Transcript Makerere-Sida-ARM-Science-Day-CoVAB

*NAMULAWA Victoria Tibenda1., KATO Charcles Drago2, NYATIA Edward2, RUTAISIRE Justus1, BRITZ Peter3
1Aquaculture Research & Development Centre, 530, Kampala Uganda
2Collage of Veterinary Medicine, Animal Resources & Bio-Security, Makerere University, 7062 Kampala Uganda
3Department of Ichthyology & Fisheries, Rhodes University 6140, Grahamstown South Africa
Abstract
The morphology of the gastrointestinal tract of adult Nile perch was described using standard SEM procedures. Investigations revealed the
presence of cardiform teeth in the oral cavity, goblet cells and finger print-like microridges on the hard palate and oesophagus lumenal
surface. Elaborate patterns and bacterial cells were observed on the stomach lumenal surface and intense foldings in the intestinal region.
These observations provide a better understanding of the morphology of the gut in Nile perch and how it is suited for its digestive function.
Introduction
The anatomical characteristics of digestive system depend upon the food,
habitat, and nutritional status of the organism (Delashoub et al., 2010). In fish, the
morphology of the gastrointestinal tract explains how food is acquired, ingested,
digested and assimilated (Sweetman et al., 2008). Nile perch (Lates niloticus) is
a freshwater carnivorous fish occurring commonly the Lake Victoria basin and
along the Nile River system (Hopson, 1972). Limited information is documented
about the morphology of its digestive system (Nakamya, 2003; Namulawa et al.,
2011), which limits the understanding of how this system functions. The objective
of this study was therefore to examine the surface architecture of the
gastrointestinal tract of Nile perch so as to better the understanding of features of
this tract in relation to its function.
Nile perch sub adult
Methodology
Sample collection
Nile perch adults (3- 5kg) were collected from Lake Victoria in Uganda, in waters around Kiggungu fish landing site, located 32ᵒ 26′ 15″E,
00ᵒ 2′ 49″N using long lines (hook No. 4 – 9).
Laboratory procedure
The oral cavity was accessed by examining the head. The head was exercised with a sharp knife just behind the operculum and fixed in
10% formalin followed by 100% alcohol for three days before they were air dried. Then socked in bleach (1% Sodium hypochlorite) to
soften the tissues attached to the bones. Teeth patches from the vomer, premaxilla, palatine, pterygoid, dentary, tongue, gill rakers and
pharynx were teased out and air dried and then critical dried for 1½ hours. Gut section was accessed by dissecting live samples (sedated
with clove oil) through an abdominal incision to reveal the digestive system. Small pieces (2 x 4 mm) of gut sections (tongue, oesophagus,
stomach, intestine, and liver) were fixed in 2.5% gultaldehyde buffered in 0.1M phosphate in 2ml epindorfs. The soft gut pieces were dried
in alcohol of increasing concentration (30%, 50%, 70%, 80% 90%, 100%), and then critical point dried for 1½ hours. The critical dried gut
and teeth specimens were each mounted onto aluminium studs and gold sputtered in a Balzer Union sputtering Device model FL-9496 for
40 minutes. The gold sputtered specimens were then scanned using a Vega TESCAN Scanning Electron Microscope Model TC100, at a
high voltage of 20.00KV.
Results
SEM Micrographs
Conclusion and discussion
•Oral cavity has cardiform teeth, with sharp
monocuspid tips, wedge shaped- obliquely
tunicate flattened crowns that bend towards the
tip. These enable Nile perch to capture live
prey, to effectively hold and push it down the
oesophagus without breaking into pieces.
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4
•The oesophagus surface cells are irregular
with finger print-like micro-ridges, covered with a
layer of mucus and bacterial cells . The musuc
eases swallowing by reducing friction, while the
ridges play an important role of protecting the
buccal-oesphageal surface from trauma and
providing an anchor to the mucus secreted from
the goblet cells
7
GB
2
5
8
•Different patterns of folds occur on the stomach
lumenal surface in the different stomach regions.
These complex foldings
provide for the
extension of the stomach capacity during
ingestion and increase the surface area during
digestion.
•Mucus, gastric pits and bacterial cells
commonly occur in all the stomach regions .
Mucus is for chemical protection while the gut
bacteria are a possible source of amylase,
cellulose, lipase and protease. They are also
important for in hydrocarbon degradation,
chemical digestion and defence.
•The ceaca and intestine lumenal surfaces are
greatly folded and covered with mucus.
The mucus protects the surface against
chemical digestion while the folds are a means
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6
9
of increasing the surface area of assimilation in
this region.
1: Oral; teeth 2: Surface of the soft palate, notice the goblet cell (GB); 3: Oesophagus lumen surface., notice the References
mucus patches (MP) , the polygon-shaped surface cells (SC) with finger print-like micro ridges (MR) and the
star- shaped bacteria; 4: Lumenal surface in the stomach cardiac region; 5: Lumenal surface of the f stomach
fundic region, notice the undulating pattern; 6: Lumenal surface of the posterior section of the fundic stomach
region , notice the honey comb-shaped pattern; 7: Lumenal surface of the stomach blind end region, notice the
surface mucous, the gastric pit openings, and bacteria; 8: Lumenal surface of the caeca, notice the folding of the
lumen surface; 9: Lumenal surface of the anterior intestine, notice the folding of the lumen surface
Delashoub M, Pousty I, Khojasteh SM (2010). Histology of Bighead carp
(Hypophthalmichthys nobilis) intestine. Global Veterinaria, 5: 302 -306.
Nakamya MF (2003). A histomorphological study of the digestive system
of the Nile perch. Bachelors of Biomedical Laboratory Technology (BBLT)
Project Report, Makerere University, Kampala, Uganda.
Namulawa VT, Kato CD, Nyatia E, Britz P, Rutaisire J (2011).
Histomorphological description of the digestive system of Nile perch (L.
niloticus). Int. J. Morphol., 29 (3): 723-732.
Sweetman J, Dimitroglou SD, Torrecillias S (2008). Nutrient Uptake: gut
morphology, a key to efficient nutrition. International Aquafeed, 26 - 30.