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Regulation of arranging structures in rows and columns for the topographic representation of facial vibrissae in the mouse brain
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CELLULAR M I G R A T I ~ IN CEREBRAL C~RTEX SLICES IN VITRO NORIYUKI MORITA "I , IKENAKA I,ICHIRO FUJINO 1, MASAHARU OGAWA .2, K ~ ~ I B A I, 'Division o - ~ - - - R ~ u l a ~ f ~ m o l e ~ n ~ , I ~ ~ O ~ R ~ O-saka U n i v e r s i ~ , ~ ~ 565, Japan, Departmen-t o__~ Ph-h-~ology, Kochi Medical School r Nangoku, Kochi 781-51 r Japan. During cortical development of cerebrum, it is widely believed that neuroblasts migrate from the germinal epithelium to their final destination in cortical layers in an "inside-out" pattern. To investigate the mechanisms involved in this process in vitro, we used an explant culture system in which neuroblasts were labeled serially at 24 h interval by two different reagents (BrdUrd follo~ed by [ H]-dThd) and were cultured in a rotary shaker. We could observe the [ H ] - d T h d - l a b e l e d cells outside the B r d U r d - l a b e l e d cell layer, indicating that neuronal cells could migrate in our in vitro system. However, the volume of culture medium needed was too large to add reagents which could affect cellular migration. Therefore, we have developed an alternative system. Slices of cerebral cortex were placed on culture plates in a small volume of medium and cultured without shaking. We detected BrdUrd-labeled cells migrated out from the ventricular zone by use of a laser scanning confocal imaging system. The cytoarchitecture of the slices was not destroyed in this system, and the time required for the analysis was greatly shortened since the step for making paraffin sections was avoided.
TR~NSPL~,~T~TION ,)F NOR~DRENERfiI£ LOCUS COERI~LEIIS NEbRONS INTO THE ~DL,LT RAT THALAHL~S. YL~ZO~ILR~TA and SADAHIKO H~,SUKO, _De~,.artment of 3,natomy, Saga ~ledicat S c h o o l , NabeshJma, Sa.~a 8 4 0 - O l , ~ _ J a ~ n . -~ c e l l s u s p e n s i o n d i s s o c i a t e d from 1 4 - d a , ~ - o l d r a t emhr,~'onic l o c u s c o e r u l e u s were i m p l a n t e d i n t o t h e medial p a r t of t h e l ~ o s t e r i o r t h a l a m i c n u c l e a r ,group ( P o ) o f a d u l t r a t s f r o m w h i c h t h e adrenergic afferents t o t h e t h a l a m u s had been e l i m i n a t e d w i t h 6 - h y d r o x y d o p a m i n e t r e a t m e n t . The g r m , t h and d i s t r i b u t i o n of n o r a d r e n a l i n e (NA) f i b e r s f r o m t h e i m p l a n t in t h e t h a l a m u s ~er'e e x amined for ,I-9 months after lhe implantation by i m m u n o h i s t o c h e m i s t r y ~ ' i t h NA o r t y r o s i n e h,~droxylase antihody. A d e n s e n e t v o r k of v a r i c o s e NA f i b e r s e x t e n d e d l a t e r a l l y from t h e i m ) l a n f ~ e r e f o u n d in Po, ~ e n t r a l p o s t e r o m e d i a l and ~,entral p o s ~ e r o l a t e r a l t h a l a m i c n u c l e i . On t h e cont r a r y , f e ~ e r ~3, f i b e r s r u n n i n g m e d i a l l y from t h e the i m p l a n t ~'ere o b s e r v e d in the c e n t r a l medial (£~1) anti m e d i o d o r s a l t h a l a m i c n u c l e i , and some of t h o s e f i h e r s seemed to go to t h e e o n t r a l a t e r a l t h a l a m i c m l c l e i . These d i s t r i b u t i o n p a t t e r n s of N& f i b e r s from the i m p l a n t n e u r o n s were s i m i l a r to t h o s e of n o r m a l a n i m a l s . E l e c t r o n m i c r o s c o p i c o b s e r v a t i o n s revealed that varicosities of S,~immHnnr:eacti~e f i b e r s formed s,xmmetric as ~ell as asymmetric a x o - d e n d r i t i c synapses with the host t h a l a m i c n e u r o n s . These r e s u l t s s u g o e s f t h a t i m p l a n t e d emhr,\'onic n o r a d r e f l e r g i c n e u r o n s s e l e c l i ~ , e l 3 i n n e r , a t e d i f f e r e n t t a r g e t r e g i o n s of the t b a l a m u s in a s i m i l a r p a t t e r n t o t h e n o r m a l b r a i n and form f u n c t i o n a l s y n a p t i c c o n t a c t ~ i t h the h o s t n e u r o n s .
