Seeds do germinate inside the fruit, or the parent plant - this condition is called vivipary (live birth), it is uncommon but it does happen usually in fruits with high moisture content such as apple, pear, peach, lemons or tomatoes.

Dear Elaheh Gerami,

Please have a look at these useful links.

Article Water Relations of Seed Development and Germination in Muskm...

http://www.plantphysiol.org/content/plantphysiol/86/2/406.full.pdf

https://www.jstage.jst.go.jp/article/jjshs1/82/3/82_227/_pdf/-char/en

Thanks!

Dear Dr Elaheh Gerami

As they get the favorable conditions to germinate inside there. Same in the Jack fruits and some other viviparous fruits. I think in case preservation in may maximize. You can avoid this if you eat the fruit just after being matured and not to make much delay.

Thanks

Viviparous sprouting has been considered to result from excess nitrate nitrogen or from depleted potassium Many researchers believe that the reason for the emergence of seeds within the soft fruits is due to the increase in the amount of nitrogen in the form of nitrate and potassium depletion within the fruit, while others believe that viviparous sprouting in muskmelon might be triggered by low levels of ABA in the fruit tissues around the placenta.

For more details lease look at pending file:

Vivipary is a physiological event , however if you look at the seedlings within the fruit you can see that they are green, why they are green without any light in the closed fruits?

Viviparous seeds resulted from lacking dormancy hormones

Seeds do germinate inside the fruit or the parent plant, this condition is called vivipary (live birth) it is uncommon but it does happen usually in fruits with high moisture content such as apple, pear, peach, lemons or tomatoes. In ripe fruits, the levels of ABA reduce which leads to over ripening and breaking seed dormancy. The water content of the fruit facilitates germination, sometimes these germinated seeds can reach the seedling stage before drying.

Agreed with Sajid Khan