What are the 3 germinal layers present in reptiles during fertilization and how are they formed

Ectoderm, mesoderm & endoderm. These r formed in the same manner as in other germinal layer formation of mammals.

The three r formed in the gastrulation stage. The first stage is the formation of the primitive gut or what u call the archenteron or gastrocoel, the second stage is the formation of the three germ layers & they serve as the foundation where the organs & systems of the body will take shape. Once the three germ layers r established, the next thing happens is the process called organogenesis where organs start to form.

CNS, sense organs & their skin derivatives (scales) originate from ectoderm.

Heart muscles, urogenital system & vertebral column originate from mesoderm.

Digestive tract & lungs originate from endoderm.

Hope I've helped.