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Behavior of chick primordial germ cells moving toward gonadal primordium in vitro: scanning electron microscopic
T Kuwana1, Y Miyayama, Y Kajiwara
1Department of Anatomy, Kumamoto University Medical School, Japan.
Insights
Chick embryonic primordial germ cells (PGCs) exhibit distinct locomotion patterns when attracted to the gonadal primordium (GR). These PGC movements, observed via scanning electron microscopy, involve pseudopodium extension and cell body flow, mimicking in vivo interstitial PGC behavior.
Area of Science:
- Developmental Biology
- Cell Biology
- Reproductive Biology
Background:
- Primordial germ cells (PGCs) are crucial for reproduction.
- Understanding PGC migration is key to developmental biology.
- Previous studies lacked detailed in vitro analysis of PGC locomotion.
Purpose of the Study:
- To investigate the in vitro locomotion mechanisms of embryonic chick PGCs.
- To analyze PGC attraction towards the gonadal primordium (GR).
- To compare PGC behavior on different collagen substrates.
Main Methods:
- In vitro culture of embryonic chick PGCs.
- Time-lapse filming and video recording to observe PGC locomotion.
- Scanning electron microscopy (SEM) for detailed morphological analysis of PGCs during migration.
- Use of thin and thick collagen layers as substrates.
Main Results:
- PGCs extend pseudopodia towards the GR on a thin collagen substrate.
- On a thick collagen substrate, PGCs elongate pseudopodia through the network, with the cell body flowing forward.
- A distinct cytoplasmic tail is formed and later incorporated into the main cell body during locomotion.
- Observed PGC behaviors resemble interstitial PGC migration in vivo.
Conclusions:
- Chick PGCs employ specific pseudopodium-driven locomotion strategies for directed migration.
- Collagen substrate influences the mode of PGC migration.
- The in vitro model provides insights into the in vivo migratory behavior of interstitial PGCs.
Abstract:
Primordial germ cells (PGCs) from embryonic chick blood were cultured in vitro and the cells being attracted by the gonadal primordium (germinal ridge; GR) were studied by scanning electron microscopy (SEM). Immediately after confirming PGC locomotion by 16-mm time-lapse filming or time-lapse video recorder under the microscope, PGCs in various phases of locomotion were prepared for SEM, and their locomotion was analyzed. With the thin collagen layer as a substrate, the sequence of the PGC locomotion was as follows: 1) The PGC produced a small pseudopodium. 2) This pseudopodium enlarged to the GR, and PGC-substrate contact was consolidated around the periphery of the pseudopodium, while the body of PGC remained detached from the substrate. 3) Finally, the PGC as a whole moved toward the GR, being trailed by the process. The locomotion of the PGC on the thick collagen layer as a three-dimensional substrate was as follows: 1) The PGC protruded a pseudopodium in the direction of the GR. 2) This pseudopodium elongated through the collagen network. 3) The tip of the pseudopodium swelled and the main body of the PGC flowed into the swelling portion, leaving a slender cytoplasmic tail. 4) The tail was finally incorporated into the leading part of the cell. This behavior of the PGC seemed to reflect the features of interstitial PGC in vivo.