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

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.     

Dental and skeletal characterization of the BR-1 minipig

This study was designed to characterize the development of oral structures in the BR-1 minipig and to compare these data with literature reports on domestic swine and other minipig lineages. Twelve male minipigs were anesthetized and given physical and radiographic examinations. The presence and chronology of tooth eruption from 3 to 15 months of age were assessed, and the radiographic results were interpreted by two certified researchers, who obtained a high index of agreement (kappa>0.81). The eruption chronology was similar to that reported for domestic swine and other minipig lineages. The results indicate that it is possible to use the BR-1 minipig in dental research.     

Pathology methods for the evaluation of embryonic and perinatal developmental defects and lethality in genetically engineered mice

The normal embryonic development of organs and other tissues in mice and all species is preprogrammed by genes. Inactivation of a gene involved in any stage of normal embryonic development can have severe consequences leading to embryonic or postnatal developmental defects and lethality. Pathology methods are reviewed for evaluating normal and abnormal placenta and embryo, especially after E12.5. These methods include pathology protocols for necropsy and histopathology in addition to references that will provide additional knowledge for embryo assessment including histology atlases and advanced embryo imaging techniques.     

Prenatal Dental Development in the Dog, Canis familiaris: Chronology of Tooth Germ Formation and Calcification of Deciduous Teeth

Observations on a sizeable collection of purebred canine fetuses of known age has afforded the opportunity to report baseline data on the timing of tooth germ development in the dog. The chronology of development of the deciduous dentition has been studied in a collection of 172 embryos and fetuses from purebred Beagles of known gestation. Microscopic examination of serial sections, enlarged reconstructions from serial sections and alizarin-stained clearings were used to visualize stages of development. These observations establish that the dental lamina is initiated at 25 days gestation and that calcification begins at 42 days in the deciduous teeth.     

牛胚胎日龄与移植时间对妊娠率的影响

为探讨胚胎移植过程中受体与胚胎日龄的最佳结合点,对移植受体牛的发情天数与胚龄进行了研究.选取北京奶牛中心的3种不同胚龄的A级胚胎,分成2组进行移植,A组采用随机移植方案,B组采用同步移植方案.B组妊娠率为(61.11%)高于A组的妊娠率(25.81%),两组之间存在显著性差异(P＜0.05).结果表明,在胚胎移植中同步移植好于随机移植的效果.通过本试验的研究,以期在生产实践中对胚胎移植技术的应用和推广有所借鉴.     

红腹锦鸡胚胎期羽毛芽发育的研究

旨在了解红腹锦鸡胚胎期羽毛毛囊的组织结构及毛囊形态发生的变化过程,为研究红腹锦鸡羽毛毛囊发育的分子调控机理奠定组织学基础。分别对5、7、8、9、10、11、13、16、18日胚龄的红腹锦鸡胚胎发育情况进行实体观察;采集上述胚龄的红腹锦鸡背部皮肤,制作石蜡切片并进行HE染色,在显微镜下观察毛囊形态结构并拍照记录。红腹锦鸡胚胎于9日胚龄时羽毛芽开始发育,可以观察到色素在毛囊内的沉积,16日胚龄时毛囊发育基本完成,体表覆盖羽毛。该研究为进一步阐明红腹锦鸡羽毛发育的分子机制奠定了组织学基础。     

Buffalo (Bubalus bubali) Late Embryo and Foetus Development: A Morphological Analysis

Many researches describe the embryonic developmental features in domestic animals; however, in farm animals, they are scarce. Most farm animal studies are related to assisted reproduction and embryos transfer techniques. But, morphological features and size measure to estimate the age gestation are rarely reported in literature. Thus, in this study, we described the developmental changes in the bubaline (Bubalus bubali) concepts from 21 to 60 days of gestation. Our results revealed that buffalo embryos similar morphological characteristics similar to other mammalian species. Also, similarities between bovine and bubaline persist; except on foetal stages when buffalos have a faster development than bovine. Therefore, buffalo's gestation period exhibits some varieties and accurate embryo age is more difficult. Yet, when we use a combination of the crown–rump, macroscopic analysis and alizarin red, it is possible to describe better the whole embryogenesis stages of the buffalo and which can contribute for future reproduction researches and applications in veterinary practice.     

Embryogenetics: gene control of the embryogenesis of the eye

In recent years there have been significant advances in our knowledge and understanding of the genetic control of embryonic development. The aim of this paper is to review the current state of knowledge regarding genetic control of embryogenesis, the first stage of ocular development. Products of numerous genes participate in signaling, induction and control during the formation of the neural plate, groove and tube, key events leading to the development of the future eye.     

