Animal Reproduction最新文献

The ability to develop oocytes from the earliest follicular stages through maturation and fertilization in vitro would revolutionize fertility preservation in human medicine and animal breeding. Instead, current assisted reproductive technologies rely only on a limited portion of the female gamete reserve, corresponding to the antral population, while the preantral follicle reserve remains unexploited, mainly due to a lack of knowledge regarding the mechanisms that guide preantral follicle differentiation and folliculogenesis in vitro. This review highlights the efforts made thus far and suggests an approach to studying the mechanisms and ovarian environment to enhance preantral follicle culture systems.

Embryo-maternal communication is a critical process that influences early embryonic development, implantation success, and pregnancy outcomes across mammalian species. This review examines the diverse in vitro systems developed to study this complex dialogue, highlighting their applications, advantages, and limitations. We explore conventional approaches such as two-dimensional (2D) cell cultures, which despite their simplicity, face challenges in replicating the three-dimensional (3D) architecture and cellular functions present in vivo. The review progresses through increasingly sophisticated models, including fluid co-culture systems that incorporate bioactive molecules, explant cultures that maintain tissue architecture, air-liquid interface systems that promote epithelial polarization and differentiation, 3D organoid systems that recapitulate complex structural organization, and organ-on-a-chip platforms that recreate mechanical forces and dynamic conditions. Special attention is given to the emerging role of extracellular vesicles (EVs) as mediators of embryo-maternal communication, transporting crucial molecular signals between the embryo and reproductive tract. By comparing these systems across species and developmental stages, we provide a comprehensive framework for selecting appropriate models based on specific research questions. The integration of these in vitro approaches with advanced analytical techniques offers promising avenues for understanding embryo-maternal cross-talk, potentially leading to improved assisted reproductive technologies and strategies to mitigate early pregnancy loss. As technology advances, the continued refinement of these systems will further illuminate the intricate molecular and cellular mechanisms underlying successful embryo development and implantation.

In the bovine dairy sector, the pursuit of rapid genetic advancement has prompted the adoption of increasingly younger parental figures for both males and females. While physiological limitations and access to gametes impose certain restrictions, the impact of age on gamete quality remains crucial yet poorly understood. We propose that the age effect encompasses environmental factors, which include the metabolic state of the parents and the conditions surrounding gametes and embryos within the reproductive tracts of both sexes. Emerging evidence indicates that this environment significantly influences not only the functionality of gametes and early embryos but also the future phenotype of the offspring. Recent research utilizing transcriptomic and epigenetic molecular analyses in bovine models has demonstrated that the age of both females and males gamete donors, can alter gene expression and programming within the embryo in a similar way that metabolic post partum conditions can. This embryo adaptation to parent's age is similarly noted in variations related to different culture conditions and the in vitro fertilization (IVF) process. A common outcome from these circumstances is the development of embryos operating in "economy" mode, where translation, cell division, and ATP production are diminished, seemingly as an anticipated adaptation to environmental conditions. Furthermore, new epidemiological studies have shown that these alterations can lead to distinct phenotypes, particularly in animals conceived through IVF, underscoring the long-term consequences that may unfold later in their lives.

In vitro embryo production (IVEP) offers an alternative approach for fertility preservation, genetic improvement, and reproductive research. However, in vivo, the female reproductive tract constitutes a dynamic microenvironment that undergoes critical changes crucial to support oocyte maturation, fertilization and embryo development. During IVEP, the absence of maternal-gamete and later maternal-embryo cross-talk can compromises both fertility and embryo development as well as quality. Extracellular vesicles (EVs) derived from the maternal reproductive tract, such as those from follicular fluid, oviductal fluid and uterine fluid, have attracted increasing attention due to their ability to carry bioactive biomolecules and partially restore this bidirectional communication when supplemented during IVEP. Moreover, EVs hold the potential to serve as indicator of the physiological or pathological state of reproductive structures as well as serving as real-time biomarkers. In addition, several studies suggest that EVs offer multiples advantages over conventional synthetics carries, opening new frontiers for modern drug or nucleotide delivery systems. Therefore, this review aims to provide a comprehensive overview of EVs derived from female reproductive tract, exploring their potential applications and challenges in enhancing IVEP outcomes and fertility treatments.

