Functional Morphology Of Hypothalamus-Pituitary-Adrenal Axis In Bactrican Camel (Camelus Bactrianus)

The ability of Bactrian camel to respond to the stress of environment was studied by exploring the properties of hypothalamus-pituitary-adrenal axis(HPAA) with morphological measuring,computed tomographical analyzing,microscope and ultrastructure observation,and comparative anatomy with other artiodactyls.The results show as follows:1.The hypothalamus of Bactrian camel is about 2.4 g in weight,0.42%of the brain and 2 cm~3 in volume,0.45%of the brain.The hypothalamus consist of nerve and neuroglia cells.Most of neurons own the structural properties of epithelioglandular cells.The neurosecretory granules were found in electron microscope,so these neurons owns secretive abilities.The emotional quotient of Bactrian camel is 1.11.It owns moderate intelligence and hypothalamus development status.We concluded that the nerve signal will translate to hormonal signal and release to the hypophysis through the hypothalamus-pituitary linkage when the Bactrian camel received the stimulation from outside.2.The pituitary gland of the Bactrian camel is about 1.54 g in weight,5 cm~3 in volume and the weight ratio is 0.00446 g/kg to body,which is quite close to adjacent body size of artiodactyls.It comprises with the developed pars distalis,pars intermedia which may relate to the resistance of the water depletion,and the undeveloped pars nervosa,by which the low productivity may relevant.Pars distalis of pituitary gland mainly consists of seven types of cells,growth hormone,prolactin, thyroid-stimulating hormone,ACTH,gonadotropic,chromophobe and stellate cells. These cells are the same as the pars distali of most animals' pituitary gland in morphology.The stellate cells are controversial,which can be separated from chromophobe cells by focusing on the morphological structure.Moreover,the Herring's bodies are observed in the nerve fiber bundles of intermedial pars nervosa. But in the peripheral zone,there are few Herring bodys,which is different from most of other animals.3.A single adrenal gland of Bactrian camel is 12.449±2.111 g in weight,10.78±1.42 cm~3 in volumn and the weight ratio is 0.0341±0.0039 g/kg to body,while the ratio is moderate in artiodactyls.The volume ratio of medulla to adrenal gland is higher than most of other animals.The adrenal gland of Bactrian camel owns not only developed capsule and comparatively developed zona glomerulosa,but a combined beam which composed by nerve fiber bundles,blood vessels and some connective tissues between the adrenal gland and kidney.So,the mineralocorticoid secreted by zona glomerulosa may enter into kidney directly without through systemic circulation to regulate the urinary function,which is significant to the adaptability of Bactrian camel to its arid and semi-arid condition.The intermediate zone can be seen evidently in female adrenal gland,but which is not the case in male.The round or elliptical cortical cuff which surrounded the small artery usually disappeared ultimately in medulla during the process of small artery extending from capsule to medulla.The lipid droplet shapes within adrenocortical cell is irregular and presents round shape with incomplete edge and low electron density.The fascicular zone has rich lipid droplets.Few lipid droplets present in glomerulosa zone and zona reticularis. Mitochondria are round or oval-shaped,in which the cristae shapes is bubbly pipe like. The adrenal gland cytoplasm presents rich smooth endoplasmic reticulum and the rough endoplasmic reticulum is hardly to be seen.Few microbodies were found within the adrenal cortex.The most obvious property of adrenal medulla cells are that they contain a huge number of electron-dense granules enveloped by the membrane, and can be further divided into noradrenaline cells and adrenaline cells.The morphologies of hypothalamus,pituitary and adrenal in Bactrian camel are similar with other artiodactyls,but it owns special or unique structures.The development status of the hypothalamus,pituitary and adrenal in Bactrian camel is moderate with consummate and systematic histological structure.It shows that the Bactrian camels are able to quickly respond to any stimulation,which has significant meaning for Bactrian camel to adapt to arid and semi-arid circumstances.