Week 1 Flashcards
Conceptus
Product of fertilization
Primordium
Organ or tissue in early stages
Embryonic Period
Weeks 3-8
Fetal period
Weeks 8-38
Trimesters
Month 1-3, 4-6, 7-9
Blastocyst parts (3)
Inner cell mass (Embryoblast)
Outer cell mass (trophoblast)
Blastocyst cavity
Blastocyst arrival in uterus (week)
Week 1
Implantation
Fusion of Trophoblast and endometrial epithelium
Cytotrophoblast
Unfused trophoblast cells
Syncytiotrophoblast
Divided trophoblast cells that are fused into endometrial epithelium
hCG
Human chorionic gonadotropin
Secreted by Syncytiotophoblast –> prevents menstruation
Gastrulation (in general)
Week 3
Bilaminar germ disk –> trilaminar germ disk
Endoderm
Mesoderm
Ectoderm
Formation of endoderm
Epiblast cells migrate through primitive streak to replace hypoblast –> form endoderm
Mesoderm formation
Epiblast cells migration through primitive streak lie between endoderm and epiblast –> mesoderm
Ectoderm formation
Non migrating epiblast cells –> ectoderm
Ectoderm develops into..
Epidermis
CNS
Endoderm develops into..
Inner lining of digestive and respiratory tracts
Mesoderm develops into..
Muscles, bones, blood, connective tissues, fat
Sacrococcygeal teratoma
Occurs when primitive streak cells persist
Tumors have a lot of tissues in them, teeth/hair
Caudal regression
Due to failure of mesoderm formation
Cranial structures normal, inferior structures underdeveloped
Locations without mesoderm after gastrulation
Cloacal membrane
Buccopharyngeal membrane
Tightly bound ecto and endoderm
Will form oral and uro-genital-digestive openings
3 mesoderm tissues
Paraxial mesoderm
Intermediate mesoderm
Lateral plate mesoderm
Formation of intraembryonic coelom
Lateral plate mesoderm splits into somatic and splanchnic mesoderm
Space in between is intraembryonoic coelom
Somatic mesoderm development –>
Body wall, conscious sensation and movement
Splanchnic mesoderm development –>
Visceral, unconscious sensation and movement
Intraembryonic coelom development –>
Body cavities
Molar pregnancy
Organism only develops placenta, no embryo
Villi swell and must be removed
Neurulation
Week 4 (end of week 3)
Notocord induces ectoderm to thicken = neuroectoderm
Neuroectoderm folds, creates neural groove
Neuroectoderm fuses –> neural tube formed (filled with amniotic fluid)
Surface ectoderm after neurulation becomes…
Epidermis
Direction of neural tube closure
First in middle, then cranially and caudally
Closing of neural tube (week)
Near week 4 end
Neural crest
Forms when ectoderm cells break off from neural tube and neuroectoderm
Lateral to neural tube
Neural crest develops..
Neural cells that are outside of CNS
Schwann cells
dorsal root ganglion
Cranial nerve ganglion
Postganglionic neurons
Paraxial mesoderm condensation results in
Somitomeres –> Somites
Somites develop into..
Bone (migrates aroung notochord), muscle, dermis
Somite divides into 2 parts
Sclerotome (bone)
Dermomyotome (muscle and dermis)
B cell development (total)
Stem cell –> Pro B –> Pre B –> Immature B –> Mature B
Pro B cell development
D-J rearrangements in H chain
Pre B cell development and Ig expression
V-D-J rearrangement in H chain
Cytoplasmic mu and pre B cell receptors
Immature B cell development and Ig expression
VJ rearrangement = Single functional light chain
IgM expressed on surfaceas receptor (can’t be activated by antigen)
Mature B cell
IgM and IgD expression
Cell exits bone marrow
Bruton’s X linked Agammaglobulinemia
Defect in btk gene
btk gene product = pro B cell –> further development
Defect = lack of humoral immunity (no B cells)
No tonsils of papable lymph nodes
2 T cell types
Alpha-beta
Gamma-Delta
T cell marker on all T cells
CD3
T cell markers on alpha beta
CD4 or CD8
Activation of T cell (3 steps)
Adhesion Signal 1 (Antigen recognition) Signal 2 (co-stimulation, B7-CD28)
Cell adhesion
Adhesion molecules help connect Tcell and APC
LFA-1/CAM-1
Transient connection
Antigen recognition and adhesion
TCR recognizes MHC/peptide –> Increased affinity of LFA-1
Leukocyte adhesion deficiency
Affects beta2 integrin subunit of LFA-1
Antigen recognition
TCR binding induces CD3 signal cascade
Costimulatory Signal
CD28-B7 (Most studied)
B7 on APC activated by microbes or innate immune response
Connect with CD28 on Tcell
B-cell activation by T cell (general overview)
B cell binds antigen –> Peptide derived and presented by MHC –> T helper cell recognizes
Helper T cell action after connected to B cell
CD40Ligand and cytokines expressed (bind to resective receptors) –> B cell activation and proliferation
Hapten
Small non immunogenic molecule
Needs carrier (eg BSA)
Carrier-hapten complex is immunogenic and Ig will react to hapten alone
ONLY AFTER COMPLEX IMMUNIZATION
IL-2
Made by activated T-cells
Binds (autocrine) to t-cells (IL-2R) and induces clonal expansion and differentiation
3 CD4 subsets
Th1, Th2, Th17
Th1 cytokine
IFN-gamma
IFN-gamma
Activates macrophages
–> increased MHC expression, cytokine secretion, reactive O-, NO, lysosomal enzymes
IL-12 and Th1
IL12 secreted by innate immunity –> promotes Th1 responses
Th2 cytokines
IL-4 –> IgE response
IL-5 –> Eosinophil activation
IL-10 –> Suppress Th1
IL-13 –> Like IL-4, hypersensitivity
IL-4
IgE response
IL-5
Eosinophil activation
IL-10
Suppresses Th1
Th17 cytokines
IL-17A
IL17-F
IL-22
IL-17
Inflammatory diseases
Neutrophil action
CD8 activation (overview)
Adhesion
Ag recognition
Co-stimulation
IL-2 (made by CD4 or CTL)
CTL mechanism of action
Initiates apoptosis pathway of cell
Releases granules (perforins/granzymes) = apoptotic pathway