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PubMed1989

Embryology, ethology and ecology of ontogenetic critical periods in fish.

Overviews of critical period concepts, as they appear at several biological levels, are presented. In embryology, critical periods generally refer to restricted periods in development during which undifferentiated groups of cells can be induced to differentiate. In neurobiology, critical periods are those during which neural circuits are particularly plastic and subject to molding by cellular processes and by experience. The ethological critical period concept advances the idea that an individual's behavioral characteristics can be more strongly influenced by a given event (some stimulus) at one stage of development than at others. For example, this is the period during which young birds imprint upon their parent(s) and learn their species' songs, or during which young salmon imprint to the odor of their home streams. The fisheries science critical period, an ecological concept, refers to a restricted time in the early life history of fish during which there is massive mortality. For many fish, this event is generally considered the primary factor controlling the size of the adult population. The cause of variable mortality between years is thought to be a result of differential food availability and predation during a critical stage in early fish larval development. At each biological level of the critical period, spatial and temporal overlap between the developing organism and specific environmental input is essential. It is likely that critical periods in embryology, neurobiology and ethology are causally interrelated in a hierarchical manner and that they can be manifested as ecological critical periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Rib anomalies in myelodysplasia. An approach to embryologic inference.

An embryologic teratogenic mechanism is reconstructed by utilizing the distribution of anomalous ribs in children with lumbosacral myelomeningocele. This methodology may help to coalesce information from experimental models of teratogenesis and from descriptive human embryology. It provides an approach to deductive reasoning about human structural anomalies based on dynamic embryonic models of teratogenesis. Availability of a developmental time scale, based for example on the distribution of defective ribs, may be useful in the study of other teratogenic and developmental processes.

Abnormalities, Multiple↗
PubMed1982

Posterior urethral valves: theoretical considerations on embryological development.

Among congenital urethral malformations, posterior urethral valves represent one of the main causes of severe infravesical obstruction in children, the etiology and embryological development of which remains unclear. Posterior urethral valves of types I and III are supposed to be related to either the persistence of connective tissue along the pathway of migration of the Wolffian duct (type I) or a residual part of the endodermal urogenital membrane (type III). A possible reason for supramontane urethral valves (type II) is seen in the persistence of crest-shaped tissue along the ureter's pathway in embryological development to its final site, although there is some doubt as to the existence of type II valves and they were not seen in the 65 cases of posterior urethral valves in our own material.

Adult↗
PubMed1998

TNM glottic: role of the vocal muscle, arytenoid cartilage, and inferior paraglottic space in impaired vocal cord mobility (T2). An embryological and clinical study.

The TNM classification is unsatisfactory regarding the impaired mobility of the vocal cord and/or the arytenoid. The authors have studied the intrinsic laryngeal musculature, with particular attention to the medial thyroarytenoid muscle, the lateral thyroarytenoid muscle, and the inferior paraglottic space. The study was conducted on serial sections of 4 embryonal and 9 fetal larynges at different stages of development. The embryological observations showed that the lateral and medial thyroarytenoid muscles have different maturation times and probably different functions: phonatory and sphincteric. The authors have found that the inferior paraglottic space is situated between these 2 muscles. It would represent a path of diffusion for glottic cancer and play a central role in impaired vocal cord and/or arytenoid mobility, according to the degree of diffusion. Embryological observations have suggested the existence of laryngeal morphofunctional units belonging to the subsites of the glottic region and related to tumoral spreading.

Arytenoid Cartilage↗
PubMed2003

Clinical-embryological and radiological correlations of oculo-auriculo-vertebral spectrum using 3D-CT.

OBJECTIVES: The purpose of this paper is to present a variety of imaging findings of oculo-auriculo-vertebral spectrum (Goldenhar syndrome) using three-dimensional reconstructed images from computed tomography (3D-CT), associating clinical and embryological patterns of the syndrome. METHODS: The study population consisted of 10 patients with oculo-auriculo-vertebral spectrum with clinically identified hemifacial microsomia. The patients were examined using spiral CT, and abnormal imaging features were grouped under facial, ear and temporal bone, vertebral, and skull base anomalies. The original CT data were transferred to a networked computer workstation with a computer graphics system to generate 3D-CT volume rendered images of the skull and vertebra. Two observers analysed the bone and muscular setting protocols to assess the relationship between bone and muscular structures. RESULTS: Asymmetric underdevelopment was a characteristic pattern of this syndrome resulting from hypoplasia of the mandibular ramus and condyle, the zygomatic, sphenoid and auricular conduct bones, and the temporal and masseter muscles. The syndrome was associated with local atrophy seen on 3D-CT images using specific bone and muscles protocols in all cases. CONCLUSIONS: Understanding the aetiology, embryology and wide imaging spectrum of this syndrome is essential to make a correct diagnosis, for treatment planning, and for evaluation when associated with a 3D-CT computer graphics system.

