title: Nuclear events from fertilisation to the early cleavage stages in the domestic fowl (Gallus domesticus)
abstract: The changes in nuclear morphology from fertilisation to the 16-blastomere stage of development in the domestic fowl were examined in sections of the germinal disc stained with DAPI (4',6'-diamidino-2-phenylindole) or with the Feulgen technique. By one hour after the estimated time of ovulation, the second meiotic division of the ovum was completed and the spermatozoal heads (3-9) in the germinal disc had transformed into pronuclei. During the following two hours all the pronuclei enlarged, and two of them became juxtaposed. Mitotic figures and large pronuclei were observed at 4 hours. The zygote nucleus went through 3-4 division cycles in synchrony. The supernumerary male nuclei divided once, at most, and all showed evidence of degeneration by the 4-blastomere stage, at about five hours. Therefore, the nuclei destined to form the future chick embryo follow a pattern of behaviour during fertilisation and early cleavage similar to that of animals in general.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000502:physiology*; D002645:Chickens / Q000502:physiology*; D002970:Cleavage Stage, Ovum / Q000648:ultrastructure*; D004396:Coloring Agents; D005260:Female; D005456:Fluorescent Dyes; D007211:Indoles; D008297:Male; D012394:Rosaniline Dyes; D013084:Sperm-Ovum Interactions; D013194:Staining and Labeling; D015053:Zygote / Q000648:ultrastructure*
chemical_list: D004396:Coloring Agents; C007722:Feulgen stain; D005456:Fluorescent Dyes; D007211:Indoles; D012394:Rosaniline Dyes; C007293:DAPI