The embryonic period occurs in which Trimester and how long does it last?
When does the Obstetrical/Gestational Calendar start?
When does the Ovulatory Calendar start?
First Trimester (0-8 Weeks) - Critical Period
LMP
Fertilization (Day 14 of Menstrual Cycle)
What parts make up the Human Ovum? (Exterior to Interior)
Corona Radiata Follicular Cells
Zona Pellucide (Glycoprotein Meshwork)
Perivitelline Space (Surrounds Cytoplasm/Nucleus)
Plasma Membrane
Nucleus (23X Haploid)
What is in the head of the sperm?
What are the parts of the tail?
- Head
- Acrosome (Enzymes)
- Nucleus (23X or 23Y Haploid)
- Neck
- Tail (Motility)
- Middle Piece w/ Mitochondrial Sheath
- Principle Piece
- End Piece
What processes occur during Week 1 (Day 0-7)?
Fertilization
Cleavage
Blastocyst Formation
ICM/Embryoblast Formation
Implantation
Where does Fertilization occur?
Distal 1/3 of Ampulla of Uterine/Fallopian Tube
What happens during Capacitation and where does it occur?
How long does it take?
What additional enzymes are used to penetrate the Zona Pellucida?
When and why does the Zona Reaction occur?
How does Perivitelline space help?
- Capacitation:
- Uterus and Uterine Tubes
- Glycoprotein Coat on Head of Sperm removed and Acrosome Reaction occurs by releasing Hyaluronidase to get through Corona Radiata
- 7 hours
- Esterases, Acrosin, Neuraminidase
- When 1 sperm gets through Zona Pellucida –> Conformation change in Zona Pellucida preventing polyspermy
- Granules released helping Zona Reaction
- Fusion of the plasma membranes of oocyte and sperm occurs, Sperm Head and Tail enter, but what does not enter the oocyte?
- Second meiotic division and formation of male pronucleus occur, then fusion of the two pronuclei create what?
Sperm Mitochondria
Zygote
What are the results of Fertilization?
Complete 2nd Meiotic Division
Restore Diploid Number of Chromosomes
Determine Chromosomal Sex of embryo
Metabolic activation of oocyte
Initiation of cleavage
What is cleavage?
What are the cells called afterward?
What happens to cells during this process?
When does cleavage start?
Division of the cells
Blastomeres
Increase in cell number; decrease in cell size
30 hours after fertilization
What is it called when it reaches the 12-32 cell stage?
What day does this occur?
What day does it enter uterine cavity?
Morula
Day 3
Day 3-4
What is it called when fluid diffuses into the cells?
What day does this occur?
What day does implantation occur?
Blastocyst (Blastocystic Cavity)
Day 5
Day 6
What does the Inner Cell Mass give rise to?
What day does the Zona Pellucida start to degenerate in the Early Embryoblast and what is the process called?
What is it called after degeneration of Zona Pellucida?
What does the Trophoblast give rise to?
Embryo
Day 5 and finishes on Day 7 = Hatching of embryo
Late Blastocyst
Placenta
After week one, how many layers?
Processes in week one can be replicated by assisted reproductive technologies including what?
How long are Embryos viable during Cryopreservation?
One Layer - ICM/Embryo
In Vitro Fertilization and Embryo Transfer; Intracytoplasmic Sperm Injection
21 Years
Where are Embryonic Stem Cells derived from?
What is the potentcy
Therapeutic cloning is also called what?
Inner Cell Mass
Pluripotent
Somatic Nuclear Transfer
Trophoblast cells release what protein as an immunosuppresant and when is it produced?
Trophoblast differentiates into what 2 parts? What are their functions?
- Early Pregnancy Factor; First 10 Days
- Cytotrophoblast
- Stem Cell Layer
- Mitotically active
- Syncytiotrophoblast
- Release proteolytic enzymes (Implantation)
- Release hCG (initial signal of pregnancy)
What is a Hydatidiform Mole and what is produced in excess?
How is a Complete Mole formed? (2)
How is a Partial Mole formed? (1) What didn’t occur?
