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Nervous system in fish   魚類의 神經系

1. Central nervous system 中樞神經系

1) Brain 腦

     --- a. Protencephalon(Prosencephalon)

             --- Forebrain or cerebrum

                   --- Telencephalon\ Diencephalon
 

 
        b. Deuterencephalon

             --- Midbrain

                   --- Mesencephalon

         c. Tritencephalon

             --- Rhombencephalon or hindbrain

                   --- Myelencephalon

                         --- Medulla oblongata

                   --- Metencephalon

                         --- The most conspicuous part of which is the cerebellum

                         --- Cerebellum\ Pons

    (1) Rhombencephalon(Tritencephalon\ Hindbrain)

         --- No definite border from the spinal cord(medulla spinalis)

               --- The passage through the foramen magnum of the skull

         --- The shape of rhombencephalon

               --- Strongly influenced by the organs of the stato-aucoustic apparatus

         a. Myelencephalon (Medulla oblongata＼Hindbrin)

              --- A transitional zone between the spinal cord and brain

                  Origins of cranial nerves below cranial nerve III (Oculomotor nerve)

             (a) Rhomboid fossa

                    --- Pronounced enlargement of central canal

                          --- A part of the 4th ventricle

                                 --- From this, lateral recesssus

                    --- The rhombic shape

                          --- Most clearly apparent in the embryo

                                 --- Later modified when the cerebellum develops

                    --- Variation in shape depending on the nucleus region

              (b) Posterior velum(Velum posticum)

                    --- A single layered epithelium of the central canal

                          <--- Ependymal lining with cilia

                                 ---> Circulation of CSF

                    --- Closing-off the fossa rhomboidea of the central canal

                    --- Strongly folded epithelium in the elasmobranchii

                          --- Less extensive, less folded in the teleostei

              (c) Posterior choroidal membrane(f)

                    --- Tela choroidea posterior

                    --- A large blood vessel plexus

                    --- Located in the folds of the velum

        # Rhombencephalic sensory and motoric zones

           Alar plate(Sensory zone)

             --- a. Somatosensory zone

                 Sulcus intermedius dorsalis

                 b. Viscerosensory zone

                 Sulcus limitans internus

           Basal plate(Motoric zone)

             --- a. Viscero motoric zone

                 Sulcus intermedius ventralis

                 b. Somatomotoric zone

                 Sulcus medianus

         b. Metencephalon

              --- The cerebellum

                    ---> A dorsal part

                          The main part of metencephalon

                  The pons

                    ---> A ventral part

                  Rostral end of the rhombencephalon

                  Fusion of alar plate

                    ---> Base of metencephalon

              --- No well-defined border between the metencephalon and myelencephalon

                    --- Rhombomesencephalic fissure

                          --- Precise border between cerebellum and mesencephalon
 

                          --- Base of it

                                 --- trochlear nerves (IV)

                                        --- Crossing of trochlear nerves

                  No precise border between mesencephalon and metencephalon

              --- Well-developed cerebellum

                    ---> Covering of the rhomboid fossa

                    a. Superficial molecularis (A fibrous layer)

                    b. Purkinje's cell layer

                    c. Deeper granularis (Perikarya)

                         --- Lined by ependyma

                         --- A component of both the area statica and cerebellum

                   ① Auriculum cerebelli on each side of cerebellum

                       --- Elasmobranchii

                       --- Formed by lateral wall of myelencephalon

                   ② Trasnverse lip in elasmobranchii

                       --- Arcus cerebellaris in teleostei

                           Archicerebellum(Vestibulocerebellum) in mammals

                      --- Connecting part between both sides of auricula

                   ③ Eminentia granularis in teleostei

             1) Elasmobranchian cerebellum

                  --- Cerebellar body(Corpus cerebelli)

