Best Answer: Crossing-over is another name for recombination or physical exchange of equal pieces of adjacent non-sister chromatids. When crossing-over occurs chromatids break and may be reattached to a different homologous chromosome. This occurs during Meiosis 1 / Prophase 1. Synapsis occurs when homologous chromosomes form tetrads and crossing-over or recombination takes place.
The best time to apply castor oil is at night, preferably couple of hours before bed time. While it is perfectly fine to use them during day time, there is a big advantage in applying them at night as this allows more time to saturate and start the process which aids in growing eyelashes.
Many have also pointed out that castor oil is just too drying for their skin. Skin around our eyes are too delicate. Granted, some of you will argue that the amount of castor oil can always be reduced in the cleansing oil mixture. Some of you will also say it really depends on skin types.