A New Model of Tubulobulbar Complex Budding in the Seminiferous Epithelium of the Testis
Bibliographic record
Abstract
Endocytic structures known as tubulobulbar complexes internalize intercellular attachments during sperm release. They are elongate structures capped with a clathrin‐coated pit. Their membranous core is a double‐membrane tube which is surrounded by a network of actin filaments. A bulbous region develops in the distal region which lacks the associated actin network but has a close association with cisternae of endoplasmic reticulum. The bulb eventually buds from the complex and enters endocytic compartments of the Sertoli cell. When rat testes were perfused for one hour ex vivo with oxygenated Krebs Henseleit buffer (with BSA) at 33°C containing either cytochalasin D (10, 20 or 40 µM) or the drug carrier (DMSO), apical TBCs at stage VII of spermatogenesis were associated with lower levels of actin in treated epithelia relative to controls. When evaluated at the ultrastructural level, the actin networks appeared patchy. In addition, ectopic bulbs and swollen tubular regions occurred. When thin sections of normal untreated samples were analyzed, large elongate bulbs and short tubular sections occasionally were observed. Together, these results suggest a new model for TBC vesiculation in which the actin network begins to disassemble and the tubular region begins to swell into a bulb. As the actin network continues to disassemble, the coated pit and most of the tubular region are incorporated into the enlarging bulb. Then the remaining short ‘neck’ of the bulb undergoes scission. Supported by a NSERC Discovery Grant to AWV.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".