After the Ālayavijñāna leaves, why doesn’t the corpse immediately disappear and rot?

At the time of death, when the manas and the Ālayavijñāna leave the physical body, the body becomes a corpse. It changes from being sustained by the individual sentient being's own Ālayavijñāna to being jointly sustained by the Ālayavijñānas of many sentient beings, and at that point it becomes an insentient object. Insentient objects are all composed of the four great elements. When they decay, the four great elements must gradually, in an orderly and continuous manner, return from the insentient object to the Ālayavijñānas of the various sentient beings. How long this process takes is not fixed; it is determined by the karmic power of sentient beings, and also depends on how solid the insentient object is. The decay of a corpse begins as soon as the Ālayavijñāna leaves the physical body, though at first it is not easily noticeable. The speed of decay also depends on the surrounding temperature and environment, as well as the amount of moisture in the corpse. This is because temperature and humidity are conditions for bacterial reproduction; the more and faster the bacteria multiply, the faster the corpse decays. In the end only the bones remain, becoming part of the material universe of mountains, rivers, and the great earth within the sentient world (bhājana-loka). After a certain time, the bones too will weather, decompose, and cease to exist.

In the short period right after the physical body has died, it is still sustained by the individual's own Ālayavijñāna, and the conscious mind may possibly arise again—this is the principle behind the worldly notion of "returning from death to life." Therefore, when a person has just died, while the Ālayavijñāna and the manas have not yet completely departed, organ transplantation must be carried out within a short time. The so-called short time means within a few hours. Within those few hours, the Ālayavijñāna is still sustaining the body's organs, the nerves are still functional, the cells are still functional, and the muscle tissue is still functional. When an organ is transplanted into another person at this time, if the two people's manas are incompatible, a state of rejection will occur; if the two people's manas are compatible and they have a good relationship and affection for each other, no rejection will occur, and the handover between the two Ālayavijñānas can be completed. If the manas is attached to the body's organs and unwilling to give them to another, the handover between the two Ālayavijñānas will not go smoothly, and other discomforting symptoms may appear—that is the body's rejection response.

Another example: when a person's finger is severed, within a short time the finger still has warmth, the blood vessels are still functional, and within this time frame blood can still flow through, the blood vessels are still usable, the nerves are still usable, and the finger can be reattached. When it is reattached, it can reconnect with the hand, heal together before long, and become functional again. But if too much time passes and the finger comes to be jointly sustained by the Ālayavijñānas of sentient beings sharing common karma, then reattaching it to the hand is useless—no matter how it is sutured, it is useless, just like attaching a piece of wood.