Effect of exogenous oestrogen on blood flow and quantitative histology of the corpora lutea of pseudopregnant rabbits

Moutos, Dean M.; Schryer, Brenda L.; Hurn, Patricia D.; Dharmarajan, Arun

doi:10.1530/jrf.0.1030357

Cited by 5 publications

(2 citation statements)

References 13 publications

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“…The reduced capacity for progesterone production in vivo is presumably related to the loss of luteal tissue as reflected by the reduced wet weights. Although previous reports [30,31] revealed a reversible loss of steroidogenic cell cytoplasmic volume after estradiol withdrawal up to 48 h, the present results indicate that withdrawal of estradiol for 60 h results in a permanent loss of steroidogenic capacity. However, the results also indicate that the surviving luteal tissue remains steroidogenic in the presence of large numbers of macrophages, suggesting that the macrophages do not exert a pervasive inhibitory effect on the surviving steroidogenic cells.…”

Section: Discussioncontrasting

confidence: 99%

Estrogen withdrawal Induces Macrophage Invasion in the Rabbit Corpus Luteum1

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et al. 1997

Biology of Reproduction

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Macrophages within the corpus luteum are associated with spontaneous luteal regression in a number of species. However, an understanding of the consequences of macrophage recruitment on the functional capacity and responsiveness of the luteal tissue has remained elusive. Here we investigate the temporal appearance of macrophages and their potential impact in corpora lutea of rabbits, in which a rapid fall in progesterone synthesis and premature regression of the corpus luteum are initiated by withdrawal of the luteotropic hormone estradiol-17beta. Removal of estradiol implants, placed subcutaneously, induced a significant increase in the average number of macrophages per high-power field (hpf) in corpora lutea (p < 0.05) within 72 h. Replacement of the estradiol implants 48 h after their removal resulted in a marginal rebound of plasma progesterone and a variable number of luteal macrophages (range: 6-160 macrophages/hpf) among the 11 rabbits. A third experiment revealed that the relative numbers of macrophages within the corpora lutea have no apparent relationship to rates of progesterone synthesis in vitro: progesterone production (ng/mg tissue) did not differ (p > 0.05) between corpora lutea of estradiol-maintained rabbits and those of estradiol-replaced rabbits despite obvious differences in numbers of luteal macrophages (2 +/- 1 vs. 42 +/- 10 macrophages/hpf, respectively; p < 0.05). We conclude that the entry/recruitment of macrophages into the rabbit corpus luteum is sensitive to the luteotropic hormone estradiol-17beta and that the presence of macrophages does not preclude the continuation of progesterone production in surviving luteal tissue revitalized after estradiol removal/replacement.

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Section: Discussioncontrasting

confidence: 99%

Estrogen withdrawal Induces Macrophage Invasion in the Rabbit Corpus Luteum1

Naftalin

Bove

Keyes

et al. 1997

Biology of Reproduction

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“…In many species, the prostaglandin PGF 2a is involved in functional CL regression (Moutos et al 1995, Davis & Rueda 2002, Stocco et al 2007, Finkenwirth et al 2010, Siemieniuch et al 2010 and it seems to also play a major role in lynxes. We could recently show that PGFM, the metabolite of PGF 2a , significantly increases at the beginning of last pregnancy trimester (Finkenwirth et al 2010); a period in domestic cats when pregnancy is not exclusively dependant upon CLs (Tsutsui et al 2009) and placental tissue might contribute towards P 4 production.…”

Section: Discussionmentioning

confidence: 99%

Histological and endocrine characterisation of the annual luteal activity in Eurasian lynx (Lynx lynx)

et al. 2012

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Lynx presents a unique sexual cycle with persistent corpora lutea (CLs) and elevated serum progesterone (P 4 ) throughout parturition and lactation. In other mammals, CLs normally disintegrate after parturition, therefore the aim of our study was to characterise the annual life cycle of lynx CLs. Ovaries from Eurasian lynxes were obtained from the National Veterinary Institute in Sweden, where tissues from killed lynx were stored at K20 8C. Ovaries from 66 animals were weighed; each corpus luteum was segmented for histology and hormone analysis. Ovary and CLs weights were constant throughout the year, peaking during pregnancy. In non-pregnant lynxes, the seasonal level of intraluteal steroids was steady for P 4 (3.2G1.9 S.D. mg/g, nZ53) and total oestrogens (18.3G15.5 S.D. ng/g, nZ53). Within histology slides, structurally intact luteal cells were found throughout the year with the highest incidence in March/April; evidence of luteal regression was predominantly found in post-breeding season. Ovaries from pregnant animals contained two types of CLs. Group A was bigger in size with large luteal cells (P 4 , 72.3G65.4 S.D. mg/g; oestrogen, 454.0G52.4 S.D. ng/g). In contrast, group B were smaller, with greater luteal regression and lower steroid concentrations (P 4 , 8.3G2.9 S.D. mg/g; oestrogen, 31.5G20.4 S.D. ng/g). Our results suggest that structural luteolysis proceeds throughout the year and into next breeding cycle, resulting in two CLs types on the same ovary.

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