150 THE DISTRIBUTION PATTERN OF PRIMORDIAL GERM CELLS IN EARLY CHICK EMBRYOS

2007 ◽  
Vol 19 (1) ◽  
pp. 192 ◽  
Author(s):  
Y. Nakamura ◽  
Y. Yamamoto ◽  
F. Usui ◽  
T. Ono ◽  
K. Takeda ◽  
...  

In all vertebrates, primordial germ cells (PGCs) appear during early stages of development in extragonadal sites, then they migrate to the gonad and give rise to ova or spermatozoa. Unlike in other species, however, in avian and reptile embryos, PGCs use the vascular system as a vehicle to transport them to the future gonadal region where they leave the blood vessels. The present study was carried out to know the details of this unique migration pathway and the proliferation of endogenous PGCs in chicken embryos. Whole of the chicken embryos during stages X [Roman numerals refer to the staging system of Eyal-Giladi and Kochav (1976 Dev. Biol. 49, 321–327) to 17 (Arabic numerals refer to the staging system of Hamburger and Hamilton (1951 J. Morphol. 88, 49-82))] or embryonic blood during stages 12 to 17 were immunohistochemical stained using specific antibody raised against chicken vasa homolog (CVH), which could be recognized as a marker for chicken PGCs. The distribution patterns and populations of PGCs in embryos were observed under a stereomicroscope. The numbers of PGCs were presented mean and standard deviation (mean � SD). Anti-CVH staining revealed the distribution and population of chicken PGCs in early chick embryos. PGCs existed mainly in the area pellucida and concentrated in the central zone at stage X. The mean number of PGCs per embryo at this stage was 130.4 � 31.9. With the formation of primitive streak, PGCs were carried anteriorly to the edge of the blastoderm. The PGCs scattered anteriorly began to concentrate to the anterior point of the head on the dorsal side of stage 10 embryos. The average number of PGCs per embryo at stage 10 was 439.3 � 93.6. The mean numbers of PGCs per embryo during stages X to 10 increased gradually as development progressed to stage 10. We found the entrance point of PGCs from anterior edge of the blastoderm to the vascular network during stages 10 to 11. In the blood, PGCs could be detected from all of the samples during stages 12 to 17. In contrast, no PGC was recognized in the future gonadal region before stage 14, and then they began to appear in the same region at stage 15. The mean numbers of PGCs that located in the future gonadal region during stages 15 to 17 increased intensively and were 97.3 � 57.3, 200.3 � 113.5, and 327.6 � 102.4, respectively. Interestingly, the numbers of PGCs within future gonadal region during stages 15 to 17 were consistently and significantly different (P < 0.05) between the left and right side of the region. The results suggest that chicken PGCs move from extraembryonic area to the vascular network during stages 10 to 11, circulate in the blood stream, and finally, they begin to leave the blood vessels actively and migrate to the future gonadal region at stage 15.

Development ◽  
1968 ◽  
Vol 20 (3) ◽  
pp. 247-260
Author(s):  
Teresa Rogulska

Suggestive evidence for the extragonadal origin of germ cells in birds was first presented by Swift (1914), who described primordial germ cells in the chick embryo at as early a stage as the primitive streak. According to Swift, primordial germ cells are originally located extra-embryonically in the anterior part of the blastoderm and occupy a crescent-shaped region (‘germinal crescent’) on the boundary between area opaca and area pellucida. Swift also found that primordial germ cells later enter into the blood vessels, circulate together with the blood throughout the whole blastoderm and finally penetrate into the genital ridges, where they become definitive germ cells. Swift's views have been confirmed in numerous descriptive and experimental investigations. Among the latter, the publications of Willier (1937), Simon (1960) and Dubois (1964a, b, 1965a, b, 1966) merit special attention. Dubois finally proved that the genital ridges exert a strong chemotactic influence on the primordial germ cells.


