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PubMed2007

A history of normal plates, tables and stages in vertebrate embryology.

Developmental biology is today unimaginable without the normal stages that define standard divisions of development. This history of normal stages, and the related normal plates and normal tables, shows how these standards have shaped and been shaped by disciplinary change in vertebrate embryology. The article highlights the Normal Plates of the Development of the Vertebrates edited by the German anatomist Franz Keibel (16 volumes, 1897-1938). These were a major response to problems in the relations between ontogeny and phylogeny that amounted in practical terms to a crisis in staging embryos, not just between, but (for some) also within species. Keibel's design adapted a plate by Wilhelm His and tables by Albert Oppel in order to go beyond the already controversial comparative plates of the Darwinist propagandist Ernst Haeckel. The project responded to local pressures, including intense concern with individual variation, but recruited internationally and mapped an embryological empire. Though theoretically inconclusive, the plates became standard laboratory tools and forged a network within which the Institut International d'Embryologie (today the International Society of Developmental Biologists) was founded in 1911. After World War I, experimentalists, led by Ross Harrison and Viktor Hamburger, and human embryologists, especially George Streeter at the Carnegie Department of Embryology, transformed Keibel's complex, bulky tomes to suit their own contrasting demands. In developmental biology after World War II, normal stages-reduced to a few journal pages-helped domesticate model organisms. Staging systems had emerged from discussions that questioned the very possibility of assigning an embryo to a stage. The historical issues resonate today as developmental biologists work to improve and extend stage series, to make results from different laboratories easier to compare and to take individual variation into account.

Anatomy, Artistic↗
PubMed1985

Bilateral distribution of implantation sites in small mammals of 22 North American species.

The distribution of activity between the left and right sides of the reproductive tract, as measured by numbers of CL, embryos and placental scars, was studied in small mammals of 22 species. Shrews ovulate from the two ovaries in a distribution that does not differ from the binomial. Implantation of blastocysts in the two uterine horns is more nearly even ('balanced') than would be predicted from the binomial distribution. Balance in this group apparently is achieved by transuterine migration of blastocysts, perhaps in conjunction with some spacing mechanism within the uterus. Some cricetid rodents show little or no balance, but in others the distribution of activity sites (embryos, CL and placental scars) departs significantly from the binomial distribution. Reproductive activity sites of heteromyid and geomyid rodents (Geomyoidea) are highly balanced; uterine balance apparently is achieved by means of ovarian rather than uterine control. We know of no previous reports of ovarian balance and suggest that physiological mechanisms controlling numbers of ovulations in the species exhibiting this characteristic may differ from those in species exhibiting a random distribution of ovulation sites. Hypotheses regarding evolutionary aspects of balance are considered in phylogenetic and ecological terms, generating several testable research questions for physiologists, anatomists, and evolutionary ecologists.

Animals↗
PubMed1990

CT appearance of the retroaortic anastomoses of the azygos system.

The terminations of the hemiazygos and accessory hemiazygos veins can be mistaken for normal or enlarged posterior mediastinal lymph nodes on CT scans of the chest. These terminations are termed the retroaortic anastomoses by anatomists. We studied the CT appearances of these veins on scans of one cadaver and seven patients. We found that the retroaortic anastomoses usually were clearly recognizable because of their continuity with the hemiazygos or accessory hemiazygos vein. However, it is sometimes possible to mistake these vessels for lymph nodes, especially when only short segments of the vessel are visible on a CT image or when the vessel is not clearly opacified by contrast material. Familiarity with the CT appearances of the hemiazygos and azygous veins can prevent their being mistaken for normal or enlarged lymph nodes.

Azygos Vein↗
PubMed1998

Signaling events during male germ cell differentiation: bases and perspectives.