REGUI.ATION OF ARRANGING STRUCTURES IN ROWS AND COLUMNS FOR THE TOPOGRAPHIC REPRESENTATION OF FACIAL VIBRISSAE 1N THE MOUSE BRAIN. MAKOTO YAMAKADO, Department of Anatomy, Jichi Medical School, M i n a m i k a w a c h i - M a c h i , Tochigi 329--04, Japan. The vibrissal system of the mouse is specialized in replicating a distinct topography as a matrix of cells which represent the arrangement of facial vibrissae in a serial order from the brain stem up to the cerebral cortex. To reveal the principles of this transfer, usual alteration patterns in this topography, made up of principal rows A to E which have four or eight columns each and four straddlers, were examined by damaging the vibrissae on the right side with electrocautelization during the critical postnatal days. Most animals were killed on p - 8 , and serial sections were stained alternately with cytochrome oxidase histochemistry and Gallocyanin for the nucleic acids. When the vibrissae in row C and in column 2 were deprivated on p--0 or l, in the left cerebral cortex, the cells in row C were fused into a band whilst those in column 2 were eliminated from the respective rows, leaving an array lacking a column. When the damage was made in the vibrissae of rows B and D on p - - 0 and then in a single vibrissa at C2 on p - 3 , a cell at C2 was eliminated correctly from the row, though the fusion of the cells was led in rows B and D. In this condition, cells in row C became dilated to some extent. In the cases of total deprivation of the vibrissae, banded structures which would show five rows were delineated in the field of the matrix. Those alterations of the topography were recognized in the thalamic relay nucleus, whilst, at the level of the brain stem, the related sites to the damaged vibrissae showed empty space of enzymatic reaction in the matrix. These results indicate that main regulation between rows and columns is biased towards the rows for arranging the cells, and the elimination a n d / o r fusion of the cells are executed within respective rows under a certain condition of the neuropil, and the final topography is adjusted at the level of the thalamus for guiding it into the cerebral cortex. The results of three additional experiments saw the elimination of the cells from a single row.
CELLULAR M I G R A T I ~ IN CEREBRAL C~RTEX SLICES IN VITRO NORIYUKI MORITA "I , IKENAKA I,ICHIRO FUJINO 1, MASAHARU OGAWA .2, K ~ ~ I B A I, 'Division o - ~ - - - R ~ u l a ~ f ~ m o l e ~ n ~ , I ~ ~ O ~ R ~ O-saka U n i v e r s i ~ , ~ ~ 565, Japan, Departmen-t o__~ Ph-h-~ology, Kochi Medical School r Nangoku, Kochi 781-51 r Japan. During cortical development of cerebrum, it is widely believed that neuroblasts migrate from the germinal epithelium to their final destination in cortical layers in an "inside-out" pattern. To investigate the mechanisms involved in this process in vitro, we used an explant culture system in which neuroblasts were labeled serially at 24 h interval by two different reagents (BrdUrd follo~ed by [ H]-dThd) and were cultured in a rotary shaker. We could observe the [ H ] - d T h d - l a b e l e d cells outside the B r d U r d - l a b e l e d cell layer, indicating that neuronal cells could migrate in our in vitro system. However, the volume of culture medium needed was too large to add reagents which could affect cellular migration. Therefore, we have developed an alternative system. Slices of cerebral cortex were placed on culture plates in a small volume of medium and cultured without shaking. We detected BrdUrd-labeled cells migrated out from the ventricular zone by use of a laser scanning confocal imaging system. The cytoarchitecture of the slices was not destroyed in this system, and the time required for the analysis was greatly shortened since the step for making paraffin sections was avoided.