NLRP9B protein is dispensable for oocyte maturation and early embryonic development in the mouse

Nlrp9a, Nlrp9b and Nlrp9c are preferentially expressed in oocytes and early embryos in the mouse. Simultaneous genetic ablation of Nlrp9a and Nlrp9c does not affect early embryonic development, but the function of Nlrp9b in the process of oocyte maturation and embryonic development has not been elucidated. Here we show that both Nlrp9b mRNA and its protein are expressed in ovaries and the small intestine. Moreover, the NLRP9B protein was restricted to oocytes in the ovary and declined with oocyte aging. After ovulation and fertilization, NLRP9B protein was found in preimplantation embryos. Confocal microscopy demonstrated that it was mainly localized in the cytoplasm in the oocytes and blastomeres. Thus, this protein might play a role in oocyte maturation and early embryonic development. However, knockdown of Nlrp9b expression in GV-stage oocytes using RNA interference did not affect oocyte maturation or subsequent parthenogenetic development after Nlrp9b-deficient oocytes were activated. Furthermore, Nlrp9b knockdown zygotes could reach the blastocyst stage after being cultured for 3.5 days in vitro. These results provide the first evidence that the NLRP9B protein is dispensable for oocyte maturation and early embryonic development in the mouse.     

Growth-promoting effects of different fractions of extra-embryonic coelomic fluid on embryonic development

In the early stages of embryonic development, many growth-promoting molecules must be provided by the maternal system. These factors may be supplied locally to the embryo, by the decidua, the placenta, or the yolk sac. In this study the growth-promoting potential of extra-embryonic coelomic fluid (EECF) and its fractions was investigated. The embryonic requirement of growth-promoting molecules may be studied by reducing the growth-supporting capacity of serum. Thus, ultrafiltration of rat serum was carried out for 8 h using Millipore filters with a molecular weight exclusion of 30 kDa. Rat embryos at 9.5 days of age were cultured for 8 days for anembryonic yolk sacs, and then EECF was collected and divided into three different molecular weight fractions by ultrafiltration. Rat embryos were cultured for 48 h in whole rat serum and the serum retenate (which has low growth-supporting capacity) in the presence and absence of EECF, its fractions, or in EECF only. Embryos grown in retenate showed severe growth retardation, and the addition of EECF significantly improved embryonic growth. The fraction which contained the molecules with molecular weight between 10 and 30 kDa had significantly more effect on embryonic development than the other fractions. This fraction of EECF was analysed by gel electrophoresis. Three of the four protein bands observed in this fraction were identified by amino-terminal sequencing as alpha-fetoprotein precursor (22 kDa), apolipoprotein A1 precursor (24 kDa) and fetal haemoglobin Y2 chain (14 kDa), none of which are likely to be responsible for the growth-promoting activity. To further investigate growth-promoting proteins, EECF was Western-blotted to nitrocellulose membranes and probed with antisera against rat prolactin, epidermal growth factor, insulin-like growth factors I and II and human placental lactogen. No immunoreactive bands were detected in the EECF, suggesting that either these proteins are not present or are present at levels too low to be detected. Although the growth-promoting effect of the EECF was demonstrated in this study, the molecules responsible remain uncharacterized.     

Comparison of heat production and plasma lipid metabolites between meat- and egg-types of Nagoya breed chicken during embryonic development

We compared heat production (HP) and plasma lipid metabolites between meat‐ and egg‐types of Nagoya breed chickens during embryonic development. To investigate HP and respiratory quotient, oxygen consumption and carbon dioxide production were measured using an open‐circuit calorimeter system. HP was significantly lower in meat‐ than in egg‐type chickens during embryonic development, and HP gradually decreased with developmental stage in both types. The respiratory quotient was constant at approximately 0.68 at every embryonic stage investigated, and the value was similar in both types. Plasma concentrations of triacylglycerol, nonesterified fatty acid, glycerol and D‐3‐hydroxybutyrate, which are associated with lipid metabolism, were similar in both types during embryonic development. These results demonstrate that chicken embryos selected for rapid growth of Nagoya breed have characteristic lower HP, and that when selecting chickens for rapid growth, HP is an important parameter during embryonic stages.     

Delay in Cleavage of Porcine Embryos after Intracytoplasmic Sperm Injection (ICSI) Shows Poorer Embryonic Development

In pigs, the embryonic developmental ability after intracytoplasmic sperm injection (ICSI) is inferior to that resulting from in vitro fertilization (IVF). We evaluated the timing of cell division up to blastocyst formation on embryonic development after ICSI using either whole sperm (w-ICSI) or the sperm head alone (h-ICSI) and IVF as a control. At 10 h after ICSI or IVF, we selected only zygotes, and each of the zygotes/embryos was evaluated for cleavage every 24 h until 168 h. We then observed a delay in the 1st and 2nd cleavages of h-ICSI embryos and also in blastocoele formation by w-ICSI embryos in comparison with IVF embryos. The rate of blastocyst formation and the quality of blastocysts in both ICSI groups were inferior to those in the IVF group. In conclusion, the delay in cleavage of porcine ICSI embryos shows poorer embryonic development.     

