Vasculogenesis in the early quail blastodisc
as studied with a monoclonal antibody recognizing endothelial cells.
Zygote to cleavage phase began from 0-1 h to 4 h after post fertilization and one day after post fertilization, it characterized with cytoplasmic growth, formation of blastodisc
at the end of animal pole, presence of different perivitelline gape and cleavage phase categorized with a sequence of meiotic partitions that resulted in several blastomeres.
One hour after fertilisation, the cytoplasm was pulled toward the animal pole, and a blastodisc
was formed (1-cell stage) (Fig.
A small circular spot on the upper surface of the yolk mass is detected, it's considered as the blastodisc
. There are also collapsed fat droplets under it (Fig.
The beginning of gastrula marks the end of the blastula stage, and it is followed by epiboly, defined as the movement of the yolk syncytial layer and blastodisc
around the yolk cell.
Gradually the blastoderm formed into several layers due to further cell division which is called blastodisc
. At this stage a space was formed between yolk and blastoderm which is called blastocoel.
On the contrary, avian PGCs originate from the central zone of blastodisc
[23, 26-29] and then migrate anteriorly to extraembryonic region called "germinal crescent" [23, 26].
Early cell divisions were evident at the animal pole (opposite of the oil droplet) and eventually formed the blastodisc
. Divisions progressed until individual blastomeres were no longer distinguishable.
Earliest stage of eggs with asymmetrical blastodisc
(Table 3), though the asymmetry may be an artifact of preservation.
The embryonic developmental stage was ranked as 0 = no embryos present beneath the abdomen; 1 = only yolk visible (newly spawned); 2 = blastodisc
present but no eye pigmentation; 3 = eye pigmentation or eye development visible, cephalothorax and pleon not separated; or 4 = egg present, little yolk, carapace and pleon separate (Bauer and Delahoussaye, 2008).
During this period dividing cells were easily distinguishable prior to blastodisc
formation, and little change in morphometry occurs.
A mathematical technique for estimating blastodisc
: yolk volume ratios instead of egg sizes.