TR~NSPL~,~T~TION ,)F NOR~DRENERfiI£ LOCUS COERI~LEIIS NEbRONS INTO THE ~DL,LT RAT THALAHL~S. YL~ZO~ILR~TA and SADAHIKO H~,SUKO, _De~,.artment of 3,natomy, Saga ~ledicat S c h o o l , NabeshJma, Sa.~a 8 4 0 - O l , ~ _ J a ~ n . -~ c e l l s u s p e n s i o n d i s s o c i a t e d from 1 4 - d a , ~ - o l d r a t emhr,~'onic l o c u s c o e r u l e u s were i m p l a n t e d i n t o t h e medial p a r t of t h e l ~ o s t e r i o r t h a l a m i c n u c l e a r ,group ( P o ) o f a d u l t r a t s f r o m w h i c h t h e adrenergic afferents t o t h e t h a l a m u s had been e l i m i n a t e d w i t h 6 - h y d r o x y d o p a m i n e t r e a t m e n t . The g r m , t h and d i s t r i b u t i o n of n o r a d r e n a l i n e (NA) f i b e r s f r o m t h e i m p l a n t in t h e t h a l a m u s ~er'e e x amined for ,I-9 months after lhe implantation by i m m u n o h i s t o c h e m i s t r y ~ ' i t h NA o r t y r o s i n e h,~droxylase antihody. A d e n s e n e t v o r k of v a r i c o s e NA f i b e r s e x t e n d e d l a t e r a l l y from t h e i m ) l a n f ~ e r e f o u n d in Po, ~ e n t r a l p o s t e r o m e d i a l and ~,entral p o s ~ e r o l a t e r a l t h a l a m i c n u c l e i . On t h e cont r a r y , f e ~ e r ~3, f i b e r s r u n n i n g m e d i a l l y from t h e the i m p l a n t ~'ere o b s e r v e d in the c e n t r a l medial (£~1) anti m e d i o d o r s a l t h a l a m i c n u c l e i , and some of t h o s e f i h e r s seemed to go to t h e e o n t r a l a t e r a l t h a l a m i c m l c l e i . These d i s t r i b u t i o n p a t t e r n s of N& f i b e r s from the i m p l a n t n e u r o n s were s i m i l a r to t h o s e of n o r m a l a n i m a l s . E l e c t r o n m i c r o s c o p i c o b s e r v a t i o n s revealed that varicosities of S,~immHnnr:eacti~e f i b e r s formed s,xmmetric as ~ell as asymmetric a x o - d e n d r i t i c synapses with the host t h a l a m i c n e u r o n s . These r e s u l t s s u g o e s f t h a t i m p l a n t e d emhr,\'onic n o r a d r e f l e r g i c n e u r o n s s e l e c l i ~ , e l 3 i n n e r , a t e d i f f e r e n t t a r g e t r e g i o n s of the t b a l a m u s in a s i m i l a r p a t t e r n t o t h e n o r m a l b r a i n and form f u n c t i o n a l s y n a p t i c c o n t a c t ~ i t h the h o s t n e u r o n s .
REGUI.ATION OF ARRANGING STRUCTURES IN ROWS AND COLUMNS FOR THE TOPOGRAPHIC REPRESENTATION OF FACIAL VIBRISSAE 1N THE MOUSE BRAIN. MAKOTO YAMAKADO, Department of Anatomy, Jichi Medical School, M i n a m i k a w a c h i - M a c h i , Tochigi 329--04, Japan. The vibrissal system of the mouse is specialized in replicating a distinct topography as a matrix of cells which represent the arrangement of facial vibrissae in a serial order from the brain stem up to the cerebral cortex. To reveal the principles of this transfer, usual alteration patterns in this topography, made up of principal rows A to E which have four or eight columns each and four straddlers, were examined by damaging the vibrissae on the right side with electrocautelization during the critical postnatal days. Most animals were killed on p - 8 , and serial sections were stained alternately with cytochrome oxidase histochemistry and Gallocyanin for the nucleic acids. When the vibrissae in row C and in column 2 were deprivated on p--0 or l, in the left cerebral cortex, the cells in row C were fused into a band whilst those in column 2 were eliminated from the respective rows, leaving an array lacking a column. When the damage was made in the vibrissae of rows B and D on p - - 0 and then in a single vibrissa at C2 on p - 3 , a cell at C2 was eliminated correctly from the row, though the fusion of the cells was led in rows B and D. In this condition, cells in row C became dilated to some extent. In the cases of total deprivation of the vibrissae, banded structures which would show five rows were delineated in the field of the matrix. Those alterations of the topography were recognized in the thalamic relay nucleus, whilst, at the level of the brain stem, the related sites to the damaged vibrissae showed empty space of enzymatic reaction in the matrix. These results indicate that main regulation between rows and columns is biased towards the rows for arranging the cells, and the elimination a n d / o r fusion of the cells are executed within respective rows under a certain condition of the neuropil, and the final topography is adjusted at the level of the thalamus for guiding it into the cerebral cortex. The results of three additional experiments saw the elimination of the cells from a single row.