In all species, reproductive function depends on the ability of the individual to produce functional differentiated gametes. Spermatogenesis is a cyclic process in which diploid spermatogonia differentiate into mature haploid spermatozoa. Thus from a genetic point of view, spermatogenesis can be divided into two phases, namely the diploid and haploid phase. Indeed, this complex differentiation process is still more intriguing since primary spermatocytes, if genetically diploid, are functionally tetraploid, while elongating spermatids, the germ cells undergoing the most dramatic morphological changes, if genetically haploid, become functionally anucleate due to ongoing condensation of chromatin resulting in an inactive nuclear DNA. This multi-step differentiative pathway is dependent on a specific environment provided by the anatomical and cellular relationships that take place in the testis and more specifically within the seminiferous tubules. Already, early anatomists (mind comes to Enrico Sertoli and Gustaf Retzius) were fascinated by the mixed cellular composition of the testis correctly deciphered as a whole of interacting and interdependent cell types despite the fact these belong to two well-established and different cell lineages, i.e, the somatic and germinal line. Since their time (the XIX century) up to-day a conspicuous bulk of experimental work and a relative massive bibliographic documentation have been provided. From this it stands out : a) a sophisticated role played by the cyclic hormonal control elicited by the hypothalamic-pituitary axis; b) the structural membrane specializations of Sertoli-germ cell communications; c) the existence and action of a paracrine and autocrine testicular regulative secretion; d) a regulation of germ cell gene expression, highly specialized both at transcriptional, posttranscriptional, and translational level; e) an active participation of the haploid genome in the final steps of cell differentiation. Each of these points has been the matter of several more and less recent reviews to which the present author hands back in the course of this note. However all these points, although topics of separate and extensive treatises, are conceptually jointed by a 'leit-motiv', that is, the intracellular transduction of an exogenous signal evoking a specific stimulatory/inhibitory, proliferative/differentiative event. The spirit with which the present author interpreted this minireview was to recall some points to which to draw attention having as a scenario the complex process of male germ cell differentiation in mammals.

Animals↗
PubMed1989

Centers of rotation during jaw movements.

Anatomists consider the articulation of movable joints to be complex, involving movable instantaneous centers of rotation (ICR). However, prosthodontists often treat the temporomandibular joint (TMJ) as a model of a simple hinge. The aim of this study was to examine the case for a movable ICR during habitual opening and closing jaw movements. Young, dentate subjects were examined with a kinesiograph. Jaw movements were performed and recorded. The center of rotation of each movement pattern was identified, and its location related to the position of the TMJ. The results showed that opening and closing jaw movements were predominantly non-coincident, with a movable ICR located at a variable distance and direction from the TMJ. There was no evidence to suggest that the TMJ functioned as a simple hinge during jaw movements.

Adult↗
PubMed1993

How we teach anatomy efficiently and effectively.

An anatomy course is presented which stresses the teaching of applied anatomy using lectures, laboratory workshops and problem-solving tutorials. Laboratory workshops include the use of prosected specimens and body imaging such as CT scan and ultrasound, but do not include dissection. The problem-solving tutorials make extensive use of clinical cases and the application of anatomical knowledge. The course is taught by anatomists and practising physicians, and needs only 98 hours of curriculum time. The performance of the students and the positive attitudes of both students and faculty are enhanced by the design of the course.

Anatomy↗
PubMed1982

The mesothelium and its reactions: a review.

The origins, nature, and reactions of the mesothelium have intrigued investigators for over 100 years. Recently, the use of sophisticated techniques has clarified earlier impressions of its development, structure, and function. The structure of mesothelium reflects its functional properties, its long slender microvilli entrapping a layer of glycosoaminoglycans, providing a frictionless free surface between the parietal and visceral serosa. Transport requirements are met by various surface modifications and both inter- and intra-cellular mechanisms occur. The presence of stomatal openings in the mesothelial membrane has been established, and they may have a major role to play in the movement of cells to and from the serosal cavities. In addition, mesothelial cells can respond to situations of increased functional demand and during the course of inflammation, the mesothelium's fibrinolytic properties are of major importance in preventing the formation of adhesions and the enhancement of healing. Of all the unanswered questions the most significant is the nature, localization, and potentialities of mesothelial precursors. A mesodermal origin is readily acknowledged, but the healing process of damaged mesothelium is less clear. It seems probable that "mature" mesothelium is one source of cell renewal, but mesenchymal cells located in the submesothelial serosa are also strong contenders. Neoplastic mesothelium can adopt a spectrum of histological appearances, reflecting its mesodermal origins. In fact, overacceptance of this concept has erroneously led to the classification of other neoplasms arising in the serosal area as mesotheliomas. Although the ocogenic sequence is still obscure, asbestos is recognized as the major etiologic agent in malignant mesotheliomas. In 1955, Hartwell described differing impressions of the peritoneum as seen through the eyes of an anatomist, an histologist, and a surgeon. In this review on the mesothelium we have attempted to unravel some of its complexities as viewed by embryologists, electronmicroscopists, cell biologists, pathologists, and oncologists.

