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90 Cards in this Set
- Front
- Back
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zygote
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fertilized egg; ceases to be a zygote when it divides into 2 blastomeres.
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embryo
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developing organism btw 2-8 weeks
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fetus
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developing organism 9 weeks to birth
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conceptus
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embryo/fetus + all its membranes (i.e., chorionic, placenta, yolk sac and whatnot)
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induction
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mechanism (signaling, protein production, etc.) by which important stuff happens (cell differentiation, cell death, etc.)
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Purpose of Selective Cell Death
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must take place so normal development can proceed (i.e., skin between rays of the hand)
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hyperplasia
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pathological increase in cell numbers
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differential growth
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one side of a tissue grows faster than the other (i.e., stomach)
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Metaplasia
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pathological de-differentiation and re-differentiation of cells
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Ectoderm products
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sweat & oil glands, hair, epidermis and papilla
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mesoderm products
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Dense CT, erector pilli mm, fat
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endoderm products
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ciliated epithelium (can become stratified squamous epithelium when exposed to cigarettes, and then can change back after quitting)
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Reciprocal induction
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one tissue induces differentiation of another, then that product in turn alters the first. (i.e., optic vesicle induces lens formation, lens induces optic cup formation).
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Process of epithelial folding
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actin filaments at the apical end of a sheet of epithelium contract; basal ends expand until a tube is formed (i.e., gastrulation/neuralation)
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Cavitation/Canalization
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spaces develop between cells in a morula, causing those cells to migrate outward, leaving a hollow center.
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Morphogens
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diffusable molecules released locally; direct cell migration; include retinoic acid, transforming GF beta, Hedgehog series, WNT/beta catenins.
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Notch/Delta
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surface proteins that interact with each other intercellularly; determine cell fate.
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Receptor Tyrosine Kinases
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attach to growth factors; regulate migration, proliferation, apoptosis, new growth, etc.
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Retinoic acid
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morphogen; responsible for ant/post specific growth (i.e., ant limb cells have higher RA concentrations)
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Transforming Growth Factor beta
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include activan; gene activation via Smad proteins.
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Hedgehog series
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morphogen; require cholesterol; activate genes via Gli molecules
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WNT/beta catenin
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morphogen; activates gene sequences; WNT prevents wing formation
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Pax Genes
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transcription factor; activate or repress specific genes
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Helix-Loop-Helix
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transcription factor; HLH; regulates cell fate & differentiation
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Receptor Tyrosine Kinase 3 domains
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extracellular ligand binding
transmembrane intracellular kinase |
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Primary Oocytes
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Lifetime maximum formed by the end of the fetal period.
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Formation of functional sperm
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spermatogonia mitoses to 1' spermatocyte meioses (I) to 2' spermatocyte meisoses (II) to spermatid undergoes spermiogenesis to spermatozoa matures to functional sperm
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Processes of Spermiogenesis
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controlled by Bcl-2 genes
condense nucleus, golgi forms acrosome, centriole becomes flagellar base. |
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Seminal secretions
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come from testis, prostate, seminal vesicle
contains alkaline fluids, fructose, enzymes and prostaglandins |
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Capacitation
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occurs in the uterus by uterine secretions; degrades glycocalyx of sperm so acrosome is ready for reaction with ovum.
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Origins of oogonia and spermatogonia
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yolk sac; 5th or 6th week
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Purpose of follicular cells
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produce estrogen and progesterone; some ovulate with the egg to protect it and prevent polyspermy; if fertlization occurs, follicular cells (corpus luteum) produce HCG.
