Structural aspects of oocyte maturation in the blue fox (Alopex lagopus)

Hyttel, Poul; Farstad, W.; Mondain-Monval, M.; Lajord, K.Bakke; Smith, A. J.

doi:10.1007/bf00186904

Cited by 33 publications

(17 citation statements)

References 21 publications

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“…Large concentric strands of smooth endoplasmic reticulum and mitochondrial clouds, which are abundant in canine preovulatory oocytes (Fig. 5c), are not observed during final maturation in any other mammalian species studied so far, even in the vixen, despite its phylogenetic vicinity (Hyttel et al 1990). The development of cytoplasmic maturation in the very late stages of folliculogenesis suggests that large antral follicles may contain more immature oocytes than in other species, another factor that may contribute to the low maturation rates obtained (see below).…”

Section: In Vivo Maturationmentioning

confidence: 89%

The canine oocyte: uncommon features of in vivo and in vitro maturation

Chastant-Maillard

Lesegno

Chebrout

et al. 2011

Reprod. Fertil. Dev.

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The biology of the canine oocyte is unusual compared with that of other mammalian females. The present paper reviews both in vivo and in vitro specificities of canine oocytes. Final follicular growth in the bitch is characterised by an early appearance of LH binding sites in the granulosa, a high proportion of polyovular follicles and a preovulatory luteinisation, starting at the time of the LH surge. Through follicular fluid, preovulatory oocytes are thus exposed to high levels of progesterone, as high as 1000-fold plasma concentrations. The composition of the follicular fluid is affected by the size of the female. The more specific aspect of oocyte biology in the bitch is ovulation: oocytes are expelled immature, at the Prophase I stage. Ovulatory follicles are 6-8 mm in diameter, releasing oocytes from 110 µm, with dark cytoplasm. Resumption of meiosis occurs from 48 h postovulation, MII stages appearing 48-54 h after ovulation. The mechanisms controlling such a late meiotic resumption are still unknown. Granulosa cells seem to play a central role as in other mammalian species, but not with cAMP as the principal mediator. The importance of a transient reactivation of oocyte transcription a few hours before meiotic resumption is to be explored. These specific features may contribute to the low efficiency of IVM. Only 10-20% oocytes reach the metaphase stage and suffer from a poor cytoplasmic maturation. Moreover, in vitro culture of canine oocytes is associated with a high proportion of degeneration. To date, IVM of the oocytes is the main limiting factor for the development of assisted reproductive techniques in the canine. A better knowledge of the basic physiology of folliculogenesis and the molecular mechanisms controlling oocyte meiosis resumption in this species may allow us to overcome this obstacle.

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Section: In Vivo Maturationmentioning

confidence: 89%

The canine oocyte: uncommon features of in vivo and in vitro maturation

Chastant-Maillard

Lesegno

Chebrout

et al. 2011

Reprod. Fertil. Dev.

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“…As in C. elegans , maturation-hormone dependent movement of the germinal vesicle from a central position to a cortical position has been documented in blue fox oocytes matured in vivo [16]. In contrast, mouse oocytes matured in vitro undergo nuclear envelope breakdown with the germinal vesicle near the center of the oocyte [17].…”

Section: Nuclear Migrationmentioning

confidence: 99%

Nuclear and spindle positioning during oocyte meiosis

Fabritius

Ellefson

McNally

2011

Current Opinion in Cell Biology

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Female meiosis is unique in that an asymmetrically positioned meiotic spindle expels chromosomes into tiny, non-developing polar bodies. The extrusion of chromosomes into polar bodies is always mediated by meiotic spindles that are attached to the oocyte cortex by one pole. The asymmetric, cortical positioning of the oocyte meiotic spindle preserves the volume and contents of the oocyte. Recent work in C. elegans and mouse has provided mechanistic details of spindle positioning in oocytes.

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“…It is well known, in fact, that in mammalian ovaries, communications through gap junctions between the somatic compartment of the follicle and the oocyte are involved in the regulation of its meiotic differentiation and maturation leading to the acquisition of meiotic and developmental competence [30]. In fox oocytes, gap junctions are present within the ovary and all junctional contacts between cumulus cell projections and the oocyte are disrupted 2-3 days after the LH-peak when the metaphase I stage is reached [15]. Viable and differentiated cumulus cells are needed to control the resumption of meiosis in vitro of fox oocytes [19].…”

Section: In Vitro Embryo Production In Dogsmentioning

confidence: 99%

Current progress on assisted reproduction in dogs and cats: in vitro embryo production

Luvoni

2000

Reprod. Nutr. Dev.

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-The objective of the development of assisted reproduction techniques in dogs and cats is their application to non-domestic canine and feline species, most of which are considered threatened or endangered. Among these techniques, an entirely in vitro system for embryo production is effectively an important tool for conservation of wildlife. In the last decade, progress has been made in embryo production in carnivores. It has been shown that canine oocytes can resume meiosis in vitro and that these oocytes can be fertilized and developed in vitro, although at a much lower rate than most other domestic animal oocytes. The reason lies in the dissimilarities of reproductive physiology of the dog compared to other species and the lack of precise information concerning the oviductal environment, in which oocyte maturation, fertilization and early embryonic development take place. Successful in vitro embryo production in the domestic cat has been attained with oocytes matured in vitro, and kittens were born after transfer of IVM/IVF derived embryos. On the basis of these results the in vitro fertilization of oocytes has also been applied in several non-domestic feline species. The effectiveness of such protocols in the preservation of genetic material of rare species can be improved by developing better techniques for long-term storage of gametes. In dogs and cats sperm cells have been successfully frozen and the cryopreservation of oocytes would greatly increase their availability for a range of reproductive technologies. Cryopreserved cat oocytes can be fertilized successfully and their development in vitro after fertilization is enhanced when mature oocytes are frozen. Thus refined techniques of oocyte maturation and fertilization in vitro coupled with oocyte cryopreservation could allow for an easy establishment of genetic combinations when male and female gametes in the desired combination are not simultaneously available, and the propagation of endangered carnivores would be facilitated.canine / feline / in vitro embryo production Résumé -Progrès récents de la reproduction assistée des chiens et des chats : production in vitro d'embryons. L'objectif du développement des techniques de reproduction assistée chez le chien et le chat ont leur application à des espèces canines et félines non domestiques, la plupart d'entre elles menacées ou en danger. En effet un système de production d'embryons entièrement Reprod. Nutr. Dev. 40 (2000) 505-512 505

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Structural aspects of oocyte maturation in the blue fox (Alopex lagopus)

Cited by 33 publications

References 21 publications

The canine oocyte: uncommon features of in vivo and in vitro maturation

The canine oocyte: uncommon features of in vivo and in vitro maturation

Nuclear and spindle positioning during oocyte meiosis

Current progress on assisted reproduction in dogs and cats: in vitro embryo production

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