MCT Tutoring 1

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MCT Tutoring 1 – Development I and II:

MCT Tutoring 1 – Development I and II -KB

Slide 2:

What does the trophoblast become? placenta Stages: Zygote – 1 cell Morula – 16-32 cells Blastocyst Outer cell mass – trophoblast Inner cell mass – becomes ??? with what type of cells?? What structure limits the size of the zygote? zona pellucida Why must it be degraded? to implant into the uterine wall


Implantation What are the three stages of implantation and at what days do they occur? Implantation occurs at days 5 or 6 Attachement Adhesion – proteins adhere to the glycocalyx of the uterine wall Penetration – invade through basal lamina to the blood vasculature The trophoblast has two parts, which part invades the endometrium through the basal layer to reach the blood vessels and form lacunae? Syncytiotrophoblast What does it secrete???


Questions What is the most common place for an ectopic pregnancy? Ampulla If there is no embryonic tissue proper but the trophoblast continues to grow what is this called? Hydatidiform mole What can this develop to? What is the major complication of ectopic pregnancy? Rupture or hemorrhage

Cell Differentiation:

Cell Differentiation The inner cell mass becomes what two layers? Epiblast  ectoderm Hypoblast  endoderm The process that yields the three germ layers is called? Gastrulation What is the depression that gives cranial/caudal orientation? What end does it develop at? Primitive Streak Develops at the caudal (tail) end


Questions The mesoderm has 4 main components, what are they and what do they become? Notochord  essential for proper neural tube development, becomes the nucleus pulpus Lateral plate mesoderm  body wall Paraxial mesoderm  somites Intermediate mesoderm  urogenital system What are the two locations on the body that don’t have mesoderm between the endoderm and mesoderm? Buccopharyngeal membrane (mouth) and the cloacal membrane (anus)


Question An infant presents with blueish skin, frequent infections and a cleft palate. What syndrome do you think this child has? DiGeorge Syndrome = Failure of neural crest cells to migrate properly What drug/micronutrient inhibits the migration of these neural crest cells?


Questions What becomes the neural tube? The neural folds that fuse and become the neural tube Neural crest cells become many structures, name 7. Lateral migration – melanocytes ( melano is really bad – this may be why) Central – adrenal medulla, dorsal root ganglia Membranous bone of skull Spiral septum of the heart Arachnoid , pia , Schwann cells, glial cells

Development II:

Development II The mesoderm is also associated with what two extra embryonic structures? Amniotic sac and yolk sac The blood islands are formed by what specialized part of the mesoderm? Cranial mesoderm What is the name of the cells that become the blood cells and the blood vessels? Angiogenic cell clusters What is unique about the early blood cells? They are nucleated. They lose their nuclei later.


Questionsss What are the “row of beads” on either side of the notochord? Somites What are the 3 groups of the somites ? Sclerotome  Dermatome  Myotome Epimere  Hypomere  The erector spinae are derived from which subcategory of the somites and are innervated by what nerves?


Questionsss What’s more common, a defect in the vertebral arch? Or defect in the vertebral body? Defect in the vertebral body – 10% of normal ppl will have defect in vertebral body Which one of these defects results in Spina Bifida Occulta ?

More Questionsss:

More Questionsss The 10 th thoracic nerve provides sensory sensation over what structure? Umbilicus -- Dermatomes are derived from the somites and provide levels of cutaneous innervation The limb buds (small paddles) are derived from what? Somites – Dermatome and Myotome The ventral part of the limb buds becomes what classification of muscles? Flexors The dorsal side? Extensors What is the precursor to the limb bones? A central core of mesenchyme that becomes a cartilage precursor to bone

Know This::

Know This: Remember Heart formation from GAR! Remember Intermediate Mesoderm from GAR!...yup.

Lateral Plate Mesoderm:

Lateral Plate Mesoderm Lateral folding happening concurrently with head and tail folding


Questions The lateral plate mesoderm folds down and pinches off the yolk sac, if this is incomplete it results in what? Meckel’s Diverticulum What is the space in between the lateral plate mesoderms after fusion? Peritoneal cavity The lateral plate mesoderm is split into what two layers and what do they become? Parietal  connective tissue of body wall Visceral  smooth muscle and connective tissue of GUT wall The midgut maintains a connection to the yolk sac, what is the connection called? Vitelline duct


Endoderm The epithelium of the urinary bladder is derived from the endoderm, name three other major organs that are derived from the endoderm that are not part of the gut tube. Pancreas, liver, lining of the lungs (alveolar epithelium) You are on the NICU service and notice that a newborn infant always vomits after feeding. What are two possible malformations that could yield this response? Blind esophageal pouch with distal tracheoesophageal fistula, two blind esophageal endings A tracheoesophageal fistula will result in what major complication? Pneumonia

MORE Questions:

