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148 Cards in this Set
- Front
- Back
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What are the 2 extra-embryonic arcs in the mammalian embryo? |
Vitelline arc- yolk sac Umbilical arc- placenta |
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How many aortic arches are there? |
6 |
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Rearrangement of anterior arterial supplies |
Loss of aortic arches I, II, V Loss of aorta between arches III & IV (separates supplies to head & trunk) Aortic arch IV Right side: right subclavian artery Left side: incorporated into (dorsal) aorta Aortic arch VI: pulmonary arteries Left arch: ductus arteriosus (fetal shunt) Loss of right dorsal aorta Left dorsal aorta becomes aorta Near-complete separation of pulmonary & systemic pathways Septation of the conotruncus (AKA bulbus cordis) separates the pathways But the ductus arteriosus unites them |
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Which structure connects the pulmonary and systemic pathways in the late fetus? |
The ductus arteriosus |
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What does aortic arch IV become? |
The right side becomes the right subclavian artery The left side becomes incorporated into the (dorsal) aorta |
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What does aortic arch VI become? |
They become the pulmonary arteries The left arch becomes the ductus arteriosus, a fetal shunt |
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Which structure becomes the aorta? |
The left dorsal aorta |
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Rearrangement of the extra-embryonic arterial supplies |
The yolk sac becomes incorporated into the midgut/intestine The vitelline arteries fuse and become the superior mesenteric artery The umbilical arteries partially generate. The distal portions become the umbilical ligaments. The proximal portions become the internal illiac arteries & the superior vesicle arteries |
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What do the vitelline arteries become? |
They fuse to become the superior mesenteric artery |
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What do the umbilical arteries become? |
Distally they degenerate to become the umbilical ligaments Proximally they become the internal illiac arteries of the pelvis & the superior vesicle arteries of the bladder |
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Where is the yolk sac incorporated in the postnatal organism? |
It is incorporated into the midgut/intestine
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What is the function of the superior mesenteric artery? |
It supplies the midgut/intestine |
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What do the umbilical ligaments do in the postnatal organism? |
Anchor the urinary bladder to the belly button / navel |
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What is the function of the internal illiac arteries? |
They supply the pelvis |
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What is the function of the superior vesicle arteries? |
They supply the bladder |
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Rearrangement of anterior and posterior venous drains |
The anterior cardinal veins become the interior jugular veins The left common cardinal vein becomes the coronary sinus The proximal right internal jugular vein contributes heavily to the superior vena cava Called the brachiocephalic vein The posterior cardinals develop the subcardinal veins & then the inferior vena cava |
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How does the brachiocephalic vein form? |
An anastomosis (connection) forms from the left internal jugular vein to the the right internal jugular vein, & some of the proximal part of the left internal jugular vein degenerates |
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Which structure(s) contributes heavily to the superior vena cava? |
The proximal right internal jugular vein (& the right common cardinal vein) |
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Which structure becomes the coronary sinus? |
The left common cardinal vein |
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How does the inferior vena cava form |
It forms from the posterior cardinal veins. The posterior cardinal veins form anastomoses, then subcardinal veins, and then degenerate The subcardinal veins fuse to form the inferior vena cava |
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How does circulation within a portal system differ from typical circulation |
Typically: heart -> arteries -> capillaries -> veins -> heart Portal systems: heart -> arteries -> capillaries -> veins -> capillaries -> veins -> heart The portal system is the "veins -> capillaries -> veins" portion of the circulatory path |
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Rearrangement of extra-embryonic venous drains |
The vitelline veins fuse to become the hepatic portal drains (veins), which enter the liver The right umbilical vein degenerates The left umbilical vein gives rise to the ductus venosus Shortly after birth, the umbilical veins degenerate to form the round ligament, & the ductus venosus degenerates to form the ligamentum venosum |
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What are the 2 elements of the hepatic portal system? |
Hepatic portal vein Hepatic capillaries |
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Where are the hepatic capillaries located? |
In the liver |
