Observation Of The Direct Projection From The Cerebellum To The Hippocampal Formation With Transmission Electron Microscopy In Chicken

Scholars have great interest in collaboration between the telencephalon and the cerebellum,while the fiber connection is not yet conclusive,especially the direct fiber contact.Two kinds of brain waves appeared in hippocampal formation(?HF)?after the cerebellar cortex of electrical stimulation in the mammalian.The long waves may be the indirect projection and the short wave may be the direct projection from the cerebellar cortex to the HF.However,it has been reported about the direct projection from the telencephalon to the cerebellar in juvenile mammalian,while contrary to in adult mammalian over the last two decades.Then,scholars found the direct projection from the HF to the cerebellar in the poultry,which had great research value in the physiological function of the cerebellum contacts with the telencephalon in mammalian.However,the current study of the direct projection from the cerebellum to the HF is still in its infancy and remains to be improved.In this study,experiments with retrograde transport of HRP and anterograde degeneration observed with electron microscopic were conducted in chicken.Following wrere the main results:1.40% horseradish peroxidase(?HRP)?was injected into the medial part of the hoppocampal formation(?APHm)?in the left telencephalon in chickens for tracing direct fiber connection and path in the telencephalon and the cerebellum.The result showed labeled neurons appeared in Nucleus septalis lateralis(?SL),Hpyerstriatum accessorium(?HA),Neostiatum(?N),the pars dorsalis and ventralis of Archistriaturn(?Ad and Av)in the left telencephalon,APHm in the hippocampal formation and SL in the right telencephlon,Nucleus superficialis parvicellularis(?SPC)?of the bilateral diencephalon,Nucleus subrotundus(?SRt)in the left mesencephalon and Area ventralis of Tsai(?AVT)in the left brainstem.The labeled terminal appeared in Nucleus ovoidalis(?OV),Nucleus rotundus(?ROT),Nucleus triangularis(?T)and Nucleus dorsomedialis anterior(?DM)in the bilateral diencephalon,Nucleus ruber(?Ru)and Formatio reticularis medialis mesencephali(?FRM)of the bilateral brainstem.The labeled neurons and terminalappeared in Purkinje cells in the cerebellar cortex of the folium?-? of the cerebellum.2.A single electrode was prepared to choose the optimal time and voltage of electrocoagulation to destroy the cerebellum in the preliminary experiment.Following lesion of the cerebellar cortex of the folium VI was destroyed by direct electron current.After survival for 7 d,the chicken was sacrificed by perfusion through heart and the brain was gained.The Hp and APHm of HF in the the anterior part of the right telencephalon,the Hp,APHm of HF,the HA and the nucleus septalis in the the medial part of the right telencephalon,the Hp and APHm of HF in the caudal part of the right telencephalon and the Hp,APHm of HF,HA and the nucleus septalis in the left telencephalon were taken for electronic microscopy observation.The results showed varying degrees' degeneration were found in all areas.Most degenerating terminals were characterized by “foam-like” aggregated vesicles and mild hydropic degeneration and most degenerating fibers characterized by disassembling stratification of the myelin.Comparison of preliminary observations: The degenerated fiber and terminal observation of the opposite side more than the same side.The largest of the degenerated fiber were observation of the nucleus septalis,the largest of the degenerated terminal were observation of APHm,a few of the degenerated terminal were observation of HA and the lowest degree of degeneration.The results indicated that there is a direct projection between the cerebellum and the telencephalon in the chicken.The main part of the projection is between the APHm of the HF and the Purkinje cells of the cerebellum,which its projection mode is bilateral,mainly interactive projection.