1992 ◽  
Vol 16 (9) ◽  
pp. 853-857 ◽  
Author(s):  
I CHANG ◽  
A TAJIMA ◽  
Y YASUDA ◽  
T CHIKAMUNE ◽  
T OHNO

1999 ◽  
Vol 12 (4) ◽  
pp. 520-524 ◽  
Author(s):  
K. Eguma ◽  
T. Soh ◽  
M. Hattori ◽  
N. Fujihara

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 385-395
Author(s):  
Noriyuki Satoh ◽  
Nobuo Egami

Mitotic and meiotic activities of germ cells during early development in the medaka, Oryzias latipes, are dealt with in this report. Primordial germ cells were obviously distinguishable from somatic cells 3 days after fertilization and began to proliferate about 7 days after fertilization. The mean number of primordial germ cells increased during a period of 7–10 days after fertilization, reaching about 90 immediately before hatching. Newly hatched fry could be classified into two types according to the number and the nucleic activity of germ cells in the gonadal rudiment. One type consisted of fry containing about 100 germ cells and no cells in the meiotic prophase. In the other type of fry the number of germ cells increased by mitotic divisions and some of the cells began to enter into the meiotic prophase. During the course of further development the fry of the former type differentiated into males and the latter into females. Therefore it can be concluded that the morphological sex differentiation of germ cells occurs at the time of hatching. However, no sexual differences in the histological structure of somatic elements in the gonad are observable at that time.


Development ◽  
1976 ◽  
Vol 35 (3) ◽  
pp. 637-648
Author(s):  
Par Eliane Didier ◽  
Noël Fargeix

Quantitative aspects of the colonization of the gonads by germ cells in the quail embryo (Coturnix coturnix japonica) A quantitative analysis made on quail embryos coming from 13 isolated parent couples reveals some significative variations of a genetic origin, between some of the off spring studied: the differences observed concern both the quantitative importance of the colonization of gonads by germ cells and the asymmetrical distribution of PGCs (primordial germ cells) between the two genital ridges. The chronological study of the colonization in the quail shows, as in both the duck and the chick, two periods of rapid and regular increase of the number of gonadic PGC, at stages from 13 to 18 and from 24 to 30 of Hamburger & Hamilton. The distribution of germ cells between the two genital ridges is, at the beginning of the colonization, not very asymmetrical. Between stages 18 and 24 the asymmetry increases and remains stable so that the mean value of D % (percentage of the number of PGC contained in the right gonad) from that moment on is equal to 29–34 %. This value is specific for the quail embryo.


2008 ◽  
Vol 20 (8) ◽  
pp. 900 ◽  
Author(s):  
Yoshiaki Nakamura ◽  
Yasuhiro Yamamoto ◽  
Fumitake Usui ◽  
Yusuke Atsumi ◽  
Yohei Ito ◽  
...  

The aim of the present study was to improve the efficiency of endogenous primordial germ cell (PGC) depletion and to increase the ratio of donor PGCs in the gonads of recipient chicken embryos. A sustained-release emulsion was prepared by emulsifying equal amounts of Ca2+- and Mg2+-free phosphate-buffered saline containing 10% busulfan solubilised in N,N-dimethylformamide and sesame oil, using a filter. Then, 75 μg per 50 μL busulfan sustained-release emulsion was injected into the yolk. To determine the depletion and repopulation of PGCs in the gonads after 6 days incubation, whole-mount immunostaining was performed. The busulfan sustained-release emulsion significantly reduced the number of endogenous PGCs compared with control (P < 0.05). Moreover, the busulfan sustained-release emulsion significantly depleted endogenous PGCs compared with other previously reported busulfan delivery systems (P < 0.05), but with less variation, suggesting that the sustained-release emulsion delivered a consistent amount of busulfan to the developing chicken embryos. The PGC transfer study showed that the proportion of donor PGCs in the gonads of busulfan sustained-release emulsion-treated embryos after 6 days incubation increased 28-fold compared with control. In conclusion, the results demonstrate that exogenous PGCs are capable of migrating and settling in gonads from which endogenous PGCs have been removed using a busulfan sustained-release emulsion.


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