15.10. 1975
Specialia
Sections in t h e p l a n e zz' for t h e n o r m a l a n d a b n o r m a l eyes were c o m p a r a b l e e x c e p t for t h e smaller size of t h e a b n o r m a i o p t i c cup. T h e t o t a l v o l u m e of t h e 2 lenses p u t t o g e t h e r a n d t h e 2 optic c u p s p u t t o g e t h e r w a s less t h a n t h a t of t h e single n o r m a l lens and single n o r m a l cup, respectively. H o w e v e r , t h e m a x i m u m c i r c u m f e r e n c e of t h e n o r m a l cup a n d t h a t of t h e a b n o r m a l l y d i v i d e d cup, as seen in serial cross sections, was c o m p a r a b l e . A l a y e r of d e a d ceils lined t h e d i v i d e d optic cup on its i n n e r face while t h e cells on t h e o u t e r side a p p e a r e d h e a l t h y (Figure 2 C). O n l y d e a d a n d d e g e n e r a t i n g cells were seen in t h e wall of t h e a b n o r m a l l y d i v i d e d optic cup in e x p e r i m e n t C (Figure 2 D). Discussion. H a e m o r r h a g e in t h e h e a r t as o b s e r v e d in Calotes h a s been one of t h e m a j o r lesions p r o d n c e d in X r a y i r r a d i a t i o n e x p e r i m e n t s w i t h n e w - b o r n pig s . Our o b s e r v a t i o n s f u r t h e r i n d i c a t e t h a t h a e m o r r h a g e is perh a p s t h e m a j o r b u t n o t t h e only f a c t o r leading to d e a t h , since we also o b s e r v e d d e a d e m b r y o s w i t h o u t h e a r t haemorrhage. Death characterized by haemorrhage and
1215
general c i r c u l a t o r y s y s t e m b r e a k d o w n has also b e e n r e p o r t e d in c h i c k e m b r y o s d u r i n g t h e first d a y a f t e r i r r a d i a t i o n ~. T h e u n i l a t e r a l n a t u r e of t h e d e f e c t s is b y n o w a w i d e l y r e p o r t e d o b s e r v a t i o n a, l ~ PISAU a n d VASSE ~ a t t r i b u t e u n i l a t e r a t i t y of d e f e c t s in t h e i r e x p e r i m e n t s w i t h Lacerta viridis to t h e p o s i t i o n of t h e e m b r y o in t h e egg. H o w e v e r , it a p p e a r s t h a t t h e p o s i t i o n of t h e e m b r y o in t h e egg m a y n o t h a v e a direct b e a r i n g on t h e u n i l a t e r a l i t y of t h e defects : in b o t h Lacerta a n d Calotes t h e e m b r y o s are r e c u m b e n t on t h e left side b u t in t h e f o r m e r t h e defects are m o r e p r o n o u n c e d on t h e r i g h t side a w h e r e a s in t h e l a t t e r t h e s e are m o r e so on t h e left side n. The m a n n e r of genesis of a ' d o u b l e optic c u p ' a n d a ' d o u b l e lens' r e m a i n s u n c e r t a i n b u t it seems p r o b a b l e t h a t t h e a l t e r a t i o n in t h e s h a p e a n d division of t h e o p t i c c u p results from an i n w a r d l y directed collapse of t h e mesial wall of t h e cup; t h e r e t i n a l layer in t h e eye of t h e r i g h t side is also d e t a c h e d f r o m t h e o u t e r b o r d e r a t a b o u t t h e p o i n t of collapse on t h e left side. This e v e n t was followed b y cell d e a t h b e g i n n i n g along t h e i n n e r face of t h e optic cup as n o t i c e d in e x p e r i m e n t A, a n d finally resulting in e x p e r i m e n t C in t h e o p t i c cup f o r m e d of o n l y d e a d a n d d e g e n e r a t i n g cells. The a b s e n c e of t h e eye defect in the e x p e r i m e n t B m a y p o s s i b l y b e due t o t h e e m b r y o s , a t t h e t i m e of e x p o s u r e to y-rays, b e i n g y o u n g e r as c o m p a r e d w i t h t h o s e in t h e e x p e r i m e n t s A a n d C.
Summary. The y - r a y i r r a d i a t i o n causes m o r t a l i t y , r e t a r d a t i o n in d e v e l o p m e n t a n d g r o w t h rate, h a e m o r r h a g e , axial defects a n d u n i l a t e r a l m i c r o p h t h a l m i a . Histological e x a m i n a t i o n of m i c r o p h t h a l m i c e m b r y o s r e v e a l e d a p a r t i a l division of t h e left optic cup a n d a ' d o u b l e lens'. j . M. CHIPLONKAR :$ and S. C. GOEL 14
Department o~ Zoology, University o~ Poona, Poona 411 007 (India), 20 May 1975.