Clinical Symptoms?
What are Choriocarcinomas? Where do they metastasize to?
- Abnormal trophoblastic proliferation; Excessive hCG produced
- Complete:
- Ferilization of empty oocyte followed by duplication of sperm
- Fertilization of empty oocyte by two different sperm
- Partial:
- Fertilization of normal oocyte by two different sperm (No Zona Reaction)
- Vaginal Bleeding, Pelvic Pressure, Enlarged Uterus, Hyperemesis Gravidarum
- Malignant tumor (3-5%) developing from Hydatidiform mole
- Liver, Lungs, Vagina, Intestines, Bone, Brain
What events occur during week 2?
What does the ICM develop into in Week 2 and what does it then give rise to?
What else is ONLY present in week 2?
- Bilaminar Disc Formation and Implantation
- Epiblast
- Ectoderm
- Amnion (Roof over Epiblast)
- Amniotic Cavity
- Hypoblast
What layers do the Hypoblast give rise to? What structures arise from this?
What other extraembryonic layer is formed and where does it come from?
- Extraembryonic Endoderm
- Prechordal Plate (Location of future mouth)
- Primary and Secondary Yolk Sac (Umbilical Vesicle)
- Extraembryonic Mesoderm (Comes from Umbilical Vesicle)
What is the extraembryonic Coelom?
What does Extraembryonic Somatic Mesoderm line?
What does Extraembryonic Splanchnic Mesoderm line?
Hollow cavity outside of embryo
Trophoblast, Connecting Stalk, and Amnion (Adjacent to Ectoderm)
Yolk Sac/Umbilical Vesicle (Adjacent to Endoderm)
What are Derivatives of the Extraembryonic Mesoderm?
- Connecting Stalk (forms Umbilical Cord)
- Extraembryonic Somatic Mesoderm
- Primitive Blood (forms in Wall of Yolk Sac)
- Extraembryonic Splanchnic Mesoderm
- Chorion (layer of Placenta)
- Extraembryonic Somatic Mesoderm
- Cytorophoblast/Syncytiotrophoblast
Where do most impantations occur in the Uterus?
What are abnormal implantations outside the uterus called?
Where are the most common places this occurs?
Posterior wall of uterus
Ectopic Pregnancies
Ampullary and Isthmic (Tubal Ectopic); Also occur in Abdomen, Infundibulus, and on Ovaries
Placenta Previa (Placenta implants over Internal Cervical Os) is indicated by what?
What is protocol for evaluating this?
Why should you avoid digital evaluation?
What are the three types? (least to most severe)
Vaginal bleeding beyond 20 weeks gestation
Sonographic evaluation prior to digital vaginal examination
Palpation can cause severe hemorrhage
Marginal, Partial, Total/Central
What occurs during week 3?
Gastrulation (Formation of all 3 germ layers)
Neurulation (CNS)
Heart and CVS development
Which initial layer do all 3 germ layers orginate from?
What structures do Ectoderm, Mesoderm, and Endoderm give rise to?
Which end does the primitive streak form during Gastrulation? What happens during this process?
- Epiblast
- Ectoderm: Skin, Hair, Nails, CNS (Brain & SC)
- Mesoderm: Muscle, Bone, Blood, Heart, Spleen
- Endoderm: Lungs, GI, Bladder, Thyroid & Parathyroid Glands, Tonsils
- Gastrulation
- Primitive Streak Formation in Caudal end
- Invagination of Epiblast leads to formation of Definitive/True/Intraembryonic Endoderm and Mesoderm
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Back Myology27
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Lecture Clinical Notes65
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Upper Extremity Myology45
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Back Arthrology10
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Back Angiology/Neurology23
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Dermatomes, Myotomes, Plexuses11
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Back Osteology11
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Upper Extremity Osteology8
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Upper Extremity Arthrology18
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Upper Extremity Neurology17
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Development of PNS15
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Development of Muscular System15
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Fertilization and Gastrulation30
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Neurulation and Neural Crest9
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Development of Limbs14
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Epithelial Tissue29
