From the skinholes of Mahā-Viṣṇu, the small particles of universes are coming into being. Everything, the nature's way, it comes a very small particle, then it grows. Anything you take. Just like our body. The small particle, the soul, which is measured as one ten-thousandth part of the tip of the hair, when it is placed in the womb of the woman by the man, then the body grows. That is the seed. Ahaṁ bīja-pradaḥ pitā (BG 14.4). Kṛṣṇa says that, "I am the seed-giving father."
So just like here, we practically see, the male semina is injected within the womb of the female, and because the living entity, very small, one ten-thousandth part of the tip of, is there, because that living entity's there, the body grows. Unless the living entity's there, there will be no pregnancy. As soon as the living entity is there, the body grows. And that is known as pregnancy. Daily grows. The mother can understand it is growing.
Similarly, without the spirit soul entering into the matter, there is no possibility of creation. In the Bhagavad-gītā also it is said, viṣṭabhya aham ekāṁśena.
athavā bahunaitena kiṁ jñātena tavārjuna viṣṭabhyāham . . . ekāṁśena sthito jagat (BG 10.42) "Because I have entered into this universe by My plenary portion, therefore it is existing." It is explained in the Bhagavad-gītā.