Pregnancy loss (PL) in cattle significantly impacts reproductive efficiency and economic viability of herds. Of particular interest, PL in in vitro embryo production (IVP) systems, represents a major challenge to the success of this technique. Establishment and maintenance of pregnancy is influenced by factors such as fertilization, maternal environment, and embryonic signaling issues. Data on dairy cattle have shown that embryo transfer (ET) may lead to greater initial pregnancy, but greater PL compared to artificial insemination (AI), and the impact of environmental conditions on reproductive outcomes seems to be manageable with proper heat stress mitigation strategies, for example. Data on beef cattle submitted to IVP and ET have shown that recipient cows had greater pregnancy per ET (P/ET) and lower PL compared to recipient heifers, with sex-sorted sperm yielding similar or even greater P/ET than conventional semen. Distinct synchronization protocols for recipients yield different reproductive outcomes, and recipient breed also affects P/ET and PL. Moreover, embryo recipients that express estrus after synchronization, as well as recipients in which better quality embryos are transferred, tend to have greater P/ET and lower PL. These findings highlight the importance of management strategies to improve fertility and reduce PL in embryo recipients.

The collection of early embryonic stages from the donor animal and their in vitro development through to transfer back into a recipient animal has gained enormous importance both in understanding embryo physiology and in its application for breeding purposes. Whereas not so long ago the focus was on embryo retrieval after superovulation from the donor animal, oocyte collection by follicular puncture followed by in vitro production (IVP) is now the main source of bovine embryos. However, as recent years of intensive research have shown, it appears to be very difficult to reproduce the extreme complex in vivo processes under laboratory conditions. Consequently, the quality/developmental capacity of embryos available for cryopreservation/storage/transport and transfer still lags behind that of embryos derived directly from animals. Embryo collection in bovine MOET programs is limited to the success of the animal's hormone treatment, embryo collection itself, and transfer on Day 7. IVP largely bypasses these developmental steps in the animal and focuses primarily on the presence of healthy follicular waves. It uses follicular puncture (ovum pick-up: OPU) to obtain immature oocytes, which undergo a three-stage in vitro process to produce embryos that are transferred to the uterus on Day 7. However, it is now known that important processes take place in the oviduct that have a lasting effect on the further development of the embryo. In animals, however, the development of embryos in the oviduct has not yet received sufficient attention. This review will present some highlights of the use of early embryonic stages from the oviduct in different species, but the scientific work mentioned is also largely based on the recent presentation at the AETE 2023 conference in Heraklion, Greece.

This study aimed to examine the efficacy of Doppler and B-mode sonography in evaluating the impact of maternal temperament on hemodynamic alterations in both the fetus and uterus during ovine gestation in addition to alteration of the angiogenic protein expression and fetal biometry. Twenty Ossimi ewes were divided into two groups, more reactive (MR: 12 sheep) and less reactive (LR: 8 sheep). Several endpoints were assessed every 2 weeks (wk) from breeding to wk 20 of pregnancy. Blood samples were taken to evaluate the expression of angiogenic proteins at parturition. The resistance (RI) and pulsatility (PI) indexes of the uterine (UtA) and fetal umbilical arteries (UMA) were measured. Biometry includes: diameter of amniotic vesicles (AVD), umbilicus (UMD), fetal thoracic diameter (FTD) and metacarpal length (MCL). The UtA-PI was higher in MR compared to LR ewes between 6-12 wks of gestation (P>0.01), while a tendency was recognized at wk 14 (P=0.054). The same was true for UtA-RI during the first 8 wk of pregnancy (P < 0.03) when MR and LR animals were compared. Similarly, UMA-RI was higher in fetuses of MR than LR ewes at wk 14 (P<0.0003) and 20 (P<0.02) of pregnancy. The differences in UMA-PI reached significance at wk 6, 8, 10, and 20 (P<0.0 -0.003). Furthermore, significant changes in fetal biometry were investigated. The expressions of VEGF, NOS3 and HIF 1α were increased in the less reactive sheep (P<0.001). In conclusion, the maternal temperaments affect the Doppler, B mode as well as the expressions of mRNAs for VEGF, NOS3 and HIF 1α genes at time of parturition.

