Ascaris Oogenesis

Materials

Prepared slides of Ascaris megalocephala maturation

Microscope

Procedure

1.Place the slide(s) of Ascaris on the microscope and focus on the eggs within the body.

Unlike the grasshopper testis where division is continuous, the ascaris egg halts its meiotic division until fertilized by a sperm. Subsequently, the final stages of meiosis are completed and nuclear fusion occurs. Within an average cross section of the female, it is usually possible to observe all of the stages of meiosis and early cleavage.

2.Using Figure 11.7 as a guide, identify, draw and label the following:

Sperm penetration

First polar body formation (first maturation division)

Second polar body formation (second maturation division)

Pronuclear stage (fusion of egg and sperm nuclei)

First cleavage division (beginning of mitosis)

3.Note the presence of any spindle fibers, and the shape and location of the chromosomes during each phase of development.