Adolescent↗
PubMed1979

The influence of embryology of the mid-face on the spread of epithelial malignancies.

A review of 150 cases of mid-face skin cancers treated by the fresh tissue technique of microscopic controlled excision has revealed local epithelial cancer spread to be markedly influenced by embryological fusion planes. Knowledge of facial embryology which is reviewed in this article should allow the surgeon to better predict and treat mid-facial skin cancer.

Adult↗
PubMed2002

"Absent" pulmonary artery in one adult and five pediatric patients: imaging, embryology, and therapeutic implications.

OBJECTIVE: The purpose of this article is to present serial clinical and imaging findings for the "absent" pulmonary artery. Data from six patients with this condition (five unilateral cases and one bilateral case) provide evidence concerning its embryology and illustrate the therapeutic implications of surgical intervention. CONCLUSION: In our series, we found the anatomy of the absent pulmonary artery to be consistent with a distal ductal origin and involution of the proximal sixth aortic arch. The absent pulmonary artery is a distinct embryologic entity that requires early detection and detailed investigation. Early surgical intervention may be justified in selected patients.

Adult↗
PubMed1993

The embryologic development of the human anterior nasal aperture.

During the final period of embryogenesis, the nasal pit is clearly apparent in the Carnegie stage 15 embryo, and extends backwards into the oral cavity forming the nasal sac. In the stage 19 embryo of about 7 weeks, abundant epithelial proliferation into the lumen forms the nasal meatal plug. The complete recanalization of this meatal plug occurs in the 16-17 week fetus, and not in the 24th week of fetal life as is generally accepted in textbooks on human embryology. The findings of the present study of the embryology of the anterior nares can well explain the anomalies of the human anterior nares aperture.

Embryonic and Fetal Development↗
PubMed1994

Use of the four-and-a-half clearing technique to study gymnosperm embryology: Cunninghamia lanceolata.

Since its introduction in 1971, the four-and-a-half clearing technique has been widely applied to the study of ovule and female gametophyte development in flowering plants as an alternative to the more arduous paraffin section methods. The technique has undergone several modifications that have broadened its application in studies of Angiosperm embryology. To date, however, the technique has not been successfully applied to embryological features of Gymnosperms. Dark coloration caused by naturally occurring substances and by-products of fixation render the clearing fluid ineffective, and special pretreatment methods used to remove dark substances in Angiosperm ovules have little or no effect on Gymnosperm material. In the technique reported here, paraffin sections of ovules and young seeds of Cunninghamia lanceolata 80-120 microns thick are cleared in benzyl benzoate-4 1/2 clearing fluid and examined with phase contrast optics. Observations of the mature female gametophyte in these cleared preparations are compared with those obtained from 10 microns sections, stained with safranin and fast green, and examined with bright-field optics. Although contrast and definition are more pronounced in stained sections than in cleared ones, the differences would not alter one's interpretation of characteristic structural features. The thick, cleared section offers an advantage over the thin, stained one in that many structural entities are contained within a single section rather than spread through several serial sections. The time required for clearing thick sections is much shorter than that required for making permanent stained preparations.

Microscopy↗
PubMed2006

Incomplete Currarino triad as an embryological variant. Case report and review of the literature.

Currarino triad is a rare embryological complex of congenital caudal anomalies, including anorectal malformation, sacral osseous defect, and presacral mass, that results from abnormal separation of the neuroectoderm from the endoderm. The authors present an unusual case of a patient who had, in addition to the classic features of this syndrome, holocord syringomyelia, low conus medullaris, and tethered cord demonstrated by magnetic resonance imaging. They also discuss the embryological significance of this clinical entity and briefly review the relevant literature.

Child↗
PubMed2002

The human fetal venous system: normal embryologic, anatomic, and physiologic characteristics and developmental abnormalities.

