الفهرس 
The oesophagusOnly 14 pages are availabe for public view
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Abstract
The present study based on : A- The examination of the macroanatomy of the alimentary canal of 32 species of b i r d s , belonging t o d i f f e r e n t orders and having d i f f e r e n t f eedine habits. B- The examination of the niicroanatomy of the alimentary canal of t h r e e species of birds, belonging t o the same order ( P a s s e r i f ormes) , and having d i f f e r e n t feeding habits. k possible correlationships between the macroh i s t o l o g i c a l s t r u c t u r e of the alimentary canal of birds and the type of food and ( o r ) between the morpho-histological s t r u c t u r e of the alimentary canal and the systematic position of the b i r d s , have beer, d.iscussed i n the present investigation. A- The macroanatomy : 1- There are f i v e diifexnt types of tongue have been found i n t h e s p e c i e s under invcstil~a-Lion;t h e s imple type i s . found i n carnivorous anii pixcivorous b i r d s . The needle type i s r epr e s ent ed i n t h e insectiiro~ousb irds..as i n -D. matjor . The t r a n s l u c e n t toii:ye its i n -P, nigricollis .The comb type c h a r a c t e r i s t i c f o r the members of f ainily iinatidae. And the feathered type is a t y p i c a l passerine tongue. 2- There are s i x types of beak; the s t r a i g h t beak is found i n irlsectivorous bi~cls I:o itid i n catching t h e i n s e c t s from t h e water as i n -. nigricollis o r in pi cking t h e w a r m s , i n s e c t s and mullusca froiii t h e e a r t h as in -S. vulgaris o r aiding i n diging the wood and picking t h e i n s e c t s i n s i d e t h e t r e e s as i n . ) I - major .!Phe lanellate f l a t buak, it is s e r r a t e d t o a s s i s t e d i n c u t t i n g the aquatic vegetation as i n -A. platyrhynchos . The long beak i s found i n p i s c i v o r o u a , it aids in gulp down their iood whole. The normal beak is found i n omnivorous, gruiiivorous and some herpivorous b i r d s , t h i s type helps i n pickin;: the seeds and fruits.’i’he conical beak is represented i n the om~ivorous and granivorous birds belonging t o t h e orde r ~~asneriformesA.n d t h e hooked beak is represented i n carnivoro1.s birds and serves i n t e a r i n g the f l e s h of prey. 3- ’The roof of the buccd cavity is armed with horny papil l a e wich are pointed pooi;oriorly as i n insectivorous t o prevent the i n s e c t s which ~tm-gled t o escape out of the buccal cavity. The herpivorous birds have a large number of spines on the roof oi the b~iccal cavity than t h a t of t h e granivorous and ca~\i?ivo~oubcu, t l e s s t h a n -the i n s e c t - ivorous b i r d s . These spines ore useful f o r grinding the food. The roof of -the bilc~al cavity of piscivorous birds is sniooth,it helps i n pxl~, doim t h e i r food whole. 4- The g l o t t i s is surroundiny by a f l e s h y laryngeal pad which is generally broadl; pyrilorm i n o u t l i n e . / :. 5- !Shere are two types of aesophagus, the first is a straight tube due t o the ab::cnce of the crop. The second type the oesophagus is di.sti.nguished three regions, upper, middle or crop arid ? ower p a r t , it is 1:epresented. i n all granivosou~ birds .Them are f i v e t;lpes of crops ,the simple crop as i n -G. p:allus ,’oilobed crop as i n -(2. livia, t h e f a l s e crop a s i n -E. -c--’-- -:;rinella, t h e r u d i c e n t aop as i n -C. c h l o r i s and s p i n d l e crop a s i n -P. montanus. 6- The stomach i s diff~~cntiabeidn t o a g l a n d u l a r proventr i c u l u s and a muscular vcntriculus ~s The proventriculus is r e l a t i v e l y small i n the granivorous and omnivorous b i r d s , with a1 intermediate s i z e i n carnivorous and insectivorous, but it is q~~iltaer g e i n -the herpivorous. There a r e t h r e e types of gizzard i n t h e present material, the compound type a s in ~;rz~r~ivoroaunds ormivorous b i r d s . It is more developed thnii -the o t h e r t y p e s , its smusculature consists of two p a i r s 02 muscle. The simple type(carnivorous) has a muscular coat for!iied of continuous layer of uniform thickness a l l around. Thc t h i r d type ;is represented i n i n s e c t i v o r o u s and piscivoro~~b-sir ds, t h e musculatu.re do not form a continuous layer 02 uniform thiclaess but f om two small masses on both sides of the organ. 7- The Neckel ’s diverticul.u!!~u iiich d i f f e r e n t i a t e s t h e i leum i n t o a proximal ad a distal limb, is well developed i n t h e -P, ’nigricollis , A-. -c.-.i--;- lc~,7 eA-~, ~ anser, -A. platyrhynclzos, -Z’. -a t r a and -G. pllus.