Leukopoiesis
Leukopoiesis is the general term for the process of making white blood cells. Megakaryocytes and proerythroblasts are stem cells derived from the same pluripotent stem cell population.
Different stimuli are used to promote the production of each distinct type of white blood cell. Granulopoiesis is the process by which a pluripotent stem cell differentiates into a neutrophil, eosinophil, or basophil. Early granulocytes are difficult to differentiate from one another because they all appear as large cells with lots of cytoplasm, large round nuclei, and a first set of nonspecific granules. Afterwards, the nonspecific granules are replaced by particular granules unique to each type of granulocyte.After being activated by a specific stimulus, pluripotent stem cells give rise to both monocytes and lymphocytes. Since they lack specific cytoplasmic granules, they are known as agranulocytes. Some of the lymphocytes produced during the process known as lymphopoiesis proliferate outside of the bone marrow. Monopoiesis is the process by which monocytes grow and mature (Table 6.2).
TABLE 6.2
Table Representing WBC Count and Differential Leucocyte Count in Different Species
| Species | Total WBC/UL(thousands) | Neutrophils | Lymphocytes | Monocytes | Eosinophils | Basophils |
| Cow | 7-10 | 25-30 | 60-65 | 5 | 2-5 | functions, not so visual but necessary for overall body function, include muscles for respiration, digestion, parturition, blood and lymph circulation, swallowing, and generation of body heat. Muscles can receive and respond to stimuli, stretching and returning to their original shape after being stretched. The animal body has three types of muscle fibres: skeletal, smooth, and cardiac. Each is characterised by microscopic structural differences and their location, function, and innervation. Skeletal muscle tissue is essential for body movement and various physiological functions. It comprises a central, fleshy, contractile muscle “belly” flanked by two tendons at each extremity. This arrangement is strategically located within the body to span joints. When these muscles contract, they shorten the distance between the origin and insertion tendons, resulting in joint bending (Figure 7.1). Skeletal muscles are under voluntary control and are crucial in locomotion, facial expressions, and posture. Smooth and cardiac muscles are associated with visceral structures, enabling activities such as organ emptying or content transportation. Skeletal muscles, except for sphincters, exert effects at a distance from their location, requiring one end to be anchored and the other attached to the movable part. An anatomical description of skeletal muscles typically involves specifying their origin (the less movable end) and insertion (the more movable end). 7.2 Source:
Rana Tanmoy (ed.). Principles of Veterinary Animal Physiology. CRC Press,2026. — 290 p.. 2026
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