Retinoic acid(RA), formed in vivo by oxidation of retinol, is known as morphogenic signal. RA plays an active role in normal embryonic development at physiological concentration, but excess RA can be a powerful teratogen in human and animals. The present study was designed to examine the direct effect of RA on murine embryogenesis(gastrulation) and to define the specific development processes perturbed by RA. Five to fifteen blastocysts were randomly assigned to separate culture dishes of the experimental group. Various concentrations of RA(10(-9) M, 10(-7) M, and 10(-5) M) were used in culturing blastocysts. In the effect of RA on the normal grouwth of embryo, the rates of development to the stages of attachment, early egg cylinder(EEC), late egg cylinder(LEC), and early somite(ES)were significantly(p < 0.01) decreased as the RA concentration increased. Stil in the yolk sac formation rate, there was a significant, dose-dependent difference(p < 0.01) according to the RA concentration. In the degeneration of embryos by RA, the effect was more apparent as the concentration of Ra increased. The production rates of embryos devoid of egg cylinder region and embryos with abnormal egg cylinder region were increased (p < 0.01)in a dose-dependent manner according to RA concentration. In conclusion, RA probably act as teratogen at gastrula stage embryos in high concentration and effect of teratogenesis is dose-dependent.
Animals ; Blastocyst ; Embryonic Development ; Embryonic Structures ; Female ; Gastrula ; Gastrulation* ; Humans ; Mice* ; Ovum ; Pregnancy ; Teratogenesis ; Tretinoin* ; Vitamin A ; Yolk Sac

Human embryology is the study of development from a single cell to a baby in 9 months. Implantation occurs at the end of the first week of development. The second week of development is known as the week of 2's. Gastrulation, the most characteristic event occurring in the third week, establishes three germ layers composed of ectoderm, mesoderm, and endoderm. The three germ layers and neural crest cells lead to the development of their own tissues and organs during the embryonic period, which extends from the third to the eighth week. Major congenital malformations occur in the embryonic period. The fetal period, from the third month to the day of birth, is the time for maturation of tissues and organs, and growth of the body. Because of the close relationship between embryology and congenital abnormalities, knowledge of human development is essential to assess the effects on the embryo when the mother has been exposed to teratogens. This paper briefly reviews the normal embryonic development and associated congenital malformation.
Congenital Abnormalities ; Ectoderm ; Embryology ; Embryonic Development* ; Embryonic Structures* ; Endoderm ; Female ; Gastrulation ; Germ Layers ; Human Development ; Humans* ; Mesoderm ; Mothers ; Neural Crest ; Neurulation ; Parturition ; Pregnancy ; Teratogens

The ubiquitous Na, K-ATPase is a membrane-bound ion pump located in the plasma membrane in all animal cells and plays an essential role in a variety of cellular functions. Studies in several organisms have shown that this protein regulates different aspects of embryonic development and is responsible for the pathogenesis of several human diseases. Na, K-ATPase is an important factor for retinal development, and combinations of the isoforms of each of its subunits are expressed in different cell types and determine its functional properties. In this study, we performed RT-PCR assay to determine temporal expression and in situ hybridization to determine spatial expression of Na, K-ATPase beta2 isoform (atp1b2) in Xenopus laevis. Focusing on retinal expression to distinguish the specific expression domain, we used retinal marker genes sox4, sox11, vsx1, and . Xenopus atp1b2 was expressed from late gastrulation to the tadpole stage. Using whole mount in situ hybridization, we showed that Xenopus atp1b2 was expressed broadly in the eye, the whole surface ectoderm, and gills. In situ hybridization on sections revealed detailed and specific expression in the outer nuclear layer of the retina, which consists of two major classes of photoreceptors, rods and cones, surface ectoderm, pharyngeal epithelium, and gills. These findings indicate that atp1b2 may play an important role for the development of Xenopus retina.
Animals ; Cell Membrane ; Ectoderm ; Embryonic Development ; Epithelium ; Female ; Gastrulation ; Gills ; Humans ; In Situ Hybridization ; Ion Pumps ; Larva ; Pregnancy ; Protein Isoforms ; Retina* ; Retinal Rod Photoreceptor Cells ; Retinaldehyde ; Xenopus laevis ; Xenopus*

Ciliary rootlet coiled coil protein (CROCC), the structural component that originates from the basal body at the proximal end of the ciliary rootlet, plays a crucial role in maintaining the cellular integrity of ciliated cells. In the current study, we cloned Xenopus CROCC and performed the expression analysis. The amino acid sequence of Xenopus laevis was related to those of Drosophila, cow, goat, horse, chicken, mouse and human. Reverse transcription polymerase chain reaction analysis revealed that CROCC mRNA encoding a coiled coil protein was present maternally, as well as throughout early development. In situ hybridization indicated that CROCC mRNA occurred in the animal pole of embryo during gastrulation and subsequently in the presumptive neuroectoderm at the end of gastrulation. At tailbud stages, CROCC mRNA expression was localized in the anterior roof plate of the developing brain, pharyngeal epithelium connected to gills, esophagus, olfactory placode, intestine and nephrostomes of the pronephric kidney. Our study suggests that CROCC may be responsible for control of the development of various ciliated organs.
Amino Acid Sequence ; Animals ; Basal Bodies ; Brain ; Chickens ; Clone Cells ; Drosophila ; Embryonic Structures ; Epithelium ; Esophagus ; Gastrulation ; Gills ; Goats ; Horses ; Humans ; In Situ Hybridization ; Intestines ; Kidney ; Mice ; Neural Plate ; Polymerase Chain Reaction ; Reverse Transcription ; RNA, Messenger* ; Xenopus laevis ; Xenopus*