                        --- (a) Anterior lobe

                            (b) Posterior lobe

                        --- Median furrow, a continuation of the sulcus medianus of the spinal cord

                        --- Sulcus transversus primus

                  --- No valvula cerebelli

                      # Sulcus marginalis --- Marginal lobe

                        Median furrow ------- Median ridge

                        Fissura postica ----- Lobus posticus

            2) Teleostean cerebellum

                (1) Corpus cerebelli

                    a. Head portion

                         --- Above the velum posticum/ therefore above the rhomboid fossa

                    b. Neck portion

                         --- The connection to the myelencephalon

                         --- A process of 4th ventricle

                         --- Inner layer of the granulosa and outer layer of molecularis

                        --- Lateral growth of the granulosa

                               ---> Emientia granularis

                                      <--- Enclosing auricular parts(partes auriculares)

                               --- Only in teleostei

                              # Auricular parts(Partes auriculares)

                                  --- Separated auricle in elasmobranchii

                (2) Valvula cerebelli

                      --- A tongue-like protrusion into the ventricle of mesencephalon

                            --- Originated from fissura rhombencephalica

                            --- Absent in elasmobranchii

                     --- A number of lobes

                           (a) A lobus medialis valvulae (Medioventralis valvulae)

                           (b) 2 lateral lobes(lobi lateralis or laterodorsalis)

                       --- Molecular layer lining of invaginated internal cavity of ventricle (Cavum crani)

                           Epithelial lining by velum anticum (= anterius) or tela mesencephalica

                           Entire valvula enclosed inside the mesencephalon

                --- Fissura postrema in elasmobranchii

                      --- The most posterior primary trqansverse fissure

                             --- Also called sulcus paraauricularis

                --- Ventral molecular layer\ Posterior cerebellar sulcus(Transverse sulcus)

         c. Mesencephalon

             --- In front of metencephalon\ In back of diencephalon

             --- The most prominent portion of the teleostean brain

            a) The floor of mesencephalon

                --- Subtectum

                      --- The floor of mesencephalon

                      --- Fusion with the rhombencephalon
 

                      --- Inner wall of subtectum

                           (a) Tori semicircularis

                           (b) Sulcus limitans(Alar\ Basal plates)

                      --- Nucleus of oculomotor nerve(III)

                          Fasciculus longitudinalis posterior

                          Sulcus interencephalicus

                            --- Located at the border with rhombencephalon

                          Commissura ansulata

                            --- Outer ventral surface of mesencephalon

                          Interpeduncular ganglion(Ganglion (Corpus) interpeduncularae)

                            --- Not always externally visible

                            --- Oculomotor nerves(III) of both sides

           2) The roof of mesencephalon

                 --- Optic tectum(Tectum opticum)

                 --- All fibres from the optic nerve

                       --- Formation of their centers (Main optic center)

                              --- All fish\ Other vertebrates

                 --- 2 dome-like hills (Right and left optic lobes)

                       --- Floor of lobes

                             --- Fomation of tela mesencephalica (A thin epithelial layer)

                                    --- After complete development of valvular cerebelli

                 --- Tori longitudinales

                       --- Adjustment of body position in space

                             --- Optic and gravitational sensations

                       --- Bulging towards the ventricle from the medial edges of the lobes

                       --- Rostrally thicker

                     Torus semicircularis

                       --- Basal portion of alar plate

                             --- # Dorsal portion of that

                                   --- Optic tectum(Tectum opticum)

                       --- A curved bulge located at the base of each optic lobe

                           Lying against the inner dorsal surface of the base of the

                           mesencephalon

                           Surrounding valvular cerebelli

            3) Ventricles of mesencephalon

                 --- Very wide in teleostei since it comprises the valvula cerebelli
 

                 --- Mesencephalic ventricle(Ventriculus mesencephali)

                       --- Very wide lumen

                       --- Narrow Sylvian aqueduct in mammals

                 --- Large valvular cerebelli

                       --- 2 flat-crevice-like openings
 

                       --- ① Recessus tecti (Dorsal one)

                               --- A closed caudal ending

                           ② Cerebral aqueduct(Aqueductus cerebri (Ventral one))

