The Pudgala (material aggregate) appropriate for aliment, which is appropriated by a Jīva (soul), at the first Samaya (smallest time-unit) of its new birth (re-incarnation), from the surrounding environment or from the zygote (i.e., ovum of the mother fertilized by sperm of the father) through its own Kārmaṇaśarīra (subtle most body formed by Karma-pudgalas (material clusters qua Karma)) and that which is utilized by the Jīva as its first aliment (Āhāra).
oja- utpattideśe āhārayogyapndgalasamūhaḥ.
(Prajñā 28.105 Vṛ Pa 510)