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What is the function of the ductus venosus? |
The ductus venosus is a fetal shunt passing through the liver that allows blood from the placenta to bypass the hepatic capillaries It connects the left umbilical vein directly to the inferior vena cava It is derived from the left umbilical vein It degenerates to form the ligamentum venosum |
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From what structure(s) is the round ligament derived, and where is it located? |
The round ligament is derived from the umbilical veins It is embedded in the liver |
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In what major ways does fetal circulation differ from adult circulation? |
The placenta is the source of oxygen, not the lungs Highly oxygenated blood enters the right atrium (Enters the left atrium in adults) The lungs & liver are not completely developed They cannot support large blood supplies The primary goal of the circulatory system is to get oxygenated blood to the brain as quickly as possible |
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Why do vascular shunts that divert pulmonary circulation develop? |
To lessen blood volume to the developing lungs No oxygen is obtained via the lungs To maintain a blood-flow balance to the left atrium, which would otherwise get too little from the pulmonary veins To exercise the right ventricle in preparation for use after birth |
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How is pulmonary circulation diverted using vascular shunts? |
Transeptal flow via the foramen ovale Connection of the pulmonary and systemic arcs by the ductus arteriosus |
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Why do vascular shunts that divert hepatic circulation develop? |
The developing liver cannot handle a large volume of blood To channel oxygen-rich blood to the heart as quickly as possible |
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How is hepatic circulation diverted using vascular shunts? |
Blood bypasses the liver via the ductus venosus (which connects the left umbilical vein to the inferior vena cava) |
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What are the 3 embryonic shunts? |
foramen ovale (pulmonary) (RA -> LA) ductus arteriosus (pulmonary) ductus venosus (hepatic) |
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Changes in neonatal circulation |
The ductus venosus constricts, forming the ligamentum venosum. Blood now alters path into liver via the hepatic portal vein The ductus arteriosus shuts, separating the systemic and pulmonary arcs There is a lowered resistance to blood flow in the lungs. The lungs expand for use in respiration and blood flow from the right atrium increases The foramen ovale closes, becoming the fossa ovale, as a result of increased pressure in the left atrium |
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Origins of the vascular tissues |
Extra-embryonic blood islands give rise to both blood vessels and blood cells Embryonic mesoderm (except chordamesoderm) gives rise only to blood vessels |
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What are blood islands |
Blood islands are an extra-embryonic tissue They are areas of condensed mesoderm existing as mesenchyme They are associated with the splanchnic lateral plate mesoderm of the yolk sac They are composed of hemangioblastic stem cells (AKA hemangioblasts) They give rise to both blood vessels and blood cells |
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What is the process of blood vessel development? |
1. Vasculogenesis 2. Angiogenesis 3. Recruitment |
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Vasculogenesis |
The de novo formation of vessel endothelium (which is contiguous with endocardium) Tube forms from condensed group of cells: Hemangioblastic stem cells of blood islands differentiate into angioblasts and hematopoetic stem cells. The angioblasts surround the hematapoetic stem cells and then undergo a mesenchyme to epithelial to form an endothelium The endothelium becomes the wall of the blood vessel |
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Angiogenesis |
The sprouting and elaboration of existing vessels Proliferation of cells and continued incorporation of cells Forms a capillary plexus (network) Can be recognized as the vessels continue to grow Vessels grow both into and away from each other, both combining and spreading |
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Recruitment |
Incorporation of surrounding mesoderm to form additional layers around blood vessel |
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What are the layers surrounding the blood vessel after recruitment composed of? |
Pericytes become highly associated with the endothelium, directing angiogenesis Smooth muscle Loose collection of fibroblasts |
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In what areas of the embryo do hematopoetic stem cells become seeded |
AGM- aorta, genital ridge, mesonephros (kidney) Secondary sites: placenta, spleen, liver Adult site: bone marrow |
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Where does the most blood development occur in the 1st trimester? |
AGM Yolk sac |
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Where does the most blood development occur in the 2nd trimester? |
Liver |
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Where does the most blood development occur in the 3rd trimester? |
Liver, then bone marrow |
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What is the primary site of hematopoesis in the fetus |
