Migration of primordial germ cells to the developing gonadal ridges in the tammar wallaby Macropus eugenii

Ullmann, Suzanne L.; Shaw, Geoff; Alcorn, G. T.; Renfree, M. B.

doi:10.1530/jrf.0.1100135

Cited by 25 publications

(17 citation statements)

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“…In the tammar wallaby, most germ cell migration is completed 1 day before birth [Alcorn and Robinson, 1983;Jiang et al, 1997;Ullmann et al, 1997]. Unlike the bandicoots Isoodon macrourus [Ullmann, 1989], M. domestica [Fadem et al, 1992;Maitland and Ullmann, 1993] and Trichosurus vulpecula [Ullmann, 1993;Frankenberg et al, 1996] in S. macroura the migration of PGC to the indifferent gonad is completed by the day of birth.…”

Section: Discussionmentioning

confidence: 99%

Oogenesis in the Marsupial Stripe-Faced Dunnart, <i>Sminthopsis macroura</i>

Kress

Merry

Selwood

2001

Cells Tissues Organs

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The timetable of oogenesis in Sminthopsis macroura is accelerated like in other marsupials showing relatively early maturation of the female. On the day of parturition (day 0) migration of primordial germ cells to the indifferent gonads has been completed. Follicular growth seems not to correspond to the biphasic pattern, in which oocyte and follicle grow synchronously until antral stages when only the follicle increases in size, but shows a continuous growth of the oocyte and the follicle up to the time of ovulation. During primordial and early primary follicle stage a paranuclear complex is present in the oocyte, consisting mainly of smooth tubules of endoplasmic reticulum. Cortical granules appear early in oocytes in secondary follicles. The conspicuous inclusions in the antral follicle are the clusters of electron-lucent vesicles in the oocyte. These inclusions grow from multivesicular bodies (MVB), which are formed from Golgi and endoplasmic reticulum vesicles. Further increase in the size of MVB involves the incorporation of endocytic vesicles and the coalescence of larger vesicles. The polarized nature of the oocyte at ovulation is due in part to the to accumulation of these vesicles in the cytoplasm opposite the eccentrically placed nuclear material.

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Section: Discussionmentioning

confidence: 99%

Oogenesis in the Marsupial Stripe-Faced Dunnart, <i>Sminthopsis macroura</i>

Kress

Merry

Selwood

2001

Cells Tissues Organs

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“…The possibility that localised determinants may play a role in embryonic pattern formation in marsupials cannot be ruled out (Selwood, 1968), but there is nothing to suggest that these determinants have anything to do with germ cells, whose earliest reported visualisation is at the 12 somite stage using alkaline phosphatase as a marker (Ullmann et al, 1997). The extreme difficulty of obtaining monotreme specimens for study (Caldwell, 1887) means that even modern studies of development in these animals often rely on histological preparations that are ~100 years old (Hughes and Hall, 1998).…”

Section: Pgcs In the Chordatesmentioning

confidence: 99%

Mechanisms of germ cell specification across the metazoans: epigenesis and preformation

Extavour¹,

Akam²

2003

Development

727

751

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Germ cells play a unique role in gamete production, heredity and evolution. Therefore, to understand the mechanisms that specify germ cells is a central challenge in developmental and evolutionary biology. Data from model organisms show that germ cells can be specified either by maternally inherited determinants (preformation) or by inductive signals (epigenesis). Here we review existing data on 28 metazoan phyla, which indicate that although preformation is seen in most model organisms, it is actually the less prevalent mode of germ cell specification, and that epigenetic germ cell specification may be ancestral to the Metazoa.

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“…In eutherians, the majority of epigenetic reprogramming occurs in utero, with some de novo methylation occurring postpartum in the oocytes (Seisenberger et al, 2012;Tomizawa et al, 2012). In marsupials, germ cells are still proliferating postpartum and do not begin to enter meiosis (females) or mitotic arrest (males) until 25 days after birth (Ullmann et al, 1997;Renfree and Shaw, 2001). Nevertheless, the relative timing and mechanisms of germ cell reprogramming are conserved between eutherians and marsupials, suggesting that these mechanisms evolved well over 160 million years ago .…”

Section: Differential Methylation As a Conserved Mechanism Of Imprintmentioning

confidence: 99%

Post-natal imprinting: evidence from marsupials

et al. 2014

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Genomic imprinting has been identified in therian (eutherian and marsupial) mammals but not in prototherian (monotreme) mammals. Imprinting has an important role in optimising pre-natal nutrition and growth, and most imprinted genes are expressed and imprinted in the placenta and developing fetus. In marsupials, however, the placental attachment is short-lived, and most growth and development occurs post-natally, supported by a changing milk composition tailor-made for each stage of development. Therefore there is a much greater demand on marsupial females during post-natal lactation than during pre-natal placentation, so there may be greater selection for genomic imprinting in the mammary gland than in the short-lived placenta. Recent studies in the tammar wallaby confirm the presence of genomic imprinting in nutrient-regulatory genes in the adult mammary gland. This suggests that imprinting may influence infant post-natal growth via the mammary gland as it does pre-natally via the placenta. Similarly, an increasing number of imprinted genes have been implicated in regulating feeding and nurturing behaviour in both the adult and the developing neonate/offspring in mice. Together these studies provide evidence that genomic imprinting is critical for regulating growth and subsequently the survival of offspring not only pre-natally but also post-natally.

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Migration of primordial germ cells to the developing gonadal ridges in the tammar wallaby Macropus eugenii

Cited by 25 publications

References 0 publications

Oogenesis in the Marsupial Stripe-Faced Dunnart, <i>Sminthopsis macroura</i>

Oogenesis in the Marsupial Stripe-Faced Dunnart, <i>Sminthopsis macroura</i>

Mechanisms of germ cell specification across the metazoans: epigenesis and preformation

Post-natal imprinting: evidence from marsupials

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