Ultrastructure of the myocardium of the least shrew, Cryptotis parva Say.
Anat Rec
; 226(1): 57-70, 1990 Jan.
Article
em En
| MEDLINE
| ID: mdl-2297084
ABSTRACT
The heart of the least shrew, Cryptotis parva Say, is an extremely active organ, capable of achieving rates of 800-1,200 beats/minute. The general features of myocardial cell ultrastructure in this insectivore are much like those of other small mammals; no single striking feature of fine structure is present to which the physiological properties of this heart might necessarily be attributed. Still there exist in these myocardial cells a number of atypical properties. These include 1) mitochondria having a wide variety of sizes and internal configurations 2) a pleiomorphic, highly ramified, small-diameter transverse-axial tubular system (TATS) 3) numerous "labyrinths," which are proliferated components of the TATS, and 4) myofibril-free regions, located both in juxtanuclear and other myoplasmic levels and populated by a concentration of TATS elements and fibrillar structures. Features (2) and (3) are also characteristic of another fast-beating heart, that of the mouse. The sinoatrial and atrioventricular nodal regions, as well as a Purkinje system, have been identified in the least shrew heart, along with sparsely distributed atrial cells whose myofibrils contain proliferated Z-band material. A feature frequently encountered in atrial working muscle cells is the occurrence of close appositions between gap junctions and tubules of sarcoplasmic reticulum; such appositions are also present in other regions of the shrew heart, as are complexes composed of gap junctions and mitochondria.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Musaranhos
/
Miocárdio
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Anat Rec
Ano de publicação:
1990
Tipo de documento:
Article