The liver is the primary site of hematopoesis in the fetus |
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Where does hematopoesis occur at birth? |
Most bones act as sites for hematopoesis |
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Where does hematopoesis occur in adults? |
Bone marrow Epiphyses of femur and humerus, sternum, pelvic bones |
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What are hematapoetic stem cells? Where are they found? And what do they produce? (Classical model of hematopoetic lineages) |
They are multipotent stem cells found in bone marrow They give rise to 2 types of committed (daughter) (stem) cells: common lymphoid cells & common myeloid/erythroid cells |
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What do common lymphoid cells give rise to? |
Lymphocytes: B-cells & T-cells |
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What do common myeloid/erythroid cells give rise to? |
Myeloid cells: Granulocytes (secretory vesicles) (innate immune system): neutrophils, esinophils, macropahges, mast cells Osteoclasts: degrade bone Erythroid cells: erythrocyte (RBC), platelets |
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Myeloid-based model of hematopoetic lineages |
Stem cells give rise to common myelo-erythroid progenitors & common myelo-lymphoid progenitors, which give rise to myeloid-B progenitors & myeloid-T progenitors All lineages give rise to phagocytes in addition to: common myelo-erythroid- erythrocytes myeloid-B- B-cells myeloid-T- T-cells |
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How does fetal hemaglobin differ from adult hemoglobin? |
Hemoglobin is a tetrameric protein Adult hemoglobin is organized as follows: α β β α Fetal hemoglobin is organized differently: α γ γ α This organization increases the likelihood of oxygen saturation |
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CNS derivatives |
Prosencephalon -> Telencephalon & Diencephalon -> only alar plate derivatives Mesencephalon Rhombencephalon -> Metencephalon & Myelencephalon Spinal cord |
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Structures of the telencephalon |
Corpus callosum (Cerebral) paleocortex (Cerebral) neocortex Corpus striatum |
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Structures of the diencephalon |
Epithalamus Epiphysis (pineal gland) Thalamus Infundibulum (posterior pituitary) Optic vesicles |
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Structures of the mesencephalon |
Tectum Tegmentum |
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Structures of the metencephalon |
Cerebellum Pons |
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Structures of the myelencephalon |
Afferent columns Efferent columns |
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Function and origin of the corpus callosum |
contralateral connections roof plate of telencephalon |
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Function and origin of the (cerebral) plaeocortex |
olfaction alar plate of telencephalon |
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Function and origin of the (cerebral) neocortex |
cognition speech visual processing alar plate of telencephalon |
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Function and origin of the corpus stratum |
relays body movement alar plate of telencephalon |
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Function and origin of the epithalamus |
relays involved in emotion, pain, & behavior alar plate of diencephalon |
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Function and origin of the epiphysis |
AKA pineal gland light reception in anamniotes & some amniotes endocrine roof plate of diencephalon |
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Function and origin of the thalamus |
relays alar plate of diencephalon |
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Function and origin of the hypothalamus |
homeostasis- endocrine alar plate of diencephalon |
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Function and origin of the infundibulum |
AKA posterior pituitary neurohypophysis- endocrine alar plate of diencephalon |
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Function and origin of the optic vesicles |
sensory pigmented retina lateral walls of diencephalon (alar plate?) |
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Function and origin of the tectum |
coordination of visual & auditory relays alar plate & roof plate of mesencephalon |
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Function and origin of the tegmentum |
motor control of eye muscles (via cranial nerves III & IV) basal plate of the mesencephalon |
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Function and origin of the cerebellum |
coordination and balance alar plate & roof plate of metencephalon |
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Function and origin of the pons |
relays basal plate of the metencephalon |
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Function and origin of the afferent columns |
sensory relays alar plate of myelencephalon |
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Function and origin of the efferent columns |
motor relays basal plate of the myelencephalon |
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Cell division patterns in the neural tube |
Germinal neuroepithelium Interkinetic nuclear migration Proliferation of neural stem cells Commitment to cell fate |
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Germinal neuroepithelium |
