A Comparative Study On The Histological Structure Of The Spleen Between The Newborn And Adualt Yak

Yak is known as "the plateau of the boat". The center of yak’s distribution is theQinghai-Tibetan plateau. It is the important source of draught animals and economy inpastoral area. The spleen is the largest secondary immune organ in the body and isresponsible for initiating immune reactions to blood-borne antigens and for filteringthe blood of foreign material and old or damaged red blood cells. Structural changesin the spleen can be very large differences between not only the species, the samespecies also due to the age and the body’s i mmune status its spleen structure differentto each other. Currently, at home and abroad a few research for yak spleen wasreported, especially the comparative study of the spleen during its development, therewas no reported both at home and abroad. This experiment was designed to study thehistological structure of yak spleen during development, to provide morphologicalevidence for changes in spleen development and maturation of the immune status, butalso laid histological basis for the study of animal immune adaptive alpine regions ofhypoxia. In this study, we used the morphology and histology methods to observe thenewborn and adualt yak spleen structure：（1）Gross anatomical, morphologicalmeasurements was used on the yak spleen, to observed anatomical location andmorphological characteristics of yak spleen.(2) Application of conventionalhistological staining and a variety of special staining methods, observed different ageyak histological structure of the spleen. by light microscopy observed yak spleenstructural features of different ages.(3) Stereology metering splenic white pulprelative area and splenic nodule number per unit area.(4) Application of electronmicroscope observe the ultrastructural features of different age yak spleen. The resultsshow that:1. yak spleen is located in the left costal zone between the diaphragm andrumen, rumen left anterior dorsal rucksacks. Eye view the visceral surface wasslightly concave, wall slightly convex flat ellipse and back side is the ventral sideslightly wide. The newborn yak spleen volume is small, soft, color was purple, the average weight of about21.78g; Length of13.92cm, a width of2.82cm, thicknessof0.798cm. Adult yak spleen volume is larger, the dark grey in colour, with anaverage weight of about556.74g; length51.06cm, width of12.37cm, thickness of1.204cm.2. Yak spleen belonged to non-sinusal type spleen, splenic cordunderdeveloped, thin and short, cells were scattered arrangement hardly splenicstreak. Newborn yak white pulp contains no spleen nodules only consists ofperiarteral lymphatic sheath; Adult yak white pulp including periarteral lymphaticsheath and splenic nodules, splenic nodules presents three different forms: primarysplenic nodules, the central cells stained edge cells lightly stained; Transition statesplenic nodules, from inside to outside the cell are light dyeing, deep dyeing, lightdyeing; Secondary splenic nodules, germinal center visible. Newborn yak white pulprelative area was Aw=5.46%, the number of splenic nodule per unit area Ns=0/mm2; Adult yak white pulp relative area was Aw=8.82%, splenic nodule number perunit area was Ns=0.145/mm2. Adult yaks were film thickness was about1.354mm,divided into two layers, between membrane surface cover was a single cubic shape.Newborn yak spleen capsule was thinner, which was about0.167mm, layeredobvious, connective tissue is not developed, surface coating flat monolayerendothelial.3. Electron microscope was observered rich reticular cells in the yakspleen, projections staggered connection between between constitute the frameworkof the spleen, various types of cells scattered distribution, red blood cells scattered inthe red pulp, no sinusoidal endothelial cells surrounding the distribution of adult yakspleen and can visible part of the cell shedding dissolved.In summary, the development of yak spleen is an ongoing process ofreconstruction and improvement, yaks spleen was non-sinus spleen and the adult yaksplenic nodule structure was special, was different from other animals. The typicalstructure of yak spleen can learn to lay the foundation for the study of tissue hypoxiaalpine region adaptive immune animals.