Ontogeny of the hypothalamo-pituitary-adrenocortical axis in the chicken embryo: a review

The embryo of the domestic fowl (Gallus domesticus) tenders one distinctive advantage over general mammalian models for investigating the development of the hypothalamo–pituitary–adrenocortical (HPA) axis. This is the relative simplicity with which the embryonic endocrine environment can be influenced without confounding maternal influences. The ease of direct manipulation of the embryonic endocrine system has facilitated analysis of the development and function of the HPA axis in the chick embryo. As the chick embryo develops, functional activation of the adrenal gland is regulated at three different levels: the adrenal gland itself, the anterior pituitary, and the hypothalamus. The adrenal gland appears capable of independent secretion of glucocorticoids from day 8 until shortly after day 14 of embryonic development, at which point the pituitary influences adrenocortical activity. Around the same age, the hypothalamic level of control also begins. The information covered in this review will describe the major steps in the development of the HPA axis in the chicken embryo and show that the chicken has an emblematic HPA neuroendocrine axis.     

Up‐Regulation of Insulin‐Like Growth Factor I and Uteroglobin in In Vivo‐Developed Parthenogenetic Embryos

Parthenote embryos are being considered as an alternative source of embryonic stem cells. However, as there is still a dearth of knowledge of this kind of embryos, a better understanding of their biology is needed for their application. In this work, we studied the differences and similarities between parthenotes and normal embryos at the blastocyst stage in vivo developed. We analysed the expression of factor OCT‐4, vascular endothelial growth factor (VEGF), insulin‐like growth factor I (IGF‐I) and uteroglobin (UG) by real‐time PCR. To do so, oocytes were recovered and after activation procedure were transferred by ventral middle laparoscopy to receptive does to undergo completely in vivo development. Does were slaughtered 6 days post‐ovulation induction, and parthenote and normal embryos were recovered for mRNA expression analysis. Our results reported that parthenotes and normal embryos showed similar mRNA expression for OCT‐4 and VEGF. However, IGF‐I and UG showed to be over‐expressed in parthenote embryos. Thus, our study highlights that despite the in vivo development of parthenotes, they still seem to have an altered expression and, therefore, to be different to normal embryos. The altered expression pattern of parthenote embryos suggests that these embryos should be studied carefully before future application.     

Effects of different concentrations of Chir98014 as an activator of Wnt/beta-catenin signaling pathway on oocyte in-vitro maturation and subsequent embryonic development in Sanjabi ewes

The present study was conducted to investigate the effects of the activator factor of the WNT pathway, chir98014, leading to the in vitro sheep oocyte maturation medium, on the cumulus cell development, different nuclear maturation stages and the following process of embryonic development. Experiments included (a) addition of different concentrations (0, 0.1, 0.5, 1 µm) of chir98014 to the maturation medium and evaluation of the cumulus cell expansion, (b) addition of different concentrations of chir98014 to the maturation medium and investigation of different nuclear maturation stages, (c) addition of different concentrations of chir98014 to the maturation medium and examination of the subsequent embryonic maturation process and (d) addition of different concentrations of chir98014 to the embryonic development culture medium (the first 48 hr) and investigation of the subsequent embryonic development process. The extracted data were analysed using the SPSS software, considering the significance level of p < .05 and making the mean comparisons. The results showed that the addition of the 0.1 µM concentration of chir98014 to the maturation medium had no significant effects on the oocyte maturation and embryo development post-fertilization but it enhanced the Cumulus-oocyte complexes (COCs) expansion. In the fourth experiment, the low concentration of chir98014 in the embryo culture media improved the embryo development process, whereas the high one had a detrimental effect on it, as compared to the control group. Thus, the presence of the lower concentrations of this compound in the embryonic culture medium had favourable effects on the development of embryos.     

DNA甲基化在猪胚胎发育过程中的研究进展

猪的胚胎发育需要经历受精、卵裂、孵化、形态转变、附植、器官分化等一系列重要的生理阶段。虽然在胚胎发育过程中基因的严格表达与正确指导是胚胎能否正常发育的决定性条件,但研究表明DNA甲基化修饰对胚胎的发育也起着必不可少的作用。DNA甲基化是一种常见且重要的表观遗传修饰,虽然不改变DNA的一级序列,但也包含可遗传信息,并在基因的转录调控中起重要作用。在猪的胚胎发育中,DNA甲基化呈现出高度动态的过程,这一过程受孕期母体营养和发育环境条件影响。本文将从胚胎早期发育、体细胞核移植和孕期母体营养三个方面来阐述DNA甲基化对胚胎发育的影响,为进一步研究猪胚胎在发育过程中的DNA甲基化机制和提高体细胞核移植的成功率提供参考。     

降钙素基因相关肽在鸭腔上囊胚胎及胚后发育过程中的表达

应用免疫组织化学技术研究降钙素基因相关肽在鸭腔上囊胚胎及胚后发育过程中的表达特征.结果显示,降钙素基因相关肽强阳性细胞出现于20 d胚龄至胚后14周龄的滤泡间上皮,20 d胚龄至胚后17周龄的小结相关上皮,新生雏至胚后14周龄的滤泡皮质,24 d胚龄至胚后14周龄的滤泡髓质,20 d胚龄至胚后14周龄的肌层和小动脉平滑肌.结果说明,降钙素基因相关肽表达于鸭腔上囊的不同部位及不同发育阶段;在腔上囊退化期,降钙素基因相关肽的表达表现出明显的变化特征,这可能是导致腔上囊退化的原因之一;滤泡间上皮与小结相关上皮在神经肽表达方面存在差异.