Fertilization & Gastrulation & Neurolation Flashcards
Parts that make up the Human Ovum
Corona radiata Zona Pellucida Nucleus Perivitelline space Plasma membrane
Chemicals happen in this space in the ovum
Perivitelline space
A morpheus cellular proteoglycan network
Zona pellucida
How many chromosomes does a ovum have
23 (haploid)
23X
Parts of the Human Sperm
Head: Acrosome & Nucleus
Neck
Tail: Middle piece, Principle piece, End piece
Has enzyme and takes up anterior 2/3 of human sperm
Acrosome
What is contained within the middle piece of the human sperm
Mitochondrial sheath
Day 0 is
Ovulation
Day 7 is
Fertilization
Where does week 1 occur?
Uterine tube
First step of Week 1
Capacitation
& Passage of sperm through corona radiata
Capacitation is
The removal of the glycoprotein coat & seminal plasma proteins from plasma membrane of sperm
What enzyme do sperm release to penetrate through the corona radiata
Hyaluronidase
Step 2 of week 1
Penetration of zona pellucida
-Zona reaction
Enzymes released to penetrate zona pellucida
Esterases, acrosin, neruaminidase
(Acrosin —> main enzyme
Zona reaction
One sperm binding to egg to stop all from penetrating
Prevent polyspermy
Step 3 of week 1
Fusion of plasma membrane of oocyte and sperm
Head & tail of sperm enter oocyte cytoplasm (mitochondria does not come with)
Step 4 of week 1
Completion of second meiotic division
Formation of male pronucleus
Fusion of male & female pronuclei
Fertilization can take up to
24 hours
What are the results of fertilization
2nd meiotic division is completed Diploid # of chromosome (46) Establish sex of embryo (XX or XY) Metabolic activation of oocyte Cleavage initiation
Results in Morula development
Cleavage
Morula enters uterus on what day
Day 4
When does cleavage occur
30 hr after fertilization
What day is the morula created
Day 3
Early blastocyst to late blastocyst occurs during which days
Day 5-7
Late blastocyst consists of
One layer
Inner cell mass
Blastocyst cavity
Trophoblast
In vitro fertilization and embryo transfer steps
Ovary stimulated to release egg
—> placement of oocytes in petri with sperm
—> cleavage until 8 cell stage are reached
—> zygote transferred to uterus.
Cryopreservation of embryos can last up to
21 years
What is intracytoplasmic sperm injection
Injection of 1 sperm to female egg
An early pregnancy factor that release immunosuppressive protein
(Placenta)
Trophoblast
Trophoblast gives rise to
Cytotrophoblast
Cytotrophoblast give rise to
Syncytiotrophoblast
Stem cell layer of placenta
Mitotically active
Cytotrophoblast
Contains proteolytic enzymes to cause loss of membrane & HCG (chorionic gonadotropin)
Responsible for implantation and initial signal of pregnancy
Syncytiotrophoblast
Abnormal trophoblastic proliferation excessive amount of hCG produced
Hydtidiform Mole
Fertilization of an empty oocyte followed by duplication of the sperm
Complete hydatidiform
Fertilization of an empty oocyte by two sperm
Complete hydatidiform mole
Fertilization of normal oocyte by two sperm
Partial hydatidiform mole
Clinical features: vaginal bleeding Pelvic pressure or pain Enlarged uterus Hyperemesis gravidarum
Partial hydatidiform mole
Malignant tumor which develops from hydatidiform mole
Choriocarcinomas
Inner cell mass consists of
Epiblast & Hypoblast
Epiblast consists of
Ectoderm
Amnion
Amniotic cavity
Extraoembryonic placeholder (week 2 only)
Hypoblast
Hypoblast gives rise to
Prechordal plate
Primary/secondary yolk sac
Extraembryonic mesoderm
Epiblast gives rise to
Ectoderm
Amnion
Amniotic Cavity
Extraembryonic mesoderm gives rise to
Extraembryonic coelom
Extraembryonic somatic mesoderm
Extraembryonic Splanchic mesoderm
Hollow cavity outside of embryo (extraembryonic mesoderm)
Coelom mesoderm
Lining the trophoblast & covering the amnion (extraembryonic mesoderm)
Extraembryonic somatic mesoderm
Lining the yolk sac (umbilical vesicle)
Extraembryonic mesoderm
Extraembryonic splanchnic mesoderm
Derivatives of extraembryonic mesoderm
Connecting Stalk
Primitive Blood
Chorion
Extraembryonic somatic mesoderm
Forms at embryonic pole
Position changes during development
Connecting Stalk
Extraembryonic splanchnic mesoderm
Forms in wall of yolk sac
Replaced in week 3
Primitive Blood
Extraembryonic somatic mesoderm
Cytotrophoblast
Synctiotrophoblast
Chorion
Implantation starts on day
6-10
Week 2 problems
Ectopic pregnancy
Placenta Previa
Implantation within uterine tube/intestines
Can cause internal hemorrhage if ruptured
Ectopic pregnancy
Placenta covers internal Os of cervix
Vaginal bleeding beyond 20 weeks gestation
Sonographic evalution before digital vaginal examination (finger)
Placenta Previa
Placenta covers adjacent to Os, not covering
Marginal PP
Placenta coves half of Os
Partial placenta previa
Placenta covers total Os
Will require C-section
Total placenta previa
Type of ectopic pregnancy in which the fertilized egg gets stuck on its way to the uterus.
