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PubMedDate not supplied

Contemporary issues in the regulation of artificial reproduction and embryology in the UK.

The Human Fertilisation and Embryology Act 1990 was one of the most comprehensive and flexible vehicles for regulation of artificial reproduction and embryology of its area. However, its serviceability has recently been brought into question by both the materialisation of unforeseen dilemmas and the response of legal actors to these dilemma's which has often been ethically and democratically deficient. Nowhere is this better demonstrated than in the reproach of the regulatory authority and judiciary to the use pre-implantation genetic diagnosis and cloning by cell nuclear replacement.

Cloning, Organism↗
PubMed2001

Unraveling the neuron jungle: the 1879-1886 publications by Wilhelm His on the embryological development of the human brain.

The neuron doctrine, one of the central paradigms of the neurological sciences, states that neurons are individual units. Wilhelm His helped to lay the scientific foundation for the neuron doctrine. This Swiss researcher's experimental approach, which was based on the examination of embryological material, is of particular interest because few investigators at that time were using it. Only selected excerpts from His' seminal 1886 work have been translated into English. Therefore, details regarding his experimental materials and primary observations are unavailable to the American reader. Our objective was to translate additional sections of the seminal 1886 publication and, when relevant, portions of previously untranslated works dating back to 1879 and 1883 so that we could better understand this embryologist's experimental materials, his primary observations, and the basis for his conclusions. By 1886, His had compiled a collection of 12 human embryos of various measured lengths and estimated gestational ages ranging from 2.15 mm to 24 mm, and 2 weeks to 8.5 weeks. He had studied the embryological development of nerve fibers in successively older specimens. For example, he contrasted the young embryo N, whose "nerves. stop only halfway and the distal part [of the extremity] is completely nerve-free," with the older embryo Zw, in which the nerves had already reached "the root of the fingers but none [were] in the territory of the end phalanges." In the 1870s and 1880s, using a discrete collection of 12 human embryos of consecutively older ages, His observed the development of nerve fibers and, from this pattern of growth, eventually suggested that nerve cells were individual units and that the transmission of impulses was possible without direct continuity between neurons. Although this age-based embryological approach seems relatively straightforward by today's standards, few other researchers were using it at the time.

Brain↗
PubMed1998

Embryologic bases of extended radical resection in pancreatic cancer.

OBJECTIVE: To analyze whether an embryologic "rationale" exists to the clinical and anatomicopathological data that suggest the execution of extended resections in patients with pancreatic cancer. METHODS: Reconstruction of serial histological sections of 18 human embryos and fetuses regarding the pancreatic region; anatomical microdissections of two 9-month fetuses. RESULTS: The ventral and dorsal pancreatic buds can be identified until the eighth week of development. A close developmental relationship between the dorsal pancreas and the lymphatic and nervous structures in the dorsal mesogastrium is observed. Other lymphatic stations are exclusively related to the ventral pancreas. The posterior fusion of the dorsal mesogastrium is a late event in embryologic development. CONCLUSIONS: The complete fusion of the 2 pancreatic buds occurs later than previously reported in the literature. The close embryologic relations of these buds with the lymphatic and nervous peripancreatic structures may support the need for extended resections in patients with pancreatic cancer.

Fetus↗
PubMed2000

Theoretical and analytical embryology of conjoined twins: part II: adjustments to union.

A previous report in this journal (Spencer, 2000) discussed the probable embryologic etiology of conjoined twins, along with a system of classification based on the embryological structures postulated to be involved in the union. Part II correlates and compares the variations in the abnormal development of the individual organ systems in more than 1,200 actual cases, revealing details of embryogenesis not considered in previous publications. The site, incidence, and range of anomalies in the conjoined structures, as well as the associated malformations, follow a definite pattern as the union proceeds from one area to another; many can be explained in relation to the proposed embryologic adjustments to union, including both temporal and spatial influences. In addition, six currently inexplicable or unclassifiable cases are briefly described (including one with 12 feet), as well as two examples of early abnormal conjoined twins.

Abnormalities, Multiple↗
PubMedDate not supplied

Embryologic concepts in the APUD system.