Thought to be stem cells Organized as pseudostratified epithelium: each spans the tissue from inner limiting membrane (tight junctions) to outer limiting membrane (basal lamina) |
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Interkinetic nuclear migration |
The nucleus migrates within the neural stem cell depending in where it is in the cell cycle S-phase nuclei are high, while M-phase nuclei are low |
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Proliferation of neural stem cells |
Cells past S-phase are cleaved horizontally Daughter cells are neural stem cells |
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Neural stem cells commitment to cell fate |
Cells past S-phase are split vertically Creates bipotential progenitors Neuronal lineage progenitor or Glial lineage progenitor |
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Neural lineage derivatives |
Necroblast (primitive neuron) Differentiates into a neuron |
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Glial lineage derivatives |
Glioblast (primitive glia) -> Macroglia Microglia |
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Macroglia lineage derivatives |
Oligodendrite Astroglia Radial Glia |
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Microglia lineage derivatives |
Phagocytes Originate from mesoderm via hematopoesis |
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Function and origin of the oligodendrocyte |
Insulates axons within CNS Derived from macroglia |
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Function and origin of the astroglia |
Physical support Nutrition Recycling of macromolecules Derived from macroglia |
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Function and origin of the radial glia |
Initial physical support function Act as a track for neuron migration Become ependymal cells: Inner lining of CNS Border ventricle of CNS Barrier function vs. CSF Become neural stem cells of adult |
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3 layers of CNS |
marginal zone intermediate layer / mantle zone ependymal layer / ventricular zone |
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Marginal zone characteristics |
Outermost layer of CNS White matter: axons & glia (oligodendrocytes) Gray matter: periphery of neocortex Inside-outside development |
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Intermediate zone/layer characteristics |
AKA mantle zone Gray matter Produces "horns" of spinal cord Resident sites for neurons (where they sit or migrate toward ventricular zone) |
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Ventricular zone characteristics |
AKA ependymal layer Innermost layer, borders lumen Cell divisions Radial glia |
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Inside-outside development of neocortex |
Composed of 6 layers Outermost layer is #1 Older cells reside in inside layers (e.g. 6) Younger cells reside in outer layers (e.g. 1) The migration of cells is determined by the environment of the cell on its "birthday" |
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Elements of the developing spinal cord |
Dorsal root ganglia Dorsal horn White matter Ventral horn |
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Dorsal root ganglia |
AKA spinal ganglia from ventral stream of trunk neural crest |
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"Horns" of spinal cord |
Dorsal horn: made of interneurons communication within CNS nerves receive signals from DRG send signals to nerves in ventral horn Ventral horn: motor horn nerves receive signals from nerves in dorsal horn send signals outside CNS (to create motion) |
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What is the function of interneurons |
Interneurons are responsible for communication within the CNS ex. neurons in dorsal horn of spinal cord |
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Reflex arc |
Signal (ex. from skin) -> Sensory ganglion -> Dorsal root ganglion -> Interneuron -> Motor axons of ventral root -> Response (trigger muscle activity) |
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Trunk neural crest contributions to CNS |
sensory neurons of DRG connective tissue glial cells: satellite cells- support & nutrition Schwann cells- insulation (Myelin sheath), same function as oligodendrocytes (insulate axons within CNS) |
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Vertebrae name, body region, & number |
Cervical (neck)- 7 Thoracic (trunk)- 12 Lumbar (lower back)- 5 Sacral (associated with hips)- 5 Coccygeal (tailbone remnants) - 3-4 |
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Growth of spinal cord relative to vertebral column |
Embryonic period- spinal cord extends posteriorly/inferiorly to end of vertebral column Fetal period- 2 major changes 1. Posterior end of spinal cord degenerates & becomes filumterminale (anchors) 2. Growth of vertebrae / limited growth of spinal chord Adult- end of spinal chord associated with 1st lumbar instead of 1st sacral |
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Neuroblast migration |
Migrate from marginal zone toward ventricular zone Migration facilitated by radial glia |
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Evolution and function of cerebrum |
Only in vertebrates Larger in more "intelligent" animals e.g. birds & mammals Roles in cognition & memory among other things Intelligence |
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Different regions of the cerebrum |
