English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

To define the origin and the ultrastructure of primordial germ cells (PGCs) in earlier chick embryos, PGCs were characterized by a transmission electron microscopic observation of embryos at stages 2, 3, 4 and 13-15. Furthermore, to clarify the dividing ability of PGCs in early chick embryos, quantity of DNA in PGCs at stage 13-15 was analyzed by an Interactive Laser Cytometer.The PGCs at stage 4 were found much closer to or inside the endoderms of the germinal crescent. PGCs were commonly round and have many glycogen granules, many lipid droplets and a large nucleus with many opaque fragmented electron masses in both samples at stage 4 and stage 13-15. However, the average diameter of PGCs at stage 4 was larger than that at stage 13-15. Moreover, PGCs at stage 4 had much yolk and more developed Golgi complex in comparison with stage 13-15. On the other hand, there were cells resembling PGCs located near the endoderm and beneath the epiblast at the upper parts of the initial primitive streak in stages 2 and 3 embryos. Some cells that were detaching from the basal plate of the epiblast were also observed. There were more cells located near the endoderm in embryos at stage 3 compared with stage 2 embryos. Quantity of DNA differed in each PGC at stage 13-15, and two peaks were recognized in the histogram of the nuclear DNA quantity of PGCs. Moreover, 3 out of 140 PGCs (2.1%) were dividing cells.From these results, it is speculated that PGCs originate in the epiblast, and that the sizes and structure of PGCs change with the advancing stage in development. PGCs circulating in the vascular system might have the periodic change of DNA in the nuclei.

Studies on the Origin, Ultrastructure and DNA Quantity of Primordial Germ Cells in Early Chick Embryo.