Early nuclear events of in vitro fertilization in the domestic fowl (Gallus domesticus).

In vitro fertilization in the domestic fowl (Gallus domesticus) was investigated by observation of the early nuclear events. Ova retrieved from the fimbria following ovulation were inseminated in vitro with 106 − 107 spermatozoa in Dulbecco's modified Eagle's medium (DMEM) for 10 min and then further incubated in DMEM + albumen for 1, 2, 3, or 4 hr. These eggs were histologically examined by epifluorescent microscopy after staining with 4′,6′-diamidino-2-phenylindole (DAPI). Nuclei of spermatozoa at various stages of transformation were observed in the ova incubated for 1–3 hr. Close pairing of two pronuclei, presumed to be male and female juxtaposition, was detected in ova incubated for 4 hr. These data provide direct evidence for the in vitro fertilization of fowl eggs and suggested that the early process of in vitro fertilization is comparable to that of in vivo fertilization.