The amalgamation of the neural and endocrine physiologic mechanisms for functional homeostasis as a neuroendocrine system is brought into focus in this chapter on the embryologic concepts in the APUD system. The neuroendocrine system, now regarded as the third division of the nervous system, is a regulatory mechanism that links the functions of the autonomic nerves and the endocrine cells throughout the body. The current realization that both neural and endocrine actions are often involved in the clinical manifestations of many syndromes is clarified by the theories on the embryologic origin of the APUD system described here. Relevant historical developments, as well as cytochemical discoveries, have been gradually integrated into the evolving theories of the embryologic origin of the APUD system. These theories have not been without controversy, but new developments stimulate new concepts and, as new investigative tools have produced a plethora of new information that continues to push investigators, basic and clinical into new horizons, earlier theories have been modified and new theories have been developed. These theories are reviewed in chronological order in this chapter.

APUD Cells↗
PubMed1992

Conjoined twins: theoretical embryologic basis.

A theoretical basis for the embryology of conjoined twins was formulated from clinical experience with ten cases and extensive review of pertinent embryologic and clinical literature, including over 500 cases. Regarding the age old question of fusion or fission, it is concluded that there is no known embryologic process by which conjoined twins can be formed by fission but firm evidence to support fusion in all cases. Whether the fusion occurs between embryos on one embryonic disc or on two is of no consequence since they are all monovular. Intact ectoderm will not fuse to intact ectoderm, and all seven types of conjoined twins are explained by seven possible sites of union in the early embryo. One new term is proposed: parapagus, from the Greek para, meaning "side," combined with pagus, meaning "fixed"; this is the group formerly called dicephalus or diprosopos. These anterolaterally united parapagus twins must result from two nearly parallel notochords in close proximity; craniopagi and pygopagi from fusion at the cranial and caudal neuropores, respectively; cephalopagi and ischiopagi from union at the pharyngeal and cloacal membranes, respectively; thoracopagi from merging of the cardiac anlage; and omphalopagi from fusion of the umbilicus or of the edges of two embryonic discs in any area not including the above sites. Parasitic twins result from embryonic death of one twin, leaving various portions of the body vascularized by the surviving autosite. The rarity of cases (2) not easily explained by the above theories, and the nearly 6% of twins with two umbilical cords arising from the placenta would seem to support these conclusions. Should one wish to learn the methods of a conjurer, he might vainly watch the latter's customary repertoire, and, so long as everything went smoothly, might never obtain a clue to the mysterious performance, baffled by the precision of the manipulations and the complexity of the apparatus; if, however, a single error were made in any part or if a single deviation from the customary method should force the manipulator along an unaccustomed path, it would give the investigator an opportunity to obtain a part or the whole of the secret.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed2005

Embryology of the internal carotid artery dural crossing: apropos of a continuous series of 48 specimens.

The aim of this study was to describe the embryologic and foetal development of the anterior paraclinoid region and more precisely the relationship of the internal carotid artery to the dura mater. This has been done by examining a collection of histological sections, representing a continuous series of 48 embryologic and foetal specimens, covering the period of the first 6 months of intra-uterine life. Neurological and vascular elements develop during the embryologic period; the internal carotid artery is recognizable in the various sections of its course and acquires a histological adult parietal constitution. The foetal period corresponds to the development of the meningeal structures. The superior, medial and lateral walls appear on the fifteenth week of amenorrhoea and do not change after that. The internal carotid artery enters subarachnoid space accompanied by a sleeve of mesenchymatous cells, which fixes it to the anterior clinoid process. The constitution of this sleeve, arising from the superior wall of the lateral sellar compartment, remained independent of the principle vascular part, which allows the formation of a plan of cleavage. The foetal relations of the dura mater and the internal carotid artery were seen to be different from those of adult subjects described in the literature, suggesting an existence of period of maturation postnatally.

Carotid Artery, Internal↗
PubMed2003

Embryology of Siparunaceae (Laurales): characteristics and character evolution.

Embryological characters of Siparunaceae, which are poorly understood, were studied on the basis of two constituent genera, an African Glossocalyx and a South American Siparuna, to better understand their evolution within Laurales. These two genera have many embryological characteristics in common with the other lauralean families. Noticeably, they share the multi-celled ovule archesporium (uncertain in Glossocalyx) as a synapomorphy with all the other lauralean families except Lauraceae, the anthers dehisced by valves as a synspomorphy with all the other lauralean families except Calycanthaceae and Monimiaceae, and the bisporangiate anther as a synapomorphy with Gomortegaceae and Atherospermataceae. Siparunaceae are, however, distinct from all other laularean families in having unitegmic ovules that were derived from bitegmic ovules, probably due to an elimination of the outer integument. Likewise, the lack of the testa (i.e., developed outer integument), the "endotegmic" seed coat, and the perichalazal seed at maturity are also characteristics of Siparunaceae. Within the family, Siparuna differs from Glossocalyx in having plural tetrads of megaspores and plural, starchy-rich, one-nucleate, tubular embryo sacs (autapomorphies). On the other hand, Glossocalyx is characterized by having bilaterally flattened seeds (autapomorphy). Although functional aspects of those autapomorphies are uncertain, both Glossocalyx and Siparuna show evolution in different embryological characters.

