Histological study of megakaryocytogenesis and thrombocytogenesis in the guinea pig bone marrow with reference to the role of adipocytes

Blood platelets play a pivotal role in hemostasis and participate directly in thrombosis and atherosclerosis. The aim of the study was to investigate the steps of platelet production, the morphological changes that occur during proplatelet production, the cytoskeletal mechanics that drive these transformations, and the possible role of stromal cells in platelet formation. Red bone marrow fragments were harvested from ten adult male guinea pigs. Toluidine blue-stained semithin sections were prepared for light microscopic examination, and ultrathin sections were examined by transmission electron microscope. In the semithin sections of the bone marrow, nearly half of the area contained hematopoietic cells, whereas the remainder was occupied by adipocytes that showed unusual bridging connections between them. In addition, the megakaryocytic lineage cells assumed a unique close association with the neighboring adipocytes. Under transmission electron microscope, the surface of the immature megakaryocytes was characteristically smooth, whereas mature megakaryocytes developed characteristic proplatelets in the form of coarse surface cytoplasmic processes that bulged to the outside and detached as preplatelets. Granules and membranes associated with microtubules were translocated from the base of proplatelets to appear in their cytoplasm, and the invaginated membrane system became extensive in the mature megakaryocytes. Sometimes, these cells extended large proplatelets through the attenuated sinusoidal walls, where they discharged preplatelets that further fragmented into platelets. The formation of proplatelets and the elaboration of granules into the newly formed preplatelets and platelets were largely dependent on the efficiency of microtubular cytoskeletal elements. Marrow stromal cells, especially adipocytes, might be involved in megakaryocytic lineage development

Estudio del polimorfismo genético de las células de la médula ósea y del sistema nervioso central de ratas mediante la técnica de RAPD / Study of genetic polymorphism of the bone marrow and the central nervous system of rats cells by RAPD technique

Los modelos experimentales en rata han sido de gran utilidad en las evaluaciones terapéuticas o de reemplazo de células en enfermedades neurodegenerativas. Se ha comprobado que las células de la médula ósea (CMO) de ratas pueden diferenciarse en células que no forman parte de sus linajes normales. Hay evidencias de estos procesos de trans-diferenciación, pero aún no se conocen los mecanismos moleculares que activan estos procesos. El propósito de nuestro trabajo fue estudiar el polimorfismo genético del ADN de los tipos celulares que conforman las CMO y las células del sistema nervioso central (SNC), estríatales y de la corteza de ratas mediante la técnica de RAPD. Las CMO, las células mononucleares (CMMO), las células estromales (CEMO) y las del SNC fueron obtenidas de ratas, y su ADN genómico fue purificado y amplificado mediante la técnica de RAPD, utilizando 15 cebadores al azar. Se construyó un dendograma de las bandas de amplificación generadas utilizando el método de UPGMA. Las células estudiadas según el análisis del RAPD quedaron en 2 grupos bien definidos, pudiéndose diferenciar las CEMO del resto de las células estudiadas. Los cebadores OPA-6, 7 y 12, mostraron el polimorfismo genético de los linajes de células estudiadas. Mediante la técnica de RAPD se demostró la variabilidad genética entre las CEMO y las CMMO, células estriadas y de corteza que mostraron una homogeneidad genética, proponiéndose marcadores específicos de RAPD para cada grupo de células. Este es el primer estudio del polimorfismo genético de las CMO y del SNC de ratas.

Experimental models have been of grate usefulness in the therapeutic or replacement cells in neurodegenerative diseases. It has been demonstrated that bone marrow cells (BMC), can be difefferentiated in cells that do not form part of their normal lineage. There is evidence of these trans-differentiation processes in these cells, but nevertheless, molecular mechanisms that activate these differentiation process still not known. The purpose of our work was to study the genetic polymorphism of those cellular types; that conform the rat bone marrow cells (BMC) as well as those of the central nervous system (CNS), striatum cells and cortex ones, trough RAPD technique. BM, mononuclear cells (BMMC), estromal cells (BMSC) and the CNS cells were obtained from rats and genomic ADN was purified and amplified through RAPD technique, using 15 random primers. A dendogram was constructed according to UPGMA method of the amplifying RAPD bands. Studied cells as- according to the RAPD analysis- were grouped into 2 well- defined groups, as CEMO coud be differentiated from the rest of studied cells. OPA-6, 7 and 12 primers showed the genetic polymorphism of the studied lineages cells. Also will be proposed specific RAPD genetic markers. Through RAPD technique permitted the genetic variability was demonstrated betwen BMEC and BMMC of striated cells and of cortex, which demonstratd a genetic homogeneity through RAPD technique so specific genetic markers of RAPD were thus propose for each group of cells. These constitute the first study on genetic polymorphism of BMC and CNS.