Embryological Studies Research Articles

To the doctrine of congenital anomalies of female genital organs. A fourteen year old girl’s ANUS PRAETERNATURALIS VESTI

Congenital anomalies of the female genital organs are, in addition to their clinical interest, also anatomical interest, serving to a known extent as a touchstone for checking the history of the development of the genital apparatus that we have. Some anomalies in the area of ​​external genital organs have given rise to new embryological studies in recent years, which gave valuable data concerning the history of the development of the ano-genital area. The same data serve for a better understanding of the way of origin of some anomalies, among other things also anomalies, known as atresiae ani vestibularis, vulvaris, hymenalis, or better anus praeternaturalis vestibularis.

Better understanding of interfacial planes in colorectal cancer surgery and the value of small vessels on fascia in the identification of interfacial planes

The introduction of total mesorectal excision and wider use of laparoscopic surgery pushed the field of colorectal surgery into an era of interfasical dissection. The Japanese suggestion of fascial arrangement of the trunk in a multilaminar, symmetrical and parallel way helps in better understanding of fascial relationship and interfascial planes surrounding the colon and the rectum. However, different interpretations of the multilayer retroperitoneal fascial relationship, complexity of fascial structures within the pelvis and dense adhesion between two apposed fasciae at special points make it still challenging for the surgeon to decide on the precise interfascial plane for colorectal mobilization. Small vessels on fasica propria of the rectum and various retroperitoneal fascia, especially ureterohypogastric fascia show distinctive features. The root of small vessels on fascia propria of the rectum helps to identify the anterolateral and posterolateral interfascial plane in the middle and low rectum. The longitudinal trajectory of small vessel on ureterohypogastric fascia and scarcity interfascial vascular communication between mesocolic and retroperitoneal fascia help the surgeon to find and stay in the interfacial plane during colorectal mobilization. More knowledge of fascial and interfascial plane will certainly help achieve better mesocolic mesorectal integrity and reduce the risk of injuries to autonomic nerves. More anatomical, histological and embryological studies are warranted with respect to relationship between small vessels and fasciae.

Ontogeny of the Moorish gecko Tarentola mauritanica with emphasis on morphogenesis of the skin and its derivatives.

Studying reptilian embryonic development provides answers to many questions related to the development of tetrapods. Reptilian skin has been recently considered in studies at the evo-devo level. The lizard epidermis has to be shed periodically. At the embryonic level, contention exists regarding the first layers to appear, whether the oberhautchen or the clear layer, and whether the shedding complex develops before hatching. Geckos exhibit diverse morphologies independently evolved multiple times within the clade, such as subdigital pad lamellae. Here we investigate the embryonic development of Tarentola mauritanica and establishing its embryonic table. Primarily we follow the development of the integument. This is a closely related species to Tarentola annularis and it is crucial to investigate whether it has the same derived digital condition of claw regression. Eleven embryonic stages are described according to the external morphological characteristics of the embryos. Interestingly, the oviposition stage appears earlier than its close relative T. annularis, and the total incubation time is less. We also describe skin development, adding clear evidence to the debate on the development of the shedding complex, which we found is developed before hatching. We describe one layer of periderm and the clear layer as the first embryonic epidermal layers. Generally, our results show the genus Tarentola to have the advantage of being a unique taxon, easily breed at the laboratory, with multiple clutches per year, and with an earlier stage at oviposition. That could be a model animal for embryonic development and experimental embryology studies.

An optimized histological proceeding to study the female gametophyte development in grapevine

BackgroundReproductive success in seed plants depends on a healthy fruit and seed set. Normal seed development in the angiosperms requires the production of functional female gametophytes. This is particularly evident in seedless cultivars where defects during megagametophyte’s developmental processes have been observed through cytohistological analysis. Several protocols for embryo sac histological analyses in grapevine are reported in literature, mainly based on resin- or paraffin-embedding approaches. However their description is not always fully exhaustive and sometimes they consist of long and laborious steps. The use of different stains is also documented, some of them, such as hematoxylin, requiring long oxidation periods of the dye-solution before using it (from 2 to 6 months) and/or with a differentiation step not easy to handle. Paraffin-embedding associated to examination with light microscope is the simplest methodology, and with less requirements in terms of expertise and costs, achieving a satisfactory resolution for basic histological observations. Safranin O and fast green FCF is an easy staining combination that has been applied in embryological studies of several plant species.ResultsHere we describe in detail a paraffin-embedding method for the examination of grapevine ovules at different phenological stages. The histological sample preparation process takes 1 day and a half. Sections of 5 µm thickness can be obtained and good contrast is achieved with the safranin O and fast green FCF staining combination. The method allows the observation of megasporogenesis and megagametogenesis events in the different phenological stages examined.ConclusionsThe histological sample preparation process proposed here can be used as a routine procedure to obtain embedded ovaries or microscope slides that would require further steps for examination. We suggest the tested staining combination as a simple and viable technique for basic screenings about the presence in grapevine of a normally and fully developed ovule with embryo sac cells, which is therefore potentially functional.

