Actos de los órganos constitucionales autónomos

The ir r e g u la r s tru c tu re o f th e c i l i a a t th e su rfa ce w hich d id n o t show a normal 9+2 c o n fig u r a tio n co u ld

p o s s ib ly have been a f ix a t i o n o r d é c a lc if ic a t io n a r t e f a c t . A number o f c i l i a ta ke n fro m th e m o d ifie d b u cca l p od ia o f E chinus e s c u le n tu s , pre pa re d u s in g th e same f ix a t i o n methods, showed u n e q u iv o c a lly th e presence o f a 9+2 s tru c tu re ( F ig . 2 0 ). I t i s u n lik e ly th a t th e ir r e g u la r s tru c tu re s o f th e c i l i a enco u nte re d i n th e o p h iu ro id s were th e re fo re a r te fa c ts o f any k in d .

FIG. 1.

Scanning m icro g ra p h o f p a r t o f tu b e fo o t from -Qphiura o p h iu ra . Numerous s e c re to ry pores a re

apparent and s m a ll ra is e d s tr u c tu r e s (a rro w s) resem ble stabchen d e s c rib e d by W h itf ie ld and Emson

(1 9 8 3 ).

S cale = 10pm.

FIG. 2 .

High m a g n ific a tio n o f s im ila r area to F ig . 1. Numerous s e c re to ry pores a re p re s e n t and

o c c a s io n a l ra is e d stabchen ( s in g le a rro w s ). O ther sm a ll s tr u c tu r e s (d o u b le a rro w s) a re n o rm a lly a s s o c ia te d w ith p a ir s o f s e c re to ry pores and tra n s m is s io n e le c tr o n m icroscopy has diown these to be m o d ifie d c i l i a .

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c

. # :-^-

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FIG. 3.

T ransverse s e c tio n o f a tu b e fo o t d io w in g s e c re to ry c e lls r e le a s in g packages o f m a te r ia l thro u g h s u rfa c e p o re s. A ra is e d stabchen type c i li a t e d s tr u c tu r e i s shown ( s in g le a rro w ). A nother c i l i a r y s tr u c tu r e (d o u b le a rro w ) i s

p re s e n t w hich does n o t p ro tru d e above th e c u t ic le (c ) i n t h i s s e c tio n .

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FIG . 4 .

L o n g itu d in a l s e c tio n th ro u g h s ta b c h e n -lik e c i l i a r y s tru c tu re s , (m t) T h is presumed re c e p to r s tr u c tu r e i s s im ila r to t h a t d e scrib e d by W h it f ie ld and Emson (1983) on b r i t t l e s t a r sp in e s . These c e lls a re c lo s e ly a s s o c ia te d w ith s e c re to ry c e lls ( s ) , and a re jo in e d t o a d ja c e n t c e lls by s e p ta te ju n c tio n s (a rro w s ). C i s th e c u t ic le . S cale s 1pm

lOLV # #

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%

V #

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FIG. 5 .

L o n g itu d in a l s e c tio n th ro u g h neck o f a

s e c re to ry c e ll ( S ) . These c e lls a re c h a ra c te riz e d by a p a llis a d e o f m ic ro tu b u le s w hich ru n

lo n g it u d in a lly ju s t beneath th e c e ll membrane (m ). Each c e ll i s jo in e d to those a d ja c e n t by an in te rm e d ia te ju n c tio n ( i ) a t th e s u rfa ce and a deeper band o f s e p ta te ju n c tio n ( S j ) .

FIG. 6 .

T ra n sve rse s e c tio n th ro u g h two s e c re to ry c e lls ( s ) show ing c h a r a c t e r is tic p e rip h e ra l

m ic ro tu b u le s . There a re presumed re c e p to r c e lls , u s u a lly tw o, a s s o c ia te d w ith each p a ir o f

s e c re to ry c e lls . These re c e p to r c e lls a ls o c o n ta in m ic ro tu b u le s and a c iliu m . T h is s e c tio n shows p a r t o f one re c e p to r c e ll a t th e le v e l o f th e c i l i a r y ro o t (a rro w ). S cale = 0.2pm . FIG . 7 . ♦ " S im ila r s e c tio n to F ig . 7 c u t n e a re r th e s u rfa c e . A c le a r 9+2 c iliu m s tru c tu re surrounded by m i c r o v i l l i (rav) i s seen and a n o th e r c ili u n (a rro w ) i s c u t i n g la n c in g s e c tio n i n a second re c e p to r c e ll. Two s e c re to ry c e ll( s ) and two re c e p to r c e lls a rra n g e d i n t h i s fa s h io n i s th e t y p ic a l arrangem ent.

FIS. 8.

C iliu m between two s e c re to ry c e lls (s ) show ing 9+0 s tr u c tu r e fro m a b r i t t l e s t a r

tu b e fo o t. A lm ost no c i l i a show a 9+2 s tr u c tu r e above th e re c e p to r c e ll s u rfa c e .