Origin of the sex cells in man

Simkins, Cleveland Sylvester

doi:10.1002/aja.1000410205

Cited by 50 publications

(8 citation statements)

References 10 publications

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“…The OSC have been implicated in the formation of oocytes in mice and humans [2,3,11,78,87,100,114,120], and it also has been suggested that the OSC are a source of granulosa cells in fetal and adult mammalian ovaries [11,87,115,121-123]. The formation of germ cells from OSC is, however, a selective process.…”

Section: Human Embryonic and Fetal Ovaries - Mechanisms Of Oocyte mentioning

confidence: 99%

“…The term secondary, or just germ cells, designates cells originating from the ovarian stem cells (OSC) in vivo . Ovarian stem cells are epithelial cells covering ovaries, and were originally called “ovarian germinal epithelium” [2,3], then ovarian surface epithelium [4-6], and now ovarian stem cells [7-10]. They are considered to be epithelial in nature, but could originate by mesenchymal-epithelial conversion from the mesenchymal precursors in ovarian tunica albuginea (TA) of adult individuals in some species, such as humans [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Immunoregulation of follicular renewal, selection, POF, and menopause in vivo, vs. neo-oogenesis in vitro, POF and ovarian infertility treatment, and a clinical trial

Bukovský

Caudle

2012

Reprod Biol Endocrinol

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The immune system plays an important role in the regulation of tissue homeostasis ("tissue immune physiology"). Function of distinct tissues during adulthood, including the ovary, requires (1) Renewal from stem cells, (2) Preservation of tissue-specific cells in a proper differentiated state, which differs among distinct tissues, and (3) Regulation of tissue quantity. Such morphostasis can be executed by the tissue control system, consisting of immune system-related components, vascular pericytes, and autonomic innervation. Morphostasis is established epigenetically, during morphogenetic (developmental) immune adaptation, i.e., during the critical developmental period. Subsequently, the tissues are maintained in a state of differentiation reached during the adaptation by a “stop effect” of resident and self renewing monocyte-derived cells. The later normal tissue is programmed to emerge (e.g., late emergence of ovarian granulosa cells), the earlier its function ceases. Alteration of certain tissue differentiation during the critical developmental period causes persistent alteration of that tissue function, including premature ovarian failure (POF) and primary amenorrhea. In fetal and adult human ovaries the ovarian surface epithelium cells called ovarian stem cells (OSC) are bipotent stem cells for the formation of ovarian germ and granulosa cells. Recently termed oogonial stem cells are, in reality, not stem but already germ cells which have the ability to divide. Immune system-related cells and molecules accompany asymmetric division of OSC resulting in the emergence of secondary germ cells, symmetric division, and migration of secondary germ cells, formation of new granulosa cells and fetal and adult primordial follicles (follicular renewal), and selection and growth of primary/preantral, and dominant follicles. The number of selected follicles during each ovarian cycle is determined by autonomic innervation. Morphostasis is altered with advancing age, due to degenerative changes of the immune system. This causes cessation of oocyte and follicular renewal at 38 +/-2 years of age due to the lack of formation of new granulosa cells. Oocytes in primordial follicles persisting after the end of the prime reproductive period accumulate genetic alterations resulting in an exponentially growing incidence of fetal trisomies and other genetic abnormalities with advanced maternal age. The secondary germ cells also develop in the OSC cultures derived from POF and aging ovaries. In vitro conditions are free of immune mechanisms, which prevent neo-oogenesis in vivo. Such germ cells are capable of differentiating in vitro into functional oocytes. This may provide fresh oocytes and genetically related children to women lacking the ability to produce their own follicular oocytes. Further study of "immune physiology" may help us to better understand ovarian physiology and pathology, including ovarian infertility caused by POF or by a lack of ovarian follicles with functional oocytes in aging ovaries. The observations indicating...

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Section: Human Embryonic and Fetal Ovaries - Mechanisms Of Oocyte mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Immunoregulation of follicular renewal, selection, POF, and menopause in vivo, vs. neo-oogenesis in vitro, POF and ovarian infertility treatment, and a clinical trial

Bukovský

Caudle

2012

Reprod Biol Endocrinol

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“…During the past, for at least 50 years many studies have shown that removing the ovarian surface epithelium (OSE) in immature mammals does not later interfere with the follicle/oocyte numbers of the ovary, and that primordial germ cells (PGCs) arise in the early human embryo outside the gonadal ridges (Simkins, 1928, 1932; Byskov, 1986). The PGCs are first identifiable in the human embryo at about 3 weeks in the epithelium of the yolk sac, which are then observed, expanded by mitosis, migrating to the connective tissue of the hind gut, and from there into the gut mesentery.…”

Section: Introductionmentioning

confidence: 99%

“…Because of that, the OSE cell layer was usually named the “germinal” epithelium (Waldeyer, 1870; Kingery, 1917; Allen, 1923; Evans and Swezy, 1931). OSE is a normal, naturally present source of germ cells in the fetal period of life (Simkins, 1928, 1932). Scanning and transmission electron microscopy have revealed numerous germ cells (10 μm in diameter) within the ovarian OSE of human fetuses from 7 to 24 weeks of intrauterine life (Motta and Makabe, 1986).…”

Section: Introductionmentioning

confidence: 99%

Putative stem cells with an embryonic character isolated from the ovarian surface epithelium of women with no naturally present follicles and oocytes

et al. 2008

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“…Shtchecolev [1933,1934], Shtcheuolev and Tepljakova 11933]) claimed that spermatogonia arc the direct progeny of gonocytes, others (Stieve 11927. 1930], Simkins [ 1928] a.o.) derived them from the coelomic (germinal) epithelium.…”

mentioning

confidence: 99%

The development of genital glands and the origin of germ cells in human embryogenesis

Falin¹

1969

Cells Tissues Organs

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Origin of the sex cells in man

Cited by 50 publications

References 10 publications

Immunoregulation of follicular renewal, selection, POF, and menopause in vivo, vs. neo-oogenesis in vitro, POF and ovarian infertility treatment, and a clinical trial

Immunoregulation of follicular renewal, selection, POF, and menopause in vivo, vs. neo-oogenesis in vitro, POF and ovarian infertility treatment, and a clinical trial

Putative stem cells with an embryonic character isolated from the ovarian surface epithelium of women with no naturally present follicles and oocytes

The development of genital glands and the origin of germ cells in human embryogenesis

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