Classics revisited, history of reptile placentology, part IV: Hanni Hrabowski's 1926 monograph on fetal membranes of lizards

In 1926, the German biologist Johanna (Hanni) Hrabowski published a study of the morphology and development of the fetal placenta in lizards that has proven to be of historical importance. Her anatomical descriptions and interpretations identified developmental patterns that differ from other amniotes -- features now recognized as unique attributes of squamate (lizards and snakes) development. Her 1926 monograph presented the first histological comparison of fetal membranes in closely-related oviparous and viviparous reptiles, thereby establishing a comparative framework for understanding placental specializations for viviparity. Hrabowski reported that yolk sac development did not differ between oviparous and viviparous species. The novel, shared components of yolk sac development she identified are now recognized as the foundation for the unique yolk sac placenta of reptiles, the omphaloplacenta. In addition, Hrabowski's extensive ontogenetic sampling and the detail and accuracy of her anatomical descriptions set high standards for subsequent studies of comparative evolutionary embryology.

Comparative embryonic development patterns in three deep-water skates from the southwest Atlantic

Embryonic development is a vulnerable and key period during the life cycle of an oviparous elasmobranch. Captivity studies are difficult to carry out on non-coastal species; hence, embryonic development can be analysed from samples collected from the seabed. Here, embryonic development of three shelf and deep-water skates from the southwest Atlantic Ocean, Bathyraja brachyurops, B. macloviana and Amblyraja doellojuradoi was studied. Egg cases containing embryos in different stages were collected from 84 to 1006 m depth in the northern part of the Argentinean continental shelf and continental slope (36°S-41°S), including the Mar del Plata Canyon (38° S). Common development patterns were observed among the three species and also with other skate species previously studied. Anatomical structures and embryo features were similar among species in initial, early and middle stages. Advanced and pre-hatching embryos showed species-specific differences regarding pigmentation and spinulation. This study sheds light on the identification of neonates of shelf and deep-water species, which could be useful to recognize specific nursery areas in the deep ocean. In addition, this embryological comparative study expands the existing database on the different chondrichthyan lineages, thus making a step forward towards understanding of their phylogenetic relationships.

Characteristics of Clinical Symptoms, Cerebral Images and Stroke Etiology in Vertebro-Basilar Artery Fenestration-Related Infarction.

Cerebral artery fenestration is a rare variant of the vascular architecture, but its existence is well documented. The common site of fenestration is the vertebra-basilar artery and it may be found incidentally with subarachnoid hemorrhage. However, fenestration-related cerebral infarction is rare. We analyzed the clinical characteristics, stroke etiology, and image findings of fenestration-related cerebral infarction of the vertebrobasilar artery. We reviewed our hospital records and previously published reports to find cases of fenestration-related cerebral infarction. We excluded those with unknown clinical features or radiological findings. We retrieved 4 cases of fenestration-related infarction from our hospital, in which vascular change, headache, vertigo/dizziness, and dissection in stroke etiology were detected. In eight previously reported cases of fenestration-related infarction, similar vascular changes were noted, but they were mainly diagnosed as embolic stroke of undetermined source. However, based on the criteria for dissection in this study, dissection as the stroke etiology was suspected in the previously reported cases. Many hypotheses have been proposed for the development of dissection, thrombus, and aneurysms in fenestration. Although an embryological and morphological study is needed, clinicians must consider basilar artery fenestration-related infarction as a differential diagnosis and intensive non-invasive image study is recommended.

