Lag phase
1. A state of apparent inactivity preceding also a latent phase.
2. The initial growth phase, during which relatively constant, prior to rapid growth.
3. The first of five growth phases of most batch-propagated cell suspension cultures, being the phase in which inoculated cells in fresh medium adapt to the new environment and prepare to divide. See growth phases.

Lagging strand
The strand of DNA that is synthesized discontinuously during replication (because DNA synthesis can proceed only in the 5' to 3' direction).

Laminar air-flow cabinet; laminar air-flow hood
Cabinet for inoculation of cultures. The working area is kept sterile by a continuous, non-turbulent flow of sterilized air through a HEPA filter. See HEPA filter; prefilter.

Lampbrush chromosomes
Large diplotene chromosomes present in oocyte nuclei, and particularly conspicuous in amphibians. These chromosomes have extended regions called loops, which are active sites of transcription.

Iandrace
In PGR: An early, cultivated form of a crop species, evolved form a wild population.

Lateral bud
A bud produced at the base of a leaf petiole. See axillary bud.

Lateral meristem
A meristem giving rise to secondary plant tissue, such as the vascular and cork cambia. The tem is sometimes used to refer to an axillary meristem.

Lattice parameter
The combination of unit cell edge lengths and interaxial angles that defines the unit cell geometry.