Fig. 2. Sections through experimental embryos showing abnormal optic cup and the lens. A) Partially divided optic cup and lens of the left side (experiment A, x 90). B) Complete division of the optic
Specialia
Sections in t h e p l a n e zz' for t h e n o r m a l a n d a b n o r m a l eyes were c o m p a r a b l e e x c e p t for t h e smaller size of t h e a b n o r m a i o p t i c cup. T h e t o t a l v o l u m e of t h e 2 lenses p u t t o g e t h e r a n d t h e 2 optic c u p s p u t t o g e t h e r w a s less t h a n t h a t of t h e single n o r m a l lens and single n o r m a l cup, respectively. H o w e v e r , t h e m a x i m u m c i r c u m f e r e n c e of t h e n o r m a l cup a n d t h a t of t h e a b n o r m a l l y d i v i d e d cup, as seen in serial cross sections, was c o m p a r a b l e . A l a y e r of d e a d ceils lined t h e d i v i d e d optic cup on its i n n e r face while t h e cells on t h e o u t e r side a p p e a r e d h e a l t h y (Figure 2 C). O n l y d e a d a n d d e g e n e r a t i n g cells were seen in t h e wall of t h e a b n o r m a l l y d i v i d e d optic cup in e x p e r i m e n t C (Figure 2 D). Discussion. H a e m o r r h a g e in t h e h e a r t as o b s e r v e d in Calotes h a s been one of t h e m a j o r lesions p r o d n c e d in X r a y i r r a d i a t i o n e x p e r i m e n t s w i t h n e w - b o r n pig s . Our o b s e r v a t i o n s f u r t h e r i n d i c a t e t h a t h a e m o r r h a g e is perh a p s t h e m a j o r b u t n o t t h e only f a c t o r leading to d e a t h , since we also o b s e r v e d d e a d e m b r y o s w i t h o u t h e a r t haemorrhage. Death characterized by haemorrhage and
1215
general c i r c u l a t o r y s y s t e m b r e a k d o w n has also b e e n r e p o r t e d in c h i c k e m b r y o s d u r i n g t h e first d a y a f t e r i r r a d i a t i o n ~. T h e u n i l a t e r a l n a t u r e of t h e d e f e c t s is b y n o w a w i d e l y r e p o r t e d o b s e r v a t i o n a, l ~ PISAU a n d VASSE ~ a t t r i b u t e u n i l a t e r a t i t y of d e f e c t s in t h e i r e x p e r i m e n t s w i t h Lacerta viridis to t h e p o s i t i o n of t h e e m b r y o in t h e egg. H o w e v e r , it a p p e a r s t h a t t h e p o s i t i o n of t h e e m b r y o in t h e egg m a y n o t h a v e a direct b e a r i n g on t h e u n i l a t e r a l i t y of t h e defects : in b o t h Lacerta a n d Calotes t h e e m b r y o s are r e c u m b e n t on t h e left side b u t in t h e f o r m e r t h e defects are m o r e p r o n o u n c e d on t h e r i g h t side a w h e r e a s in t h e l a t t e r t h e s e are m o r e so on t h e left side n. The m a n n e r of genesis of a ' d o u b l e optic c u p ' a n d a ' d o u b l e lens' r e m a i n s u n c e r t a i n b u t it seems p r o b a b l e t h a t t h e a l t e r a t i o n in t h e s h a p e a n d division of t h e o p t i c c u p results from an i n w a r d l y directed collapse of t h e mesial wall of t h e cup; t h e r e t i n a l layer in t h e eye of t h e r i g h t side is also d e t a c h e d f r o m t h e o u t e r b o r d e r a t a b o u t t h e p o i n t of collapse on t h e left side. This e v e n t was followed b y cell d e a t h b e g i n n i n g along t h e i n n e r face of t h e optic cup as n o t i c e d in e x p e r i m e n t A, a n d finally resulting in e x p e r i m e n t C in t h e o p t i c cup f o r m e d of o n l y d e a d a n d d e g e n e r a t i n g cells. The a b s e n c e of t h e eye defect in the e x p e r i m e n t B m a y p o s s i b l y b e due t o t h e e m b r y o s , a t t h e t i m e of e x p o s u r e to y-rays, b e i n g y o u n g e r as c o m p a r e d w i t h t h o s e in t h e e x p e r i m e n t s A a n d C.
Summary. The y - r a y i r r a d i a t i o n causes m o r t a l i t y , r e t a r d a t i o n in d e v e l o p m e n t a n d g r o w t h rate, h a e m o r r h a g e , axial defects a n d u n i l a t e r a l m i c r o p h t h a l m i a . Histological e x a m i n a t i o n of m i c r o p h t h a l m i c e m b r y o s r e v e a l e d a p a r t i a l division of t h e left optic cup a n d a ' d o u b l e lens'. j . M. CHIPLONKAR :$ and S. C. GOEL 14
Department o~ Zoology, University o~ Poona, Poona 411 007 (India), 20 May 1975.
Fig. 2. Sections through experimental embryos showing abnormal optic cup and the lens. A) Partially divided optic cup and lens of the left side (experiment A, x 90). B) Complete division of the optic
