Morphological and Histochemical Studies on the Stomach with special emphasis on the Glandular Sacs of the Camel Camelus dromedarius

Abstract

Camel glandular sac areas were previously considered as water stores. Recently these sacs are found to be glandular areas which probably perform absorption, fermentation and secretion functions. This investigation which was conducted on thirty five adult camels and ten camel fetuses which were collected from Tamboul slaughterhouse during the period 2|2013 – 2|2014, aimed to study the morphology (gross anatomy, histology, ultrastructure, histometry) and histochemistry of camel glandular sacs. The camel stomach was composed of four compartments; compartment 1, compartment 2, compartment 3, and compartment 4. Compartment 1 which was the largest extended from the diaphragm to the caudal border of the 12 th thoracic rib and presented glandular (cranioventral and caudodorsal sacs) and non-glandular areas. The cranioventral sac was oval in shape with more or less smooth external surface. The caudodorsal sac was irregular in shape and it was larger and more sacculated. Compartment 2 was small and bean-shaped and smaller than compartment 1. Compartment 3 was long and tubular. Compartment 4 was bean- shaped and smaller than compartment 3 and divided into fundic and pyloric regions. Compartment one contained both non glandular and glandular regions. Cranioventral and caudodorsal sacs formed the glandular region of compartment 1; they contained glandular pits. The four walls of each pit were formed by two longitudinal and two transverse pillars which surrounded the pit floor. The pit walls and floor consisted of four tunics; mucosa, submucosa, muscularis and serosa. The pit wall mucosa was non-glandular and lined by keratinized stratified squamous epithelium; the floor mucosa contained serous secreting glands which were lined by simple columnar epithelium. The mucosa of compartment 2 was IIImainly glandular and the glands opened in shallow pits and lined by simple columnar epithelium. The mucosae of compartment 3 and 4 were glandular. No significant histometric differences were observed between the cranioventral and caudodorsal sacs in the glandular size and thickness of wall tunics. In scanning electron microscopy the surface of the glandular region of cranioventral and caudodorsal sacs was folded and contained cup-shaped, cap- shaped and flower-shaped glands. In transmission electron microscopy the glandular columnar cells of cranioventral and caudodorsal sacs were closely packed together and contained Golgi apparatus, dense bodies and numerous secretory granules especially in the apical cytoplasm. The glandular epithelial cells of cranioventral and caudodorsal sacs showed strong positive PAS reaction; glycogen digestion was detected in glandular tissue. Blue cells, red cells and purple cells were also observed in the glands following PAS and AB reactions. Alkaline phosphatase reaction was positive in glandular tissue of cranioventral and caudodorsal sacs especially in the luminal parts of epithelial cells. The results revealed no significant differences between the morphology of cranioventral and caudodorsal sacs except that the pits of cranioventral sacs were larger than those of caudodorsal. Histochemically, these sacs are suggested to secrete neutral mucopolysacharides. In addition, some cells secrete both neutral and acid mucopolysacharides and others showed glycogen in some glandular tissue.