The Reproductive Physiology of the Plains Viscacha, Lagostomus Maximus

Weir, Barbara J.

doi:10.1530/jrf.0.0250355

Cited by 94 publications

(88 citation statements)

References 7 publications

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“…It is tempting to speculate that this suppression is responsible for sculpting the striking anatomy of the adult ovary of the plain viscacha. Our description of the ovary is in close agreement with the observation of Weir (1971b). Nonetheless, foetal ovary (Weir 1971b, Jensen et al 2005 and neonatal ovary (Weir 1971b) show a normal mammalian type of ovoid and solid organ.…”

Section: Suppressed Apoptosis In the Manmalian Ovarysupporting

confidence: 91%

“…Our description of the ovary is in close agreement with the observation of Weir (1971b). Nonetheless, foetal ovary (Weir 1971b, Jensen et al 2005 and neonatal ovary (Weir 1971b) show a normal mammalian type of ovoid and solid organ. Invaginations of the germinal epithelium and the tunica albuginea through the cortex into the medulla began to appear at 6 weeks of age (Weir 1971b).…”

Section: Suppressed Apoptosis In the Manmalian Ovarysupporting

confidence: 91%

“…These females ovulate between 400 and 800 oocytes in each cycle and show extensive formation of corpora lutea, with a considerable number of oocytes lost before ovulation by luteinisation of the follicle (Weir 1971b). Consequently, oocyte loss in each oestrous may exceed a 1000 germ cells, taking account of ovulation and luteinisation rates (Weir 1971b).…”

Section: Introductionmentioning

confidence: 99%

“…Despite the extreme polyovulation displayed by L. maximus, a few, eight to ten oocytes, seem to be fertilized, and only one or two embryos are gestated to term (Weir 1971b). The high ovulation rate has been mainly explained as a consequence of the small size of the ovulatory follicle and the greatly convoluted anatomy of the ovary that increases the surface for ovulation (Weir 1971b).…”

Section: Introductionmentioning

confidence: 99%

“…The high ovulation rate has been mainly explained as a consequence of the small size of the ovulatory follicle and the greatly convoluted anatomy of the ovary that increases the surface for ovulation (Weir 1971b).…”

Section: Introductionmentioning

confidence: 99%

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Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

Jensen

Willis²,

Albamonte³

et al. 2006

Reproduction

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It has been widely accepted that mammalian females are born with a non-renewing, finite pool of oocytes that will be continuously cleared by atresia, with only a small proportion of them reaching ovulation. Apoptosis regulates this mass germ cell death, especially through the balance between pro-and anti-apoptotic proteins encoded by the BCL-2 gene family. The caviomorph rodent Lagostomus maximus, the South American plains viscacha, displays the highest ovulation rate known for a mammal releasing 400-800 eggs per cycle. We tested the hypothesis that in L. maximus massive polyovulation is a consequence of reduced apoptosis resulting in suppressed follicular atresia. We found that anti-apoptotic BCL-2 gene is markedly expressed in all kind of follicles from primordial to fully mature antral stages in the adult ovary of L. maximus. On the other hand, pro-apoptotic BAX gene showed weak signals or was undetectable by immunohistochemical examination. Western blot against both proteins confirmed immunohistochemical results. Screening for DNA fragmentation by TUNEL assay was conspicuously negative in ovaries from both pregnant and non-pregnant females. In addition, a-oestrogen receptor also showed an enhanced expression from primordial stage to fully mature antral follicles. Our results show that natural preferential expression of BCL-2 and restricted BAX expression greatly suppresses apoptosis in the ovary of L. maximus. This prevents the decline of the oocyte reserve by abolishing follicular atresia and enables the highest ovulation rate known for a mammal, 400-800 or more eggs per cycle.

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Section: Suppressed Apoptosis In the Manmalian Ovarysupporting

confidence: 91%

Section: Suppressed Apoptosis In the Manmalian Ovarysupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

Jensen

Willis²,

Albamonte³

et al. 2006

Reproduction

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Structural specializations of the eye in the vizcacha (Lagostomus maximus maximus)

Lascano

Soler²,

Ornstein

et al. 1999

Anat. Rec.

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Vizcachas (Lagostomus maximus maximus, Chinchillidae) are nocturnal rodents living in burrows in many regions of Argentina, Bolivia, and Chile. We have studied the eye of the vizcacha using several light and electron microscopic procedures, with the purpose of understanding the role of vision in the behavior of this species. Our observations demonstrated an avascular, rod-rich retina, with a specialized region spanning through most of the equator of the eye. In this central band, all neural retinal layers exhibited a high cell density, whereas the photoreceptor layer was characterized by the presence of very long rods. In addition, the central region was associated with a distinct pigmentation pattern, including scarce granulation of the pigment epithelium, low pigmentation of the choroid, and the selective attachment of suprachoroidal cells to the inner scleral surface. These central modifications probably form the structural basis of a reflecting tapetum. The eye of the vizcacha received both long and short ciliary vessels, and a specialized cilio-sclero-choroidal vascular network appeared at the equatorial region. Our findings suggest that the equatorial region of the eye of the vizcacha could be a highly sensitive light detector related to foraging behaviors during crepuscular or nocturnal hours.

show abstract

Structural specializations of the eye in the vizcacha (Lagostomus maximus maximus)

Lascano¹,

Soler²,

Ornstein³

et al. 1999

Anat. Rec.

View full text Add to dashboard Cite

show abstract

The Reproductive Physiology of the Plains Viscacha, Lagostomus Maximus

Abstract: Summary. Plains

Cited by 94 publications

References 7 publications

Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

Structural specializations of the eye in the vizcacha (Lagostomus maximus maximus)

Structural specializations of the eye in the vizcacha (Lagostomus maximus maximus)

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