Frontal lobe (Primary) motor cortex Temporal lobe (Primary) somatosensory cortex Parietal lobe Occipital lobe Regional variations in layers e.g. # of layers |
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Placode |
Thickening via invagination or ingression Give rise to special senses Derived from non-neural & non-neural crest ectoderm Origins similar to epidermal epithelium Produce "non-epidermal cell types) Forms tissues other than squamous stratified epithelium Cells undergo drastic changes relative to surrounding, non-placodal cells |
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Categorization of placodes |
Integumental Placodes Pan-placodal placodes |
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Characteristics of integumental placodes |
associated with epidermal ectoderm (skin) ex. hair, feathers, (reptilian) scales, glands associated with the skin, teeth |
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Characteristics of pan-placodal placodes |
"True" placodes Derived from the pan-placodal region of ectoderm Become associated with the CNS ex. nasal cavity & olfactory receptors, lens of the eye, inner ear, cranial nerve ganglia Peripheral nervous system & head senses (smell, sight, etc.) |
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Names of pan-placodal placodes |
Adenohypophyseal Olfactory Lens Trigeminal Otic Epibranchial (AKA epipharyngeal)- locatyed above pharyngeal arches- geniculate, petrosal, nodose |
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Placode induction events |
1. Specify the pan-placodal region 2. Specify individual placodes |
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Specification of the pan-placodal region |
Occurs during primary induction Planar- neural tissue is the source Transverse- mesoderm & ectoderm are the sources |
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What happens during primary induction? |
An organism acquires polarity & germ cell regions |
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Specification of individual placodes |
Done via secondary inductions Each placode has its own source of inductive signals |
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Methods of placode formation |
Thickening/columnarization (lengthening of cells) first Then invagination (e.g. lens vesicle) AND/OR epithelial-mesenchyme transition |
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Pan-placodal derivatives |
Neurogenic placode- produce neurons: Epibrachial, lsteral line, otic, trigeminal, (dorsolateral,) olfactory Non-neurogenic placode- do not produce neurons Lens, adenohypophyseal |
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Lens placode & the development of the lens vesicle |
Lens placode invaginates & pinches-off to form lens vesicle The lens vesicle also contributes to the cornea |
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3 tunics (layers) of the eye |
1. Sensory tunic- retina (sensory & pigmented) 2. Vascular tunic (blood vessels to support retina) Choroid- consists of 2 meninges: pia mater & arachnoid (derived from somitomeres 3. Fibrous tunic- sclera (dura mater) (derived from somitomeres) & extrinsic eye muscles |
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Germ layer regions of the eye |
Neural ectoderm- sensory & pigmented retina, iris Paraxial mesoderm- sclera, choroid(?), extrinsic eye muscles Placodal ectoderm- lens, corneal epithelium Cranial neural crest- corneal stroma, iris (pigment), intrinsic (smooth) eye muscle Epidermal ectoderm- corneal epithelium |
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Development of the adenohypophyseal placode |
Invaginates as Rathke's pouch Stalk degenerates, severing connection from mouth & creating vesicle Palate bone grows in underneath vesicle |
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Development of the lens placode |
Differentiation of lens Lens fiber cells- give refractive properties & produce proteins (crystallins) Lens epithelium- stem cells that will produce more lens fiber cells |
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Lateral line system |
Not in mammals Detect movement in water Derived from placodes |
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Cranial nerves in an amniote |
I Olfactory (tract) II Optic (tract) III Oculomotor IV Triochlear V Trigeminal VI Abducens VII Facial VIII Auditory IX Glossopharyngeal X Vagus XI Accessory XII Hypoglossal |
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Sensory nerves |
AKA afferent nerves Have only ganglion VIII Vestibulocochlear/Auditory |
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VIII: Vestibulocochlear nerve Origin Target Function(s) Associated ganglia & their origins |
AKA Auditory nerve Origin: otic placode Target: inner ear Afferent function: auditory Ganglia: vestibuloacoustic from otic placode & neural crest |
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Motor nerves |
AKA efferent nerves III Oculomotor IV Trovhlear VI Abducens XI (Spinal) Accessory XII Hypoglossal |
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III: Oculomotor nerve Origin Target Function(s) Associated ganglia & their origins |
Origin: mesencephalon Target: eye muscles Efferent function: eye muscles- pupillary response |
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IV: Trochlearnerve Origin Target Function(s) Associated ganglia & their origins |
Origin: mesencephalon Target: eye muscles Efferent function: eye muscles |
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VI: Abductensnerve Origin Target Function(s) Associated ganglia & their origins |
