---
kind: "section"
citation: "9 C.F.R. § 101.6"
title: "9"
number: "101.6"
heading: "Cell cultures."
url: "https://uscodex.org/cfr/9/101.6"
---

# §101.6. Cell cultures.


When used in conjunction with or in reference to cell cultures, which may be referred to as tissue cultures, the following terms shall mean:

- (a) **Batches of primary cells.** A pool of original cells derived from normal tissue up to and including the 10th subculture.
- (b) **Cell line.** A pool of cells which are 11 or more subcultures from the tissue of origin.
- (c) **Subculture.** Each flask to flask transfer or passage regardless of the number of cell replications.
- (d) **Master Cell Stock (MCS).** The supply of cells of a specific passage level from which cells for production of biologics originate.

## Notes

### Amendments

[38 FR 8426, Apr. 2, 1973, as amended at 40 FR 45419, Oct. 2, 1975; 49 FR 22624, May 31, 1984]

### Authority

Authority: 21 U.S.C. 151-159; 7 CFR 2.22, 2.80, and 371.4.

### Source

Source: 38 FR 8426, Apr. 2, 1973, unless otherwise noted.

### Amendments

[38 FR 8426, Apr. 2, 1973, as amended at 40 FR 45419, Oct. 2, 1975; 49 FR 22624, May 31, 1984]