Luteal phase length, endometrial edema, and behavior differentiate post-ovulatory events in a giant panda (Ailuropoda melanoleuca).

Despite decades of reproductive research on the giant panda (Ailuropoda melanoleuca), the post-ovulatory phase continues to confound zoologists in conservation and breeding centers around the world, often resulting in significant investments of time and resources without reproductive success. The purpose of this project was to document and compare post-ovulatory characteristics during a non-productive and productive breeding in the same individual in consecutive years. A multidisciplinary approach was used to monitor the visiting female giant panda at the Toronto Zoo through the luteal phase of her first two full reproductive cycles in 2014 and 2015. Monitoring occurred via urine-endocrine analysis, weekly ultrasound examinations, and continuous behavioral observations. The 2014 reproductive cycle consisted of a pseudopregnancy, characterized by an extended luteal phase (241 days), the identification of endometrial edema and folding during ultrasound examinations, and a lack of strong association between behavior patterns and urinary progestagen secretion. The 2015 reproductive cycle included increased feeding time through the primary progestagen rise compared to the previous year, followed by simultaneous decrease in appetite and increases in inactivity, resting, sitting upright, and pre-partum-associated behaviors. These changes began 25 days before the birth of twins on Day 153 post-ovulation. Both fetuses were detected via ultrasound 15 days pre-partum. These results suggest that an absence of pre-partum behaviors, ultrasound evidence of endometrial edema without a fetus, and an extended luteal phase may be indicative of pseudopregnancy in giant pandas. Simultaneous monitoring of morphology, behavior, and urinary-endocrine profiles showed clear differences between successful and unsuccessful reproductive years.

Alternative reproductive strategies provide a flexible mechanism for assuring mating success in the European badgers (Meles meles): An investigation from hormonal measures.

Selection-pressures differ with population density, but few studies investigate how this can affect reproductive physiology. European badger (Meles meles) density varies from solitary to group-living across their range, with reported mating periods throughout the entire year to specific seasonal periods. Badger reproduction is evolutionarily distinct, interrupting the direct progression from conception to gestation with delayed implantation (DI), allowing for superfecundation (SF). To establish the tactical mating flexibility afforded by DI*SF, we used cross-sectional population-level seasonal variation of circulating sex-steroids for 97 females from a high-density population. Oestradiol was highest in spring among non-parous females, then lower in summer, and remained low during following seasons, suggesting that the mating period was restricted to just spring. Oestrone was consistently higher than oestradiol; it was elevated in spring, lowest during summer, peaked in autumn, and remained elevated for pregnant females in winter. This suggests that oestrone sustains pre-implanted blastocysts throughout DI. Progesterone was low throughout, except during winter pregnancy, associated with implantation and luteal development. In contrast to multiple mating periods reported by lower-density studies, our oestradiol data suggest that, at high-density, females exhibit only one mating period (congruent with testosterone patterns in males studied previously in this same population). While additional mating periods during DI enhance fertility assurance at low-density, at high-density, we propose that when coitus is frequent, fertilisation is assured, precluding the need for further cycles and associated mating risks. This endocrinologically flexible DI*SF mating strategy likely represents a form of balancing selection, allowing badgers to succeed at a range of regional densities.

Utilizing a rat delayed implantation model to teach integrative endocrinology and reproductive biology.

In this teaching laboratory, the students are directed in an exercise that involves designing and performing an experiment to determine estrogen's role in regulating delayed implantation (diapause) in female rats. To encourage active participation by the students, a discussion question is provided before the laboratory exercise in which each student is asked to search the literature and provide written answers to questions and to formulate an experiment to test the role of ovarian estrogen in inducing implantation in female rats. One week before the laboratory exercise, students discuss their answers to the questions with the instructor to develop an experiment to test their hypothesis that estrogen is involved with inducing implantation in the rat. A rat delayed implantation model was established that utilizes an estrogen receptor antagonist (ICI 182,780), which inhibits the action of ovarian estrogens. Groups of mated females are treated with either carrier (control) or ICI 182,780 (ICI) every other day, starting on day 2 postcoitus (pc) until day 8 pc. One-half of the females receiving ICI are injected with estradiol-17ß on day 8 pc to induce implantation 4 days after the controls. If the ICI-treated females are not administered estradiol, embryo implantation occurs spontaneously ~4 days after the last ICI injection on day 8. This is a very simple protocol that is very effective and provides an excellent experiment for student discussion on hormone action and the use of agonists and antagonists.

