Histological and Histochemical Studies on the Esophagus, Stomach and Small Intestines of Vara-nus niloticus
📝 Abstract
The aim of the current study was to investigate the morphological structure of one of the most common reptilian species in Egypt, Varanus niloticus or Nile monitor. Specimens for histological examination were collected from the esophageus, stomach and small intestine of the Nile monitor and processed for paraffin embedding. Sections were stained with haematoxylin and eosin for general morphology. Periodic Acid Schiff’s (PAS) and Alcian Blue (AB) staining methods were applied to detect the different types of the mucous con-tents of the gastro-intestinal tract. Some paraffin sections were stained with Grimelius silver impregnation technique for localization of the enteroendocrine cells. The folded esophageal mucosa had ciliated columnar epithelium with mucous secreting goblet cells, which stained positive with PAS and AB. The esophageal mucosa was folded and the lining epithelium was ciliated columnar epithelium with mucous secreting goblet cells, which stained positive with PAS and AB. The stomach was divided into fundic and pyloric regions. The mucosa was thrown into gastric pits, into which the gastric glands opened. The surface epithelium was mucous secreting columnar cells and stained positive with PAS but negative with AB. The fundic gland was made by oxynticopeptic cells and few mucous cells, while the entire pyloric gland was made by mucous cells stained positive for both PAS and AB. The small intestine showed many villi but occasional poorly developed intestinal crypts were. The intestinal mucosa was lined with absorptive columnar epithelium with goblet cells, which stained positive with PAS and AB. Enteroendocrine cells were of different shapes; rounded, spindle, oval or pyramidal and were localized in the surface epithelium of the esophagus and small intestine, and among the cells of the gastric glands.
💡 Analysis
The aim of the current study was to investigate the morphological structure of one of the most common reptilian species in Egypt, Varanus niloticus or Nile monitor. Specimens for histological examination were collected from the esophageus, stomach and small intestine of the Nile monitor and processed for paraffin embedding. Sections were stained with haematoxylin and eosin for general morphology. Periodic Acid Schiff’s (PAS) and Alcian Blue (AB) staining methods were applied to detect the different types of the mucous con-tents of the gastro-intestinal tract. Some paraffin sections were stained with Grimelius silver impregnation technique for localization of the enteroendocrine cells. The folded esophageal mucosa had ciliated columnar epithelium with mucous secreting goblet cells, which stained positive with PAS and AB. The esophageal mucosa was folded and the lining epithelium was ciliated columnar epithelium with mucous secreting goblet cells, which stained positive with PAS and AB. The stomach was divided into fundic and pyloric regions. The mucosa was thrown into gastric pits, into which the gastric glands opened. The surface epithelium was mucous secreting columnar cells and stained positive with PAS but negative with AB. The fundic gland was made by oxynticopeptic cells and few mucous cells, while the entire pyloric gland was made by mucous cells stained positive for both PAS and AB. The small intestine showed many villi but occasional poorly developed intestinal crypts were. The intestinal mucosa was lined with absorptive columnar epithelium with goblet cells, which stained positive with PAS and AB. Enteroendocrine cells were of different shapes; rounded, spindle, oval or pyramidal and were localized in the surface epithelium of the esophagus and small intestine, and among the cells of the gastric glands.
📄 Content
J. Vet. Anat. Vol 2 No1, (2009) 35 - 48
35
Varanus niloticus Ahmed et al.
Histological and Histochemical Studies on the
Esophagus, Stomach and Small Intestines of Vara-
nus niloticus
Ahmed YA1, El-Hafez AAE2, Zayed AE2
1 Faculty of Veterinary Science, South Valley University, Qena, Egypt.
2 Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt.
Email: ya_abd@yahoo.com
With 4 figures Received June 2009; accepted for publication October 2009 Abstract Information on the digestive system of the reptiles is based on relatively few studies on some of the now present 7500 reptilian species. Yet, the gap between our understanding of the major similarities and / or differences between the mammalian and reptilian digestive system does not seem satisfiable. The aim of the current study was to investi- gate the morphological structure of one of the most common reptilian species in Egypt, Varanus niloticus or Nile moni- tor. Specimens for histological exami- nation were collected from the esopha- geus, stomach and small intestine of the Nile monitor and pro-cessed for pa- raffin embedding.
Sections
were
stained with haemat-oxylin and eosin
for general morpho-logy. Periodic Acid
Schiff’s (PAS) and Alcian Blue (AB)
staining methods were applied to detect
the different types of the mucous con-
tents of the gastro-intestinal tract.
Some paraffin sections were stained
with Grimelius silver impregnation tech-
nique for localization of the enteroendo-
crine cells.
The folded esophageal mucosa had
ciliated columnar epithelium with muc-
ous
secreting
goblet
cells,
which
stained positive with PAS and AB.
The esophageal mucosa was folded
and the lining epithelium was ciliated
columnar epithelium with mucous se-
creting goblet cells, which stained posi-
tive with PAS and AB.
The stomach was divided into fundic
and pyloric regions. The mucosa was
thrown into gastric pits, into which the
gastric glands opened. The surface
epithelium was mucous secreting co-
lumnar cells and stained positive with
PAS but negative with AB. The fundic
gland was made by oxynticopeptic cells
and few mucous cells, while the entire
pyloric gland was made by mucous
cells stained positive for both PAS and
AB. The small intestine showed many
villi but occasional poorly developed
intestinal crypts were. The intestinal
mucosa was lined with absorptive co-
lumnar epithelium with goblet cells,
which stained positive with PAS and
AB. Enteroendocrine cells were of dif-
ferent shapes; rounded, spindle, oval or
J. Vet. Anat. Vol 2 No1, (2009) 35 - 48
36
Varanus niloticus Ahmed et al.
pyramidal and were localized in the sur-
face epithelium of the esophagus and
small intestine, and among the cells of
the gastric glands.
This is the first report about the histolo-
gy of the alimentary tract of the Varanus
niloticus. Further studies are required
for investigation the possibility of using
this animal as a model for studying the
regulation of the digestive processes as
well as to understand the theory of de-
velopment.
Key words:
Reptiles, Varanus niloticus , Alimentary
Tract, Morphology
Introduction
It has been suggested that reptiles
could serve as a model” Reptiles have
been suggested to be a future useful
model for studying the physiological
regulation of the digestive process as
they have well responses to feeding
even more than other commonly used
experimental mammals such as mice,
rats, rabbit and pigs (Secor and Di-
amond, 1998). Reptiles include as
many as 7500 different species, most
known are; alligators, turtles, tortoises,
lizards and snakes (Elliott, 2007).
One of these reptiles is the Varanus
niloticus or the Nile monitor, which is
the biggest African lizard and one of the
most voracious predators (Capula,
1990). It lives along the Nile; it has
been found mainly in swamps and lakes
(Smith et al., 2008). Nile monitor has a
powerful body with an elongated snake-
like head, sharp claws, and a long and
strong tail, which is used to defend itself
when threatened (Alden et al., 2005).
This species of reptiles used to eat any
thing it can overpower or find as a car-
rion such as arthropods, frogs, fish,
birds, small mammals and other smaller
reptiles as well as the eggs of the Nile
crocodiles (Capula, 1990; Smith et al.,
2008 ). Depending upon its powerful
tail, the Nile monitor is an excellent
swimmer and it can stay under the wa-
ter for up to one hour (Capula, 1990),
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