Out of the following, which do not show tissue culture or do not grow invitro

Options

A. (a) Viruses
B. (b) E. coli
C. (c) PPLO
D. (d) Bacteroids

Answer

To determine which of the following options do not show tissue culture or do not grow in vitro, we can analyze each option provided:

1. **Viruses (Option A)**:
- Viruses are obligate parasites, meaning they cannot reproduce or carry out metabolic processes outside of a host cell. They rely entirely on the host's cellular machinery for replication and survival. Therefore, they cannot grow in vitro (outside a living organism).

2. **E. coli (Option B)**:
- E. coli is a type of prokaryotic bacterium that can grow independently in a suitable culture medium. It does not require a host to survive and can be cultured in vitro.

3. **PPLO (Option C)**:
- PPLO stands for Pleuropneumonia-like organisms, which are also known as Mycoplasma. These are prokaryotic bacteria that can survive and grow independently in a culture medium, thus they can grow in vitro.

4. **Bacteroids (Option D)**:
- Bacteroids are a group of bacteria that can also survive and grow independently in culture. They are not dependent on a host for growth and can be cultured in vitro.

Based on this analysis, the only option that does not show tissue culture or does not grow in vitro is **A. Viruses**.

### Final Answer:
**A. Viruses**