New embryological and palaeontological evidence sheds light on the evolution of the archosauromorph ankle

The homology and evolution of the archosaur ankle is a controversial topic that has been deeply studied using evidence from both extinct and extant taxa. In early stem archosaurs, the astragalus and calcaneum form the ancestral proximal tarsus and a single ossification composes the centrale series. In more recent stem archosaurs, the centrale is incorporated to the proximal row of tarsals laterally contacting the astragalus. This bone is subsequently lost as an independent ossification before the last common ancestor of birds and crocodilians, but the evolutionary fate of this element remains mostly unexplored. Here, we integrate embryological and palaeontological data with morphogeometric analyses to test the hypothesis of loss of the centrale or, alternatively, its incorporation into the archosaurian astragalus. Our results support the latter hypothesis, indicating that the astragalus developed ancestrally from two ossification centres in stem archosaurs and that the supposed tibiale of bird embryos represents a centrale. This conclusion agrees with previous embryological studies that concluded that the tibiale never develops in diapsids.

The phenotypic morphology of human lumbar plexus roots associated with changes in the thoracolumbar vertebral count and trade-off

This study investigated the developmental basis for the human phenotypic morphology of the interaction between the vertebrae and the nerve plexus by evaluating changes in the human lumbar plexus according to various thoracolumbar formulas. The dissection found that the changes in lumbar nerve roots reported by experimental embryology studies to be concomitant with thoracolumbar trade-off, i.e., a change in vertebrae from thoracic to lumbar with no change in the overall thoracolumbar count, were not apparent in humans with the usual 17 or mutant 16 thoracolumbar vertebrae. When vertebral changes in two segments were examined by comparing spines with a reduced thoracolumbar count of 16 to those with an increased count of 18, this tended to show only a single-segment caudal shift of the lumbar plexus. We cannot provide evidence for the phylogenetic difference in the concomitant changes of lumbar nerves and vertebrae, but comparisons between experimental rodents and humans highlighted fewer and shorter lumbar vertebra and more complicated lumbar plexus in humans. Therefore, these multiple differences may contribute to a human phenotypic morphology that is not evident in the concomitant transformation of vertebrae and lumbar nerves reported in experimental rodents.

Application of Tactical Models in Embryology Teaching for Visually Disabled

Objective: Apply the idea of tactile models as a tool for embryology teaching for the visually impaired, facilitating learning by encouraging student, sharpening his curiosity and facilitating the teaching-learning process. Method: It was proposed to make tactile models based on the schemes and photos used by normovisual students found in the base books of the study of Embryology, using cheap and easy-to-handle materials. Results: The models were used by the visually impaired student during classes following the discipline schedule and were also used as objects of assessment. Conclusion: The applicability of the tactile models met expectations, since the student can obtain full knowledge of the subject in an inclusive manner and can have the same type of learning as the normovisual students.

The Iron Man of the Renaissance: the contribution of Girolamo Fabrizi d'Acquapendente.

To highlight the most relevant contributions of the Italian Renaissance surgeon Girolamo Fabrizi d'Acquapendente in the field of orthopaedics and traumatology. An extensive research on the life and achievements of Girolamo Fabrizi was conducted on University Libraries as well as on electronic databases like PubMed. Girolamo Fabrizi d'Acquapendente is known for his embryology and physiology studies, particularly on sensory organs and blood circulation. He founded the world's first permanent anatomical theater established at the University of Padua and inaugurated in 1595. His most notable publications include surgical and definitely orthopedics works such as "De fracturis" (On fractures) and "De luxationibus" (On joint displacement). He outlined some principles of treatment that are still valid nowadays such as anatomical reduction and stabilization of the fracture, that were applied using the equipment available at that time. He described and illustrated maneuvers and instruments, such as pulleys, winches, splint, and bandages. He further depicted the famous "Oplomochlion" ("the armored man"), which is actually a collection of all of the braces used at the time to correct congenital and post-traumatic deformities. Bracing and prosthetic replacements have accompanied medical history throughout the centuries, from Ancient Egypt to the present, but it was the ingenuity of Renaissance surgeons that pushed biomedical technology to new heights: Girolamo Fabrizi d'Acquapendente was one of the most illustrious contributors to these great achievements.

