[Code of Federal Regulations]
[Title 9, Volume 1]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 9CFR101.6]

[Page 623]
 
                  TITLE 9--ANIMALS AND ANIMAL PRODUCTS
 
  CHAPTER I--ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF 
                               AGRICULTURE
 
PART 101_DEFINITIONS--Table of Contents
 
Sec. 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.

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