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Nuclear inclusions in the periaqueductal gray matter (PAG) neurons of the cat
Abstracts of The XIV Congress of the Italian Society of Electron Microscopy
This work was f r o m the I t a l i a n 1. 2.
supported C.N.R.
by
a grant
I. pasquali Ronchetti et al., Exp. Mol. Pathol. 35 (1981) 42. A. Ruggeri et al., Histochem. J. 7 (1975) 187.
w i t h the h y p o t h e s i s that microtubules a r e s o m e h o w i n v o l v e d in the m o v e m e n t of mitochondria a l o n g the axon.
NUCLEAR AL GRAY R.
MICROTUBULE DENSITY AND DISTRIBUTION IN M O T O R A N D S E N S O R Y A X O N S E. M.
P a n n e s e , L. R i g a m o n t i , P. L e d d a a n d G. A r c i d i a c o n o
133
INCLUSIONS IN T H E P E R I A Q U E D U C T MATTER (PAG) N E U R O N S O F T H E C A T
Bianchi,
M.
Agrifoglio
a n d M.
Gioia
Istituto di A n a t o m i a Umana Normale, Via M a n g i a g a l l i 31, 2 0 1 3 3 M i l a n o
Procacci,
Institute of Histology, Embryology and Neurocytology, University of Milan, Via M a n g i a g a l l i 14, 2 0 1 3 3 Milan, Italy
The s e g m e n t of the v e n t r a l r o o t immediately a d j a c e n t to the s p i n a l c o r d a n d the s e g m e n t of the d o r s a l r o o t j u s t d i s t a l to the s p i n a l g a n g l i o n of a d u l t lizards ( L a c e r t a m u r a l i s ) w e r e f i x e d in a formaldehyde and glutaraldehyde solut i o n in s o d i u m c a c o d y l a t e b u f f e r , m o s t f i x e d in O s O 4 in the s a m e b u f f e r a n d e m b e d d e d in E p o n - A r a l d i t e resin. The t o t a l n u m b e r of m i c r o t u b u l e s a n d the cross-sectional a r e a w e r e d e t e r m i n e d on p h o t o s of m y e l i n a t e d a x o n s t a k e n at random and enlarged 100,000x; from these v a l u e s the d e n s i t y of m i c r o t u b u l e s ( a v e r a g e n u m b e r of m i c r o t u b u l e s p e r ~m 2 of a x o p l a s m i c area) w a s c a l c u l a t e d . The d e n s i t y of m i c r o t u b u l e s was determined a l s o in the p e r i m i t o c h o n d r i a l bands (0.i ~m in w i d t h ) . In t o t a l , 156 m o t o r a n d 148 s e n s o r y a x o n s w e r e a n a l y z e d . T h e d a t a thus o b t a i n e d w e r e s u b j e c t e d to s t a t i s t i c a l analysis. The average number and density of microtubules w e r e f o u n d to be r e l a t e d to the c r o s s - s e c t i o n a l a r e a of the a x o n in b o t h m o t o r a n d s e n s o r y a x o n s . In particular, a linear relationshi~ was f o u n d b e t w e e n the l o g a r i t h m of the m i crotubular d e n s i t y a n d the c r o s s - s e c t i o n a l a r e a of the axon. No significant difference in the m i c r o t u b u l a r density was detected between motor and s e n s o r y a x o n s of c o r r e s m o n d i n g size, a n d so in the p r e s e n t m a t e r i a l the m i c r o t u b u l a r d e n s i t y c a n n o t be u s e d to d i s t i n g u i s h the t w o t y p e s o f axon. In b o t h m o t o r a n d s e n s o r y a x o n s , m i crotubules a p p e a r e d to be m o r e h i g h l y concentrated a r o u n d the m i t o c h o n d r i a t h a n in the r e s t o f the a x o p l a s m . The statistical analysis carried out showed t h a t the a s s o c i a t i o n between microtubules a n d m i t o c h o n d r i a is n o t a c c i d e n t a l ; so the l a t t e r o b s e r v a t i o n is c o n s i s t e n t
