Die Keimbahn des Menschen

Politzer, G.

doi:10.1007/bf02119003

Cited by 57 publications

(11 citation statements)

References 31 publications

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“…The extragonadal origin of PGCs was con fi rmed by the subsequent studies by Kohno [ 11 ] and Hamlett [ 12 ] and above all, by Politzer [13][14][15] and Witschi [ 16 ] the yolk sac to the gonadal ridges. In an embryo 0.6 mm long (about 3 weeks), Politzer [13][14][15] counted 40 PGCs which increased to 600 in the 4 mm long embryo (4 weeks). Similarly, Witschi [ 16 ] counted 30-50 PGCs in the endoderm of the yolk sac around the end of the third week and 109 PGCs in an embryo a couple of days older.…”

Section: Comparing Mouse and Human Pgc Formationmentioning

confidence: 86%

Origin, Migration, and Proliferation of Human Primordial Germ Cells

Felici

2012

Oogenesis

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The fi rst histological observations about the origin of the precursors of gametes termed primordial germ cells (PGCs) in extragonadal regions and their subsequent migration into the developing gonads in human embryos date back to the early twentieth century. Fuss (Anat Am 39:407-409, 1911, Anat EntwMech 81:1-23, 1912 and Felix (Die Entwicklung der Harn-und Geschlechtsorgane. In: Keibel-Mall Handbuch der 1qEntwick-lungageschichte des Menshen, vol 2. Leipzig, Hirzel, pp 732-955, 1911) were apparently the fi rst ones to describe the extragonadal location of PGCs in human embryos. In the youngest, 2.5 mm long, embryo examined (23-26 days postfertilization), These authors described PGCs in the endoderm of the yolk sac wall as cells identi fi able by their large size and spherical shape. Subsequently, Politzer (Z Anat Entw Gesch 87: 766-80, 1928, Z Anat Entw Gesch 93:386-428, 1930, Z Anat EntwGesch 100:331-336, 1933 and Witschi (Contr Embryol Carnegie Inst 209:67-80, 1948) studied the distribution of PGCs in a considerable number of embryos from presomite stages (0.3-0.8 mm, about 3 weeks) to 8.5 mm (5 weeks). Both authors described the migration of PGCs from the yolk sac to the developing gonads. Following a hot debate, it is now generally accepted that after their arrival into the gonadal anlage, PGCs give rise to the oogonia/oocytes and gonocytes (or prespermatogonia) in the embryonic ovary and testis, respectively. These germ cells enter a complex series of events that in the

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Section: Comparing Mouse and Human Pgc Formationmentioning

confidence: 86%

Origin, Migration, and Proliferation of Human Primordial Germ Cells

Felici

2012

Oogenesis

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“…During embryonic development PGCs colonize the gonadal ridge and mitotically divide as they populate what will eventually become either an ovary or a testis. In humans, there is a major void in our current understanding of the molecular mechanisms that govern the processes of PGC specification, migration, proliferation, and entry into meiosis due to limitations with sample availability (De Felici, 2013), though histological evidence has shown that PGCs are identifiable during the third week of embryo development in the endoderm of the yolk sac (Witschi, 1948), proliferate extensively between the 3rd and 4th week (Witschi, 1948; Politzer, 1933) and colonize the developing ovary by the end of the 5th or beginning of the 6th week (Makabe et al, 1991). While the earliest stages of embryonic development differ dramatically between humans and mice, much of the contemporary knowledge of mammalian PGC specification, proliferation, migration and colonization has been generated using mice as a model, in which the process is well characterized and can be studied with relative ease.…”

Section: Ovarian Germ Cells: Primordial Germ Cells (Pgcs) and Oogomentioning

confidence: 99%

Ovarian regeneration: The potential for stem cell contribution in the postnatal ovary to sustained endocrine function

Truman

Tilly

Woods

2017

Molecular and Cellular Endocrinology

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The endocrine function of the ovary is dependent upon the ovarian follicle, which on a cellular basis consists of an oocyte surrounded by adjacent somatic cells responsible for generating sex steroid hormones and maintenance of hormonal stasis with the hypothalamic-pituitary axis. As females age, both fertility and the endocrine function of the ovary decline due to waning follicle numbers as well as aging-related cellular dysfunction. Although there is currently no cure for ovarian failure and endocrine disruption, recent advances in ovarian biology centered on ovarian stem cell and progenitor cell populations have brought the prospects of cell- or tissue-based therapeutic strategies closer to fruition. Herein, we review the relative contributions of ovarian stem cells to ovarian function during the reproductive lifespan, and postulate steps toward the development of ovarian stem cell-based approaches to advance fertility treatments, and also importantly to provide a physiological long-term means of endocrine support.

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“…The extent of the division that occurs during the migration of the germ cells is illustrated by estimates of 1575 to 1625 germ cells at 11 days (Chiquoine, 1954) and 5711 on the 12th day when migration is said to be complete (Mintz, 19 57). For human embryos, Witschi (1948,1956 has put thenumbers in the endoderm of the yolk sac at the 12-13-somite stage as from 30 to 50 increasing to 109 in a 16-somite embryo, while counts varying from 330 to 1366 have been made for later human embryos (Politzer, 1933 ;Hamlett, 1935 ;Witschi, 1948). A similar picture of increasing numbers during the migration of the germ cells has been found in counts on pig (Fuss, 1912) and guinea-pig embryos (Rubaschkin, 1912).…”

Section: Phrynosoma Cornutummentioning

confidence: 99%

The Numbers of Vertebrate Primordial Germ Cells

Hardisty

1967

Biological Reviews

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Die Keimbahn des Menschen

Cited by 57 publications

References 31 publications

Origin, Migration, and Proliferation of Human Primordial Germ Cells

Origin, Migration, and Proliferation of Human Primordial Germ Cells

Ovarian regeneration: The potential for stem cell contribution in the postnatal ovary to sustained endocrine function

The Numbers of Vertebrate Primordial Germ Cells

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