                               --- Connected to the ventricles of diencephalon and myelencephalon

         d. Diencephalon

             --- Pituitary

                 Epiphysis (= pineal- and parietal organ)

                 Saccus vasculosus

                  <=== Endocrine functions

             --- No precise borders of the diencephalon

                 ① Border from the telencephalon

                      --- Paraphysis and velum transversum(as anterio-dorsal border)

                          Optic recess(as anterior-ventral border)

                         # Velum transversum

                              --- Epithelial invagination projecting into the 3rd ventricle

                 ② Border from the mesencephalon

                      --- Posterior commissure(Posterior dorsal border)

                          Mammillary body(Posterior ventral border)

            1) Roof of the diencephalon

                 --- Epithalamus

               Side walls of that

                 --- Thalamus

               Floor of that

                 --- Hypothalamus in infundibular region

           2) Paraphysis

                 --- Thin-walled, tub-like cone

                 --- Rostral evagination from the roof of the diencephalon

                 --- No known function

                 Velum transversum

                    --- Invagination into ventricle behind paraphysis

                    --- Thin-walled epithelial structure

                    --- A plexus choroideus located

                 Saccus dorsalis

                    --- Further caudal to velum transversum

            3) Parietal (Parapineal) or pineal organs

                 --- Dorsal to the habenular ganglion

                     On the epiphygeal padding

                 --- Clearest in the agnatha

                       --- Regressed in all of the gnathostomes

                           Light-sensitive in pineal organ in petromyzon

           4) Epiphysis

                --- Developing from the pineal organ
 

                --- Anterior to epiphysis

                      ---> Parietal organ

                          # Parietal organ and pineal organs (pineal body)

                               --- Disappearance of parietal organ

                         # Habenular ganglia

                              --- Nervous interconnection

            5) Posterior commissure
 

                --- The posteriormost portion of the epithalamus

                      --- ie., situated directly in front of the mesencephalon

            Epithalamus
 

            Thalamus

              --- The lateral wall of the diencephalon/ Being protruded into the 3rd ventricle

              --- Dorsal border

                    --- Sulcus subhabenularis

                  Ventral border

                    --- Sulcus limitans (Sulcus ventralis)

                  Caudal border

                    --- Recessus metathalamicus/ Eminentia commissuralis/  Corpus postcommissurale

              --- Division of thalamus by sulcus medius

                    --- ① Caudo-dorsal portion

                        ② Rostro-ventral portion

            Hypothalamus

             --- Dominant part of the diencephalon

                 Subdivision by a large number of furrows or sulcus and process of 3rd ventricle

             a. Lateral lobes (inferior lobes\ right and left ones)

                 --- Lateral protrusion from the infundibular region

                 --- Occupying entire lateral wall

                 --- Egg-, kidney- or bean-shaped

             b. Mammillary body

                 --- By mammillary sulcus

                 --- Location of mammillary ganglion

             c. Saccus vasculosus

                  --- At the caudal fusion of both of the mammillary lobes

                     # Not being paired in teleostei

             d. Posterior recess

                 --- Teleosts

                 --- Usually a small, well-defined protrusion

                 --- Between the saccus and the raphe between the right and left lobi inferiores and

                     mammillares

             e. Medial lobe

                 --- Between the lobi inferiores (laterales)

                 --- Attached to hypophysis (pituitary gland)

             f. Pituitary

                 --- Pituitary stalk

                       --- Infundibular recess

                    # Solid stalk in the elasmobranchii

             g. Lateral optic recess

                 --- In the ventro-lateral wall of the 3rd ventricle

                 --- Situated at the level of the crossing of the optic nerves

             h. Chiasma opticum (Crossing of optic nerves)

                 --- Ventral to the lamina terminalis

             --- Structure of the 3rd ventricle

                   --- Recessus

                         --- Infundibulum\ Mammillary body\ Parapophysis\ Epiphysis\ Saccus  vasculosus

                   --- Path into the 4th ventricle

                         --- Ventral to the posterior commissure
 

                         --- Subcommissural organ

                               --- Secretion of the thread of Reissner

                               --- 4th ventricle <---> Central canal of the spinal cord

         e. Telencephalon

              --- Olfactory brain (rhinencephalon) in fish

                    --- Olfactory organ

                         ----------------> Telencephalon

                         Afferent nerves

                       (Olfactory nerve)