Biological Evolution↗
PubMed2004

Embryology of Gomortegaceae (Laurales): characteristics and character evolution.

The embryological characteristics of Gomortegaceae, which are poorly understood, were investigated on the basis of Gomortega nitida, the only species of the family, to understand better the evolution of this group within Laurales. Comparisons with other Laurales and Magnoliales (a sister group of Laurales) show that Gomortega has many embryological features in common with the other lauralean families. Notably, Gomortega shares a testa without or with at best only a poorly developed mesotesta as a synapomorphy with all other Laurales. The genus further shares anthers dehisced by valves as a synapomorphy with the other Laurales (except for Calycanthaceae and Monimiaceae), and a non-multiplicative testa and bisporangiate anther as synapomorphies with Atherospermataceae and Siparunaceae (although the non-multiplicative testa occurs as a homoplasy in Monimiaceae, and the bisporangiate anther in Monimiaceae pro parte, Lauraceae pro parte and Hernandiaceae, respectively). Gomortega shows simultaneous cytokinesis to form pollen grains, a one-celled ovule archesporium and non-specialized chalaza, all or part of which may be synapomorphies shared with Atherospermataceae. Gomortega appears to have no embryological autapomorphies, but further comparison with Atherospermataceae is required.

Biological Evolution↗
PubMed1993

Immature endodermal teratoma of the ovary: embryologic correlations and immunohistochemistry.

Two grade 2 ovarian immature, predominantly endodermal teratomas are reported. The teratomas were in stage I and occurred in two girls, 9 and 10 years of age, who were treated with triple chemotherapy. These neoplasms differed from the usual immature ovarian teratoma as they contained no neuroectodermal components and had high alpha-fetoprotein and low human chorionic gonadotropin levels as their serum markers despite the absence of other concomitant germ cell tumors. The epithelia of the teratomas demonstrated exclusively the embryologic development of endoderm, ranging from early endoderm to tissues similar to esophagus, liver, and intestinal structures. All epithelial derivatives were positive for alpha-fetoprotein and alpha 1-antitrypsin. Liver and esophagus expressed fibrinogen, while intestine and esophagus were positive not only for carcinoembryonic antigen and chromogranins but also for thyroglobulin, thus reflecting yet another type of endodermal differentiation into thyroid. Focal human chorionic gonadotropin positivity associated with primitive intestinal and esophageal epithelia may reflect the early embryologic relationships between endoderm and trophoblast. These cases demonstrate that simultaneous alpha-fetoprotein and human chorionic gonadotropin secretion may occur in immature teratoma. The mesenchymal component also showed a wide range of differentiation, from primitive mesoblastic cells to differentiated cells, such as hemopoietic foci, smooth muscle, bone, and cartilage. Both the primitive endoderm and the mesenchyme co-expressed vimentin and keratin, reflecting their intimate developmental relationships and possibly supporting the hypothesis of mesenchyme originating from endoderm, as suggested by previous embryologic studies. Since endodermal and mesenchymal areas similar to those described here are found in association with yolk sac tumors and embryonal carcinoma, it is possible that the present cases may represent an endodermal differentiation accomplished by either of these developmentally related germ cell tumors.

Child↗
PubMed2005

Embryology of the adrenal glands and its relevance to diagnostic imaging.

An understanding of the embryology of the adrenal glands is necessary to appreciate the location of adrenal ectopic, or rest, tissue which can occur anywhere along the course of gonadal descent. This tissue usually has no clinical significance, but may become hyperplastic in patients with primary or secondary adrenal pathology. In congenital adrenal hyperplasia, hyperplastic rest tissue may present as a soft-tissue mass, particularly in the gonads and retroperitoneum, and may be mistaken for tumour. The adrenal in the neonate is proportionately much larger than in the adult; in renal ectopy or agenesis the ipsilateral adrenal is normally sited and may be mistaken for a kidney because of its size. This review article illustrates the embryology of the adrenal with particular emphasis on the relevance of embryology to pathology.