Integrating trans-abdominal ultrasonography with fecal steroid metabolite monitoring to accurately diagnose pregnancy and predict the timing of parturition in the red panda (Ailurus fulgens styani).

Red pandas (Ailurus fulgens styani) exhibit a variable gestation length and may experience a pseudopregnancy indistinguishable from true pregnancy; therefore, it is not possible to deduce an individual's true pregnancy status and parturition date based on breeding dates or fecal progesterone excretion patterns alone. The goal of this study was to evaluate the use of transabdominal ultrasonography for pregnancy diagnosis in red pandas. Two to three females were monitored over 4 consecutive years, generating a total of seven profiles (four pregnancies, two pseudopregnancies, and one lost pregnancy). Fecal samples were collected and assayed for progesterone (P4) and estrogen conjugate (EC) to characterize patterns associated with breeding activity and parturition events. Animals were trained for voluntary transabdominal ultrasound and examinations were performed weekly. Breeding behaviors and fecal EC data suggest that the estrus cycle of this species is 11-12 days in length. Fecal steroid metabolite analyses also revealed that neither P4 nor EC concentrations were suitable indicators of pregnancy in this species; however, a secondary increase in P4 occurred 69-71 days prior to parturition in all pregnant females, presumably coinciding with embryo implantation. Using ultrasonography, embryos were detected as early as 62 days post-breeding/50 days pre-partum and serial measurements of uterine lumen diameter were documented throughout four pregnancies. Advances in reproductive diagnostics, such as the implementation of ultrasonography, may facilitate improved husbandry of pregnant females and allow for the accurate prediction of parturition.

Can Time of Implant Placement influence Bone Remodeling?

Since the alveolar process is tissue "dental dependent," after the extraction of the dental element, this process suffers some degree of atrophy during the healing process, which can be reduced with the installation of immediate implants, aiming to maintain the original bone architecture. The aim of this study was to investigate the influence of the time of implant placement on bone formation around them. Seven dogs were selected and randomly divided into two groups: Group 1, where implants were placed immediately after extraction of two lower premolars without flap elevation, and group 2, where implants were delayed by 4 months after extractions. Each group received 14 implants, and 4 months after the second surgery, the samples were processed and analyzed histomorphometrically. A mean average analysis and the Kruskal-Wallis test (p < 0.05) were performed. The buccal bone-implant contact (BIC) mean average was found larger in immediate implants (42.61%) compared with delayed implants (37.69%). Group 1 had statistically higher outcomes in bone formation and BIC on the buccal bone wall. It was concluded that performing immediate implants with the palatal approach technique and leaving a buccal GAP enables a higher or at least equal rate to BIC and bone area around them, when compared with delayed implants. Actually, the patients and dentists want to do a shorter treatment with satisfactory results, but it is necessary to understand whether different times of implant placement can influence the results and longevity of the treatment.

Papilla dimension and soft tissue level after early vs. delayed placement of single-tooth implants: 10-year results from a randomized controlled clinical trial.

