Other studies reported that qPGCs aggregating on the blastodisc
of young embryos migrated actively through the dorsal mesentery towards the genital ridges [27, 48].
Early developmental stages with visible cell cleavage were not found, but blastodisc
and late-stage eggs were collected in June (Table 3).
Mean Variance Character LP LG LP LG Clutch size 12.0 > 6.8 99.0 > 33.9 Activation rate (%) 79.4 > 61.1 602.9 1027.2 Yolk diameter (in mm) 1.060 <1.201 2.6 2.7 Yolk volume (in [mm.sup.3]) 0.628 < 0.911 7.7 1.4 Yolk shrinkage (%) 6.96 6.95 13.460 10.445 Blastodisc
height (in mm) 0.153 0.146 1.0 1.0 Blastodisc
width (in mm) 0.614 0.645 6.0 8.0 Blastodisc
volume (in [mm.sup.3]) 0.029 0.031 2.2 2.0 Blastodisc
:yolk ratio (%) 4.8 > 3.5 6.6 3.5
The teleost embryo first appears as a clump of cells along the thickened margin of the blastodisc
. The embryonic axis forms with the appearance of the notochord and a solid neural keel that later cavitates.
After fertilization, squid egg ooplasm streams toward the animal pole to create a clear lens-shaped blastodisc
cap where meroblastic cleavage occurs (1).
If no embryogenesis was apparent to the naked eye, the area of the yolk around the blastodisc
was salvaged and stored as described, but it was only possible to identify the sex in 5 of 11 cases where this was done (2 males, 3 females); failures to determine sex may represent cases where eggs were not fertilized, rather than PCR failure, although we cannot distinguish the two at present.
Typically, these eggs also exhibited a pink blastodisc
with adjoining vitelline blood vessels, visible through the shell ("candling," e.g., Ewert 1979).
The zygote post fertilization (dpf) characterized through cytoplasmic continues growth to make the blastodisc
at animal - cleavage period (0-1-4 h post fertilization (hpf), 1 day pole and the arrival of a different peri vitelline space and cleavage stage categorized through a series of mitotic partitions, caused in several blasto-meres.
The right uterus of the one gravid female observed during late September had one single ovum capsule with no visible embryos, along with several blastodisc
or nutritive capsules, whereas the contents of other uterus appeared to have been aborted.
After fertilization, cytoplasm streams from the vegetal region of the squid egg towards the animal cap to form a blastodisc
where meroblastic cleavage will occur [1, 2].
Because the embryo (blastodisc
) is visible to the eye as a pink spot on the eggs without "candling" (a technique used with avian eggs), the embryo can be avoided when the syringe is inserted.
divided after 35-60 min into two blastomeres.
The list of abnormalities found among early embryos includes enlarged segmentation cavity under the blastodisc
, developmental retardation or arrest, and abnormal cell proliferations during gastrulation (Fig.
were produced as result of Blastulation process
At [T.sub.n] = 1.0, the blastodisc
divides into two blastomeres.