A morDho-quantitative analysis was c a r r i e d o u t on the u l t r a s t r u c t u r e and the d i s t r i b u t i o n of n u c l e a r i n c l u s i o n s in the n e u r o n s o f the p e r i a q u e d u c t a l gray matter (PAG) of the cat. T h e nuclear inclusions are a l m o s t all of a filamentous t y p e (98%) w i t h an o r g a n i z a t i o n of the f i l a m e n t s w h i c h c a n b e t r a c e d b a c k to d i f f e r e n t p a t t e r n s : n u c l e a r rods (45.8%), s h e e t - l i k e inclusions with filaments arranged parallel to o n e a n o t h e r a l o n g the l o n g i t u d i n a l a x i s (33.2%) a n d s h e e t - l i k e inclusions w i t h the f i l a m e n t s a r r a n g e d to f o r m a paracrystalline orqanization (21%). O n l y 2% of the n u c l e a r i n c l u s i o n s are of t h e p e r i c h r o m a t i n g r a n u l e type. The quantitative evaluations on the distribution of the i n c l u s i o n s h a v e s h o w n t h a t in the n e u r o n a l p o p u l a t i o n of the PAG, 30% o f the n e u r o n s s i t u a t e d f u r t h e s t f r o m the c e n t r a l a q u e d u c t h a v e n u c l e a r i n c l u s i o n s , w h i l e in t h e zone a d j a c e n t to the a q u e d u c t o n l y 2% of t h e n e r v e c e l l s h a v e them. T h e r e is a c l e a r t e n d e n c y for the i n c l u s i o n s to be l o c a l i z e d in the o u t e r m o s t n e u r o n s . T h e r e fore, the s u g g e s t i o n p u t f o r w a r d in the l i t e r a t u r e t h a t the n u c l e a r i n c l u s i o n s in n e u r o n s in c l o s e c o n t a c t w i t h the ventricular c a v i t y are e x p r e s s i o n s of environmental micro-influence is n o t s u p p o r t e d b y the t o p o g r a p h i c a l distrib u t i o n o f the i n c l u s i o n s i n s i d e the P A G neurons. The observation t h a t in zone n e a r e s t to the c e n t r a l a q u e d u c t the g l i a l c o m p o n e n t is n o t o n l y m o r e d e v e l o p e d b u t a l s o s u r r o u n d s e a c h n e u r o n in a m o r e complete way, delimiting it w i t h r e s p e c t to the s u r r o u n d i n g area, l e a d s to h y m o t h e s i z e t h a t the i n c i d e n c e of i n c l u s i o n s m a y be i n f l u e n c e d b y the n e u r o n / glia relationship a f f e c t i n g the e a s e of e x c h a n g e s b e t w e e n n e r v e c e l l s a n d the surrounding environment.
This work was f r o m the I t a l i a n 1. 2.
supported C.N.R.
by
a grant
I. pasquali Ronchetti et al., Exp. Mol. Pathol. 35 (1981) 42. A. Ruggeri et al., Histochem. J. 7 (1975) 187.
w i t h the h y p o t h e s i s that microtubules a r e s o m e h o w i n v o l v e d in the m o v e m e n t of mitochondria a l o n g the axon.
NUCLEAR AL GRAY R.
MICROTUBULE DENSITY AND DISTRIBUTION IN M O T O R A N D S E N S O R Y A X O N S E. M.
P a n n e s e , L. R i g a m o n t i , P. L e d d a a n d G. A r c i d i a c o n o
133
INCLUSIONS IN T H E P E R I A Q U E D U C T MATTER (PAG) N E U R O N S O F T H E C A T
Bianchi,
M.
Agrifoglio
a n d M.