Floral anatomy of the plant Psittacanthus schiedeanus (Loranthaceae)

Anatomía floral de la planta Psittacanthus schiedeanus (Loranthaceae). Loranthaceae hemiparasitic family comprises 76 genera and about 1 050 species distributed in temperate and tropical regions. The subtribe Psittacanthinae contains 14 genera of neotropical mistletoe including Psittacanthus with over 120 species, characterized by large, brightly colored (red, orange, yellow) flowers that are mostly pollinated by hummingbirds. During the 20th century, a number of morphological and embryological studies were conducted mainly on Old World Loranthaceae genera. More recently, attention has been focused on neotropical Psittacanthinae where among the 14 genera, floral anatomy has been examined in only seven. The aim of this study is to describe the floral anatomy of Psittacanthus schiedeanus and compares the results with those derived from related mistletoe, interpreting the variation of the floral characters of the calyculus, nectary, gynoecium and from floral dissections and serial histological sections, detailing the structure of androecium and gynoecium and anthers in the context of the new phylogenetic information. Flowers of P. schiedeanus at different developmental stages were examined using stained serial sections visualized with light microscopy. These flowers have a vascularized, cupular pedicel fused to a bracteole, a non-vascularized calyculus, an annular nectary, a unilocular gynoecium with a single central mamelon and an androecium formed by epipetalous septate stamens. The morphological comparison of pedicel, bracteole and calyculus provides support for the interpretation of the calyculus as a reduced calyx. The annular nectary seems to be a character shared by the entire subtribe Psittacanthinae, which distinguishes it from Ligarinae which has stylar nectary. The unilocular gynoecium formed by a single central structure is a character shared with other genera in Psittacanthinae except Tripodanthus. The androecium is composed of dithecal, tetrasporangiate stamens with septate locules that are here considered an adaptation for pollen releasing over an extended time period rather than previous suggestions that they result from evolutionary pressure to reduce anther size or to facilitate the nutrition of microspores in large anthers.

Embryo microinjection of the lecithotrophic sea urchin Heliocidaris erythrogramma.

Microinjection is a common embryological technique used for many types of experiments, including lineage tracing, manipulating gene expression, or genome editing. Injectable reagents include mRNA overexpression, mis-expression, or dominant-negative experiments to examine a gene of interest, a morpholino antisense oligo to prevent translation of an mRNA or spliceoform of interest and CRISPR-Cas9 reagents. Thus, the technique is broadly useful for basic embryological studies, constructing gene regulatory networks, and directly testing hypotheses about cis-regulatory and coding sequence changes underlying the evolution of development. However, the methods for microinjection in typical planktotrophic marine invertebrates may not work well in the highly modified eggs and embryos of lecithotrophic species. This protocol is optimized for the lecithotrophic sea urchin Heliocidaris erythrogramma.

Microanatomy of the stem-turtle Pappochelys rosinae indicates a predominantly fossorial mode of life and clarifies early steps in the evolution of the shell

Unlike any other tetrapod, turtles form their dorsal bony shell (carapace) not from osteoderms, but by contribution of the ribs and vertebrae that expand into the dermis to form plate-like shell components. Although this was known from embryological studies in extant turtles, important steps in this evolutionary sequence have recently been highlighted by the Triassic taxa Pappochelys, Eorhynchochelys and Odontochelys, and the Permian Eunotosaurus. The discovery of Pappochelys shed light on the origin of the ventral bony shell (plastron), which formed from enlarged gastralia. A major question is whether the turtle shell evolved in the context of a terrestrial or aquatic environment. Whereas Odontochelys was controversially interpreted as aquatic, a terrestrial origin of turtles was proposed based on evidence of fossorial adaptations in Eunotosaurus. We report palaeohistological data for Pappochelys, a taxon that exemplifies earlier evolutionary stages in the formation of the bony shell than Odontochelys. Bone histological evidence reveals (1) evolutionary changes in bone microstructure in ribs and gastralia approaching the turtle condition and (2) evidence for a predominantly amphibious or fossorial mode of life in Pappochelys, which support the hypothesis that crucial steps in the evolution of the shell occurred in a terrestrial rather than fully aquatic environment.

Patterned Vascularization of Embryonic Mouse Forebrain, and Neuromeric Topology of Major Human Subarachnoidal Arterial Branches: A Prosomeric Mapping.

