Circulating progesterone concentrations and ovarian functional anatomy in the African elephant (Loxodonta africana)

Villiers, D. J. de; Skinner, J. D.; Hall-Martin, A.J.

doi:10.1530/jrf.0.0860195

Cited by 18 publications

(10 citation statements)

References 17 publications

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“…Postmortems on culled, pregnant African elephants showed that all CLs are equally capable of producing P m (Hodges et al 1997). We were unable to determine a correlation between CL number, size, and peripheral P m which agreed with an earlier study (De Villiers et al 1989).…”

Section: Luteogenesis In Elephantscontrasting

confidence: 75%

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Luteogenesis during the estrous cycle in Asian elephants (Elephas maximus)

Niemuller¹,

Gray²,

Rich³

et al. 2010

Reproduction

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The occurrence of multiple corpora lutea (CLs) in the ovaries of the cycling and pregnant elephant, a monovulatory mammal, has driven scientific discussions during the past five decades. However, fundamental knowledge on luteogenesis is lacking. In this long-term study, CL formation and regression throughout the estrous cycle were monitored using transrectal 2D-and 3D ultrasonography in 33 captive Asian elephants. Serum or urinary progestagens (P m ) were measured to determine the reproductive cycle stage. In seven females, serum P m and LH concentrations were directly related to ovarian events. We have found two different modalities of luteal development: one for the accessory CL (acCL) and one for the ovulatory CL (ovCL). acCLs were derived from luteinization of larger, subordinate follicles after the first anovulatory LH peak. The dominant follicle produced the largest CL after the second (ovulatory) LH peak. The first luteal tissue formation became visible w10 days after the respective LH peak. After ovulation, it took 29.8G5.0 days for the acCLs to reach their maximum diameter, whereas the ovCL reached a significantly larger size (33.2G2.3 mm, P!0.0001) about 10-15 days later. All CLs were visible throughout the new follicular phase, with some of the larger ones still present in the subsequent luteal period. In this study, we have demonstrated that Asian elephants have evolved a novel method for luteal development and function, and by repeatedly forming two types of distinctly different CLs for every reproductive cycle, they have ensured that there will be sufficient luteal capacity for maintaining a 22-month pregnancy should conception occur.

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Section: Luteogenesis In Elephantscontrasting

confidence: 75%

“…The mean number of CLs in cycling elephants is not different from pregnant elephants and progestagen concentrations do not increase over consecutive cycles (De Villiers et al 1989, Hodges et al 1997. These findings led Hodges (1998) to disagree with the theory of CL accumulation.…”

Section: Introductionmentioning

confidence: 98%

Luteogenesis during the estrous cycle in Asian elephants (Elephas maximus)

Niemuller¹,

Gray²,

Rich³

et al. 2010

Reproduction

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“…In addition, maternal blood progesterone concentrations are at about 7 ng/ml between 50 and 100 days of gestation (Echternkamp et al 2006), which is lower than the 20-150 ng/g progesterone concentration seen in fetal ovaries between 60 and 75 days of gestation. Previous literature has established that maternal and fetal progesterone levels are different from each other and may be regulated independently in macaques (Ducsay et al 1985, Thau et al 1976), humans (Donaldson et al 1991), sheep (Nicol et al 1997) and elephants (de Villiers et al 1989). This suggests that ovarian fetal progesterone is regulated to control the initiation or progression of primordial follicle assembly, independent of maternal progesterone levels.…”

Section: Discussionmentioning

confidence: 99%

Progesterone regulation of primordial follicle assembly in bovine fetal ovaries

Nilsson

Skinner

2009

Molecular and Cellular Endocrinology

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Fertility in mammals is dependant on females having an adequate primordial follicle pool to supply oocytes for fertilization. The formation of primordial follicles is called ovarian follicular assembly. In rats and mice progesterone and estradiol have been shown to inhibit follicle assembly with assembly occurring after birth when the pups are removed from the high-steroid maternal environment. In contrast, primordial follicle assembly in other species, such as cattle and humans, occurs during fetal development before birth. The objective of the current study is to determine if progesterone levels regulate primordial follicle assembly in fetal bovine ovaries. Ovaries and blood were collected from bovine fetuses. Interestingly, ovarian progesterone and estradiol concentrations were found to decrease with increasing fetal age and correlated to increased primordial follicle assembly. Microarray analysis of fetal ovary RNA suggests that progesterone membrane receptor and estrogen nuclear receptor are expressed. Treatment of fetal bovine ovary cultures with a higher progesterone concentration significantly decreased primordial follicle assembly. Observations indicate that progesterone affects ovarian primordial follicle assembly in cattle, as it does in rats and mice.

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“…Given that prolactin is luteotropic in other mammals, the increase after 20-28 weeks could account for some of the progestagen activity observed later in pregnancy. The lack of a correlation between circulating progestagen levels and luteal volume [de Villiers et al, 1989], and the positive relationship between fetal progestagen concentrations and gestational age [de Villiers et al, 1989] both suggest that the placenta may be a source of progestagens.…”

Section: Discussionmentioning

confidence: 99%

Successful artificial insemination of an Asian elephant at the National Zoological Park

et al. 2004

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For decades, attempts to breed elephants using artificial insemination (AI) have failed despite considerable efforts and the use of various approaches. However, recent advances in equipment technology and endocrine-monitoring techniques have resulted in 12 elephants conceiving by AI within a 4-year period (1998)(1999)(2000)(2001)(2002). The successful AI technique employs a unique endoscope-guided catheter and transrectal ultrasound to deliver semen into the anterior vagina or cervix, and uses the ''double LH surge'' (i.e., identifying the anovulatory LH (anLH) surge that predictably occurs 3 weeks before the ovulatory LH (ovLH) surge to time insemination. This study describes the 6-year collaboration between the National Zoological Park (NZP) and the Institute for Zoo Biology and Wildlife Research (IZW), Berlin, Germany, that led to the refinement of this AI technique and subsequent production of an Asian elephant calf. The NZP female was the first elephant to be inseminated using the new AI approach, and was the fifth to conceive. A total of six AI trials were conducted beginning in 1995, and conception occurred in 2000. Semen was collected by manual rectal stimulation from several bulls in North America. Sperm quality among the bulls was variable and was thus a limiting factor for AI. For the successful AI, semen quality was good to excellent (75-90% motile sperm), and sperm was deposited into the anterior vagina on the day before and the day of the ovLH surge. Based on transrectal ultrasound, ovulation occurred the day after the ovLH surge. Pregnancy was monitored by serum and urinary progestagen, and serum prolactin analyses in samples collected weekly. Fetal development was assessed at 12, 20, and 28 weeks of gestation using transrectal ultrasound. Elevated testosterone measured in the maternal circulation after 36 weeks of gestation reliably predicted the calf was a male. Parturition was induced by administration of 40 IU oxytocin 3 days after serum progestagens dropped to undetectable baseline levels. We conclude that AI has potential as a supplement to natural breeding, and will be invaluable for improving the genetic management of elephants, provided that problems associated with inadequate numbers of trained personnel and semen donors are resolved.

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Circulating progesterone concentrations and ovarian functional anatomy in the African elephant (Loxodonta africana)

Abstract: Summary. Mean

Cited by 18 publications

References 17 publications

Luteogenesis during the estrous cycle in Asian elephants (Elephas maximus)

Luteogenesis during the estrous cycle in Asian elephants (Elephas maximus)

Progesterone regulation of primordial follicle assembly in bovine fetal ovaries

Successful artificial insemination of an Asian elephant at the National Zoological Park

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