Biological Transport↗
PubMed1977

Entrapment of median nerve by supracondylar process of the humerus. Case report.

The supracondylar process of the humerus has been described by anatomists and anthropologists in man and lower animals. Infrequently this process may cause compression of the median nerve. We are presenting such a case along with a brief review of the literature. Excision of the bone process led to immediate disappearance of symptoms.

Adult↗
PubMed1992

The death of Henry II of France.

On June 30, 1559, King Henry II of France (1519-1559), against the advice of his court ministers, participated in a fateful joust. The wooden lance of his younger opponent pierced the King's headgear, shattered into fragments, and penetrated his right orbit and temple. The King survived for 11 days following the mortal wound and was treated by two of the most distinguished physicians of the Renaissance: Ambroise Paré (1510-1590), the master surgeon, and Andreas Vesalius (1514-1564), the great anatomist. The unfortunate event, the nature of the injury, and the medical consultation between these eminent physicians should all be of interest to neurosurgeons. The historical consequences of this event are briefly reviewed.

Brain Injuries↗
PubMed1995

Luigi Rolando and his pioneering efforts to relate structure to function in the nervous system.

The fissure separating the motor from the sensory cortex and the substantia gelatinosa capping the posterior horn of the spinal cord are still known by the name of the Italian anatomist Rolando, Luigi Rolando was born in Turin, Italy, in 1773 and died in 1831. His life was not easy, the first of his problems being the death of his father when Rolando was still very young. Three people were to be influential in his life and career: Father Maffei, his maternal uncle who raised him; Dr. Cigna, the anatomy professor who discovered his talent; and Dr. Anformi, a general practitioner who introduced him to the practice of medicine and to the best circles of the city. Forced to leave Turin by the Napoleonic invasion of the country, Rolando first stopped in Florence, where he learned about anatomical dissection, drawing, and engraving and studied the appearance of nervous tissue under the microscope. Later he went to Sardinia where, although cut off from European cultural circles, he developed his major theories. Rolando pioneered the idea that brain functions could be differentiated and located in specific areas and discovered the fixed pattern of cerebral convolutions, highlighting motor and sensory gyri. He demonstrated the complexity of the central gray matter of the spinal cord, describing the "substantia gelatinosa," and he deduced that nervous structures are connected in a network of nervous fibers linked by electrical impulses. Rolando had to struggle for recognition, however, as the priority of his discoveries was challenged by the almost contemporaneous work of Gall and Spurzheim on cerebral localization and of Flourens on cerebellar function. Nevertheless, his efforts contributed greatly to the clarification of brain function. His observations on nervous anatomy have been especially accurate, as shown by the nomenclature "fissure of Rolando."

History, 19th Century↗
PubMed2003

Bilateral sternalis with unusual left-sided presentation: a clinical perspective.

An unusual variation creates interest among anatomists, but is a cause of concern among clinicians when it mimics a pathology. The sternalis muscle is one such variant of the anterior chest wall located subcutaneously over the pectoralis major, ranging from a few short fibers to a well-formed muscle. We observed a bilateral case, which was accompanied by an atypical presentation on the left side where a huge, bulky sternalis muscle was associated with the absence of the sternal fibers of the pectoralis major. The fibers arose as a lateral strip from the upper two-thirds of the body of the sternum and costal cartilages 2 through 6 with the intervening fascia and aponeurosis of the external oblique. The right sternalis was strap-like and was placed vertically over the sternal fibers of the pectoralis major, arising from the underlying fascia and aponeurosis of the external oblique. The sternalis muscles, on each side, converged into an aponeurosis over the manubrium that was continuous with the sternal heads of the right and left sternocleidomastoid muscle, respectively. This rare anomaly has puzzled radiologists and surgeons in confirming diagnosis, missing it all together or mistaking it for a tumor on mammography or CT scan. These findings prompted us to review its topography, development, and application in relation to the anterior chest wall.

Adult↗
PubMed1989

Distal first metatarsal epiphysis. A common pediatric variant.

While most anatomists have referred to a distal epiphyseal growth plate in the first metatarsal as rare or occasional, one definitive study has shown this accessory growth center to be extremely common in children under the age of 12 years. The authors discuss the significance of this phenomenon, and present a literary review, a clinical case report, and a retrospective radiographic study of 217 pediatric feet, confirming the incidence of the distal growth plate.