The prosomeric brain model contemplates progressive regionalization of the central nervous system (CNS) from a molecular and morphological ontogenetic perspective. It defines the forebrain axis relative to the notochord, and contemplates intersecting longitudinal (zonal, columnar) and transversal (neuromeric) patterning mechanisms. A checkboard pattern of histogenetic units of the neural wall results, where each unit is differentially fated by an unique profile of active genes. These natural neural units later expand their radial dimension during neurogenesis, histogenesis, and correlative differential morphogenesis. This fundamental topologic framework is shared by all vertebrates, as a Bauplan, each lineage varying in some subtle aspects. So far the prosomeric model has been applied only to neural structures, but we attempt here a prosomeric analysis of the hypothesis that major vessels invade the brain wall in patterns that are congruent with its intrinsic natural developmental units, as postulated in the prosomeric model. Anatomic and embryologic studies of brain blood vessels have classically recorded a conserved pattern of branches (thus the conventional terminology), and clinical experience has discovered a standard topography of many brain arterial terminal fields. Such results were described under assumptions of the columnar model of the forebrain, prevalent during the last century, but this is found insufficient in depth and explanatory power in the modern molecular scenario. We have thus explored the possibility that brain vascularization in rodents and humans may relate systematically to genoarchitectonic forebrain subdivisions contemplated in the prosomeric model. Specifically, we examined first whether early vascular invasion of some molecularly characterized prosomeric domains shows heterochrony. We indeed found a heterochronic pattern of vascular invasion that distinguishes between adjacent brain areas with differential molecular profiles. We next mapped topologically on the prosomeric model the major arterial branches serving the human brain. The results of this approach bear on the possibility of a developmentally-based modern arterial terminology.

Using the Xenopus Developmental Eye Regrowth System to Distinguish the Role of Developmental Versus Regenerative Mechanisms.

A longstanding challenge in regeneration biology is to understand the role of developmental mechanisms in restoring lost or damaged tissues and organs. As these body structures were built during embryogenesis, it is not surprising that a number of developmental mechanisms are also active during regeneration. However, it remains unclear whether developmental mechanisms act similarly or differently during regeneration as compared to development. Since regeneration is studied in the context of mature, differentiated tissues, it is difficult to evaluate comparative studies with developmental processes due to the latter’s highly proliferative environment. We have taken a more direct approach to study regeneration in a developmental context (regrowth). Xenopus laevis, the African clawed frog, is a well-established model for both embryology and regeneration studies, especially for the eye. Xenopus eye development is well-defined. Xenopus is also an established model for retinal and lens regeneration studies. Previously, we demonstrated that Xenopus tailbud embryo can successfully regrow a functional eye that is morphologically indistinguishable from an age-matched control eye. In this study, we assessed the temporal regulation of retinal differentiation and patterning restoration during eye regrowth. Our findings showed that during regrowth, cellular patterning and retinal layer formation was delayed by approximately 1 day but was restored by 3 days when compared to eye development. An assessment of the differentiation of ganglion cells, photoreceptor cells, and Müller glia indicated that the retinal birth order generated during regrowth was consistent with that observed for eye development. Thus, retina differentiation and patterning during regrowth is similar to endogenous eye development. We used this eye regrowth model to assess the role of known mechanisms in development versus regrowth. Loss-of-function studies showed that Pax6 was required for both eye development and regrowth whereas apoptosis was only required for regrowth. Together, these results revealed that the mechanisms required for both development and regrowth can be distinguished from regrowth-specific ones. Our study highlights this developmental model of eye regrowth as a robust platform to systematically and efficiently define the molecular mechanisms that are required for regeneration versus development.

Raman spectroscopy on live mouse early embryo while it continues to develop into blastocyst in vitro

Laser based spectroscopic methods can be versatile tools in investigating early stage mammalian embryo structure and biochemical processes in live oocytes and embryos. The limiting factor for using the laser methods in embryological studies is the effect of laser irradiation on the ova. The aim of this work is to explore the optimal parameters of the laser exposure in Raman spectroscopic measurements applicable for studying live early embryos in vitro without impacting their developmental capability. Raman spectra from different areas of mouse oocytes and 2-cells embryos were measured and analyzed. The laser power and exposure time were varied and further embryo development was evaluated to select optimal conditions of the measurements. This work demonstrates safe laser irradiation parameters can be selected, which allow acquisition of Raman spectra suitable for further analysis without affecting the early mouse embryo development in vitro up to morphologically normal blastocyst. The estimation of living embryo state is demonstrated via analysis and comparison of the spectra from fertilized embryo with the spectra from unfertilized oocytes or embryos subjected to UV laser irradiation. These results demonstrate the possibility of investigating preimplantation mammalian embryo development and estimating its state/quality. It will have potential in developing prognosis of mammalian embryos in assisted reproductive technologies.

