Cleavage events and sperm dynamics in chick intrauterine embryos.
This study was undertaken to elucidate detailed event of early embryogenesis in chicken embryos using a noninvasive egg retrieval technique before oviposition. White Leghorn intrauterine eggs were retrieved from 95 cyclic hens aged up to 54-56 weeks and morphogenetic observation was made under both bright field and fluorescent image in a time course manner. Differing from mammals, asymmetric cleavage to yield preblastodermal cells was observed throughout early embryogenesis. The first two divisions occurred synchronously and four polarized preblastodermal cells resulted after cruciform cleavage. Then, asynchronous cleavage continued in a radial manner and overall cell size in the initial cleavage region was smaller than that in the distal area. Numerous sperms were visible, regardless of zygotic nuclei formation. Condensed sperm heads were present mainly in the perivitelline space and cytoplasm, and rarely in the yolk region, while decondensed sperm heads were only visible in the yolk. In conclusion, apparent differences in sperm dynamics and early cleavage events compared with mammalian embryos were detected in chick embryo development, which demonstrated polarized cleavage with penetrating supernumerary sperm into multiple regions.
WCU Biomodulation Major, Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea.
Hyung Chul
HC
Lee
Hee Jung
HJ
Choi
Tae Sub
TS
Park
Sang In
SI
Lee
Young Min
YM
Kim
Deivendran
D
Rengaraj
Hiroki
H
Nagai
Guojun
G
Sheng
Jeong Mook
JM
Lim
Jae Yong
JY
Han
D000818:Animals; D002642:Chick Embryo; D002645:Chickens; D048749:Cytokinesis / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D005260:Female; D008297:Male; D010063:Ovum / Q000166:cytology* / Q000378:metabolism*; D013084:Sperm-Ovum Interactions / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology*