Abstract:
Meriones rex (King jird), Meriones libycus
(Libyan jird), Acomys dimidiatus (Eastern spiny
mouse), Acomys cahirinus (Egyptian spiny mouse), and
Dipodillus dasyurus (Wagner’s dipodil) are five species
of small rodents of the superfamily Muroidea with distributions
in Eastern Africa, Egypt, and the desert
regions of the Arabian Peninsula. Water is scarce in
these regions and may result in relatively lowdigestible
food. The aim of the present study is to
describe and compare the gastrointestinal tract morphology
and morphometry of these five species in order
to elucidate whether morphology is influenced by phylogeny
or dietary preference. Each segment of the gastrointestinal
tract of each species was macroscopically
examined and the length and basal surface area of
each segment was measured. Standard histologic procedures
were performed to determine a surface enlargement
factor to determine the mucosal luminal surface
area. A unilocular-hemiglandular stomach was
observed in all the species examined. The caeca of all
the species were long and arranged into a loose spiral
toward the caecal tip with the ileocaecal and caeco-colic
openings positioned close together. Two rows of oblique
folds could be observed in the proximal colon of all species
except in D. dasyurus which had longitudinal
folds. Morphometric analysis showed the largest stomach
in A. cahirinus and the largest caecum and colon
in M. libycus. All the species can be grouped in the
family Muridae in two subfamilies and similarities
were observed including the hemiglandular stomach
and relatively large caecum. It could be concluded that
phylogeny plays an important role in determining gastrointestinal
morphology while diet plays a subordinate
role in the desert rodents in the present study.