AIM: To present the10-year esthetic outcome data for single-tooth implants placed early or delayed after tooth extraction. MATERIAL AND METHODS: Forty-four patients randomly allocated to two equal size groups were treated with a single-tooth implant approximately 10 days (Ea; N = 22), or 3 months (De; N = 22) after tooth extraction. Healing abutments were mounted after 3 months of submerged healing, and metal-ceramic crowns cemented after one additional month. Presence of buccal bone defects was registered at the second-stage surgery. Patients attended control visits 1 week and 1-1.5 years after mounting of the crown and 5 and 10 years after implant placement. Marginal bone level at the implant and the adjacent teeth as well as the distance between the implant and the teeth were measured in standardized periapical radiographs. The papilla dimension and clinical crown height (CCH) were assessed on clinical photographs by an experienced prosthodontist. RESULTS: Two Ea and one De implants failed to osseointegrate. Twenty-eight patients (13 Ea and 15 De) who attended all four control visits were included in the data analysis. Complete papilla fill interproximally was achieved in one-third of the cases and an appropriate clinical crown height in <60% after 10 years. Although not statistically significant, early-placed implants tended to be superior to delayed-placed implants regarding soft tissue appearance just after crown delivery and after 10 years. An improvement in papilla dimensions was seen during the follow-up period for both groups while the CCH was unchanged. The implant region (anterior vs. posterior) did not significantly influence the papilla or CCH scores while younger patients (<50 years of age) received significantly better papilla scores than older patients (≥ 50 years). An apically located bone level at the tooth neighboring the implant influenced negatively the papilla dimension. In contrast, the presence of a bone defect buccally to the implant at second-stage surgery did not have a negative impact on the CCH 10 years after implant placement. CONCLUSION: Early placement of single-tooth implants after tooth extraction performed equally to delayed placement in regard to the esthetic outcome of the soft tissues after 10 years in function.

Fate of the buccal bone at implants placed early, delayed, or late after tooth extraction analyzed by cone beam CT: 10-year results from a randomized, controlled, clinical study.

AIM: To present 10-year cone beam CT (CBCT) data on the fate of buccal bone at single-tooth implants placed early, delayed, or late after tooth extraction. MATERIAL AND METHODS: Sixty-three of 72 patients, originally randomly allocated to three equal-size groups, received a single-tooth implant on average 10 days (Ea; N = 22), 3 months (De; N = 22), or 1.5 years (La; N = 19) after tooth extraction. Healing abutments were mounted after a 3-month period of submerged healing and metalceramic crowns were cemented after one additional month. At the second stage surgery, presence of buccal bone defects (dehiscences or intrabony) and their dimensions were registered. CBCT scans recorded with a Scanora(®) 3D unit and standardized periapical (PA) radiographs of the implants were obtained at the 10-year control. Interproximal bone levels (i.e., the distance from the implant platform to the first bone-to-implant contact; BIC) measured in CBCT image sections and PA were compared, and the buccal bone level was determined in the CBCT images. RESULTS: Two Ea and one De implants failed to osseointegrate. Forty-nine patients attended the 10-year control and due to poor quality of 5 CBCT scans, useful CBCT images were available from 44 patients (Ea:12, De:17, La:15). No significant differences between CBCT and PA images in measurements of the interproximal bone levels were observed. Ten years after implant placement, BIC at the buccal aspect was located on average 2 mm apically to the implant platform (2.39 ± 1.06 mm [median = 2.36] for Ea, 2.22 ± 0.99 mm [median = 2.16] for De, and 1.85 ± 0.65 mm [median = 1.95] for La implants) with no significant difference among the groups (P = 0.20). Mean buccal bone level (bBL) for implants with an intrabony or a dehiscence defect at second stage surgery was 2.51 ± 1.12 mm [median = 2.70] and 2.84 ± 0.70 mm [median = 2.79], respectively, while 1.78 ± 0.74 mm [median = 1.93] for the implants with no defect. The difference in bBL between the implants without a defect and those with a dehiscence was significant at 10 years (P = 0.0005). CONCLUSION: Time of placement of single-tooth implants after tooth extraction did not significantly influence the peri-implant buccal bone level, while presence of a buccal bone dehiscence at second stage surgery resulted in significantly more apically located BIC buccally at 10 years.

Early, delayed, or late single implant placement: 10-year results from a randomized controlled clinical trial.

