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Scanning and transmission electron microscopic observations of chick primordial germ cells with special reference to
A Ukeshima1, K Yoshinaga, T Fujimoto
1College of Medical Science Kumamoto University, Japan.
Insights
Chick primordial germ cells (PGCs) leave blood vessels using filopodia during migration. These specialized cells then move via amoeboidism to colonize the developing gonadal epithelium.
Area of Science:
- Developmental Biology
- Cell Biology
- Embryology
Background:
- Primordial germ cells (PGCs) are crucial for reproduction.
- Understanding PGC migration is key to developmental biology.
- The extravasation process of PGCs from blood vessels remains incompletely understood.
Purpose of the Study:
- To investigate the morphological characteristics of chick PGCs during extravasation.
- To elucidate the mechanism by which PGCs exit the bloodstream.
- To observe PGC interaction with the gonadal epithelium.
Main Methods:
- Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were utilized.
- Chick embryos at developmental stages 16 and 17 were examined.
- High-resolution imaging focused on PGCs within and exiting blood vessels.
Main Results:
- PGCs exhibited a round profile with microvilli within blood vessels.
- Extravasating PGCs displayed fewer microvilli, with prominent filopodia extending towards the vessel wall.
- Post-extravasation, PGCs utilized amoeboid movement to invade the gonadal epithelium, adopting a rugged surface.
Conclusions:
- Filopodia play a role in PGC adhesion to and emergence from blood vessels.
- PGC extravasation is a distinct morphological process.
- PGCs employ amoeboidism for colonization of the gonadal niche.
Abstract:
Chick primordial germ cells (PGCs) in the final course of their migration were observed by scanning (SEM) and transmission (TEM) electron microscopy, with an emphasis on their extravasation. The profile of the PGCs leaving blood vessels were first revealed under SEM. Chick embryos at stages 16 and 17 (about 2.5 days of incubation) were employed for the present study, since the PGCs emerging out of the vessels in teh gonadal area could be observed in high frequency at this developmental period. PGCs in the vessels showed a round profile, possessing many microvilli, while extravasating PGCs were rather oligovillous except the one side of the cell, where long filopodia extended toward the wall of the vessels. These filopodia seem to adhere to the wall of the vessels prior to emerging out. After extravasation, PGCs moved toward adjacent prospective gonadal epithelium and invaded it by amoeboidism. Following the settling down in the epithelium, PGCs showed rugged surface with few microvilli.