Child↗
PubMed1993

The ventricles of the brain in the N. American mink (Mustela vison (Brisson, 1756)).

Using anatomical as well as radiographic and tomographic methods, sixty brains of the N. American mink were examined. It was found that the brain consists of four ventricles. Also, it was noted that the posterior horn was missing and that there was the olfactory recess present in the lateral ventricle, a large-size interthalamic connection present in the third ventricle, and a flat, necklace-like bottom in the fourth ventricle. Only recently, the ins and outs of the mink's anatomical structure have begun to absorb anatomists. Apparently, it is related to the fact that furry animals, among them the mink, are being domesticated as if "before our eyes". For this reason and because of the easy access to material, examining of the brain ventricles in the mink was taken up.

Animals↗
PubMed1999

Anatomy education in a changing medical curriculum.

How we educate students in the first two years of medical school is changing at many institutions. Effective medical education should be viewed as a continuum, integration of the basic sciences and clinical medicine should occur throughout the curriculum, and self-directed, life-long learning should be emphasized. Curricular revision may be appropriate if these fundamental concepts are absent. The principles of three curricular models are discussed: traditional, problem-based, and systems-oriented. The ideal curriculum may draw from each of these: A truly integrated curriculum. However, the curricular model chosen must meet the needs of the institution and its students. As anatomists we should not shy away from this process of change. With progressive educational approaches, we can be leaders in this climate of curricular reform. Anatomy courses are laboratory based and the laboratory is an outstanding small group, faculty/student interactive opportunity. However, we must show flexibility and innovation in our educational approaches whatever the curricular design being proposed.

Anatomy↗
PubMed1999

[The biphalangy of the thumb. General review of the literature].

The thumb has only two phalanges whereas the other fingers present three. For two millennia, many anatomists tried to solve this riddle. Four different theories can be found in the review of literature, to explain what element misses in the radial column. In the first theory (Galen), the first metacarpal should be the proximal phalanx of the thumb. The particular ossification of the first metacarpal advocates for this theory. In the second theory (Sappey), the first metacarpal should result from the fusion between the true first metacarpal and the proximal phalanx of the thumb, and the proximal epiphysis should be constituted from both metacarpal and phalangeal parts. In the third theory (Paturet), the middle phalanx is thought to be missing. Apart morphological considerations, the main argument refers to symbrachydactyly, which consists in decreasing digital ray length (by reducing the middle phalanx), and usually affects digits excluding the thumb. In case the thumb is affected (in complex symbrachydactylies), the reduction concerns thus the first metacarpal, suggesting that the thumb middle phalanx has already disappeared. In the fourth theory (Pfitzner), the distal phalanx of the thumb should result from the fusion between the second and third phalanges of the thumb. This mechanism, named symphalangy, is well known in the foot, especially in the fifth toe, but also for the other toes, and even in the two ulnar fingers.

Humans↗
PubMed1999

[Clinical anatomy in the operating room. A model of integrated medical education].

Clinical relevance of theoretical knowledge is advantageous to be demonstrated early during preclinical education in medical schools. We describe a new way for anatomists and surgeons of teaching anatomy together during surgical procedures in the operating theatre, thus demonstrating successfully the need of keen insight in the field of gross anatomy. The students reported to be motivated to learn anatomy. A questionnaire was completely answered by 24 students after having finished the 96/97 course of anatomy in the operating theatre. The students reported that they have learned a lot as well as to be highly motivated to continue their efforts of gaining knowledge on the field of gross anatomy because of its clinical relevance.

Anatomy↗
PubMedDate not supplied

Plus ça change ... from rinderpest to bovine spongiform encephalopathy.

Cattle plague (rinderpest) caused serious loss of cattle in Europe up to the beginning of the 20th century. Effective control measures were developed in the 18th century by Lancisi in Italy and Vicq d'Azyr in France long before the viral nature of the disease was understood. Similar measures are used to control BSE, which unlike rinderpest, also infects man. Much can be learned from earlier work on such problems as failure to notify outbreaks, inadequate application or deliberate evasion of control measures, and the value of compensation. Still renowned as a comparative anatomist, Vicq d'Azyr not only practised comparative medicine but as permanent secretary of the Societé Royale de Médecine in Paris (1776-1793) developed a national scheme for collecting public health data. His views on how doctors face an unknown disease and on the problems of administration could have been written today.

Animals↗