Investigations of BrdU incorporation in roe deer blastocysts in vitro

Lengwinat, T.; Meyer, H. H. D.

doi:10.1016/s0378-4320(96)01573-4

Cited by 19 publications

(15 citation statements)

References 4 publications

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“…Based on histological sections of individual roe deer blastocysts, it has been described that during diapause the blastocysts have a rather low mitotic index [4,11]. Lengwinat and Meyer performed a BrdU incorporation assay [12] and revealed that in October and November, less than 5 % of trophoblast cells underwent DNA synthesis within a 4 h culture period. In late November and December, the percentage of BrdU positive cells increased to over 10 % [12].…”

Section: Introductionmentioning

confidence: 99%

Trophectoderm and embryoblast proliferate at slow pace in the course of embryonic diapause in the roe deer (Capreolus capreolus)

Rüegg¹,

Bernal²,

Moser³

et al. 2020

Proc

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The European roe deer (Capreolus capreolus) was the first mammal in which embryonic diapause has been described. While diapause is characterized by a complete developmental arrest in some species, roe deer blastocysts show a very slow, yet continuous growth. To date, it is neither known whether this growth is accompanied by developmental progression nor whether it is uniform in both, the trophectoderm (TE) and the inner cell mass (ICM). We collected roe deer blastocysts during the regular hunting season from September 2018 to January 2019, and quantified the fraction of cells expressing the proliferation marker Ki67 by immunofluorescence and light-sheet microscopy. We found that the cell number increased from around 300 cells in September to over 20'000 cells per blastocyst in December before elongation occured. Concurrently, we observed considerable morphological changes, i.e. cavity formation and transition to a disk-like shape of the inner cell mass. During diapause, less than 10% of all cells displayed positive Ki67 staining. Strikingly, the relative increase in cell number was lower in the ICM compared to the TE, whereas the fraction of Ki67 positive cells appeared to be lower in the TE than in the ICM. Our findings thus confirm that roe deer blastocysts display developmental progression in the course of diapause. We hypothesize that while the overall duration of the cell cycle is longer in the ICM than in the TE, the fractional distribution of cell cycle phases differs, with TE cells having a longer G1 phase than cells of the ICM.

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Section: Introductionmentioning

confidence: 99%

Trophectoderm and embryoblast proliferate at slow pace in the course of embryonic diapause in the roe deer (Capreolus capreolus)

Rüegg¹,

Bernal²,

Moser³

et al. 2020

Proc

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“…In roe deer, the latter idea seems to fit in with the delayed implantation of the fertilized blastocyst, which is a pronounced feature of the sexual cycle of female roe deer (Aitken 1974;Lengwinat & Meyer 1996). The actual implantation may only occur if conditions remain suitable during the critical season, being mid-winter.…”

Section: General Assumption: Females Affect the Sex Ratio Prenatalmentioning

confidence: 99%

“…A major determinant in this respect is the variance in the duration of the receptive period (estrus) among female roe deer. Births are highly synchronized (Gaillard et al 1993c;), but due to delayed implantation of the fertilized blastocyst (Aitken 1974;Lengwinat & Meyer 1996), some degree of variance in the timing of estrus is possible. However, the degree of this variance is unknown.…”

Section: Polygynousmentioning

confidence: 99%

Existing theories do not explain sex ratio variation at birth in monomorphic roe deer (Capreolus capreolus)

Vreugdenhil

Breukelen²,

Wieren

2007

Integrative Zoology

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The phenomenon of skewed sex ratios at birth has been reported in many ungulate species. So far, no consistent trend has emerged for roe deer (Capreolus capreolus), because male-biased, female-biased and equal sex ratios at birth have all been found. Nevertheless, both the Trivers-Willard hypothesis and the theory of local resource competition have gained support. Despite the great number of studies carried out regarding the ecology of roe deer, too many aspects remain unclear, and contradictory results have been produced with respect to several crucial elements. Without further research, the discussion on which theory applies will therefore remain inconclusive. We put forward the argument that eventually the theories of Trivers-Willard and local resource competition can be considered as being not essentially different. After all, both theories explain the observed skewed sex ratios as being due to the effect of the progeny s sex on the mother s body condition and hence her reproductive success in subsequent years. Furthermore, neither theory is likely to prove to be suitable for roe deer, as several assumptions are unlikely to be met. In roe deer, skewed ratios probably only have a temporal character. As a matter of fact, several observations of skewed sex ratios in birds and mammals did not withstand the accumulation of further data, as sex ratios that were initially believed to be biased turned out to be equal in the long term. This is likely to be the case in roe deer as well. We hypothesize that roe deer, as r-strategists, will produce as many offspring as possible, regardless of sex.

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“…Twins are common; even triplets can occur occasionally (Aitken, ; Gaillard, Delorme, & Jullien, ; Lincoln & Guinness, ). The blastocyst loses its zona pellucida after reaching the uterus, and for a certain period, the development of the embryo is reduced, but a minimal level of mitotic activity is maintained (Aitken, ; Lengwinat & Meyer, ; Renfree and Shaw, ). The duration of the embryonic diapause is determined from early August until early January (Aitken et al., ; Aitken, ; Lincoln & Guinness, ; Short & Hay, ).…”

Section: Introductionmentioning

confidence: 99%

Description of post‐implantation embryonic stages in European roe deer (Capreolus capreolus) after embryonic diapause

Beyes

Nause

Bleyer

et al. 2017

Anat Histol Embryol

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The embryonic stage of development is defined as the period between fertilization and the establishment of most of the organ systems by the end of this period. Development in this stage is rapid. In many mammalian species, particularly in humans, the interval between fertilization and implantation is exactly determined and continuous without intermission. However, European roe deer (Capreolus capreolus) embryos undergo a reversible retardation of development. This interesting reproduction strategy is called embryonic diapause (delayed implantation). After this period of embryonic arrest, development continues without further interruption. The aim of this study was to investigate embryonic development after diapause in European roe deer. Because of the embryonic diapause and the unknown date of fertilization, it was impossible to assign the embryos to a certain gestational age (days). This study describes normal stages of embryonic development mainly based on the external morphological traits of 56 well-preserved post-implantation roe deer embryos and attempts to assign the embryos to certain development stages. Carnegie stages of human embryos were used as an orientation for staging roe deer embryos. We observed a considerable range of variation of embryonic stages investigated until the end of January. We found post-implantation stages of embryonic development already at the end of December and foetuses at the end of January. Moreover, assigning the embryos to a particular stage of development allows the comparison between pairs of twins and triplets. We showed that twins and triplets were always at the same development level, despite the discrepancy in inter-twin and inter-triplet size.

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Investigations of BrdU incorporation in roe deer blastocysts in vitro

Cited by 19 publications

References 4 publications

Trophectoderm and embryoblast proliferate at slow pace in the course of embryonic diapause in the roe deer (Capreolus capreolus)

Trophectoderm and embryoblast proliferate at slow pace in the course of embryonic diapause in the roe deer (Capreolus capreolus)

Existing theories do not explain sex ratio variation at birth in monomorphic roe deer (Capreolus capreolus)

Description of post‐implantation embryonic stages in European roe deer (Capreolus capreolus) after embryonic diapause

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