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An immunohistochemical study on neurons and paraneurons of the pre- and post-natal chicken lung
Insights
This study maps the development and location of key neurotransmitters in chicken lungs from embryo to adult. It reveals how serotonin, bombesin, VIP, substance P, and galanin change in chicken respiratory systems over time.
Area of Science:
- Neuroscience
- Pulmonology
- Developmental Biology
Background:
- The chicken lung's nervous system, particularly its neuroendocrine and neuronal components, is not fully understood.
- Investigating the ontogenesis and distribution of specific neuropeptides and neurotransmitters is crucial for understanding lung function and development.
- Serotonin (5HT), bombesin, vasoactive intestinal polypeptide (VIP), substance P (SP), and galanin are key neurochemicals involved in respiratory regulation.
Purpose of the Study:
- To investigate the ontogenesis and distribution of neurons and paraneurons expressing serotonin (5HT), bombesin, VIP, SP, and galanin in chicken lungs.
- To map the developmental changes of these neurochemical markers from embryonic stages to adulthood (6 months).
Main Methods:
- Indirect immunoperoxidase (PAP) staining technique was employed.
- Chicken lung specimens were analyzed across various developmental stages: embryos (6 days to hatching), chicks, and adult chickens (up to 6 months).
Main Results:
- Serotonin-immunoreactive paraneurons were detected early in embryonic lung mesenchyme (8 days) and later in bronchial epithelium and air sacs.
- VIP, galanin, and SP immunoreactivities were observed in intrapulmonary ganglia and nerve fibers, with VIP and galanin neurons becoming more numerous in adults.
- Bombesin-immunoreactive paraneurons appeared in the epithelium of primary and secondary bronchi in adult chickens.
Conclusions:
- The study elucidates the developmental timeline and spatial distribution of key neurochemicals within the chicken respiratory system.
- Findings provide a foundational map for understanding the neurochemical innervation and regulation of the chicken lung throughout its development.
- This detailed mapping contributes to the broader understanding of neuroendocrine cell development in avian respiratory systems.
Abstract:
The indirect immunoperoxidase (PAP) method was used on chicken lung specimens from embryos ranging in age from 6 days to hatching, chicks and adult chickens of up to 6 months. The ontogenesis and distribution of neurons and paraneurons containing immunoreactivities for serotonin (5HT), bombesin, vasoactive intestinal polypeptide (VIP), substance P (SP) and galanin were investigated. Serotonin-immunoreactive paraneurons were first detected in the pulmonary mesenchyma of 8-day-old embryos, while in the 12-day-old embryos the following neurons and paraneurons were first detected in their respective locations: serotonin-immunoreactive paraneurons in the bronchial epithelium; VIP- and galanin-immunoreactive ganglionic cells and SP-immunoreactive nerve fibres in the intrapulmonary ganglia. At hatching, serotonin-immunoreactive paraneurons in the epithelium of the air capillaries and air sacs, and bombesin-immunoreactive paraneurons in the epithelium of the primary bronchus, VIP-, galanin- and SP-immunoreactive nerve fibres in the lamina propria of the primary and secondary bronchi and in the pulmonary septa could also be shown. Some serotonin-immunoreactive small paraneurons were also found in the intrapulmonary ganglia. In the adult specimens, VIP-, galanin- and SP-immunoreactive nerve fibre networks were observed throughout the primary bronchus wall and in the lung septa. In intrapulmonary ganglia, VIP- and galanin-immunoreactive neurons and serotonin-immunoreactive small paraneurons could be more numerously demonstrated. Moreover, bombesin paraneurons occurred in the epithelium of primary and secondary bronchi, and serotonin-immunoreactive paraneurons were found in the epithelia of the bronchi and air sacs and in some pluricellular bodies in the lamina propria of the air sac ostia.