Related Experiment Videos
The development of innervation in the rat atrioventricular node
Cell and Tissue Research
|March 1, 1977
Summary
The rat atrioventricular node develops dual innervation by the fourth postnatal day, with cholinergic nerve endings significantly outnumbering adrenergic ones by day six. This electron microscopy study reveals early nerve presence and intimate cell-axon contacts.
Area of Science:
- Cardiovascular Physiology
- Neuroscience
- Developmental Biology
Background:
- The innervation of the atrioventricular (AV) node is crucial for cardiac function.
- Previous light microscopy studies suggested limited information on the precise timing and nature of AV node innervation development.
- Understanding the cellular interactions during innervation is key to comprehending cardiac electrophysiology.
Purpose of the Study:
- To investigate the developmental process of rat AV node innervation using electron microscopy.
- To identify the types of nerve endings (cholinergic and adrenergic) innervating the AV node.
- To compare electron microscopy findings with previous light microscopy observations.
Main Methods:
- Electron microscopy was employed to examine the ultrastructure of the developing rat AV node.
- The 5-hydroxydopamine tracer technique was utilized to differentiate between cholinergic and adrenergic axons.
- Observations were made during the early postnatal period, starting from the second day.
Main Results:
- Nerve bundles were observed near the AV node by the second postnatal day.
- Vesiculated axons were present throughout the AV node by the fourth postnatal day.
- Intimate contacts between nodal cells and both cholinergic and adrenergic axons were frequently identified, with cholinergic endings being more numerous by day six.
Conclusions:
- The rat AV node exhibits a dual innervation pattern, established early in postnatal development.
- Cholinergic innervation is predominant over adrenergic innervation in the early postnatal AV node.
- Electron microscopy provides a more detailed understanding of AV node innervation compared to light microscopy, with implications for theories on nerve-induced nodal differentiation.