Journal of Reproduction and Development

This study sought to examine the impact of negative photoperiod on the incidence of multiple ovulations and pregnancies in dairy cattle. The study population consisted of 5,373 pregnant cows in their third or greater lactation that experienced their first post-partum pregnancy after spontaneous estrus. The positive photoperiod (increasing day-length) extends from December 22 to June 21, whereas the negative photoperiod (decreasing day-length) extends from June 22 to December 21. The odds ratios (ORs) for multiple ovulations and pregnancies in cows that became pregnant during the negative photoperiod and the remaining cows that became pregnant during the positive photoperiod were 1...

The aim of the present study was to develop a semi-quantitative urine pregnancy test for mares based on the Cuboni reaction and to verify the reliability of this test. The urine specimens were hydrolyzed by heating in the presence of hydrochloric acid. The resulting free estrogen were extracted from the urine matrix using toluene. Sulfuric acid was added to the toluene extract and the mixture was heated again. The lower layer in the test tube containing sulfuric acid was used for fluorescence measurements with excitation at 355 nm and measurement at 535 nm...

Incorporation of bovine serum-derived albumin formulation (AlbuMAX) into a basic culture medium, MEMα, enables the completion of in vitro spermatogenesis through testicular tissue culture in mice. However, this medium was not effective in other animals. Therefore, we sought an alternative approach for in vitro spermatogenesis using a synthetic medium without AlbuMAX and aimed to identify its essential components. In addition to factors known to be important for spermatogenesis, such as retinoic acid and reproductive hormones, we found that antioxidants (vitamin E, vitamin C, and glutathione) and lysophospholipids are vital for in vitro spermatogenesis...

Communication between oocytes and the surrounding granulosa cells during follicular development is essential for complete oocyte growth. Oocytes contain lipid droplets (LDs), organelles assembled in the endoplasmic reticulum (ER) that store neutral lipids, including triglycerides and cholesterol esters. Although the LD content varies among animals, LDs stored in oocytes have been shown to play an important role in oocyte maturation and preimplantation embryonic development. However, knowledge is lacking regarding how and when LDs are initially produced in developing oocytes within follicles...

Poly(A)-binding proteins (PABPs) play roles in mRNA maturation, translational activity, and decay. The functions of PABPs, especially PABPN1 and PABPC1, in somatic cells have been well-studied. However, little is known about the roles of PABPs in oocytes because of the unique mechanisms of mRNA metabolism in oocytes. This study focused on PABPN1L and generated Pabpn1l knockout (KO) mice using the CRISPR/Cas9 system. After mating tests, we found that Pabpn1l KO females were infertile due to the failure of the embryos to develop to the 4-cell stage...

Pre-ovulatory follicles are cooler than the neighboring reproductive organs in cows. Thus, measuring the temperature of reproductive organs could be a useful method for predicting estrus and ovulation in cows, and the establishment of a non-invasive technique is required. In this study, we used infrared thermography (IRT) to measure ocular surface temperature as a potential surrogate for reproductive organ temperature. Five Japanese Black cows with synchronized estrus were subjected to temperature measurements in five regions of the ocular surface, including the nasal conjunctiva, nasal limbus, center cornea, temporal limbus, and temporal conjunctiva, twice a day (0800 h and 1600 h) during the experimental period...

Insulin-like growth factor-1 (IGF-1) plays a crucial role in follicular growth and stimulates steroid hormone production in bovine follicles. Steroid hormones are synthesized through the actions of steroidogenic enzymes, specifically STAR, CYP11A1, HSD3B, and CYP19A1 in both theca cells (TCs) and granulosa cells (GCs), under the influence of gonadotropins. Particularly, estradiol 17β (E2) assumes a central role in follicular development and selection by activating estrogen receptors β (ESR2) in GCs...

Senescent cells play a detrimental role in age-associated pathogenesis by producing factors involved in senescence-associated secretory phenotype (SASP). The present study was conducted to examine the possibility that senescent cells are present in aged ovaries and, if so, to determine the tissue region where senescent cells accumulate using a mouse model. Female mice at 2-4 and 8-10 months were used as reproductively young and aged models, respectively; the latter included mice with and without reproductive experience...

Spermatogonial stem cells (SSCs) possess a unique ability to recolonize the seminiferous tubules. Upon microinjection into the adluminal compartment of the seminiferous tubules, SSCs transmigrate through the blood-testis barrier (BTB) to the basal compartment of the tubule and reinitiate spermatogenesis. It was recently discovered that inhibiting retinoic acid signaling with WIN18,446 enhances SSC colonization by transiently suppressing spermatogonia differentiation, thereby promoting fertility restoration...

Induced pluripotent stem (iPS) cells are generated from somatic cells and can differentiate into various cell types. Therefore, these cells are expected to be a powerful tool for modeling diseases and transplantation therapy. Generation of domestic cat iPS cells depending on leukemia inhibitory factor has been reported; however, this strategy may not be optimized. Considering that domestic cats are excellent models for studying spontaneous diseases, iPS cell generation is crucial. In this study, we aimed to derive iPS cells from cat embryonic fibroblasts retrovirally transfected with mouse Oct3/4, Klf4, Sox2, and c-Myc...

Dynamic changes in the endometrium are crucial for establishing early pregnancy in ruminants. Blastocyst elongation and implantation require hormones and nutrients to be secreted from the maternal endometrium. The fatty acid-binding protein FABP4 is a widely expressed fatty acid transport protein that promotes cell proliferation, migration, and invasion and is involved in conceptus implantation. However, the mechanism underlying the functional regulation of endometrial epithelial cells (EECs) by FABP4 during ovine peri-implantation remains unclear...

