Morphology and ultrastructure of pharyngeal sense organs of Drosophila larvae

Reviewer #1 (Public review):

Summary:

The authors provide a detailed ultrastructural analysis of the larval pharyngeal sensory organs, including the dorsal pharyngeal sensilla, dorsal pharyngeal organ, ventral pharyngeal sensilla, and posterior pharyngeal sensilla. Using electron microscopy and 3D reconstruction, Richter et al., present a comprehensive mapping and classification of pharyngeal sensory structures, defining mthe orphological type of pharyngeal sensilla based on ultrastructure and generating a neuron-to-sensillum map. These findings significantly advance our understanding of internal larval sensory systems and establish a robust framework for future functional studies in coordination with external sensory systems.

Strengths:

The application of high-resolution electron microscopy and 3D imaging analysis successfully overcomes technical challenges associated with visualizing deep internal structures. This enables an unprecedented level of anatomical detail of the larval pharyngeal sensory system. Thus, the study complements and completes existing maps of larval sensory circuits, contributing a comprehensive neuroanatomical characterization of larval sensory input pathways. These insights will inform future studies on larval behavior, sensory processing, and may also have applied relevance for insect control strategies.

Weaknesses:

While the manuscript is concise, clearly written, and methodologically rigorous, it primarily addresses a specialized readership with expertise in insect neuroanatomy.

Reviewer #2 (Public review):

Summary:

This manuscript documents the structure of the pharyngeal nervous system of the Drosophila larva. The authors wanted to achieve a detailed ultrastructural reconstruction of the gustatory sensory organs in the Drosophila pharynx. Using serial EM and the associated bioinformatics tools, they have achieved their goal. The paper is written clearly and illustrated beautifully with 3D models and annotated sections. The data will significantly enrich the field of Drosophila neurobiology.

Strengths:

Given the dataset, the findings presented are solid and will be an important work of reference for the future.

Weaknesses:

Previous work, including EM, on the pharyngeal sensory organ is not sufficiently referenced and used for comparison with the data presented in this study.

Author Response:

We thank the reviewers and editors for their thoughtful and constructive feedback on our manuscript, “Morphology and ultrastructure of pharyngeal sense organs of Drosophila larvae.” We are pleased that both reviewers found our ultrastructural analysis and 3D reconstructions of the larval pharyngeal sensory system to be of high quality, and we appreciate the recognition of the study’s significance and potential impact on the Drosophila neurobiology field.

We want to address the concern raised regarding the limited referencing and comparison with previous work on pharyngeal sensory organs, particularly in adult Drosophila and other insect species.

As noted by the reviewers, our manuscript is concise and focused. We want to clarify that we initially prepared and submitted this study with the intention of it being considered as a Short Report, which comes with limitations on the number of characters and figures that can be included. During the submission process, we were asked by the editors if we would like to submit our work as a full-length Research Advance, which we agreed to.

That said, we are now happy to expand the discussion in the broader context of related studies — including prior EM and anatomical work — which would enrich the manuscript and provide readers with a deeper comparative perspective.

We are grateful for the positive assessment of our manuscript and for the opportunity to clarify this point.

Sincerely,

Vincent Richter and Andreas S. Thum