AIM: The aim of this study was to present the 10-year clinical and radiographic data from a RCT on single-tooth implants placed early, delayed, or late after tooth extraction. MATERIALS AND METHODS: Sixty-three patients were randomly allocated to three groups and received an implant on average 10 days (Ea), 3 months (De), or 17 months (La) after tooth extraction. Second-stage surgery was performed after 3 months of submerged healing; metal-ceramic crowns were cemented after one additional month. Standardized periapical radiographs were taken 1 week after implant placement (TP), 1 week (TC) and 1-1.5 year (T1) after crown delivery, and 10 years after implant placement (T10). Pocket depth (PD) and bleeding on probing were registered during controls (TC - T10). RESULTS: Two Ea and one De implants failed to osseointegrate. Seven patients (4 Ea, 1 De, and 2 La) were not available at T10 . No significant differences were found among groups regarding implant survival or radiographic peri-implant marginal bone levels (Ea: 1.15 ± 0.77; De: 1.53 ± 1.06; La: 1.42 ± 1.07) at T10 . Similarly, no differences were observed among groups in the number of implants with PD ≥ 5 mm (Ea: 29%; De: 35%; La: 44%) or the average depth of the sites with PD ≥ 5 mm (Ea: 5.4 ± 0.7; De: 6.1 ± 1.4; La: 5.4 ± 0.5) at T10 . Peri-implant mucositis was found in 70% of the cases; peri-implantitis was diagnosed only in two implants (1 De, 1 La) corresponding to 4.3%. CONCLUSION: Single-tooth implants placed early or delayed after tooth extraction show high survival rates and limited peri-implant marginal bone resorption or biological complications, similar to what is observed with implants placed according to the conventional (late) protocol.

Transforming growth factor-beta 1 (TGF-B1) liberation from its latent complex during embryo implantation and its regulation by estradiol in mouse.

Transforming growth factor-beta (TGF-B) plays an important role in embryo implantation; however, TGF-B requires liberation from its inactive latent forms (i.e., large latent TGF-B complex [LLC] and small latent TGF-B complex [SLC]) to its biologically active (i.e., monomer or dimer) forms in order to act on its receptors (TGF-BRs), which in turn activate SMAD2/3. Activation of TGF-B1 from its latent complexes in the uterus is not yet deciphered. We investigated uterine latent TGF-B1 complex and its biologically active form during implantation, decidualization, and delayed implantation. Our study, utilizing nonreducing SDS-PAGE followed by Western blotting and immunoblotting with TGF-B1, LTBP1, and latency-associated peptide, showed the presence of LLC and SLC in the uterine extracellular matrix and plasma membranous protein fraction during stages of the implantation period. A biologically active form of TGF-B1 (~17-kDa monomer) was highly elevated in the uterine plasma membranous compartment at the peri-implantation stage (implantation and nonimplantation sites). Administration of hydroxychloroquine (an inhibitor of pro-TGF-B processing) at the preimplantation stage was able to block the liberation of biologically active TGF-B1 from its latent complex at the postimplantation stage; as a consequence, the number of implantation sites was reduced at Day 5 (1000 h), as was the number of fetuses at Day 13. The inhibition of TGF-B1 showed reduced levels of phosphorylated SMAD3. Further, the delayed-implantation mouse model showed progesterone and estradiol coordination to release the active TGF-B1 form from its latent complex in the receptive endometrium. This study demonstrates the importance of liberation of biologically active TGF-B1 during the implantation period and its regulation by estradiol.

Observation of the clinical effect of immediate implantation and delayed implantation in the maxillary and maxillary molars.

