Ultrastructural and morphometric features of nodal and impulse-conducting cardiac myocytes of the bat Pipistrellus pipistrellus.
Cells of the impulse-generating and conducting tissues of the insect-eating bat Pipistrellus pipistrellus were studied and evaluated using ultrastructural morphometry. Sinoatrial node cells are smaller than working atrial cells and measure about 6.5 microm in diameter. Their mitochondira and myofibril content constitute 23% and 19% of cytoplasmic volume, respectively. Corresponding values for working atrial cells are 23% and 52%. Atrioventricular node cells are 4.2 microm in diameter and contain abundant glycogen in the cytoplasm. The fractional volume of mitochondria in about 24% while that of myofibrils is 7%. Cells of the bundle of His are larger (6-8 microm diameter) and contain more cellular organelles than do nodal cells. Their mitochondria and myofibril contents are 25% and 25%, respectively. Cells in the proximal part of the right bundle branch are slender with diameters averaging 3.4 microm. Mitochondrial content is 23% while myofibrils occupy 20% of the cytoplasmic volume of these cells. Distally located bundle branch cells measure 7-10 microm in diameter with mitochondria and myofibril volumes of 30% and 33%. Subendocardial cells in the ventricular free wall are large reaching 28 microm in diameter (cf. 14-18 microm in working ventricular cells) and have mitochondira and myofibril volume fractions of 32% and 29%, respectively (35% & 40% for working ventricular cells).
Tagoe
C N
CN
Department of Anatomy, University of Ghana Medical School, Accra.
Ayettey
A S
AS
Dennis
E
E
Yates
R D
RD
D000818:Animals; D020517:Atrial Appendage / Q000378:metabolism / Q000648:ultrastructure; D002036:Bundle of His / Q000378:metabolism / Q000648:ultrastructure; D002685:Chiroptera / Q000033:anatomy & histology* / Q000378:metabolism; D004699:Endocardium / Q000378:metabolism / Q000648:ultrastructure; D006352:Heart Ventricles / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron; D009206:Myocardium / Q000378:metabolism / Q000648:ultrastructure*; D011690:Purkinje Fibers / Q000378:metabolism / Q000648:ultrastructure; D012849:Sinoatrial Node / Q000378:metabolism / Q000648:ultrastructure*