Origin: myelencephalon, r5-r6 Target: eye muscles Efferent function: eye muscles |
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XI: (Spinal) Accessory nerve Origin Target Function(s) Associated ganglia & their origins |
Origin: myelencephalon, r7-r8 Target: pharyngeal arch IV derivatives Efferent function: neck & shoulder muscles |
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XII: Hypoglossalnerve Origin Target Function(s) Associated ganglia & their origins |
Origin: myelencephalon, r8 Target: tongue muscles Efferent function: tongue |
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Mixed nerves |
Have both afferent and efferent parts V Trigeminal VII Facial IX Glossopharyngeal X Vagus |
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V: Trigeminal nerve Origin Target Function(s) Associated ganglia & their origins |
Origin- metencephalon, r2 Target- pharyngeal arch I derivatives Afferent function- sensory from the face Efferent function- mastication (chewing) Ganglia: semilunar from dorsolateral placodes & neural crest |
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VII: Facial nerve Origin Target Function(s) Associated ganglia & their origins |
Origin: myelencephalon, r4 Target:pharyngeal arch II derivatives Afferent function: taste Efferent function: facial expression, exocrine glands Ganglia: geniculate from geniculate placode & neural crest |
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IX: Glossopharyngealnerve Origin Target Function(s) Associated ganglia & their origins |
Origin: myelencephalon, r6 Target: pharyngeal arch III derivatives Afferent function: taste Efferent function: pharyngeal muscles, swallowing Ganglia: superior from neural crest & petrosal from petrosal placode |
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X: Vagusnerve Origin Target Function(s) Associated ganglia & their origins |
Origin: myelencephalon, r7-r8 Target: pharyngeal arch IV & VI derivatives, viscera Afferent function: sensory from heart, GI tracts, & lungs, taste Efferent function: motor control to heart, GI tracts, & lungs Ganglia: jugular from neural crest & nodose from nodose placode |
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CN I olfacory nerve & CN II optic nerve |
Technically tracts, not nerves Not part of the PNS |
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Products of otic placode/vesicle |
membranous labryth (inner ear) CN VIII vestibulocochlear nerve Vestibular apparatus- balance Cochlea- hearing |
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What are groups of cell bodies called in the CNS? In the PNS? |
CNS- nucleus PNS- ganglion |
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What are bundles of axons called in the CNS? In the PNS? |
CNS- tracts PNS- nerves |
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Olfactory placode development &contributions |
1. Expands to form nasal cavities 2. Olfactory epithelium (olfactory neurons) 3.Vomeronasal epithelium (sense pheromones) (not in humans) 4. Subset of cells migrating into hypothalamus become endocrine cells- produce GnRH |
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Integument |
The skin and its associated tissues / secondary structures |
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Layers of the integument |
1. epidermis- stratified (layered) squamous (flattened) empthelium 2. dermis- loose connective tissue |
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Integumental apendages |
hair glands teeth |
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What is required to produce the integument? |
Epithelium & mesenchyme Undergo reciprocal inductions called epithelial-mesenchyme interactions (EMI) |
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What happens when you add different kinds of mesenchyme to 1 type of epithelium? |
The epithelium produces accessory structures associated with the origin of the mesenchyme |
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Spemann & Schotte |
Frog-newt reciprocal transplants Epithelium fated to become flank (normal skin) inserted into the area of the garstrula where the oral structure will form Conclusions: 1. Oral mesenchyme can induce epithelium to produce the oral structure 2. Epithelium is innately fated towards species-specific structure |
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4 origins of epidermal epithelium |
dorsal head- somitomeres dorsal trunk- somites (dermatome) ventral head- cranial neural crest dorsal trunk- somatic lateral plate |
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Histogenesis of epidermal epihelium |
1. EMI- epidermal ectoderm & dermal mesenchyme 2. 2 layers: basal layer- site of epidermal stem cells periderm- squamous, protective, lost during fetal develpment (vernix caseosum) 3. Intermediate layer forms keritinocytes (skin cells)- produced from basal layer, differentiate 4. stratification of the epidermis stratum basal (stem cells) stratum spinosum- undifferentiated keratinocytes stratum granulosum- containes granules- aggregates of intermediate filament- keratin (acquires pigment) & filaggrin (holds keratin together) stratum corneum- becomes squamous, loses cells, dies |
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Invasion of cells into epithelium |
melanocytes/melanoblasts- dorsolateral trunk NC Merkel cell- melanoreceptor Interacts w/sensory nerve ending From epidermal ectoderm Dendritic cell- innate immune system From splanchnic lat plate mesoderm |
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Accessory structures of hair |
sebaceous gland arrector pili |