MORE Questions The liver is composed of what germ layer/s? Endoderm yields the hepatocytes and the mesoderm yields the blood supply and connective tissue The lung is derived from what what germ layer/s? Endoderm yields the alveoli lining and the mesoderm yields the blood A mesodermal derived cancer is termed? Sarcoma A endodermal derived cancer is called? adenocarcinoma The anterior pituitary gland is derived from what germ layer? Surface ectoderm The lens of the eye is derived from what germ layer? The retina? Lens = Surface ectoderm Retina = neural tube from neuroectoderm The medulla of the adrenal gland is derived from what? Neural crest cells The posterior pituitary is derived from what layer? Neuroectoderm


questionsss What is the definition of a stem cell? A cell that can self replicate indefinitely and become several tissue types (i.e. if a stem cell divides, the 2 daughter cells can either become stem cells or can differentiate into different tissues) Totipotent stem cells are derived from what embryonic structure? Morula or earlier Cells that can become embryonic and extraembyonic structures are called? totipotent A cell that is derived from the inner cell mass is called? Pluripotent or embryonic (can become all 3 germ layers) The basal epithelium of the skin would be termed this type of stem cell? unipotent Embryonic stem cells are derived from this structure? Inner cell mass


questionsss Differentiation means? Process where determined cell expresses end phenotype Determination means? Narrowing of the potential expression What is an example of the multipotent stem cell? Hematopoietic stem cells Blood cells are derived from this type of stem cell? Hematopoietic stem cells Autologue donation means? Donor is the same person Allogenic donation means? Donor is a different person ( xenogenic is from an animal) Plasticity refers to? Differentiating into tissue other than the one they originated from

The Nervous System:

The Nervous System What are the three electrophysiological events for the transduction of a nerve signal? Receptor potential, action potential, synaptic transmission Schwann cells are derived from what embryologic origin? Neural crest cells The CNS is derived from what embryologic orgin ? neuroectoderm The perikaryon is also called? Soma or cell body The rough ER in the cell body is called what in neurons? Nissel bodies

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. What is an example of a pseudounipolar neuron? Dorsal root ganglion What is an example of a bipolar cell? Retinal bipolar cell These motor neurons innervate skeletal muscle: alpha These motor neurons innervate muscle spindles: Gamma Most neurons are what type? interneurons

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. Where are pyramidal cells found? cerebrum Where are purkinje cells found? cerebellum

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. An experiment is done by radiolabaling some proteins within a neuron. Your results show them moving at 390 mm/day. What direction is the protein traveling, what is doing the moving, and what is the protein labeled most likely to be? Anterograde , kinesin , neurotransmitters Experiment on day two reveals a radio labeled molecules to be traveling 100 mm/day. What direction is it going, what is doing the moving, and what is being moved? Retrograde, dynein , used membrane

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. Synapses occur between axons and ______ a. dendrites b. soma c.axons All of the above The hyperdense area on a presynaptic ending is called__________________ and contains__________________________. Active zone, synaptic vesicles The hyperdense area on postsynaptic endings is called_______________________ and contains________________________. Postsynaptic density, receptors

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. What are the six steps of synaptic transmission starting with depolarization of the presynaptic membrane? Presynaptic membrane depolarization Calcium channels open Calcium influx activates exocytosis of synaptic vesicles What protein(s) allows vesicles to fuse with the membrane? SNARE proteins Neurotransmitter is released into the synaptic cleft Neurotransmitter binds to postsynaptic receptors Excitatory postsynaptic potential (EPSP) or inhibitory postsynaptic potential (IPSP – yields hyperpolarization )

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. What is the function of astrocytes ? Remove neurotransmitters and potassium from extracellular space Provide structural support What do oligodendrocytes do? Myelinate CNS neurons What are microglial cells? Phagocytes of the CNS Where are ependymal cells found and what do they do? In ventricles of the brain and spinal canal, have cilia that move cerebrospinal fluid (know these cells in lab webslide )

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. The diencephalon is what part of the brain? Thalamus and hypothalamus The telencephalon is what part of the brain? Cerebral cortex and basal ganlgia You are bitten by a raccoon and contract the rabies virus. The virus is unable to get through which nervous layer? perineurium Schwann cells are directly surrounded by epineurium / perineurium / endoneurium ? Endoneurium

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. Meylin in the CNS is composed of what cells? oligodendrocytes In the PNS? Schwann cells Myelinnation yields what type of conduction to occur? Salutatory conduction What is/are mesaxons ? Schwann cells wrap around a nerve, where the schwann cell comes together is the mesaxon . There is an inner and outer mesaxon

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. There is a special name for nerve degeneration what is it? Wallerian degeneration What are the three features of chromatolysis ? Cell body swells Nucleus and RER move to periphery Increase in free ribosomes Why does the regenerating neuron need free ribosome’s? Free ribosomes generate intracellular proteins for regeneration How fast do neurons regrow ? Slow anterograde movement is 1 mm/day (movement via cytoplasm –NOT kinesin )

Nervous Tissue Questions cont.:

Nervous Tissue Questions cont. Where are blood vessles found within nerve bundles? Within the epineurium but outside the perineurium You observe a microscope slide that shows chromatolysis of a neuron, will the neuron regenerate? No necessarily. Chromatolysis shows nerve injury but doesn’t tell you if it is regenerating.

Tips for MCT:

Tips for MCT Scribes should be good. Remember the weekly tutorials on blackboard (these may not be really high yield on the test, but it will be the ONLY time you will see this information again before you need to know it for STEP-studying) Review the embryology lectures from GAR before the exam. If you don’t have it already – Robbins Pathologic Basis of Disease – might be good to get because you’ll be needing it the rest of first yearish and all of second year. (Don’t need to buy if you are okay reading the book online from the UTMB website) It really helps for PBL (you won’t have to waste as much time on Google finding the answers for learning issues)

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