embryology

kalalaḿ tv eka-rātreṇa pañca-rātreṇa budbudam
daśāhena tu karkandhūḥ peśy aṇḍaḿ vā tataḥ param

bhagavad purana 3-31-2

On the first night, the sperm and ovum mix, and on the fifth night the mixture ferments into a bubble. On the tenth night it develops into a form like a plum, and after that, it gradually turns into a lump of flesh or an egg, as the case may be.

māsena tu śiro dvābhyāḿ bāhv-ańghry-ādy-ańga-vigrahaḥ
nakha-lomāsthi-carmāṇi lińga-cchidrodbhavas tribhiḥ

bhagavad purana 3-31-3

In the course of a month, a head is formed, and at the end of two months the hands, feet and other limbs take shape. By the end of three months, the nails, fingers, toes, body hair, bones and skin appear, as do the organ of generation and the other apertures in the body, namely the eyes, nostrils, ears, mouth and anus.


caturbhir dhātavaḥ sapta pañcabhiḥ kṣut-tṛḍ-udbhavaḥ
ṣaḍbhir jarāyuṇā vītaḥ kukṣau bhrāmyati dakṣiṇe

bhagavad purana 3-31-4

Within four months from the date of conception, the seven essential ingredients of the body, namely chyle, blood, flesh, fat, bone, marrow and semen, come into existence. At the end of five months, hunger and thirst make themselves felt, and at the end of six months, the fetus, enclosed by the amnion, begins to move on the right side of the abdomen.