CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial...
Transcript of CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial...
![Page 1: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/1.jpg)
Embryology
/organogenesis/
Development and teratology
of nervous system.
![Page 2: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/2.jpg)
2
NOTOCHORD
DEVELOPMENT
NOTOCHORD
- induces neural plate development
Neuroectoderm
Neural plate
![Page 3: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/3.jpg)
3
Neural plate – thickened area of embryonic ectoderm neuroectoderm
Pharyngeal
membrane
Primitive
streak
and node
Cloacal membrane
Notochord
pseudostratif.
columnar ep.
![Page 4: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/4.jpg)
4
NEURULATION – invagination of neural plate (day 16 - 24)
- neural folds
- neural groove
- neural tube
- neural crest
notochord
![Page 5: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/5.jpg)
5
Day 20
Neural folds
![Page 6: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/6.jpg)
6
Neuroporus anterior
Neuroporus
posterior
Day 22, 23 closes
on D 25
closes
on D 27
![Page 7: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/7.jpg)
7
NEURAL CREST
![Page 8: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/8.jpg)
8
Odontoblasts
Leptomeningeal cells
![Page 10: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/10.jpg)
10
Histogenesis of neural tube The wall of neural tube:
(simple → pseudostratified neural epithelium)
Cell proliferation 3 zones:
Ependymal Intermediate Marginal
zone
Ependyma Gray matter White matter
(in medulla spinalis)
![Page 11: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/11.jpg)
11
HISTOGENESIS of NEURAL TUBE
Marginal zone (white matter)
Intermediate zone (gray matter)
(mantle zone)
Ependymal zone (germinal)
![Page 12: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/12.jpg)
12
Histogenesis of neural tissue
Three zones line neural tube (the spinal cord and brain stem).
Marginal zone (white matter) – without neurons, but with axons of neurons
and glial cells
Mantle zone (gray matter) – neuroblasts + spongioblasts give rise to
bodies of neurons and glial cells
Ependymal zone (germinal) – lining of central canal
ependyme
gray matter
white matter
In spinal cord
![Page 13: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/13.jpg)
13
ependyme
white matter
gray matter
In brain and cerebellum
In brain and cerbellum:
mantle zone cells migrate through marginal layer and the gray matter coveres
white matter. Some neurons stay in white matter nuclei.
![Page 14: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/14.jpg)
14
Spinal cord development
Dorsal
horns
Ventral
horns
motor zone
sensory zone
future white matter
future gray matter
![Page 15: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/15.jpg)
15
SPINAL CORD:
1. Ependymal layer (germinal)
2. Mantle layer (gray matter)
3. Marginal layer (white matter)
![Page 16: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/16.jpg)
16
Positional changes of spinal cord
Vertebrate canal grows more rapidly than spinal cord
and caudal end of spinal cord doesn‘t extend the
entire length of canal in adult; it terminates at L2 in
adults # .
the end fo the 2nd month the 5th month new-born child #
Cauda equina
![Page 17: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/17.jpg)
Brain development
• Brain develops from cranial part of neural
tube
• Week 4 – three primary brain vesicles:
- prosencephalon (forebrain)
- mesencephalon (midbrain)
- rhombencephalon (hindbrain)
17
![Page 18: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/18.jpg)
18
week 5 3 primary → 5 secondary vesicles:
Lamina terminalis
Prosencephalon
Mesencephalon
Rhombencephalon
Telencephalon
Diencephalon
Metencephalon
Myelencephalon
1
2
4
1 – ventriculi lat., 2 – ventriculus tertius, 3 – aqueductus cerebri, 4 – ventriculus quartus
3
Optic vesicle
Neurohypophysis
Epiphysis
Cerebellum
Pons
week 4
![Page 19: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/19.jpg)
19
Midbrain flexure Cervical flexure
![Page 21: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/21.jpg)
21
Myelination of nerve fibers from the 4th prenatal month
to the end of 2nd postnatal year
![Page 22: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/22.jpg)
22
CNS malformations
• failure neurulation (absence of notochord inductive
influence or teratogen influence on neuroectodermal
cells)
• defects of spinal cord
• defects of brain
• difficult malformations of CNS are usually connected with
skull or spinal column (vertebral) defects.
Etiology: usually multifactorial (fever, drugs during gravidity,
hypervit. A etc.) or hereditary disposition.
Folic acid use influence normal development of CNS.
Sonography detects anomalies.
![Page 23: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/23.jpg)
23
Spinal cord malformations
Defects (clefts) of vertebral
arches
• Menigocele
• Menigomyelocele
• Menigohydromyelocele
• Myeloschisis – complete cleft
of spinal column in the whole
length
spina
bifida
cystica
![Page 25: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/25.jpg)
25
![Page 26: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/26.jpg)
26
Urodynamics
Examples of external signs of spina bifida:
1) hairy patch 2) hemangioma
3) skin appendage 4) lipomatous mass
![Page 27: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/27.jpg)
27
Brain malformations
• Anencephalia (†) (with myeloschisis)
![Page 29: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/29.jpg)
29
Brain malformations
MICROCEPHALIA ANENCEPHALIA
![Page 30: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/30.jpg)
30
![Page 31: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/31.jpg)
31
Hydrocephalus
- accumulation of abundant cerebrospinal fluid in brain ventricular system,
- etiology: stenosis or obliteration of aqueductus cerebri between 3rd and 4th
ventricles fluid is accumulated in lateral ventricles pushes on the
brain tissue (is thinned); internal pressure complicates drenage of fluid
insubarachnoid space;
- until skull suture don‘t ossify – skull can grows extremely .