Objective: To study the clinical application effect of two kinds of implants in the upper and lower molars. Methods: A selection of 120 patients (134 teeth) who underwent implant treatment in the upper and lower molars in the army hospital of the Chinese people's liberation army from January 2018 to June 2019 were divided into an immediate group (using immediate implantation) and a delayed group (using delayed implantation) using a random number table 60 cases (60 teeth) in each group; differences in implant success rate, buccal keratinized gingival width before and after treatment, alveolar bone absorption, periodontal pocket depth, and gingival aesthetic indicators were compared between the two groups. Results: The gingival aesthetics effect of the immediate group was better than that of the delayed group on the whole and the difference was statistically significant (P<0.05); after 12 months of restoration, the implantation success rate of the immediate group was 96.67%. The deferred group was 93.33%, and the difference between the two groups was not statistically significant (P>0.05). Conclusion: Both delayed restoration and immediate implant restoration can achieve good results in implant restoration treatment in the maxillary and maxillary molars. However, immediate implantation has certain advantages in reducing the amount of alveolar bone absorption and maintaining the aesthetic effect of the gums.

Immediate implant placement with simultaneous bone augmentation versus delayed implant placement following alveolar ridge preservation: A clinical and radiographic study.

OBJECTIVE: The present study aimed to evaluate the clinical and radiographic outcomes of immediate implant placement (IIP) with guided bone regeneration (GBR) as compared to delayed implant placement (DIP) following alveolar ridge preservation (ARP) and to identify the potential risk factors influencing these outcomes. METHODOLOGY: A total of 56 patients (IIP = 28 vs. DIP = 28) with class I or II bony defects received 56 implants were included. GBR procedure using Bio-Oss® bone substitute mixed with advanced platelet-rich fibrin (A-PRF) and covered by Bio-Gide® membrane and additional A-PRF membrane was performed either simultaneously with the IIP or earlier at the time of ARP in DIP. Clinical and 3-D radiographic analyses of bone level, thickness, and density were performed at three-time intervals (T1, immediately; T2, 6-7 months; and T3, 1.5 to 2 years post-implantation), corresponding to the neck, coronal, middle, and apex of implants. RESULTS: The survival rate was 100% in both groups. IIP showed significant favorable outcomes regarding distal marginal bone level (anterior maxilla, T1-T3) and neck and coronal horizontal facial bone thickness (HFBT) (posterior maxilla, T1; and anterior maxilla, T1-T3, respectively) compared to DIP. However, DIP showed significant facial bone density at the neck and coronal parts in the anterior maxilla (T1) and the coronal part in the posterior maxilla (T3). The facial marginal bone level change was positively correlated with HFBT change (P = 0.007), which is negatively correlated with the secondary implant stability (P = 0.019). The implant region (anterior or posterior maxilla) was the only factor affecting on Implant stability quotient value (ISQ) and change in HFBT (P Ë‚ 0.05). CONCLUSION: Overall, the IIP combined with GBR in the post-extraction sites with pre-implant class I or II bony defects had some favorable outcomes compared to DIP after ARP. However, the clinical outcomes, ISQ value, and changes in bone level, thickness, and density from T1-T3 were comparable.

DNA Methylation and Histone Modification Are the Possible Regulators of Preimplantation Blastocyst Activation in Mice.

Under ovarian hormone control, dormant blastocysts obtain implantation capacity (known as blastocyst activation) through their global gene expression. After the activated blastocysts communicate with the receptive uterus, the implantation-competent blastocysts start the implantation. Although dormant and activated blastocysts have different gene expression levels, the regulatory mechanisms underlying these transcriptions remain unclear. Hence, this study aimed to analyze epigenetic marks in dormant and activated blastocysts. In mice, blastocyst dormancy is artificially induced by daily progesterone injection without estrogen supplementation after peri-implantation ovariectomy; when estrogen is administered concomitantly, blastocyst activation and implantation occur. These phenomena demonstrate a mouse model of delayed implantation. We collected dormant and activated blastocysts from a delayed implantation mouse model. RNA-seq, methylated DNA immunoprecipitation (MeDIP)-seq, and chromatin immunoprecipitation (ChIP)-seq for H3K4 me3 and H3K27 me3 were performed using dormant and activated blastocysts. Cell cycle-related transcripts were affected during blastocyst activation. DNA methylations were accumulated in downregulated genes in the activated blastocysts. Histone H3 trimethylations were globally altered between the dormant and activated blastocysts. Dormant and activated blastocysts have unique methylation patterns on DNA and histone H3, with high correlation to gene expression. DNA methylation and histone modification can regulate preimplantation blastocyst activation.