Adrenal Gland Neoplasms↗
PubMed2002

Thalamic neuron theory: meridians=DNA. The genetic and embryological basis of traditional Chinese medicine including acupuncture.

This hypothesis proposes a mechanism by which the genetic information contained in the one-dimensional genome may be converted into a three-dimensional body plan for development. Prior to mitosis of the fertilized egg, the chromatids, after being unpackaged from the chromosomes, link up to form a giant circular loop which is then folded upon itself into a wired-frame structure that embodies the architectural embryological developmental scheme. This intranuclear spatial body design is then translated into a three-dimensional cellar plan surrounding the fertilized egg with the positional value of each surrounding daughter cell preferentially activated by specific spatially oriented gene products diffused through the neatly arranged nuclear pores of the cell nucleus of the fertilized egg. This group of cells of the primitive embryo then leads to the formation of the Spemann Organizer, which directs embryological development of the brain as well as the rest of the body. The Spemann Organizer thus retains control over the CNS which in turn controls the development and functions of the peripheral tissues. The chains of cells that compose the Spemann Organizer, forming a homunculus in the image of the wired frame formed by the chromatids are believed to be the equivalents of acupuncture meridians. To support the hypothesis, evidence is also presented to substantiate the intimate relationships between the acupuncture meridians and embryological development, evolution, the central nervous system as well as the genome. This theoretical model is capable of dispelling the mystery of acupuncture, traditional Chinese medicine and myriads of modern clinical observations, and may have the potential to usher in a multitude of innovative therapeutic methods for many difficult to treat medical conditions.

Acupuncture↗
PubMed2002

Physio-mitotic theory and a new concept of embryological differentiation.

According to the physio-mitotic theory described previously by the authors (10,11), general mitosis consists of two different types: essential duplication and converted maturation. In general embryological differentiation, progression for the most fundamental blastocysts of the three germ layers to the immature stem cells comprising functional organic tissues is dependent on the essential duplication mitosis. This mitosis replicates stem cells while gradually initiating latent cellularities whereas the converted maturation process merely amplifies these latent cellularlities by maturing the basic cells in differentiated functional end cells with a pre-determined life span. The differentiation from the three-germ layer to embryologically organized tissues is dependent on duplication mitosis while being regulated by interactions with maturation mitosis. Thus, the complicated embryonic differentiation must be established in each type of organic tissue. During the process, these two types of mitosiseach play an antagonistic role in the embryological development of the other. This is another application of the physio-mitotic theory.

Animals↗
PubMed1993

[Comparison of vaginal and abdominal ultrasound measurements with embryologic growth curves in early pregnancy].

Body lengths and chorionic diameters of 225 early pregnancies with known fertilisation age, measured by transvaginal sonography (TVS), were compared with measuring results of measurements from abdominal ultrasound and of embryological specimen from the literature. The TVS measuring results were made according to the Carnegie classification. It is shown that the growth curve obtained by TVS is very similar to valid embryological growth curves, although the "Greatest Length" (GL) is measured by sonography not the Crown-Rump-Length (CRL). Between the sixth and eighth gestational week, the TVS curve shows strong resemblance to abdomino-sonographical curves. After that period, the TVS results tend to be systematically lower. The earliest TVS measurement of the human embryo in possible in the sixth gestational week, one week earlier than with abdominal ultrasound. There is a good correlation between the development of a structure and its earliest detection by TVS, active movements of the embryo can even be shown earlier than assumed by embryologists (stage 20/ninth week of gestation). Due to terminological reasons, in ultrasound the established term "Crown-Rump-Length" should be replaced by "Greatest Length". In a TVS-examination of an embryo (gestational weeks 4 to 11), morphological criteria must be additional contributions to the determination of maturity and integrity of a pregnancy. The application of the specimen-derived Carnegie classification to TVS measurements seem to be possible, as well as the utilization of TVS results in embryology.

Adult↗
PubMed1998

Murine duodenum does not go through a "solid core" stage in its embryological development.

Embryological development of duodenum is believed to go through a "solid core" stage which subsequently vacuolizes. Failure of vacuolization is thought to be the cause of duodenal atresia. This study examines the embryological development of rat duodenum. Thirty-six time-mated Sprague-Dawley rats were studied. Six fetal duodenal specimens were obtained for each gestational day from day 9 to day 20. These specimens were fixed with formalin, sectioned, stained with haematoxylin and eosin and examined under microscope. The duodenal diameters and the lumen diameters at each gestational date were measured. The foregut started to form at the gestation stage of day 10. The lumen was narrowest on days 12 and 13, but the duodenum did not become a "solid core". No vacuolization was detected through out the development of the duodenum. Embryological development of rat duodenum did not go through a "solid core" stage.

