Spectrin and plectin are present at apical tubulobulbar complexes in the seminiferous epithelium
Bibliographic record
Abstract
Tubulobulbar complexes (TBCs) are actin‐related double membrane structures that are suspected to internalize intercellular junctions, a process that is crucial for junction turnover and sperm release. At apical sites of adhesion between spermatids and Sertoli cells, each TBC consists of a tubulobulbar projection of the spermatid plasma membrane, the surrounding attached plasma membrane of the adjacent Sertoli cell, and an actin network cuff. In other systems, spectrin is part of the membrane skeleton that links actin filaments to the plasma membrane. Others previously have reported that the protein is present at differentiating germ cells and epididymal spermatozoa. Plectin links cytoskeletal elements to each other and to the plasma membrane. We probed the seminiferous epithelium for spectrin, plectin and actin on fixed frozen sections of rat testis and fixed epithelial fragments. Both in sections and in epithelial fragments, beta‐spectrin II and plectin are localized to apical actin‐related tubulobulbar. Neither protein is concentrated at actin‐related intercellular adhesion junctions (ectoplasmic specializations). Our results demonstrate that both spectrin and plectin are present in Sertoli cells at tubulobulbar complexes. Supported by an NSERC Discovery Grant to AWV. Grant Funding Source : NSERC
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".