![Page 32: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/32.jpg)
32
HYDROCEPHALUS
ventriculoperitoneal shunt
![Page 33: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/33.jpg)
33
![Page 34: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/34.jpg)
34
Brain and meninges hernia(tion)
![Page 35: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/35.jpg)
35
![Page 36: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/36.jpg)
36
![Page 37: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/37.jpg)
Neurohypophyseal diverticle
of diencephalon floor
+
Rathke‘s pouch
of stomodeum roof
![Page 39: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/39.jpg)
Pineal gland (epiphysis) – diverticulum of the roof of diencephalon
the floor of diencephalon
![Page 40: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/40.jpg)
Thyroid gland
![Page 41: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/41.jpg)
Descensus of thyroid gland
Ductus thyroglossus
Ultimobranchial body – the 4th endodermal pouch – parafollicular cells
![Page 44: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/44.jpg)
CORTEX
- mesoderm
(coelomic epithelium)
MEDULLA
- neuroectoderm
(neural crest)
![Page 46: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/46.jpg)
46
![Page 47: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/47.jpg)
47
Terms
• Neuron – perikaryon – axon (= neurite) – dendrite(s)
• Nissl bodies = rough ER
• Axon hillock
• Myeline sheath
• Schwann sheath
• Mesaxon
• Internodium
• Node of Ranvier
• Neuron – classification
• Synapse (presynaptic knobe, synaptic cleft, postsynaptic memrane)
• Neurotransmitters
![Page 48: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/48.jpg)
48
Terms
• Neuroglia - classification
• Oligodendroglia
• Astrocytes
• Microglia (of Horteg)
• Ependyma - tanycytes
• Schwann cells
• Satelite cells
in CNS
in PNS
![Page 49: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/49.jpg)
49
• Structure of the brain cortex. Cyto- and
myeloarchitecture.
• Structure of the cerebellum. Synapses of
the cerebellum.
• Microscopic structure of the spinal cord.
• Microscopic structure of ganglia and
peripheral nerves.
• Ependyma, plexus chorioideus and
meninges.
Special histology - questions
![Page 50: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/50.jpg)
50
Terms
• Brain cortex – 6 layers (lamina)
• Cajal cells, Martinotti cells, granular and pyramidal
cells
• Membrana limitans gliae superficialis et profunda
(seu perivascularis)
• Brain barrier
• Cerebellum – 3 layers of cortex (stratum)
• Purkinje cells, basket cells, granular cells
• Glomeruli cerebellares
• Mossy and climbing fibers
![Page 51: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/51.jpg)
51
Terms
• Dura mater – arachnoidea – pia mater
• Endoneurium – perineurium – epineurium
• Plexus chorioideus
![Page 52: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/52.jpg)
52
![Page 53: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/53.jpg)
53
![Page 54: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/54.jpg)
54
Fig. 1 (a) A myelinated axon in the
peripheral nervous system and (b) its
development. Each Schwann cell
myelinates a single axon, to which it is
directly apposed. During development
(anticlockwise) Schwann cells loosely
ensheath axons and the myelin sheath
grows around the axon to form
concentric layers, which become tightly
apposed
![Page 55: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/55.jpg)
55
Fig. 3 Myelination in the central
nervous system. A single
oligodendrocyte myelinates numerous
axons (a) and, in section, concentric
layers of myelin are seen to spiral
around the axon (b). Myelin sheaths
are arranged along axons in segments
1 mm long separated by short nodes,
and would appear as large sheets if
they were unwrapped from around the
axon
![Page 56: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/56.jpg)
56
![Page 57: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/57.jpg)
57
![Page 58: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/58.jpg)
58
![Page 59: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/59.jpg)
59
roof plate
central canal
ependymal
layer
mantle
layer
marginal
layer
floor plate
![Page 62: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/62.jpg)
62
Invagination of neural plate neural folds + neural groove
![Page 63: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/63.jpg)
63
Neural tube and neural crest
Neuroporus ant., post.
Neural tube
Neural crest
![Page 64: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/64.jpg)
64
future brain
future spinal cord
future spinal and autonomic ganglia
![Page 65: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/65.jpg)
65
![Page 66: CENTRÁLNÍ A PERIFERNÍ NERVOVÝ SYSTÉM Mikroskopická … · Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells . CORTEX - mesoderm](https://reader036.fdocuments.us/reader036/viewer/2022081410/60919a00b51d5c511c44231f/html5/thumbnails/66.jpg)
66