On the regional histology and histochemistry of the epididymis of the camel (Camelus dromedarius).

Distinct morphological regions, initial, middle and terminal segments, were distinguishable histologically; the middle segment was further subdivided into proximal, intermediated and distal parts. PAS-positive, diastase-resistant reaction was detected in the blood vessels, subepithelial tissue and stereocilia of all segments. Acid phosphatase was demonstrated in the epithelial cells with the highest activity being in the proximal part of the middle segment. Non-specific esterase gave a similar reaction but the strongest activity was in the terminal segment. Alkaline phosphatase, adenosine triphosphatase and adenosine monophosphatase were of similar activity in the subepithelial tissue, blood vessels, stereocilia and luminal contents; the strongest reaction occurred in the middle segment. Lactate, succinate, glutamate and glucose-6-phosphate dehydrogenases were examined; LDH was more active than the others particularly in the terminal segment. Some reaction was found in the epithelial cells, subepithelial tissue and luminal contents.     

Levels of glycosylated haemoglobin in the Arabian camel (Camelus dromedarius)

Proportions of glycosylated haemoglobin (Hb) were determined in 10 Arabian camels (Camelus dromedarius) and were compared with normal controls (n = 59) and diabetic patients (n = 47) using the thiobarbituric acid (TBA) method. The level of glycosylated haemoglobin (5.5%) in camels is significantly different from that of normal healthy humans (4.9%) (P less than 0.001). Whereas the glucose levels were comparable, this difference in percentages of glycosylated haemoglobin may be explained by the difference in survival time between human and camel red blood cells.     

Morphological, micromorphological and histochemical studies on the parotid salivary glands of the one-humped camel (Camelus dromedarius).

The morphology, blood and nerve supply of the parotid salivary glands of the one-humped camel were studied in detail. The intraglandular portion of the duct system was also examined. The histological and histochemical studies showed that the parotid salivary glands of the camel are of the tubuloacinar type and are serumocoid in nature. The secretory acini and tubules show themselves in 3 different forms according to the different phases of their secretory cycle. The duct system of the gland contains goblet cells between its lining epithelium. The intercalated ducts show ampullation followed by narrowing that help in mixing the secretion. Intraepithelial glands are found in the terminal part of the parotid duct.     

Spermatogenesis in the camel (Camelus dromedarius)

Spermatogenesis was studied with the aid of the light and electron microscopes in fourteen sexually mature camels slaughtered at different times of the year. The testes were fixed by vascular perfusion with glutaraldehyde. Spermatogenesis in the camel was generally similar to that of most mammalian species, although some features specific for the camel were observed. Spermatogenesis was found to be continuous throughout the year.     

The locomotion of the camel (Camelus dromedarius)

The feet and gaits of many camels Camelus dromedarius were studied and filmed in Mauritania, Africa. The camel has a digitigrade stance, large feet to support the animal in soft sand, and soles of flexible pads that step readily onto small stones where necessary. The walking stride is long and slow, with the body supported for much of each stride on the two right or two left legs. The pattern of supporting legs was significantly different in slow compared to fast walking camels, and in young compared to adult camels and compared to adults pulling water at the wells. There was no difference in pattern in one individual's walk, when it was either loaded or unloaded. The angles that the leg bones made with each other and with the horizon are depicted for the walk and the pace. The camel is the only animal which paces often and never trots. The pace is an unstable gait only suitable for flat terrain such as that in deserts. It may have evolved from the pace-like walk which is by far the dominant gait in this animal, which spends most of each day walking from plant to plant browsing or grazing. The pace is not used by all camelids, as one author has claimed. The pace and the gallop were only used by the camels at wells, when the animals were chased from the water by men.     

Purification and characterization of cationic chymotrypsin from the pancreas of the Arabian camel (Camelus dromedarius)

This study reports on the purification and characterization of a cationic enzyme with chymotryptic activity from camel pancreas. The enzyme was purified 52-fold in a 48% yield by a three-step chromatographic procedure consisting of anion-exchange, cation-exchange and affinity chromatographies. The purified enzyme was homogeneous on gel isoelectric focusing and on SDS gel electrophoresis. Its isoelectric point was estimated to be 7.3 and its molecular mass was found to be 23,600 Da. The enzyme was identified as a cationic chymotrypsin according to its physiochemical properties, substrate specificity and susceptibility to inhibition. It was active towards esters of aromatic amino acids but much less active towards a leucine ester. In all cases, the k_cat values of the camel enzyme were less than the corresponding values of bovine chymotrypsin A. It also showed a lower level of kininase activity. Camel chymotrypsin was more susceptible than its bovine equivalent to inhibition by soybean trypsin inhibitor and aprotinin. It showed the same pH optimium as bovine chymotrypsin A for its esterolytic activity, but was more dependent on CaCl₂ for long-term stability.     

