Comparative analysis of vertebrates reveals that mouse primordial oocytes do not contain a Balbiani body

Oocytes spend the majority of their lifetime in a primordial state. The cellular and molecular biology of primordial oocytes is largely unexplored; yet, studying these is necessary to understand the mechanisms through which oocytes maintain cellular fitness for decades, and why they eventually fail with age. Here, we develop enabling methods for live-imaging based comparative characterization of Xenopus, mouse and human primordial oocytes. We show that primordial oocytes in all three vertebrate species contain active mitochondria, Golgi apparatus and lysosomes. We further demonstrate that human and Xenopus oocytes have a Balbiani body characterized by a dense accumulation of mitochondria in their cytoplasm. However, despite previous reports, we did not find a Balbiani body in mouse oocytes. Instead, we demonstrate what was previously used as a marker for the Balbiani body in mouse primordial oocytes is in fact a ring-shaped Golgi apparatus that is not functionally associated with oocyte dormancy. Our work provides the first insights into the organisation of the cytoplasm in mammalian primordial oocytes, and clarifies relative advantages and limitations of choosing different model organisms for studying oocyte dormancy.

Higher levels of procoagulant microparticles in women with recurrent miscarriage are not associated with antiphospholipid antibodies

STUDY QUESTION

Are the levels of circulating cell-derived microparticles (cMPs) in patients with recurrent miscarriage (RM) associated with the antiphospholipid syndrome (APS)?

SUMMARY ANSWER

cMPs in women with RM are not associated with antiphospholipid antibodies (aPLs).

WHAT IS KNOWN ALREADY

Previous studies have focused on cMP levels in RM patients. Most studies have shown higher levels of cMPs in RM patients whereas others have reported lower levels. Data regarding cMPs in patients with the APS are scanty in the literature.

STUDY DESIGN, SIZE, DURATION

A case-control study including three groups of patients. A total of 154 women were prospectively recruited from September 2009 to October 2013. Four patients refused to participate. The APS group consisted of 50 women that had been previously diagnosed with primary APS and had had ≥3 consecutive first trimester miscarriages. The uRM group included 52 couples with ≥3 consecutive first trimester miscarriages of unknown etiology. The fertile control (FER) group was composed of 52 healthy fertile women with no history of pregnancy losses. Miscarriage was defined as intrauterine pregnancy loss at <10 weeks' size on ultrasound.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Venous blood samples for coagulation studies and cMP determinations were obtained. All patients underwent a thrombophilia study.

MAIN RESULTS AND THE ROLE OF CHANCE

cMP levels were significantly higher in the APS and uRM groups versus the FER group (P < 0.0001 and P = 0.009, respectively) (cMP number × 10(3)/ml plasma [mean ± SD]: APS: 18.5 ± 13.6; uRM: 16.3 ± 13.8; FER: 9.7 ± 4.6). There were no statistically significant differences in cMP levels between the APS and uRM groups.

LIMITATIONS, REASONS FOR CAUTION

The sample size was arbitrarily decided according to previous studies analyzing cMPs in RM patients. Different cMP subtypes were not investigated.

WIDER IMPLICATIONS OF THE FINDINGS

The present study adds further data on the subject showing that patients with RM, irrespective of testing positive for aPLs, have increased levels of cMPs compared with healthy fertile controls. The presence of elevated cMPs in RM women may reflect an ongoing systemic pathological, albeit asymptomatic, status that can become deleterious in the setting of pregnancy.

STUDY FUNDING/COMPETING INTERESTS

This study was supported in part by grant from FIS-PI11/01560 within the 'Plan Nacional de I+D+I' and co-funded by the 'ISCIII-Subdirección General de Evaluación' and the 'Fondo Europeo de Desarrollo Regional (FEDER)'. The authors have no competing interests to disclose.

TRIAL REGISTRATION NUMBER

Not applicable.