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Ontogenesis of the myenteric plexus in the cat gastrointestinal sphincters. III. Synaptogenesis
Insights
Synaptogenesis, the formation of synapses, begins early in fetal development and continues postnatally. This study details the structural and quantitative changes in synaptic development within cat digestive tract sphincters.
Area of Science:
- Neuroscience
- Developmental Biology
- Gastroenterology
Background:
- The myenteric ganglia are crucial for gastrointestinal motility.
- Understanding synaptogenesis in these ganglia is key to comprehending digestive system development.
Purpose of the Study:
- To investigate the process of synaptogenesis in the myenteric ganglia of three feline sphincters.
- To characterize the temporal and structural dynamics of synaptic formation and maturation.
Main Methods:
- Histological and electron microscopy techniques were employed.
- Synaptic structures were analyzed in fetal and postnatal feline specimens.
Main Results:
- Synaptogenesis initiates in early fetal life, with immature axosomatic and axodendritic synapses.
- Synaptic maturation involves increased contact area, vesicle number, and morphological complexity, continuing to adulthood.
- Distinct developmental dynamics were observed across the lower esophageal, pyloric, and ileocecal sphincters.
Conclusions:
- Synaptogenesis is a prolonged and dynamic process in the feline myenteric ganglia.
- Neuronal and synaptic differentiation advance in parallel, with a notable relationship between desmosomal junctions and synapses.
- The findings provide insights into the development of enteric neural circuits.
Abstract:
Synaptogenesis in the cat myenteric ganglia of the lower esophageal, pyloric and ileocecal sphincters in the fetal life and at different postnatal stages of development was examined. The synaptic formation began in the early fetal period. The first immature synapses were of axosomatic and axodendritic types. The new formation and maturation of the synaptic contacts was an active process in the fetal period and in the first postnatal weeks, but it continued to the adult level. It was expressed quantitatively in the increase of the surface area of the synaptic contact zones, the number of the synapses, the length of the synaptic contact zones and the number of the synaptic vesicles. Fine structural features of the synaptic maturation were the increased pleomorphism of the synaptic vesicles, widing and lengthening of the thickening of the opposed membranes, the appearance of the coated evaginations and vesicles. Synaptic morphology became more complex because of the including of different in size and structure pre- and postsynaptic components. The frequency of the synapses on dendritic spines and synapses "en passant" increased. The synaptogenesis in the three sphincters studied exhibited a different dynamics. The parallel advance in the neuronal and synaptic differentiation and the relationship between the desmosomal junctions and synapses were discussed.