Adverse weather during in utero development is linked to higher rates of later-life herpesvirus reactivation in adult European badgers, Meles meles.

Maternal immune and/or metabolic conditions relating to stress or nutritional status can affect in utero development among offspring with subsequent implications for later-life responses to infections. We used free-ranging European badgers as a host-pathogen model to investigate how prenatal weather conditions affect later-life herpesvirus genital tract reactivation. We applied a sliding window analysis of weather conditions to 164 samples collected in 2018 from 95 individuals born between 2005-2016. We test if the monthly mean and variation in rainfall and temperature experienced by their mother during the 12 months of delayed implantation and gestation prior to parturition subsequently affected individual herpes reactivation rates among these offspring. We identified four influential prenatal seasonal weather windows that corresponded with previously identified critical climatic conditions affecting badger survival, fecundity and body condition. These all occurred during the pre-implantation rather than the post-implantation period. We conclude that environmental cues during the in utero period of delayed implantation may result in changes that affect an individual's developmental programming against infection or viral reactivation later in life. This illustrates how prenatal adversity caused by environmental factors, such as climate change, can impact wildlife health and population dynamics-an interaction largely overlooked in wildlife management and conservation programmes.

Immediate versus delayed implant placement in the esthetic zone: a prospective 3D volumetric assessment of peri-implant tissue stability.

PURPOSE: To evaluate the volumetric stability of peri-implant soft and hard tissue prospectively, this study compared immediate versus delayed implants placed in the anterior esthetic region. METHODS: This non-randomized controlled clinical study included 25 patients, who received an immediate (type 1) or a delayed (type 4) implant placement for the replacement of a single anterior tooth. The anterior maxillae were intraorally scanned at three timepoints: before surgery (S0), 6 months (S1), and 12 months (S2) after surgery. A specific region of interest (ROI), divided into marginal and apical regions, was determined and superimposed for volumetric changes analysis. At 6 and 12 months, the probing depth (PD), bleeding/suppuration on probing (BOP/SUP), modified plaque index (PI), keratinized mucosa (KM) width, mucosal recession (MR), and implant stability (PTV) by means of periotest were recorded. RESULTS: Between S0-S2, tissue surrounding immediate implants was reduced in 0.37 ± 0.31 mm, whereas delayed implants gained 0.84 ± 0.57 mm mean tissue volume. Peri-implant tissue loss at type 1 implants occurred primarily in the marginal section of the ROI (0.42 ± 0.31 mm), whereas tissue gain at type 4 implants occurred mainly in the apical section (0.83 ± 0.51 mm). These values were significantly different between both groups for the entire ROI (p = 0.0452) and the marginal region (p = 0.0274). In addition, the mean buccal KM width around type 1 implants was significantly wider in comparison with the type 4 implants group after 12 months (p = 0.046). There were no significant differences between groups regarding PD, BOP/SUP, or PTV. CONCLUSIONS: The results suggest that type 1 implants placed in the esthetic region experience more tissue loss than type 4 implants, thus marginal tissue remodeling should be considered for planning immediate implants placement in the anterior maxillae.

Incidence of pregnancy loss and characterization of fetal development in red pandas.