Hydroxyproline concentrations in ocular tissues of Arabian camel (Camelus dromedarius Linn.)

Hydroxyproline (Hyp) concentrations (total, free, peptide-bound and protein-bound) in camel eye tissues were determined. Total Hyp concentration was highest in iris, followed by ciliary body, sclera, cornea, lens and retina; the difference between total Hyp concentration of iris and sclera (P < 0.05) and cornea, lens and retina (P < 0.001) was statistically significant. Cornea had the highest concentration of free Hyp, followed by ciliary body, retina, iris, sclera and lens (P < 0.001). Peptide-bound Hyp concentration was highest in iris, followed by lens, cornea, ciliary body, retina and sclera (P < 0.001). Iris also had the highest concentration of protein-bound Hyp, followed by ciliary body, sclera, cornea, retina and lens; the difference in the protein-bound Hyp concentration between iris and sclera (P < 0.05) and cornea, retina and lens (P < 0.001) was statistically significant. Iris was also found to have the highest concentration of collagen, followed by ciliary body, sclera, cornea, lens and retina; the difference between the collagen concentration of iris and sclera (P < 0.05) and cornea, lens and retina (P < 0.001) was statistically significant. These variations may result from differences in the collagen structure and/or composition in these tissues.     

Forestomach motility in the camel (Camelus dromedarius)

There is a cyclical pattern of motility in compartments 1 and 2 of the forestomach of the camel which can be categorized into A- and B-contractions. An average motility cycle is composed of 7 A- and 5 B-contractions and lasts 5 min, including a pause of 2.3 min. The glandular sacs within the caudal sac of compartment 1 contract 1.7 sec earlier than the caudal sac. The proximal part of the canal between compartment 2 and 3 contracts 1.2 sec prior to the distal part. Forestomach motility is stimulated by distention of the cranial sac of compartment 1 and inhibited by distention of the tubiform portion of compartment 3.     

The purification, characterization and regulatory properties of liver phosphofructokinase in the Arabian one-humped camel (Camelus dromedarius)

1. Phosphofructokinase from camel liver was purified to homogeneity more than 3600-fold, and the yield of the preparation was 46%. 2.The sodium dodecyl sulphate-treated purified enzyme migrated as a single band in 10% polyacrylamide gel. 3. The enzyme is a tetramer, with a monomer Mr 90,000. 4. The regulatory properties of the purified enzyme from camel liver were studied at pH 7.0. 5. The enzyme displayed cooperativity with respect to fructose 6-phosphate and was inhibited by high concentrations of ATP. 6. The enzyme was also inhibited by citrate, phosphocreatine and 2,3-bisphosphoglycerate. 7. On the other hand, ADP, AMP, glucose 1,6-bisphosphate and fructose 2,6-bisphosphate were all found to be strong activators for camel liver phosphofructokinase.     

Characterization of the nucleotide sequence of a polyubiquitin gene (PUBC1) from Arabian camel, Camelus dromedarius

Molecular amplification and sequencing of genomic DNA that encodes camel polyubiquitin (PUBC1) was performed by a polymerase chain reaction (PCR) using various sets of primers. The amplification generated a number of DNA fragments, which were sequenced and compared with the polyubiquitin coding sequences of various species. One DNA fragment that conformed to 325 bp was found to be 95 and 88% homologous to the sequences of human polyubiquitin B and C, respectively. The DNA translated into 108 amino acids that corresponded to two fused units of ubiquitin with no intervening sequence, which indicates that it is a polyubiquitin and contains at least two units of ubiquitin. Although, variations were found in the nucleotide sequence when compared to those of other species, the amino acid sequence was 100% homologous to the polyubiquitin sequences of humans, mice, and rats. This is the first report of the polyubiquitin DNA coding sequence and its corresponding amino acid sequence from camels, amplified using direct genomic DNA preparations.     

Purification and comparison of phosphoenolpyruvate carboxykinase from the liver and kidney of the Arabian camel (Camelus dromedarius)

1. Phosphoenolpyruvate carboxykinase was partially purified from camel liver and kidney by ammonium sulphate fractionation, gel filtration and ion-exchange chromatography. 2. The specific activity of the purified preparation from liver was 39.2 mumol/min per mg protein. 3. When isolated from the kidney the specific activity of the enzyme was very much higher 155.5 mumol/min per mg protein. 4. The enzyme from the two sources were similar in their pH optimum which was approx. 7.2 and their relative stability to thermal inactivation at 60 degrees C. 5. The mol. wt of the enzyme from both organs was estimated at 80,000 +/- 5000.     