OBJECTIVE: The introduction of high-resolution ultrasonography combined with color-coded Doppler imaging offered a breakthrough in the evaluation of the human fetal venous system, considerably enhancing our understanding of fetal venous circulation in normal physiologic conditions, as well as providing us the ability to study circulatory changes in abnormal circumstances. The purpose of this study was to describe the normal anatomic development and complex of anomalies of the human fetal venous system and to review recently published series of these anomalies. METHODS: Normal embryologic and anatomic development is described. An English language literature search of recent MEDLINE listings was performed to glean data from recently published series reporting prenatal diagnosis of the various anomalies and their associated malformations. RESULTS: Anomalies of the human fetal venous system occur sporadically, often associated with cardiac or other malformations. The pathophysiologic mechanisms leading to abnormal in utero development of the human venous system remain largely undetermined. On the basis of the type of vein involved, embryologic precursor, and etiologic correlation (primary or secondary), classification into 4 major groups is described. CONCLUSIONS: Prenatal evaluation of fetuses found to have anomalies of the venous system should include a careful search for cardiac anomalies, including pulmonary venous drainage, and a detailed anatomic survey of the umbilical, portal, hepatic, and ductal systems to determine aberrant communication and, if possible, to discover clues to systemic diseases or thromboembolic phenomena.

Ductus Arteriosus↗
PubMed2006

Fetus in fetu and fetaform teratoma in 2 neonates: an embryologic spectrum?

OBJECTIVE: The purpose of this study was to describe the imaging and pathologic findings of 2 cases of complex neonatal abdominal masses and to discuss the probable common embryologic etiology of fetus in fetu (FIF) and fetaform teratomas. METHODS: Two male neonates had complex cystic abdominal masses, 1 of which was diagnosed prenatally, and both had abdominal sonography. One patient also had abdominal computed tomography. Both patients subsequently underwent surgical resection, with pathologic and genetic analysis of these masses. RESULTS: One patient had typical imaging, pathologic, and genetic findings of FIF. The second patient had a well-formed mass that was diagnosed pathologically as a teratoma yet had most of the criteria for FIF that have been set forth in recent embryologic literature. CONCLUSIONS: Recent concepts regarding the origin of FIF suggest that it is part of a spectrum of monozygotic twinning gone awry, ranging from conjoined twins at one end to fetaform teratomas at the other. The imaging and pathologic features of these 2 cases serve to reinforce this concept.

Adult↗
PubMed1999

Anterior choroidal artery supply to the posterior cerebral artery distribution: embryological basis and clinical implications

OBJECTIVE AND IMPORTANCE: We report four cases of anomalous anterior choroidal artery supply to the temporal, parietal, and occipital cortical regions normally supplied by branches of the posterior cerebral artery. Three of these cases were associated with significant intracranial vascular pathology. We examine the embryological basis for the anomalous vascular anatomy to emphasize the potential variability of the anterior choroidal artery distribution and illustrate the spectrum of this variability angiographically. These variants may also have significant implications for surgical and endovascular treatment. CLINICAL PRESENTATION: One patient was diagnosed with an arteriovenous malformation, and two patients were diagnosed with aneurysms, one of which presented with a subarachnoid hemorrhage. INTERVENTION: The patient with the arteriovenous malformation underwent preoperative embolization and surgical resection, one patient with an aneurysm was treated via surgical clipping, and the other aneurysm underwent endovascular coiling. CONCLUSION: This group of patients illustrates an underemphasized but potentially important vascular anomaly. Phylogeny and embryology of the intracerebral vessels suggest a mechanism related to transposed distributions. Careful attention must be directed to the microvascular anatomy of the intracerebral circulation so that these anomalies are recognized and, if necessary, factored into surgical and interventional planning.

Journal Article↗
PubMed1999

A developmental and evolutionary analysis of embryology in Platanus (platanaceae), abasal eudicot.

The Platanaceae are an early derived eudicot lineage and therefore occupy a key position for understanding reproductive character diversification associated with the early evolutionary radiation of flowering plants. We conducted an embryological study of Platanus racemosa in order to provide critical data on defining angiosperm reproductive characters for this important group. Female gametophyte development is monosporic. Embryogenesis occurs in a series of stages including zygote elongation and division, development of a linear proembryo, formation of the embryo proper, histogenesis, organogenesis, and growth. Endosperm development is a complex process that includes four distinct phases: free nuclear proliferation, cellularization of the chalazal zone, centripetal cellularization of the micropylar zone, and cellular differentiation and growth. Only the outer endosperm layer persists at seed maturity. Our findings differ significantly from previously published reports for Platanus, in which endosperm development was described as ab initio cellular. A comparison of endosperm development in Platanus with several closely and distantly related free nuclear taxa reveals considerable developmental variability, consistent with a hypothesis of multiple origins of free nuclear endosperm in angiosperms. Our analysis indicates that much remains to be learned about embryology in basal angiosperms. Additional developmental and comparative studies will likely reveal critical insights into the early evolution of flowering plants.

