The spleen of the one humped camel (Camelus dromedarius) has a unique histological structure.

The histology and structure of 38 spleens of the dromedary (aged 0.5-15 y) were studied in relation to age. The spleen was found to have a thick capsule (292+/-106 mm) divided into an outer layer (113+/-39 mm) composed mainly of connective tissue and an inner layer (180+/-81 mm) consisting mainly of smooth muscle cells. Vascular and avascular trabeculae extend from the capsule, the former containing arteries and nerves but no trabecular veins, the latter being divided structurally into primary and secondary trabeculae. Subcapsular and peritrabecular blood sinuses around primary and vascular trabeculae are unique to the camel spleen. The central artery emerges from the periarterial lymphatic sheath and branches into up to 4 penicilli which extend as sheathed arterioles (42+/-8 microm). These are found near or surrounded by blood sinusoids of the red pulp. A wide marginal zone surrounds the white pulp and contains sheathed arteries but no marginal sinuses. The red pulp is characteristically divided into cords by secondary trabeculae and contains venous sinusoids of different sizes. The camel spleen is of a sinusal type that can store blood. The thick muscular capsule and trabeculae pump the stored blood according to the body's need. Both closed and open circulations are found. The venous return is unique as the blood flow is from the venous sinusoids of the red pulp to the peritrabecular sinuses to the subcapsular sinuses to the splenic vein. No significant structural differences related to age were found.

The prenatal development of hair follicles and hair in the one-humped camel (Camelus dromedarius).

The development of the hair follicles started in the prescapular region of CRL 15 cm-fetuses as follicular plugs. At CRL 31 cm, they became cylindrical cell cords. In the CRL 45 cm-fetus two types of growing follicles, primary and secondary ones, could be differentiated, while the tertiary follicles were still follicular plugs. The follicles formed groups, and the primary follicles attained their complete structure at CRL 79 cm, while the secondary follicles at CRL 83 cm. The tertiary follicles were present in the full-term fetus. The latter follicles showed the phenomenon of pairing, where two, three, four or five follicles shared in a common hair canal and arose from the epidermis independently.

The development of the sweat and sebaceous glands in the skin of the one-humped camel (Camelus dromedarius).

The sweat gland primordium appeared as a solid bud from the ental side of the epithelial cords of the growing hair follicles in the CRL 36 cm-fetus from the primary hair follicles and in the CRL 64 cm-fetus from the secondary ones. In the CRL 68 cm-fetus the glands were tubular with a slight curving of their lower third, which became convoluted at the CRL 83 cm-stage. At the latter age, clear myoepithelial cells were observed in the secretory portion as also in the duct. The buds of the sebaceous glands could be observed in the CRL 45 cm-fetus from the primary hair follicles and in the CRL 68 cm-fetus from the secondary ones. At the CRL 83 cm-fetal stage, the branched glands were elongated in shape and opened into the follicles by two separated ducts, united at the hair canal. The glands were in function nearly from its early development.

Studies on the histogenesis of the tunica mucosa of the small and large intestines of the camel (Camelus dromedarius). II. Histogenesis of the colonic mucosa.

The colon is at first a simple tube, and its mucosa has a smooth luminal surface, surrounding a previous lumen. At the 150 mm stage the mucosa is thrown into a number of stout projections, each has a vascularized mesenchymal core and an epithelial cloth. These projections are in turn split into finger-like villi by transverse furrows. The villi reach their maximal length at the 260 mm stage and then gradually degenerate and slough into the lumen. The villi were completely disappeared at the 730 mm stage. The colonic glands were firstly observed at the 200 mm stage as downgrowths of the intervillous epithelium and they increase in number by dichotomous division of their bases. The Lamina muscularis mucosae is completely constructed at the 730 mm stage.

Studies on the histogenesis of the tunica mucosa of the small and large intestines of the camel (Camelus dromedarius). I. Histogenesis of the small intestinal mucosa.

The histogenesis of the small intestinal mucosa passes through a previllous stage, comprising development until the formation of villi (at a C RL of about 15 cm), and a villous stage, comprising the further development. In the previllous stage, the mucosa consists of a Lamina epithelialis made up of undifferentiated cells with stratified nuclei and a Lamina propria/submucosa made up of homogeneous mesenchyme. The villi appear as luminal epithelial outgrowths associated with vascularized mesenchymal stalks and their growth advances in a cranio-caudal direction. The intestinal glands were firstly observed at the 26 cm-stage as downgrowths of the intervillous epithelium into the underlying mesenchyme.

The prenatal development of the skin in the one-humped camel (Camelus dromedarius).

The epidermis of the camel started its development as a single layer of cuboical cells. The second layer occurred at the fetal stage of C RL 5 cm and the intermediate cell layer at the C RL 10 cm-stage. In the C RL 83 cm - fetus the epidermis is differentiated into the Stratum basale, Stratum spinosum, Stratum granulosum and Stratum corneum. In the dermis the collagenic and reticular fibres were observed in the 2 cm - fetus, and the elastic ones at the C RL 20 cm - stage.

Histological and histochemical studies on the fundic mucosa of the camel's stomach (Camelus dromedarius).

The one-humped camel, like our domestic ruminants, has a capacious compartmentalized stomach and is a ruminating animal. In our studies wer followed the currently predominant opinion that the camel stomach consists of three compartments (Vallenas, cummings, Munnel 1971). The third one of it is considered as the tubular portion following the second compartment or reticulum and extends till to the pylorus. The Tunica mucosa in the terminal dilated part (distal one-fifth) of this third compartment bears at its greater curvature very thick folds enclosing flat furrows which divide the mucosa into nearly regular areas (gastric areas). This portion of the third compartment contains the proper gastric glands (fundic glands) which differ somewhat from those in the advanced ruminants, especially in the arrangement of the parietal cells and the behaviour of the chief cells which can store mucosubstance during fastening or diminishing of the food in the camel.

Morphological observations on the normal cardiac glands of the camel (Camelus dromedarius).

The camel's stomach consists of 3 compartments. The third one was subdivided according the external and internal appearance into 3 parts: initial dilated part, middle long narrow part and terminal dilated part with a thick wall. The mucosa in the first 2 parts contain simple tubular glands separated by a clearly visible Lamina propria mucosae, heavily infiltrated with lymphocytes which aggregates to form true lymph nodules especially in the retiform of the initial dilated part. It is concluded that these glands are cardiac glands.