Previous reports indicate that red pandas (Ailurus fulgens styani) may experience fetal loss during gestation; however, neither the rate nor timing of pregnancy failure has been described in this species. The objective of this study was to utilize ultrasound video and images collected between 2010 and 2020 at the Cincinnati Zoo and Botanical Garden to better characterize pregnancy loss and fetal development. Trans-abdominal ultrasound examinations were performed on six female red pandas over a 10-year period, resulting in 12 profiles. Pregnancy was diagnosed via ultrasound in 10 of 12 profiles, and 40.0% of pregnancies showed evidence of fetal loss prior to parturition. Pregnancy loss was classified into lost (2 of 10; 20.0%), in which no cubs were produced, or partial loss (2 of 10; 20.0%), in which two concepti were visualized via ultrasound, but only one cub was born. Fetal loss occurred between days 51 and 23 pre-partum. Fetal growth characteristics were documented, including skeletal ossification (occurring between days 32 and 27 pre-partum), crown-rump length, head length, cranial length, and fetal heart rate (173-206 b.p.m.). These findings provide novel insights into pregnancy loss, may serve as a reference for milestones of fetal development, and may be useful in diagnosing pregnancy and assessing pregnancy loss in red pandas. LAY SUMMARY: For many wildlife species, there is no non-invasive method of determining pregnancy; therefore, the rate of pregnancy loss oftentimes is unknown. Many red pandas in human care that are paired for breeding are observed exhibiting normal mating behaviors; however, only a relatively low proportion of females produce cubs. We utilized animals conditioned for ultrasound examination to diagnose pregnancy and characterize the incidence and timing of pregnancy loss. In total, 12 potential pregnancies were monitored, beginning after breeding season and ending ~2 weeks prior to anticipated cubbing. Of these, ten were (83.3%) were diagnosed as pregnant, with 40% undergoing either full or partial pregnancy loss. Fetal growth characteristics, such as body length and head size, are described which may be useful for monitoring pregnancies and estimating fetal age. Results of this study provide novel data on pregnancy loss in red pandas. Insights into the rate and timing of reproductive failure may illuminate causes and contributing factors, ultimately allowing for improvements in husbandry which may result in greater reproductive success of individuals recommended for breeding.

Poly(ADP-ribose) polymerase-2 is essential for endometrial receptivity and blastocyst implantation, and regulated by caspase-8.

Embryo implantation is a very complex process and several factors play important roles. Using a mouse model, we investigated the functions of PARP-2 and caspase-8 during endometrial receptivity for blastocyst implantation. We found that PARP-2 was upregulated at the receptive stage's implantation region and predominantly expressed in the endometrial stromal region, but downregulated during pregnancy failure and pseudopregnancy. To reinforce the necessity of PARP-2 for embryo implantation, we pharmacologically inhibited PARP-2 'before' & 'after' embryo arrival and observed a reduction in blastocyst implantation. Conversely, elevated caspase-8 expression and activity during pseudopregnancy, delayed implantation, and embryo implantation failure conditions and decreased levels in the decidualization exhibited an inverse pattern with PARP-2, suggesting caspase-8 as a negative regulator for embryo implantation. In vitro caspase-8 downregulates the PARP-2 activity in the mouse endometrial epithelial and stromal cells. These data suggest that PARP-2 and its negative regulation by caspase-8 constitute a crucial step in embryo implantation.

A physiological role of contractions in hatched mouse blastocysts.

Purpose: Using mouse blastocysts with implantation delayed for 7 days (dormant blastocysts) and time-lapse videomicrography, we examined the physiological role of contractions in hatched blastocysts. Methods: The degree and number of contractions in dormant blastocysts were analyzed in images recorded for 48 h of culture, and compared with those in dormant blastocysts in which implantation was induced (activated blastocysts), and dormant blastocysts cultured with estrogen or progesterone. Results: Activated blastocysts exhibited a significantly smaller number of weak contractions and a significantly larger number of strong contractions, compared with dormant blastocysts. Furthermore, the numbers of weak and strong contractions in dormant blastocysts cultured with estradiol-17ß were significantly less frequent or more frequent than those in dormant blastocysts cultured with progesterone and those cultured without steroids. Expression of estrogen receptor mRNA was also detected in dormant blastocysts by the method of reverse transcription-polymerase chain reaction. Conclusion: These results suggested that activated blastocysts enhance the contractions as a preparation for the implantation, and that the enhanced contractions in those serve as a physical stimulation for maternal recognition of pregnancy.

