Relational Organization and Directional Stability Across Mouse Organogenesis

Developmental atlases compare independently sampled tissues across time, making the definition of biological comparability an upstream part of directional inference. This paper asks how that comparison space shapes relational organization in mouse organogenesis using the Mouse Organogenesis Spatiotemporal Transcriptomic Atlas from E9.5 through E16.5, spanning 4.10 million spatial roots from 53 sections and 37 biological embryos.

A spatial-relational carrier is constructed from source-authored tissue annotations, local neighborhood context, and discretized numeric descriptors, with developmental-stage labels excluded from relation construction. The carrier shows extensive recurrence, many-to-many organization, and strong direct-versus-composed overlap. Architecture-preserving references reproduce nearly all of the raw two-step agreement, with residual Jaccard excess bounded below 8×10⁻⁴.

All seven adjacent developmental contrasts remain within same-stage biological variation under the primary comparison space. Their accumulated chronological score is negative and remains stable under biological-embryo resampling, embryo and edge deletion, mapped-support conditioning, relation-tolerance sensitivity, density ablation, secondary-support handling, neighborhood-scale reconstruction, distance-weighted transport, equal metric weights, and embryo-balanced descriptor discretization.

Changing the comparison context changes what becomes locally visible. Coarsening exact comparability from root-plus-neighborhood tissue context to root tissue identity alone expands the adjacent relation graph from 1.70 million to 144.92 million pairs and brings two local developmental contrasts above their edge-specific biological references. The results separate architectural magnitude, local directional resolution, and aggregate directional stability, establishing relational comparability as part of the biological information used to infer developmental direction.