Animals↗
PubMed2000

Anatomical segmentectomy of the head of the pancreas along the embryological fusion plane: a feasible procedure?

BACKGROUND: Less extensive resection of the head of the pancreas has been the procedure of choice recently for low-grade malignant neoplasms. The anatomical detail of the head of the pancreas is currently insufficient for segmental resection along the embryological fusion plane. METHODS: The anatomy of the head of the pancreas was analyzed in 31 consecutive autopsy specimens. An anterior (n = 10) or posterior (n = 10) segmentectomy of the head of each pancreas was performed along the macroscopically found fusion plane. The pancreatic arteries, the portal vein, the bile duct, and the pancreatic duct were visualized by injecting 3 silicon dyes of different colors. Another 11 specimens were examined by pancreatography before and after anterior (n = 5) or posterior (n = 6) segmentectomy. Eight of these 11 specimens were stained immunohistochemically to reveal the distribution of pancreatic polypeptide cells after segmentectomy. RESULTS: The cleavage between the anterior and posterior segments was discovered at the anterior inferior edge or at the posterior superior edge of the head of the pancreas. Anterior segmentectomy was accomplished while preserving the anterior and posterior pancreaticoduodenal arcades and the lower bile duct in the posterior segment. Posterior segmentectomy involved the removal of the lower bile duct and the posterior pancreaticoduodenal arcades. Pancreatography after segmentectomy showed the division of the ducts of Wirsung and Santorini with the peripheral branches. The immunohistochemical boundary of pancreatic polypeptide cells coincided with the surgical plane. These results showed the anterior and posterior segments were originated from the embryologically dorsal and ventral primordia, respectively. CONCLUSIONS: The current anterior or posterior segmentectomy of the head of the pancreas corresponded to the resection of the embryologically dorsal or ventral primordium, respectively. Anterior segmentectomy of the head of the pancreas might be a clinically applicable procedure; however, posterior segmentectomy involving the resection of the lower bile duct may be impractical.

Adult↗
PubMed2000

Has clinical practice been changed by the Human Fertilisation and Embryology Act 1990?

The birth in 1978 of the first baby to be conceived through in vitro fertilization caused both wonder and controversy. Concerns that this technology would be abused led the Government of the United Kingdom to appoint a Committee of Enquiry into human fertilization and embryology, which led to the publication in 1984 of what has become known as the Warnock Report. This made recommendations on the creation of human embryos in vitro, the storage of human eggs, sperm and embryos, and research on human embryos. This report led eventually to the passing by Parliament of the Human Fertilisation and Embryology Act 1990 and the creation of the Human Fertilisation and Embryology Authority, which since 1991 has licensed and regulated all centres and practitioners of assisted reproductive technology. The effects of these regulations are considered in this article. Clinical practice has been affected by the Act, but it has generally led to higher standards of clinical and laboratory practice, improved patient information and care, and improved ethical standards.

Journal Article↗
PubMed2006

Experimental contributions to the study of the embryology of the vagina.

BACKGROUND: Acién's hypothesis, deduced from patients with malformations of the female genital tract, especially those with renal agenesis and ipsilateral blind hemivagina, affirms the embryology of the human vagina as deriving from the Wolffian ducts and the Müllerian tubercle and could explain the embryological origin of all the female genital malformations reported. In this study, we investigated the hypothesis in rats. METHODS: Twenty-five pregnant rats were used to analyse female embryos (64) from day 15 (stage indifferent) to day 20 postcoitum (vagina completely formed). We performed transverse and longitudinal sections of embryos, haematoxylin-eosin tinction and immunohistochemical staining using markers specific to Wolffian derivatives. We also analysed the presence of these markers in the vagina of four adult rats. RESULTS: The Müller ducts converge until they fuse into one tube, but caudally they diverge and finally they fuse with the 'urogenital sinus bulbs' that are actually the distal portion of the Wolffian ducts according to the immunohistochemical marking with GZ1 and GZ2. The Müllerian tubercle is observed between those elements. Then, the immunohistochemical staining can be seen all along the completely formed vagina, which is also observed in the vagina of the adult rat. CONCLUSION: We prove the participation of Müller tubercle and Wolffian ducts in the formation of the vagina in rats, so we confirm experimentally Acién's hypothesis about the human vagina embryology.

Animals↗