Assiut university researches
Structure of the Digestive Tract of some Nile
Fishes in Relation to Their Food and Feeding
Habits: A Light and Electron Microscope
Study
‫ت رك يب ال ق ناة ال ه ضم يةب ال غذاء وال عادات ال غذائ ية‬
‫ درا سة ب امجهر ال ضوئ ى‬:‫ل ب عض اال سماك ال ن ي ل ية‬
.‫واالل ك ترون ى‬
Kamal Ahmed Awadh Baaoom
‫ك مال أحمد عوا ضه ب ع قوم‬
Usama Mohamed Mahmoud, Gamal Hassan El-Sokkary
‫ جمال ح سن ال س كرى‬،‫أ سامة محمد محمود‬
Abstract:
It was found that mucosal layer in the anterio-middle region is
thicker than in the posterior region of the oesophageal wall of
the fish species studied except in C. auratus. Thickness of
muscularis layer in the anterio-middle region is larger than in
the posterior region of the oesophageal wall in the fish
species studied. Mucosal layer of the stomach of C. auratus
in the middle region is thicker than that of the anterior and
posterior regions. In M. kannume, the mucosal layer of the
stomach in the anterio-middle region is thicker than that of the
posterior region. In S. schall, mucosal layer of the stomach
has the same thickness in the two regions. Mucosal layer in
the intestinal wall in the anterio-middle region is thicker than
that of the posterior region in B. bynni and S. schall . Mucosal
layer in the middle-posterior region is thicker than that of the
anterior region in C. auratus. Mucosal layer in the posterior
region of intestine is thicker than that of the anterio-middle in
M. kannume. 2. Histology The oesophageal wall has the
same structure in fishes under study except absence of
oesophageal glands in B. bynni. The results of the present
study revealed that C. auratus, M. kannume and S. schall
showed almost the same structures in the different regions of
the stomach with the exception of the absence of gastric
glands in S. schall. Using PAS –AB reaction, there was
distinct goblet cells through the mucosa of the intestinal wall.
The mucous cells (goblet cells) are numerous in the posterior
region than in the anterior one. 3. Scanning electron
microscope There are no teeth recorded in the anterior region
of the roof and the floor of B. bynni, the superior and inferior
pharyngeal teeth of this fish were rounded in shape. All teeth
of the carnivorous C. auratus were pointed canine-like teeth.
Carnivorous M. kannume has two kinds of teeth; the 1st form
was molariform teeth and the 2nd form was pointed caninelike teeth. Omnivorous S. schall has four kinds of teeth; the
1st form was pointed canine-like teeth, the 2nd form was
curved and have blunt surfaces, the 3rd form was more
curved and pointed and the 4th form was short and conical in
shape. In the present work, two types of taste buds (type I
and type II) were recorded in the pharyngeal cavity of B.
bynni, (type I and type III) were observed in C. auratus and
M. kannume and (type I, type II and type III) were recorded in
S. schall. There are some different patterns of mucosal folds
throughout the digestive tract, concerning oesophagus,
stomach and intestine of fish under study.