GROSS AND MICROANATOMICAL STUDIES ON THE INTESTINES OF GUINEA PIG {Caviaporcellus)
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Date
2021
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Abstract
The present study was undertaken to access the gross and microanatomy of
intestines in guinea pigs of prenatal and postnatal age groups. Segments of both
small and large Intestines (duodenumjejunum,ileum,caecum,colon and rectum)
were collected from the guinea pigs which were received from Department of
Laboratory Animal Medicine, Chennai-51. Gross anatomical observations and
morphometrical measurements were recorded. Tissue pieces of intestines in all the
age groups were subjected to routine and special histological, histochemical,
immunohistochemical and scanning electron microscopic techniques.
Duodenum, the first part of the small intestine of guinea pig was found to
be started as a dilated part from the pylorus of the stomach and was covered
ventrally by the left medial lobe of the liver. It then crossed transversely to the
right side of abdomen under the right lobes of the liver where it formed a ‘S’
shaped bend or curve. Jejunum was made up of closely arranged coils which were
attached by the mesentery and located on the right side of the abdominal cavity.
Ileum was the shortest portion of small intestine of guinea pig. The caecum
occupied the most area of the ventral third of left side of abdominal cavity. Colon
was divisible into three parts viz., ascending, transverse and descending colon.
Rectum was the terminal portion of the large intestine and was observed in the
left of pelvic cavity. The morphometric parameters of both small and large
intestines were found to increase with age.
In prenatal age groups, tunica mucosa of both small and large intestines
was thrown into ridge like folds with variable heights in 30 day-old guinea pig
foetuses. In 45 day-old foetuses, tunica mucosa had both folds and villi. In 62
days-old guinea pig foetuses well developed villi were observed in the tunica
mucosa of small intestine. Only folds were noticed in the large intestine.
Surface epithelium of tunica mucosa of both the segments of small and
large intestines of 30 day-old guinea pig foetuses was made up of stratified to
simple columnar epithelium. In 45 day-old fetuses stratified epithelium was
observed only in few places. In 62 day-old fetuses, simple columnar epithelium
was evident. The occurrence of goblet cells gradually increased from 30 day-old
to 62 day-old foetuses in the segments of both small and large intestines.
Cytoplasm of goblet cells showed positive reaction to PAS, AB pH 2.5 and
combined AB-PAS methods. The crypts of Liberkuhn were observed to be more
in 62 day-old fetuses of small and large intestines. Evidence of Bruimer’s glands
was noticed in the submucosa of duodenum of 62 day-old foetuses. But, in 45
day-old foetuses, submucosa of the ileum showed the presence of lymphocytic
infiltration along with a few solitary lymphoid nodules. Well developed
submucosa and tunica muscularis was evident in 62 day-old foetuses in both small
and large intestines. Tunica serosa of both small and large intestines was found to
be present in all the prenatal age groups.