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Published on: May 29, 2013
Development and birthdates of vasoactive intestinal peptide immunoreactive neurons in the chick proventriculus
M L Epstein1, M J Saffrey, K T Poulsen
1Department of Anatomy, University of Wisconsin Medical School, Madison 53706.
Insights
Vasoactive intestinal peptide (VIP) neurons in the avian stomach develop early, appearing by embryonic day 6.5. Most VIP neurons are born between embryonic days 3-10, with peak neurogenesis at day 7, informing transmitter phenotype development.
Area of Science:
- Neuroscience
- Developmental Biology
- Gastroenterology
Background:
- The enteric nervous system (ENS) controls gut function.
- Understanding ENS development, particularly neurotransmitter phenotype regulation, is crucial for gastrointestinal health.
- Vasoactive intestinal peptide (VIP) is a key neurotransmitter in the ENS.
Purpose of the Study:
- To investigate the developmental timeline and neurogenesis of VIP-expressing myenteric neurons in the chicken proventriculus.
- To identify the critical periods for VIP neuron development and transmitter phenotype determination.
Main Methods:
- Combined immunocytochemistry for VIP and radioautography using [3H]-thymidine.
- Analysis of whole mounts and sections of the chicken proventriculus myenteric plexus at various embryonic and post-hatch stages.
- Birthdating studies by administering thymidine during specific embryonic periods.
Main Results:
- VIP-immunoreactive (VIP-IR) neurons first appear in the distal proventriculus around embryonic day 5.5-6.5.
- The number of VIP-IR neurons increases, peaking at embryonic day 15.5, and then declines post-hatch.
- Neurogenesis of VIP-IR myenteric neurons occurs between embryonic days 3-10, with a peak at embryonic day 7, and terminal divisions between days 5-9.
Conclusions:
- The study elucidates the precise developmental window for VIP-expressing myenteric neuron formation in the avian ENS.
- These findings provide a temporal framework for understanding the cellular decisions governing neurotransmitter phenotype expression during ENS development.
- The data are valuable for future research into the factors influencing ENS cell fate and differentiation.
Abstract:
To gain insight into the mechanisms regulating expression of transmitter phenotypes in the enteric nervous system, we have studied the development and birthdate of vasoactive intestinal peptide immunoreactive (VIP-IR) myenteric neurons in the chicken proventriculus (secretory portion of the avian stomach) by a combination of immunocytochemistry and radioautography. The appearance and numbers of VIP-IR neurons in whole mounts of the myenteric plexus from chick embryos and chickens were examined. We found that VIP-IR neurons first appeared at embryonic day (E) 5.5-6.5 in the distal part of the proventriculus. At E7.5, VIP-IR neurons were found singly, in pairs, or in small groups, which together with unlabeled cells formed primitive myenteric ganglia. VIP-IR fibers were found within the developing fiber tracts which connected the ganglia. The number of VIP-IR neurons was found to be maximum in the E15.5 embryo and to decline to 68% of maximum in the 4 week old chicken. Birthdate studies were performed by application of either single pulses or cumulative doses of [3H]-thymidine to embryos between E3 and E14. Whole mounts of the myenteric plexus from the proventriculus of these embryos were immunostained for VIP at E10 or E17. The whole mounts were subsequently sectioned and processed for radioautography. We found that VIP-IR myenteric neurons were born between E3 and E10 with a peak at E7. Most cells underwent terminal division between E5 and E9. These data will be useful in determining the time and conditions when cells make decisions about transmitter phenotypes.
