• Development and Reproduction
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• v.27 no.3
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• pp.137-147
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• 2023

Pharyngeal pouches are an important epithelial structure controlling facial skeletal development in vertebrates. A series of pouches arise sequentially in the pharyngeal endoderm through collective cell migration followed by rearrangement of pouch-forming cells. While crucial transcription factors and signaling molecules have been identified in pouch formation, a role for Neuropilins (Nrps) in pouch development has not yet been analyzed in any vertebrates. Nrps are cell surface receptors essential for angiogenesis and axon guidance. In all vertebrates, the two Nrp family members, Nrp1 and Nrp2, are conserved in the genome, with two paralogs for Nrp1 (Nrp1a and Nrp1b) and Nrp2 (Nrp2a and Nrp2b) being identified in zebrafish. Here, I report a potential requirement of Nrp signaling in pouch development in zebrafish. nrp1a and nrp2b were expressed in the developing pouches, with sema3d, a ligand for Nrps, being expressed in the pouches. Knocking down Nrps signaling in the pharyngeal endoderm led to severe defects in pouches and facial cartilages. In addition, blocking Mitogen-activated protein kinase (MAPK) activities, a downstream effector of Nrp signaling, in the pharyngeal endoderm caused similar defects in pouches and facial skeleton to those by knocking down Nrps signaling. My results suggest that Nrp signaling acts for pouch formation through MAPK.

• Development and Reproduction
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• v.28 no.2
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• pp.55-65
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• 2024

In vertebrates, Fgf signaling is essential for the development of pharyngeal pouches, which controls facial skeletal development. Genetically, fgf3 and fgf8 are required for pouch formation in mice and zebrafish. However, loss-of-function phenotypes of fgf3 and fgf8 are milder than expected in mice and zebrafish, which suggests that an additional fgf gene(s) would be involved in pouch formation. Here, we analyzed the expression, regulation, and function of three fgfs, fgf4, fgf24, and fgf17, during pouch development in zebrafish. We find that they are expressed in the distinct regions of pharyngeal endoderm in pouch formation, with fgf4 and fgf17 also being expressed in the adjacent mesoderm, in addition to previously reported endodermal fgf3 and mesodermal fgf8 expression. The endodermal expression of fgf4, fgf24, and fgf17 and the mesodermal expression of fgf4 and fgf17 are positively regulated by Tbx1 but not by Fgf3, in pouch formation. Fgf8 is required to express the endodermal expression of fgf4 and fgf24. Interestingly, however, single mutant, all double mutant combinations, and triple mutant for fgf4, fgf24, and fgf17 do not show any defects in pouches and facial skeletons. Considering a high degree of genetic redundancy in the Fgf signaling components in craniofacial development in zebrafish, our result suggests that fgf4, fgf24, and fgf17 have a potential role for pouch formation, with a redundancy with other fgf gene(s).

• Development and Reproduction
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• v.26 no.1
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• pp.23-36
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• 2022

Pharyngeal pouches, a series of outgrowths of the pharyngeal endoderm, are a key epithelial structure governing facial skeleton development in vertebrates. Pouch formation is achieved through collective cell migration and rearrangement of pouch-forming cells controlled by actin cytoskeleton dynamics. While essential transcription factors and signaling molecules have been identified in pouch formation, regulators of actin cytoskeleton dynamics have not been reported yet in any vertebrates. Cofilin1-like (Cfl1l) is a fish-specific member of the Actin-depolymerizing factor (ADF)/Cofilin family, a critical regulator of actin cytoskeleton dynamics in eukaryotic cells. Here, we report the expression and function of cfl1l in pouch development in zebrafish. We first showed that fish cfl1l might be an ortholog of vertebrate adf, based on phylogenetic analysis of vertebrate adf and cfl genes. During pouch formation, cfl1l was expressed sequentially in the developing pouches but not in the posterior cell mass in which future pouch-forming cells are present. However, pouches, as well as facial cartilages whose development is dependent upon pouch formation, were unaffected by loss-of-function mutations in cfl1l. Although it could not be completely ruled out a possibility of a genetic redundancy of Cfl1l with other Cfls, our results suggest that the cfl1l expression in the developing pouches might be dispensable for regulating actin cytoskeleton dynamics in pouch-forming cells.

• Journal of Veterinary Science
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• v.19 no.6
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• pp.835-839
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• 2018

Auditory tube diverticula, also known as guttural pouches, are naturally occurring dilations of the auditory tube in horses that communicate with the nasopharynx through a small ostium. Infection and select other conditions can result in inflammation and narrowing of the nasopharyngeal ostium, which prevents drainage of fluid or egress of air and can lead to persistent infection or guttural pouch tympany. Auditory tube diverticulotomy allows continuous egress from the auditory tube diverticula and is a feature of disease treatment in horses, in which medical treatment alone is not successful. Transpharyngeal endoscopic auditory tube diverticulotomy was performed using a diode laser either at a single dorsal pharyngeal recess location or bilaterally caudal to the nasopharyngeal ostium in 10 horse head specimens. Both methods resulted in clear communication between the nasopharynx and auditory tube diverticula. Diverticulotomy performed in the dorsal pharyngeal recess required less laser energy and activation time and had a shorter surgical duration than diverticulotomy performed caudal to the nasopharyngeal ostium. Further study related to the clinical application of both techniques is warranted.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1993.05a
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• pp.109-109
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• 1993

Fourth branchial pouch anomaly is an extremely rare condition involving the pharyngeal apparatus with only about 30 cases having been reported in the last 20 years. It almost invariably occurs on the left side and typically presents with repeated episodes of neck swelling, recurrent thyroiditis, or repeated bouts of retropharyngeal abscess. This is a presentation of 2 patient with pyriform sinus fistula, presumably of fourth branchial origin, which, were successfully closed with 10ole trichloroacetic acid chemical cautery. Details of the cases along with the summary of embryology and fourth branchial anomaly are given.