Research advances on embryonic diapause in mammals.

Embryonic diapause occurs in over 130 species of mammals. In embryonic diapause, there is a reversible cessation phase in embryo development and subsequent reactivation and continuation of development with no adverse effects. This allows animals to prolong gestation and give birth to offspring at a more favorable time from a survival perspective. Embryonic diapause is divided into two types: facultative diapause which is induced by physiological conditions and obligate diapause which is induced by season of the year. The process of embryonic diapause includes three phases: onset, maintenance, and reactivation. With facultative diapause the suckling stimulus promotes secretion of prolactin, which suppresses development and secretion activity of the corpus luteum (CL). The decrease of progesterone, secreted by CL, subsequently results in embryos in the diapause state. The embryonic diapause that occurs in mink is of the obligate type and is regulated by photoperiod. The short daylight (<12 h) before the vernal equinox induces an increase in the release of melatonin from the pineal gland. The secretion of prolactin is suppressed and the production of progesterone from CL is reduced. During these phases, many others factors that regulate embryonic and uterine status, hormonal profile, polyamines, and uterine secretion, have been monitored. In recent times, the understanding of the role of different molecular events in embryonic diapause has been advanced. The present review summarizes the research advances related to embryonic diapause to enhance the understanding of this phenomenon and to be considered when there are future research endeavors related to embryonic diapause.

Geographical Origin, Delayed Implantation, and Induced Ovulation Explain Reproductive Seasonality in the Carnivora.

Patterns of reproductive seasonality in the Carnivora are difficult to study comparatively, due to limited numbers of species for which information is available. Long-term databases of captive populations could overcome this difficulty. We apply a categorical description and a quantitative high-resolution measure (birth peak breadth, the number of days in which 80% of all births occur) based on daily observations in captivity to characterize the degree of reproductive seasonality in the Carnivora for 114 species with on average 1357 births per species. We find that the majority of species retained the birth seasonality displayed in the wild. Latitude of natural origin, delayed implantation, and induced ovulation were the main factors influencing reproductive seasonality. Most species were short-day breeders, but there was no evidence of an absolute photoperiodic signal for the timing of mating or conception. The length of the gestation period (corrected for body mass) generally decreased with birth seasonality but increased in species with delayed implantation. Birth seasons become shorter with increasing latitude of geographical origin, likely because the length of the favorable season declines with increasing latitude, exerting a strong selective pressure on fitting both the reproductive cycle and the interval offspring needs for growth following the termination of parental care into the short time window of optimal environmental conditions. Species with induced ovulation exhibit a less seasonal reproductive pattern, potentially because mates do not have to meet during a short time window of a fixed ovulation. Seasonal species of Carnivora shorten their gestation period so reproduction can occur during the short time window of optimal environmental conditions. Alternatively, other Carnivora species lengthen their gestation periods in order to bridge long winters. Interestingly, this occurs not by decelerating intrauterine growth but by delaying implantation.

Endoglin (CD105) coordinates the process of endometrial receptivity for embryo implantation.

Endoglin is a TGF-ß receptor that is expressed in uterine endothelial and stromal cells in addition to trophoblast expression. However, the functional importance of endoglin in the embryo implantation process is not clear. We observed endoglin expression in the endometrium throughout the stages of its receptivity; however, its expression was enhanced during the receptive stage. Endoglin expression was predominant in epithelial cells of the lumen and glands, but showed a milder expression in stromal cells. Endoglin expression was initially observed in the primary decidual zone and later extended to the secondary decidua zone. Knockdown of endoglin via siRNA reduced the implantation sites along with the blastocyst numbers. Mouse blastocyst with endoglin-silenced endometrial epithelial cells (human and mouse origin) showed poor trophoblast outgrowth, which suggests an essential role for endoglin during endometrial receptivity. In conclusion, our findings reveal the association of endoglin with endometrial receptivity, which is important for embryo attachment.