Morphometric and histological studies on the adrenal glands of the camel Camelus dromedarius

The adrenal gland of the camel consists of an outer cortex and an inner medulla. The general disposition of the cortex and medulla, however, differs occasionally from that of other mammals. Extensions of medulla could reach as far as the periphery of the cortex. Islet of medullary tissue may be found in sections of the cortex and cortical tissue consisting of all zones of the cortex may occur around arteries or nerves in the medulla. The medulla may be separated from the cortex by connective tissue especially in old camels. The arrangement of noradrenaline-secreting cells is different from that in other ruminants; they are found in groups scattered between the adrenaline-secreting cells. Bundles of smooth muscle occur in venules at the corticomedullary interface. Accessory adrenal glands are found embedded in the renal fat. They are similar in structure to the adrenal gland. The adrenal cortex forms 74% of the volume of the gland and the ratio of the cortex to medulla is 4:1. The zona glomerulosa, fasciculata and reticularis constitute about 13%, 53%, and 29% by volume of the cortex, respectively.     

The intratesticular excurrent ducts of the camel (Camelus dromedarius)

The histology and fine structure of the epithelial cells of the intratesticular excurrent ducts were studied in material collected from fourteen adult camels and fixed by perfusion. The intratesticular excurrent ducts consisted of a terminal segment of the seminiferous tubule, a tubulus rectus, and a rete testis. The terminal segment was lined with modified Sertoli cells which formed a plug-like structure in the receptacle. The tubulus rectus was subdivided into the receptacle, the narrow main part, and the wider distal part, and these parts were lined with different types of epithelium. The rete testis occupied an axial mediastinum testis, and the height of its epithelium varied quite considerably. Degenerated spermatozoa were seen engulfed by the epithelial cells of the entire intratesticular duct system. Light cells, lymphocytes, and macrophages were observed. The fine structure of the epithelium of the intratesticular ducts is discussed in relation to its possible functions.     

A comparative study of glycosylated haemoglobin level in the Arabian camel (Camelus dromedarius) during different seasons

1. The extent of haemoglobin glycosylation from 60 camels has been determined (4.39%) in blood samples drawn during winter. 2. Phosphate (9.45 mg/dl), DPG (2.9 mumol/ml) and glucose (138 mg/dl) levels were also recorded. 3. In addition the P50 at pH 7.4 was measured (22.8 Torrs). 4. The data obtained compared with human blood levels and with levels reported for camels during summer sampling. 5. Despite the fact that camels have higher blood glucose levels than humans, the extent of glycosylation is much less in camel blood than in human blood.     

Control of luteolysis in the one-humped camel (Camelus dromedarius)

Blood plasma concentrations of 13,14-dihydro-15-keto PGF2 alpha (PGFM) were measured in groups of mature non-pregnant and pregnant camels to study PGF2 alpha release patterns around the time of luteolysis and the timing of the signal for pregnancy recognition. Injection of each of four camels with 10 and 50 mg of PGF2 alpha showed clearly that five times the dose of exogenous hormone produced five times the amount of PGFM in peripheral plasma, thereby indicating that, as in other animal species, PGFM is the principal metabolite of PGF2 alpha in the camel. Serial sampling of three non-pregnant camels on each of days 8, 10 and 12, and three pregnant camels on day 10, after ovulation for 8 h showed a significant (P < 0.05) rise in mean plasma PGFM concentrations only on day 10 in the non-pregnant, but not the pregnant, animals. A single intravenous injection of 20, 50 or 100 iu oxytocin given to three groups of three non-pregnant camels on day 10 after ovulation did not increase their basal serum PGFM concentrations. However, daily treatment of six non-pregnant camels between days 6 and 15 (n = 3) or 20 (n = 3) after ovulation with 1-2 g of the prostaglandin synthetase inhibitor, meclofenamic acid, inhibited PGF2 alpha release and thereby resulted in continued progesterone secretion throughout the period of meclofenamic acid administration. These results showed that, as in other large domestic animal species, release of PGF2 alpha from, presumably, the endometrium controls luteolysis in the dromedary camel. Furthermore, reduction in the amount of PGF2 alpha released is associated with luteal maintenance and the embryonic signal for maternal recognition of pregnancy must be transmitted before day 10 after ovulation if luteostasis is to be achieved. However, the results also indicate that, in contrast to ruminants, the release of endometrial PGF2 alpha in the non-pregnant camel may not be controlled by the release of oxytocin.     

Clinical and anatomical studies of the camel (Camelus dromedarius) genitalia

Clinical and anatomical studies of the genitalia of 294 camel (197 males and 97 females) were carried out between May 1984 and October 1985. Preslaughter (clinical) examination was followed by detailed post-mortem (anatomical) examination and dissection of genitalia at the abattoir. Measurements and weights of the various segments of genitalia were made to establish the baseline data for breeding soundness evaluation in the dromedary in Northern Nigeria.     

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.