Aubria subsigillata (Dumeril 1856) is a frog under increasing threat that is intensely harvested by Beninese people. The aim of this study was to develop a captive breeding program to repopulate the natural habitat of frogs in Benin Republic in view to conserve anuran biodiversity. The methodology adopted consisted of combining broodstock not injected with ovulin (hCG) in netted cages (natural reproduction) and broodstock injected with ovulin in tanks (assisted reproduction). In vitro fertilization of unfertilized female eggs by male milt was also carried out (controlled reproduction). In natural reproduction, A. subsigillata eggs or tadpoles are not produced. The concentration of 0.2 IU/g administered by intra-femoral injection resulted in the release of gametes in both sexes. Assisted reproduction enabled eggs to be obtained from the three coupling tanks after a post-injection lag time varying between 93 and 94 hours (Tank one = 304 eggs; Tank two = 125 eggs; Tank three = 56 eggs) and at a water temperature of 26°C; however, there was no incubation of eggs. For controlled reproduction, the average time between injection and first spermiation was 13 hours for males and 27 hours for females post-injection at a temperature of 28.5°C. Fecundity varied between 56 and 329 eggs. The eggs had an average weight of 1 mg and were incubated between 164 and 168 hours after fertilization. However, the incubation rate decreased on the 5^th day due to infection of the eggs by Saprolegnia sp. These results suggest that the experiment is partially viable: while hormonal stimulation can induce spawning and fertilization under controlled conditions, the success of incubation and development remains limited, highlighting the need for improvements in biosecurity and egg management to ensure full viability of captive breeding efforts.

Ovarian follicles usually involve only one oocyte. However, the existence of follicles with more than one oocyte has been described in different species. Therefore, this study evaluated the occurrence and number of Polyoocyte Follicles (POFs) in the ovaries of cats undergoing the ovariohysterectomy technique. For this purpose, ovaries from 33 cats were collected and submitted to histological preparation and analysis. The slides were evaluated under a microscope by two evaluators, who quantified the presence of follicles containing one or more oocytes and classified the follicular stage. Monoocyte follicles (MOFs) were found in all ovaries. POFs were observed at similar frequencies in both the right and left ovaries. The frequency of POFs with two oocytes was 79.03% in the right ovaries and 75.75% in the left ovaries. Follicles with three oocytes were found in 16.12% of the right ovaries and 27.27% of the left ovaries. The mean number of follicles with zero, one, two, three or more oocytes was similar between the ovaries, being 6.58, 310.5, 3.25, and 0.29 in the right ovary and 6.25, 312.7, 4.25, and 0.41 in the left ovary (p-values ​​of 0.7569, 0.9654, 0.4785, and 0.5015, respectively). POFs containing from two to five oocytes were identified in different stages of development. POFs at all stages of development were found in both ovaries, and the occurrence of these structures was influenced by the age, number of pregnancies, number of estrus, and weight of the cats studied.

A total of 216 Cobb 500 broiler breeder hens were randomly distributed across two treatments consisting of diets supplemented with 0 or 1% spray-dried plasma (SDP), resulting in 27 replications per treatment and four birds per pen. In addition, 36 roosters, housed in individual pens, were allocated to the same treatments, with each bird considered a replicate, in order to assess the influence of SDP on semen and hatching characteristics. The experimental diets were fed from 26 weeks until the conclusion of the study, at 65 weeks of age. Semen quality, embryonic mortality and quality of newly hatched chicks were evaluated at 29, 45, and 63 weeks. Hens were inseminated with fresh semen, and eggs were incubated following standard procedures. Semen from 63-week-old roosters had higher sperm concentration than other age groups, while 29-week-old rooster semen exhibited higher progressive motility than semen from older roosters (P < 0.001). The 45-week-old roosters had the lowest values for the analyzed semen quality parameters (average path velocity, straight-line velocity and curvilinear velocity). Additionally, sperm from 45-week-old roosters, regardless of SDP supplementation, had fewer total morphological defects than 63-week-old roosters. However, 1% SDP in the diet reduced total sperm cell defects at 63 weeks of age, as well as total sperm head and tail defects (P < 0.05) compared to unsupplemented birds. Dietary SDP reduced late embryonic death in 63-week-old breeders (P < 0.05). The results demonstrate that 1% SDP in breeder diets reduced late embryonic mortality and sperm cell defects, mainly in aged birds, enhancing the reproductive performance of broiler breeders.