             --- Types of telencephalon in fish

                    --- a. Elasmobranchii\ Dipnoi

                        b. Teleostei

                        c. Chondrostei (intermediate type)

                   # The 1st\ 2nd ventricles in the 2 separate ventricular lumen of the telencephalon divided

                       by the longitudinal dorsal furrow

                         --- Elasmobranchii/ Dipnoi

              --- Teleostean telencephalic ventricle

                    --- The 1st\ 2nd ventricles

                          ---> Common ventricle

                                        Fusion   ---> Intercephalic sulcus

                                                           (Between copora striata)

                    --- Corpus striatum

                          --- Determinator of telencephalic shape

                          --- Basal portion of the telencephalon

                              Corresponding to the basal plate of the spinal cord

                        Corpus epistriatium (Basal pallium)

                          --- Corresponding to the alar plate

                         --- Epithelial plate or epithelial pallium

              --- Olfactory bulb

                    --- Directly in front of the corpora striata

                    a. Salmonid type

                         --- Majorty of teleosts

                         --- Olfactory bulb (In front of corpora striata)

                               ------------------------> Nasal capsule

                                (Olfactory nerve)

                    b. Cyprinid type

                         --- Cyprinids\ Silurids\ Gadidae

                         --- Widely separated from the telencephalon

                             Directly behind the olfactory organ

                         --- Extremely short nervus olfactoarius

                             Long olfactory tract

2) Spinal cord 脊髓

    (1) Embryological aspect
 

          --- Neural plate

                ---> Neural groove

                       ---> Neural canal

                              <--- Central canal
 

    (2) Anatomical aspect

           --- a. Gray matter
 

                      --- The center of the spinal cord

                             --- H \ Upside-down of Y-shape (More frequent in fish)

                             --- Dorsal\ Ventral horns (Columns\ Ridges)

               b. White matter
 

                      --- Central nervous pathways

                      --- Dorsal\ Lateral\ Ventral fasciculus (Bundle of nerve fibres)

               c. Central canal

                     --- Ependyhe barbs or barbels

 --- Appendage occurring near the mouth opening
        --- Shape/ Length/ Number
              --- Species-specific

              --- The cod(Gadus morrhua)
                   The catfish(Ameiurus(Ictarulus) nebulosus)

              --- Agonus cataphractus(Perciformes)
                   Solea lutea(Pleuronectiformes)

 --- Generally provided with taste buds and free nerve endings
        --- Considered as sensory organs

      Generally round/ occasionally oval in cross-section
      Sometimes drawn-out at their bases to form wing-like flaps

 --- Core of more or less thick cartilagenous rod giving it solidity
        --- Attached to a bony element of the skull

      Very long barbs usually extending far beyond the body

 --- Usually a number of thick nerve strands from the trigeminal nerve(V) or sometimes fibres from the
      facial nerve(VII)
ma (Glial cells)

                           --- "Reissner's thread" in the middle

                                  <--- A secreting product of the subcommissural organ of the diencephalon

                    --- Ampulla caudalis

         --- Longitudinal septum\ Ventral fissure in teleostei

               --- Esox lucius (Pike)

               --- Separation of dorsal\ ventral fasciculi

         --- Generally impossible to separate the white matter from gray matter in teleosts

         --- Plates (Roof plate\ Alar plate\ Basal plate\ Floor plate)

               --- Strands

                      --- Thus, plates are not always well-defined

             Medulla oblongata

               --- Easily observed with large central canal

             # Alar plates
                   --- Interneurons of the sensory roots
 

                Basal plates
                  --- Motoric nuclei

                   ===> Sulcus limitans (Internus) or His's bordering furrow running between the 2 plates on

                            each side

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