Journal Article↗
PubMed1999

Lower auricular malformations: their representation, correction, and embryologic correlation.

Seventy-seven lower auricular malformations in 74 patients treated during the last 6 years were analyzed. Sixty cases (77.9 percent) were of malformations involving the earlobe; 54 cases involved the earlobe alone, and 6 cases were of complex deformities involving the earlobe and adjacent helix and/or tragus. Cleft earlobe was the most common lower auricular malformation (49 cases, 63.6 percent); four subtypes and their corrective methods are described. Cases of complex earlobe malformations, corrected by fabricated costal cartilage and expanded skin flap, are presented. A question mark ear (5 cases, 6.5 percent), a malformation with an ectopic anthelical fold (5 cases, 6.5 percent), and a malformation with a lower conchal stria (5 cases, 6.5 percent) are considered to be major lower auricular malformations. An attempt has been made to correlate the presented malformations with the embryologic-fetal development of the auricle. It is suggested that "clefting" ear malformations such as the cleft earlobe, the question mark ear, and the ectopic anthelical fold deformity may provide clues to understanding the embryologic-fetal development of the human auricle. It appears that hillocks 1 and 6 produce the earlobe and that hillock 4 or 5 produces the anthelix or helix.

Adolescent↗
PubMed1998

[Embryology of the human carpal bones (triangular cartilage, central carpal bone, morphogenesis of the scaphoid)].

Wax reconstructions according to Born's methods were performed from serial 10-micron sections of the wrists of human embryos (B. Tardif) to study the triangular cartilage and central bone of the carpus. A subsequent morphological study of the adult scaphoid bone was conducted in the light of embryological data. The triangular cartilage was observed in 4 of 38 carpi of embryos with a craniocaudal length of 40 to 69 mm, flatten between the ulna and triquetrum, on the inferior surface of the mesenchymal bud of the triangular ligament. The central bone of the carpus is constant in the embryo, between the inferior surface of the radial chondrification centre, capitatum, trapezium and trapezoid. In one case, the two wrists of the same embryo presented two central nuclei, leading to the distinction of two different formations:--the constant C2 embryonic central bone, trapped between capitatum, trapezoid and trapezium, which participates in the constitution of the scaphoid by fusion with the radial chondrification centre;--the C1 central bone, a rare supernumerary bone in adults, close to the inferolateral angle of the lunatum, on the dorsal surface of the carpus. These embryological data support. Westoll's theory concerning the filiation of the thoracic limb since the fin of crossopterygians, with deviation of the mechanical axis related to the development of weightbearing on the ground. The scaphoid bone must to be assimilated to a cube, but to an irregular tetrahedron, composed of two inverted pyramids joined by their bases. The inferior pyramid, articulating with he trapezium, trapezoid and capitatum, is concerned by morphological variations of the bone, which can present variable configurations between the two extreme morphotypes: the massive type and the strangulated type. The inferior pyramid, constituting the scaphoid, is derived from the central cartilage and presents the same relations. Variations of the volume of this inferior part of the bone are related to the more or less marked regression of this chondrification centre of the embryonic carpus. These variations of the bone can be expressed in terms of a scaphoid index, by calculating the relationship between the greatest dimension and the width of the narrowed portion.

Adult↗
PubMed2000

Embryology of dolphins. Staging and ageing of embryos and fetuses of some cetaceans.

Comparative embryology has been neglected in the past decades. In our opinion the decreased interest has been caused by the fact that the time factor has not sufficiently been respected. Therefore we used the Staging and Ageing Method (Stĕrba 1999) to determine the ontogenetic age of embryos and to state the time tables and time relations of various ontogenetic events. We examined 167 embryos and fetuses of four dolphin species (collection Dr. Senckenbergische Anatomie, Frankfurt am Main). The study of intrauterine development and growth while consistently respecting the time factor enabled us to determine the time course of organogenesis of all organ systems. The resulting comparison with other mammals detected the time lag in ossification, retardation of odontogeny, the time of the origin and development of the fluke, dorsal fin and flipper, etc. We believe the Staging and Ageing Method serves for a much more efficient evaluation of existing embryological collections which very often contain embryos of unknown age.

Animals↗