The adenohypophysis is comprised of the anterior and intermediate lobes (AL and IL, respectively). Cluster of differentiation 9 (CD9)- and sex-determining region Y-box 2 (SOX2)-positive cells are stem/progenitor hormone-producing cells in the AL. They are located in the marginal cell layer (MCL) facing Rathke's cleft between the AL and IL (primary niche) and the parenchyma of the AL (secondary niche). We previously showed that, in rats, CD9/SOX2-positive cells in the IL side of the MCL (IL-side MCL) migrate to the AL side (AL-side MCL) and differentiate into prolactin-producing cells (PRL cells) in the AL parenchyma during pregnancy, lactation, and diethylstilbestrol treatment, all of which increase PRL cell turnover...

Accelerating age at first calving (AFC) is a strategy for sustainable dairy farming, whereas the impact of a reduction in AFC on long-term performance remains unclear. In this study, longevity and milk productivity until the end of the third lactation period were investigated retrospectively according to AFC. A total of 169 cows were categorized according to AFC as young, moderate, old, and very old (< 22.5, 22.5 -< 24.0, 24.0 -< 25.5, and ≥ 25.5 months). The young AFC group had approximately 70 kg lower body weight before first calving (620 vs...

The signals of the transforming growth factor β (TGF-β) superfamily play a critical role in follicular development in mammals. ACVR1B/TGFBR1/ACVR1C receptors mediate the signaling of several TGF-β superfamily ligands in granulosa cells. Although the requirement for ACVR1B/TGFBR1/ACVR1C receptor signaling in follicular development has been confirmed using mutant mouse models, the detailed roles of the signaling in granulosa cell and oocyte development have not been clearly defined. In the present study, we examined the requirement for ACVR1B/TGFBR1/ACVR1C receptor signaling in granulosa cells using an in vitro growth culture of oocyte-granulosa cell complexes (OGCs) and SB431542, a potent inhibitor of the receptor signaling...

Progesterone (P) is a well-known enhancer of hyperactivation which is associated with the success of in vitro fertilization (IVF). In this study, we examined whether P-enhanced hyperactivation affected IVF success in rats. When rat spermatozoa were exposed to 10, 20, and 40 ng/ml P, 20 ng/ml P enhanced hyperactivation via the membrane progesterone receptor. In addition, the enhancement of hyperactivation by 20 ng/ml P was regulated by phospholipase C, transmembrane adenylate cyclase, and protein kinase A. However, 20 ng/ml P did not affect IVF success...

A high temperature-humidity index during summer has deleterious effects on mitochondrial function, reducing oocyte developmental competence. 5-Aminolevulinic acid (5-ALA) and sodium ferrous citrate (SFC) are both known to support mitochondrial function and have strong anti-oxidant and anti-apoptotic activities. This study aimed to determine the mechanism of action of 5-ALA/SFC on oocyte quality. Bovine oocytes were collected from medium-sized follicles during summer (July-September, temperature-humidity index:76...

We investigated the effects of differences in milk production during early pregnancy on placental characteristics at full term, calf birth weights, and their metabolic status. Thirty-four Holstein cows were categorized into three groups (Low, n = 9; Middle, n = 16; High, n = 9) based on the quartile of average daily 4% fat-corrected milk production during early pregnancy. The High group showed higher milk component production than the other groups (P < 0.05) during early and mid-pregnancy. Although most placental characteristics did not differ significantly among the groups, cows in the High group had larger individual cotyledons and fewer medium-sized cotyledons than those in the Low group (P < 0...

Although embryo transfer is widely applied in cattle, many of the transferred embryos do not result in pregnancy. To determine a new parameter for bovine embryo evaluation, we investigated the relationships between in vitro hatchability and embryo morphological parameters using optical coherence tomography (OCT) that we established recently. Bovine embryos were obtained from Japanese Black cattle by in vitro fertilization (IVF). The quality of the blastocysts was examined under an inverted microscope and confirmed as Codes 1-3 according to the IETS standards for embryo evaluation...

Hypothalamic kisspeptin neurons are master regulators of mammalian reproduction via direct stimulation of gonadotropin-releasing hormone and consequent gonadotropin release. Here, we generated novel Kiss1 (kisspeptin gene)-Cre rats and investigated the developmental changes and sex differences in visualized Kiss1 neurons of Kiss1-Cre-activated tdTomato reporter rats. First, we validated Kiss1-Cre rats by generating Kiss1-expressing cell-specific Kiss1 knockout (Kiss1-KpKO) rats, which were obtained by crossing the current Kiss1-Cre rats with Kiss1-floxed rats...

Intrauterine extracellular vesicles (EVs) are involved in establishing proper conceptus-endometrial communication, which is essential for conceptus implantation and subsequent successful placentation. Despite several studies on intrauterine EVs, the composition and quantitative changes in conceptus and endometrial EVs, as well as the effects of intrauterine EVs on endometrial epithelial cells (EECs) during the peri-implantation period, have not been well characterized. To elucidate global changes in proteins in EVs extracted from uterine flushings (UFs) during the pre-implantation (P17), just-implantation (P20), and post-implantation (P22) periods, the datasets of the proteome iTRAQ analysis were compared among P17, P20, and P22 EVs...