Leptontene:

• The chromosomes becomes visible, shorten and thick.
• The size of the nucleus increase.
• The homologous chromosomes start getting closer to each other.

Zygotene:

• Paternal and maternal chromosomes come together and pair up.
• This pairing of homologous chromosomes is called synapsis.
• This pairing is highly specific and exact point for point, but with no definite starting points.
• The paired chromosomes are described as bivalents or tetrad.