cavity enlarges & occupies all the cavity
Chromatid
One of the two strands of a chromosome joined together by a centromere
Chromosomal Crossover
An important set in genetic recombination in which two chromosomes, normally homologous (functionally the same), pair up and exchange DNA. The shuffling of genes is called independent assortment
The parent of stem cells that produce sperm are called
Spermatogonia
What are the stages in spermatogeneis
- Spermatogonium
- Primary Spermatocyte
- Secondary Spermatocytes (meiosis I)
- Spermatids (meiosis II)
- Spermatozoa
What are the stages in Oogenesis
- Oogonium
- Primary Oocyte
- Secondary Oocyte (meiosis I)
- Ootid (meiosis II)
- Ovum (differentiation)
Define Aneuploidy
Numerical error in chromosome division. Too many or too few.
Define NonDisjunction
The process of separation of homologous chromosome pairs fails.
(e.g) Trisomy disorders, named for chromosomes involved
What is the genotype for Klinefelter
47 XXY
What is the genotype for Turner’s Syndrome?
45 XO
Define Teratogens
External agents (extrinsic to the fetus) that produce developmental Malformations.
Give a few examples of potential Teratogens
Radiation, prenatal infections, temperature extremes, prescription drugs/dietary supplements, Mechanical forces
Major events of Embryogenesis
Cleavage: Division of zygote & formation of blastocyst
Gastrulation: Formation of Germ Layers
Organogenesis: Germ layers differentiate so as to give rise to all organs in the human body
What is the fetal period?
Includes the remaining weeks of development prior to birth (weeks 9-38)
The fetus continues to grow
It’s organs increase in complexity
What steps are involved leading up to the the “Morula”
Before the 8-cell stage, cells are not tightly bound together, but after the third cleavage division, then they become more compact and form a ball called the morula.
What are the steps of implantation
- by the end of 1st week after fertilization, the blastocyst enter the lumen of the uterus.
- the zonula pellucia around the blastocyst beings to break down as the blastocyst prepares to invade the endometrium.
- implantation is the process by which the blastocyst burrows into and embeds within the endometrium.
Ectopic Pregnancy
implantation of the blastocyst outside the uterine cavity
Can be predisposed by conditions that have caused inflammation & scarring of uterine tubes.
Implantation Steps
( second opportunity for cellular differentiation)
- Trophoblast cells differentiate
- Embryoblast cells differentiate
- Two cavities form
What is the hormone that signals the ovary to continue to secrete hormones to maintain the pregnancy
hCG, Human chorionic gonadotrophin.
List the events occurring during Gastrulation
- Beginning of morphogenesis (development of body form)
- Forms a trilaminar embryonic Disk
- Process that establishes the 3 primary germ layers of endoderm, mesoderm & ectoderm
- These three layser give rise to all the tissues & organs of the adult
What marks the beginning of gastrulation?
The primitive streak
What is a sacrococcygeal teratoma?
Remnants of primitive streak, derivatives of all three germ layers. Bizarre mixture of tissue types (all layers)
What is caudal dysplasia
Germ layer disorder. total or partial failure of development of the lower vertebrae, including the sacrum, which results in associated abormalities of the lower extremities, spine, kidneys, gastrointestinal and genitourinary tracts. Associated with maternal diabetes
Functions of the Notochord
Structure: Acts as a rigid axis around which the embryo develops
Skeletal: foundation upon which the vertebral column will form
-forms part of intervertebral discs
Induction: Will bring about formation of the neural tube Drives development of CNS
What is chordoma
Primary malignant bone cancer, develops from remnants of embryonic notochord, found in skull-base and spine
explain the role of “cross-talk” in induction for normal development
Communication between “inducer” and “responder” cells or tissues
List the three early brain segments
Prosencephalon, mesencephalon, Rhobencephalon
Forebrian, midbrain, hindbrian.
The primary brain vesicle, prosencephalon, develops into what two secondary vesicles?
Telencephalon —–>lateral ventricles —-> cerebrum
and diencephalon —–>third ventricle ——> epithalamus, thalamus, hypothalamus
The primary brain vesicle, mesencephalon, develops into what secondary?
Mesencephalon —-> mesencephalic aqueduct —–> cerebral peduncles, superior colliculi, inferior colliculi
The primary brain vesicle, rhombencephalon, develops into what two secondary vesicles?
metencephalon —-> rostral part of fourth ventricle —-> pons cerebellum
Myelencephalon —–> caudal part of fourth ventricle; central canal caudally —-> medulla oblongata.
Iniencephaly:
Extreme retroflexion of the head, short and almost absent neck, Hyper-extended spine
Encephalocele:
Cranium Bifida, cranial defect with herniation of intracranial contents, common in occipital region,
Meningoencephalocele- contains meninges and brain
Meningophyroencephalocele- contains menines, brain and ventricular system
Arnold-chiari malformation
herniation of cerebellar vermis or tonisils through the foramen magnum blocking the flow of CSF
Spina bifida occulate
(can occur without you knowing)
- vertebral arches fail to unite
- tufts of hair
- spinal cord is normal
Spina Bifida
Failure of neural arches to form
Spina bifida meningocele
dura and arachnoid also protrude
spina bifida meningomyelocele
neural tissue also protrudes
