Historical clue formulations

• There are approximately 30 trillion of these in the human body — 2026-05-01
• Cytologists' study — 2025-11-29
• Prison divisions — 2024-09-24
• Spreadsheet boxes — 2024-07-16
• Bar rooms? — 2021-04-18
• They multiply by dividing — 2019-08-18
• Holders of many selfies — 2014-03-14
• Organules, e.g. — 2011-05-06
• Biologists' study — 2008-09-13
• Lockup lineup — 2003-05-02
• You use gray ones — 2002-04-23
• Cubbyholes — 1994-10-01