पुरुषे ह वा अयमादितो गर्भो भवति यदेतद्रेतः तदेतत्सर्वेभ्योऽङ्गेभ्यस्तेजः सम्भूतमात्मन्येवात्मानं बिभर्ति तद्यदा स्त्रियां सिञ्चत्यथैनज्जनयति तदस्य प्रथमं जन्म ॥ १ ॥
In plain words
In a man, this indeed is at first an embryo: it is the seed. That -- the essence gathered from all the limbs -- he bears as self within self. When he pours it into a woman, he thereby begets it. That is his first birth.