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Purpose of cumulus
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key role in moving the oocyte to the correct place (out of peritoneum and into uterine tube)
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life span of oocyte
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12-24 h
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Sources of infertility (female)
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Pelvic Inflammatory Disease
Chlamydia Gonnorhea endometriosis polycystic ovarian syndrome other hormonal issues (autoimmune, thyroid, etc.) leading to premature ovarian failure |
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Mode of transportation of sperm
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peristalsis of ductus deferens
contractions of bulbospongiosis m uterine peristalsis fluid like cervical mucosa |
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Sperm motility & life span
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new sperm motile 5-6 d
after capacitation, life span 24-48 h |
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Oligospermia
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low count
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Asthenospermia
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low motility
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Teratospermia
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poor morphology
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Blocks to polyspermy
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depolarization of oocyte membrane and cortical granule secretion by zona prevents further fusion
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Parthinogenesis
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all female population reproduces by cloning
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1st cleavage
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@ 30 hours; zygote enters uterine tube
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Morula
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@ day 3; solid ball of 12-32 cells
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blastocyst
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@ day 4; hollow ball of 12-32 cells w/in zona
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trophoblast
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outermost cells of a blastocyst
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embryoblast
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innermost cells of a blastocyst
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Clinical Applications (5)
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1. artificial insemination
2. Gamete intra-fallopian transfer 3. in vitro 4. intracytoplasmic sperm injection 5. assisted hatching |
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Assisted hatching
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breaks up zona pellucida
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Syncytiotrophoblast
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derived from trophoblast; mass of fused cells becomes placenta; cell membranes indistinguishable.
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Cytotrophoblast
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derived from trophoblast; normal cell membranes
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hypoblast
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1st epithelium; derived from embryoblast
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epiblast
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derives from embryoblast.
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start time: gastrulations
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day 15
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mesenchyme
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undifferentiated migratory cells; give rise to CT, mm & epith
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Mesoderm
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middle of the 3 primary germ layers; consists of mesenchyme cells.
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extra-embryonic cells
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part of mesoderm; develop between yolk sac epithelium and cytotrophoblast; 2nd week
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intra embryonic cells
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develop from epiblast; 2nd week
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chorionic
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same as exocelomic
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yolk sac
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forms the primary and secondary umbilical vesicles.
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Connecting stalk
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forms bulk of umbilical cord which begins to work day 23
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early structures on the epiblast
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primitive streak and prechordal plate
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beginnings of neurulation
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induced along the primitive streak; mesenchymal cells invaginate and proliferate between the basal lamina of ecto- and endo-derms.
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directions of migration of the mesoderm
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laterally then anteriorly
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origin of notochord
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primitive node
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oropharyngeal membrane
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name change of the prechordal plate once the notochord reaches it.
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SHH genes
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Sonic Hedgehog genes; differentiate noto cord, somites and R/L axes.
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somites
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2 groups of 50 "footballs" on either side of notochord; form vertebrae, skeletal mm below the neck.
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Neurulation tissues
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descend from ectoderm overlying notocord
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neural plate
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thicker ectoderm over the notocord
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neural folding
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activated by SHH
apical actin filaments contract into a groove, then fuse to form a canal. |
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neural fold
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edges of the neural groove; gives rise to the neural crest
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timeline: neural fold formation, midline
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occurs day 20
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timeline: neural fusion at midline and continuing ant/pos
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day 22
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timeline: neural fusion complete
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day 23; only rostral and caudal neural pores remain
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rostral caudal pore gives rise to
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brain & brainstem:
prosencephalon, mesencephalon, rhombencephalon |
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stomadeum
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primordial mouth formed from split prechordal plate
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consequence of delays in closing neural tube
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failure of overlying mesoderm to form protective structures:
delay rostral pore: exencephaly delay caudal pore: spina bifida |
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timeline: rostral pore closure
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day 25
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timeline: caudal pore closure
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day 27
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allantois
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blind sac to connecting stalk
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Connection between gut tube & umbilical vesicle
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vitelline duct
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products of ectoderm
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EPIdermis & glands, hair, nails, inner ear labyrinth, lens, corneal epith, anterior pituitary, tooth enamel.
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products of neuroectoderm
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brain, brainstem, spinal cord, retina, pigmented layer, part of iris, optic n, pars nervosa (pituitary)
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products of endoderm
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alimentary epithelium, parenchyma of pancreas/liver, thyroid, parathyroid, thymus, lung, trachea, middle ear epith, urinary bladder and epith, vaginal epith.
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somatopleure
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lateral plate associated with ectoderm; forms bone, cartilage and other peripheral CT & associated vasculature.
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splanchnopleure
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lateral plate associated with endoderm; forms visceral smooth muscle, fascia and CT with associated vasculature.
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somites differentiate to 2 layers
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dermomyotome, forms skeletal mm
scleromyotome forms bones and intervertebral discs |
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products of intermediate mesoderm
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kidney, ureter, gonads, ductus deferens
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Products of neural crest
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melanocytes, peripheral nervous system, head bones, cartilage and CT, adrenal MEDULLA, meninges and spiral septum of the heart.
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