Page 401 - Anatomy and Physiology of Farm Animals, 8th Edition

386 / Anatomy and Physiology of Farm Animals

h
i
VetBooks.ir g f

f b
d

f
e
a

C
Caudal C Cranial

Figure 20-15. Gastrointestinal tract of the horse. a, stomach; b, duodenum; c, jejunum; d, ileum; e,
cecum; f, ascending (great) colon; g, transverse colon; h, descending colon; I, rectum.

i h i h
g
f g
f b
b
e
e a
d a* d

C f
C
f C
Caudal C Cranial C

Figure 20-16. Gastrointestinal tract of the ox.
a*, abomasum; b, duodenum; c, jejunum; d, ileum;
e, cecum; f`, proximal loop; f`` = spiral loop; C Cranial
f``` = distal loop; g, transverse colon; h, descend­ Caudal
ing colon; i, rectum.
Figure 20-17. Gastrointestinal tract of the pig.
a, stomach; b, duodenum; c, jejunum; d, ileum;
The jejunum is the longest part of the small e, cecum; f``, spiral loop; g, transverse colon;
intestine (e.g., as much as 28 m in the h, descending colon; i, rectum.
horse). Histologically, the jejunum is simi­
lar to the duodenum, although lymph
nodules at the mucosal–submucosal junc­ found in the right caudal part of the
tion may be more numerous. abdominal cavity in all species. The ileal
The ileum is the short last part of the epithelium features numerous mucous
small intestine. It is distinguished from the cells, and aggregates of lymph nodules in
jejunum by a fold of mesentery between it this region are more abundant than in
and the cecum. This ileocecal fold is found other parts of the small intestine. Their
on the side of the intestine opposite the especially prominent arrangement in the
attachment of the mesentery (the anti- ileum has led to the use of the term Peyer’s
mesenteric side). The lumen of the ileum patches to distinguish them.
communicates with that of the large intes­ The mesenteries that suspend the small
tine at the ileal orifice; this junction is intestine from the dorsal body wall can be