Gioia
Istituto di A n a t o m i a Umana Normale, Via M a n g i a g a l l i 31, 2 0 1 3 3 M i l a n o
Procacci,
Institute of Histology, Embryology and Neurocytology, University of Milan, Via M a n g i a g a l l i 14, 2 0 1 3 3 Milan, Italy
The s e g m e n t of the v e n t r a l r o o t immediately a d j a c e n t to the s p i n a l c o r d a n d the s e g m e n t of the d o r s a l r o o t j u s t d i s t a l to the s p i n a l g a n g l i o n of a d u l t lizards ( L a c e r t a m u r a l i s ) w e r e f i x e d in a formaldehyde and glutaraldehyde solut i o n in s o d i u m c a c o d y l a t e b u f f e r , m o s t f i x e d in O s O 4 in the s a m e b u f f e r a n d e m b e d d e d in E p o n - A r a l d i t e resin. The t o t a l n u m b e r of m i c r o t u b u l e s a n d the cross-sectional a r e a w e r e d e t e r m i n e d on p h o t o s of m y e l i n a t e d a x o n s t a k e n at random and enlarged 100,000x; from these v a l u e s the d e n s i t y of m i c r o t u b u l e s ( a v e r a g e n u m b e r of m i c r o t u b u l e s p e r ~m 2 of a x o p l a s m i c area) w a s c a l c u l a t e d . The d e n s i t y of m i c r o t u b u l e s was determined a l s o in the p e r i m i t o c h o n d r i a l bands (0.i ~m in w i d t h ) . In t o t a l , 156 m o t o r a n d 148 s e n s o r y a x o n s w e r e a n a l y z e d . T h e d a t a thus o b t a i n e d w e r e s u b j e c t e d to s t a t i s t i c a l analysis. The average number and density of microtubules w e r e f o u n d to be r e l a t e d to the c r o s s - s e c t i o n a l a r e a of the a x o n in b o t h m o t o r a n d s e n s o r y a x o n s . In particular, a linear relationshi~ was f o u n d b e t w e e n the l o g a r i t h m of the m i crotubular d e n s i t y a n d the c r o s s - s e c t i o n a l a r e a of the axon. No significant difference in the m i c r o t u b u l a r density was detected between motor and s e n s o r y a x o n s of c o r r e s m o n d i n g size, a n d so in the p r e s e n t m a t e r i a l the m i c r o t u b u l a r d e n s i t y c a n n o t be u s e d to d i s t i n g u i s h the t w o t y p e s o f axon. In b o t h m o t o r a n d s e n s o r y a x o n s , m i crotubules a p p e a r e d to be m o r e h i g h l y concentrated a r o u n d the m i t o c h o n d r i a t h a n in the r e s t o f the a x o p l a s m . The statistical analysis carried out showed t h a t the a s s o c i a t i o n between microtubules a n d m i t o c h o n d r i a is n o t a c c i d e n t a l ; so the l a t t e r o b s e r v a t i o n is c o n s i s t e n t
A morDho-quantitative analysis was c a r r i e d o u t on the u l t r a s t r u c t u r e and the d i s t r i b u t i o n of n u c l e a r i n c l u s i o n s in the n e u r o n s o f the p e r i a q u e d u c t a l gray matter (PAG) of the cat. T h e nuclear inclusions are a l m o s t all of a filamentous t y p e (98%) w i t h an o r g a n i z a t i o n of the f i l a m e n t s w h i c h c a n b e t r a c e d b a c k to d i f f e r e n t p a t t e r n s : n u c l e a r rods (45.8%), s h e e t - l i k e inclusions with filaments arranged parallel to o n e a n o t h e r a l o n g the l o n g i t u d i n a l a x i s (33.2%) a n d s h e e t - l i k e inclusions w i t h the f i l a m e n t s a r r a n g e d to f o r m a paracrystalline orqanization (21%). O n l y 2% of the n u c l e a r i n c l u s i o n s are of t h e p e r i c h r o m a t i n g r a n u l e type. The quantitative evaluations on the distribution of the i n c l u s i o n s h a v e s h o w n t h a t in the n e u r o n a l p o p u l a t i o n of the PAG, 30% o f the n e u r o n s s i t u a t e d f u r t h e s t f r o m the c e n t r a l a q u e d u c t h a v e n u c l e a r i n c l u s i o n s , w h i l e in t h e zone a d j a c e n t to the a q u e d u c t o n l y 2% of t h e n e r v e c e l l s h a v e them. T h e r e is a c l e a r t e n d e n c y for the i n c l u s i o n s to be l o c a l i z e d in the o u t e r m o s t n e u r o n s . T h e r e fore, the s u g g e s t i o n p u t f o r w a r d in the l i t e r a t u r e t h a t the n u c l e a r i n c l u s i o n s in n e u r o n s in c l o s e c o n t a c t w i t h the ventricular c a v i t y are e x p r e s s i o n s of environmental micro-influence is n o t s u p p o r t e d b y the t o p o g r a p h i c a l distrib u t i o n o f the i n c l u s i o n s i n s i d e the P A G neurons. The observation t h a t in zone n e a r e s t to the c e n t r a l a q u e d u c t the g l i a l c o m p o n e n t is n o t o n l y m o r e d e v e l o p e d b u t a l s o s u r r o u n d s e a c h n e u r o n in a m o r e complete way, delimiting it w i t h r e s p e c t to the s u r r o u n d i n g area, l e a d s to h y m o t h e s i z e t h a t the i n c i d e n c e of i n c l u s i o n s m a y be i n f l u e n c e d b y the n e u r o n / glia relationship a f f e c t i n g the e a s e of e x c h a n g e s b e t w e e n n e r v e c e l l s a n d the surrounding environment.