Development of the thalamus: From early patterning to regulation of cortical functions

The thalamus is a brain structure of the vertebrate diencephalon that plays a central role in regulating diverse functions of the cerebral cortex. In traditional view of vertebrate neuroanatomy, the thalamus includes three regions, dorsal thalamus, ventral thalamus, and epithalamus. Recent molecular embryological studies have redefined the thalamus and the associated axial nomenclature of the diencephalon in the context of forebrain patterning. This new view has provided a useful conceptual framework for studies on molecular mechanisms of patterning, neurogenesis and fate specification in the thalamus as well as the guidance mechanisms for thalamocortical axons. Additionally, the availability of genetic tools in mice has led to important findings on how thalamic development is linked to the development of other brain regions, particularly the cerebral cortex. This article will give an overview of the organization of the embryonic thalamus and how progenitor cells in the thalamus generate neurons that are organized into discrete nuclei. I will then discuss how thalamic development is orchestrated with the development of the cerebral cortex and other brain regions. This article is categorized under: Nervous System Development > Vertebrates: Regional Development Nervous System Development > Vertebrates: General Principles.

The aptness of antagonistic protocol in intracytoplasmic sperm injection: Embryologic study

Background and objective: Infertility and poor ovarian response are serious problems in our society; fortunately the in vitro fertilization and intracytoplasmic sperm injection technique dissolve many of these problems. This study aimed to assess the effect of an individualized GnRH antagonist regimen on intracytoplasmic sperm injection process especially the aptness of it in given mature reiterative oocytes, normal fertilization, and acceptably zygote cleavage which enhance pregnancy. Methods: The population of the study consisted of 877 couples attending the in vitro fertilization-infertility center in the maternity teaching hospital and chose to undergo intracytoplasmic sperm injection after using of antagonist protocol for stimulation of women ovaries. The women ages ranged between 24 and 44 years. The collected data included a number of reiterative oocytes; fertilization, embryo grades and lastly estimates the pregnancy results Results: A significant association (P <0.001) was found in the numbers of reiterative oocytes between the age groups of the study. A significant association (P = 0.005) was also found concerning to quality of fertilization process. The study of the zygote cleavage and blastomeres formation followed the fertilization show variable grade of embryos and analyzed data of embryo grades in this study indicate presence of significant association (P = 0.003). The rate of pregnancy showed significant association between the groups of the study with the <30 years age group have chance of pregnancy higher than other groups. Conclusion: The antagonist protocol of ovary stimulation according to the results of this study is a qualified protocol; besides it is rapid and can be reversed. This protocol can give effective results in the intracytoplasmic sperm injection process especially for young women, and enhance the pregnancy.

Ernst Haeckel's contribution to Evo-Devo and scientific debate: a re-evaluation of Haeckel's controversial illustrations in US textbooks in response to creationist accusations.

As Blackwell (Am Biol Teach 69:135-136, 2007) pointed out, multiple authors have attempted to discredit Haeckel, stating that modern embryological studies have shown that Haeckel's drawings are stylized or embellished. More importantly, though, it has been shown that the discussion within the scientific community concerning Haeckel's drawings and the question of whether embryonic similarities are convergent or conserved have been extrapolated outside the science community in an attempt to discredit Darwin and evolutionary theory in general (Behe in Science 281:347-351, 1998; Blackwell in Am Biol Teach 69:135-136, 2007; Pickett et al. in Am Biol Teach 67:275, 2005; Wells in Am Biol Teach 61:345-349, 1999; Icons of evolution: science or myth? Why much of what we teach about evolution is wrong. Regnery Publishing, Washington, 2002). In this paper, we address the controversy surrounding Haeckel and his work in order to clarify the line between the shortcomings and the benefits of his research and illustrations. Specifically, we show that while his illustrations were not perfect anatomical representations, they were useful educational visualizations and did serve an important role in furthering studies in embryology.