Q.Describe longitudinal binary fission in Euglena.

In transverse binary fission of a ciliate, the anterior daughter is the proter and the posterior daughter is the opisthe.

Explanation:

• In ciliate protozoans such as Paramecium, asexual reproduction occurs by TRANSVERSE binary fission - the body divides across (at right angles to) its longitudinal axis into two halves.
• The two daughter individuals so formed are distinguished as:
  • PROTER: the ANTERIOR (front) daughter individual, which retains the original mouth (cytostome). …

Proter and opisthe are the two daughter cells produced when a ciliate divides transversely; the proter is the front (anterior) daughter and the opisthe is the rear (posterior) daughter.

Background: Paramecium and other ciliates reproduce asexually by binary fission, which is transverse (across the body, roughly at right angles to the longitudinal ciliary rows) rather than longitudinal as in flagellates.

During this division, the parent cell's nucleus (macronucleus and micronucleus) divides, and the cell constricts transversely into two daughter cells of roughly equal size:

• Proter - the anterior daughter cell. It retains the parent's original cytostome (mouth), gullet, and anterior contractile vacuole, since these structures lie in the front half of the parent. …

During transverse binary fission in ciliate protozoans, the front daughter cell is called the proter and the rear daughter cell is called the opisthe — they differ in which structures they inherit versus must regrow.

In protozoans such as Paramecium, asexual reproduction typically occurs by transverse binary fission, where the parent cell divides across its body (perpendicular to the long axis) into two daughter cells:

• Proter — the anterior daughter cell. It retains the original oral groove/cytostome (mouth apparatus) and its associated ciliary structures from the parent, but must regenerate a new posterior end, including a new contractile vacuole pore where needed.
• Opisthe — the posterior daughter cell. It inherits the parent's posterior end but must develop an entirely new cytostome (mouth/oral groove) and its associated feeding apparatus from scratch. …