Fallopian tube is inflamed or misshappen
Tubal pregnancy
Describe gastrulation
Formation of 3 primary germ layers
Ectoderm consists of
Skin, hair, CNS, eyes, fingernails
Mesoderm consists of
Muscle, bone, blood, lymph, spleen, heart
Endoderm consists of
GI tract, liver, lungs, bladder
Primitive Streak consists of
Primitive knot (primitive node)
Primitive groove
Primitive pit
Primitive streak forms along
Epiblast (embryonic ectoderm)
Week 3 Problems
Teratoma
Chordoma
Neurocristopathies
Benign tumor involving all three germ layers
Teratoma
Teratoma surrounding anus
Stem cell remnants from primitive streak
Sacrococcygeal teratoma
Teratoma surrounding mouth,
Stem cell remnants from week 2 germ cell
Oropharyngeal teratoma
Rare slow growing aggressive neoplasms of bone
Malignant tumor within brain and sacral regions
Remnants of notochord
Chordoma
neural crest cell diseases that results in Hirschsprung’s disease
Trunk neural crest
Neural crest cell disease that results in cleft lip/palate, digeorge syndrome, dental anomalies
Cranial Neural Crest
Neural crest cell disease (tumor)
Neuroblastoma
Neural crest cell disease (skin)
Albinism
Failure of caudal neuropore closure
Spina bifida
Sunfused vertebral arch, missing spinous process, tuft of hair
Spina bifida occults
Cyst with CSF, spinal cord still in vertebral column
Spina bifida meningocele
Cyst filled with CSF, spinal cord & meninges located in cyst
Spina bifida meningomyelocele
Spinal cord exposed to environment
Spina bifida myelocele
Notochord process happen in what layer
Mesoderm
Notochord purposes
Template for vertebral column
Induces neural plate
Sites of abnormal implantation
Ampullary
Isthmic/intraliga
Pr. Ovarian
Endoderm Template for umbilical arteries & vein Become urachus (attaches to bladder)
Allantois
Types of Mesoderm
Paraxial
Intermediate
Lateral Plate
Paraxial Mesoderm gives rise to
Somites
Somites give rise to
Muscle
Skeleton (vertebral)
Dermis
Intermediate Mesoderm gives rise to
Urogenital
Urogenital gives rise to
Kidneys & Gonads
Later plate gives rise to
Connective tissue
Lateral plate’s connective tissue gives rise to
Blood
Lymph
Mesenteries
Cardiovasclar
Splanchnopleure is what type of germ layer and gives rise to
Mesoderm next to endoderm that gives rise to organs
Somatic mesoderm lies next to
Endoderm
Rostral Neurpore closes on day
25
Caudal Neuropore closes on day
28
Rostral neuropore: open end or closed end
Open
Caudal neuropore: open or closed end
Closed end
Primary Neurulation Days
Day 22-23 to 27-28
Primary Neurulation process
Neural plate -> neural folds -> Neural tube + neural crest + surface ectoderm
Formation of Caudal & Rostral Neuropore
Zipper up & away from center to ends
Primary Neurulation
Primary Neurulation gives rise to
CNS:
Brain through Lumbar Spinal Cord
Secondary Neurulation occurs on what days
Day 20 to 42
Secondary Neurulation process
Caudal Guinence fuses with caudal neuropore
Secondary neurulation gives rise to
CNS: sacral & coccyx spinal cord
Neural Crest Derivatives : Ectomesenchyme
Bone & Cartilage
Walls of large arteries from aortic arches
Connective tissue of uvea & sclera (eye)
Enamel & dentin
Neural Crest Cell derivatives: neurons
Spinal ganglia
(Sensory neurons)
Autonomic ganglia
Neural Crest Cell derivatives: supporting cells
Schwann cells
Leptomeninges (pia & arachnoid matar)
Neural Crest derivatives: pigment cells
Melanocytes
Neural crest derivatives: endocrrine
thyroid gland
Failure of rostralneuropore to close
Congential (cranial) Neural Tube Defects
Missing neocortex & top of cranial skull bones
Incompatible with life
Anencephaly
Cystic growth on head
Encephalocele