scholarly journals The intracranial vascular system of sphenodon

This memoir contains a detailed description, with illustrations, of the intracranial blood-vessels of the Tuatara, of which no account has hitherto been published. The description is belived to be more complete than any hithero given for any reptile, and a considerable number of vessels are described which have not hithero been noted in Lacertilia. This comparative completeness of detail is largely due to the employment of a special method of investigation. By this method the entire contents of the cranial cavity are fixed and hardened in situ , and are then in excellent condition either for dissection or for histological purposes. The brain does not occupy nearly the whole of the cranial cavity, there being a very large subdural space (especially above the brain), across which many of the blood-vessels run, together with delicate strands of connective tissue which connect the dura mater with pia. The eyeballs are removed and an incision is made on each side in the cartilaginous wall which separates the cranial cavity from the orbit. Acetic bichromate of potash (made up according to the formula given by Bolles Lee) is injected in to the cranial cavity through these incision, and the entire animal, after opening the body cavity, is suspended in a large volume of the same fluid for about five days, and then graded up to 70 per cent. Alcohol. When the cranial cavity is now opened up the cerebral vessels are seen with extraordinary distinctness, although they have not been artifically injected. Futher details were made out by means of serial sections, both transverse and longitudinal, and both of the adult and of advanced embroyes (Stage S). In most respect the arrangement of the intracranical blood-vessels agrees with found in the Lacertilia, so far as these have been investigated, but there is an important difference in the fact that the posterior cephalic vein leaves the cranial cavity through the foramen jugulare and not through the foramen magnum, while a slightly more primitive condition is shown in the less complete union of the right and left halves of the basilar artery. Sphenodon makes some approach to the condition of the Chelonia in this latter respect, but differs conspicuously from this group in the fact that the circle of Willis is not completed anteriorly, as well as in the fact that no branch of the posterior cephalic vein leaves the cranial cavity through the foreman magnum. A very characteristic features of Sphenodon is the development of large transverse sinues resembling those of the crocodile, but these communicate with the extracranial vascular system in quite a different manner from that described by Rathke in the latter animal.

In the course of my investigations on the Pineal Apparatus of the Tuatara ( Sphenodon punctas ) I have found it desirable to make as complete a study as possible of the arrangement of the intracranial arteries and veins, of which no description has as yet been published. As any facts relating to the structure of Sphenodon are of more than usual interest, and as I hope to be able to give a more complete account of the subject than has yet been given for any reptile, I have decided to offer my results for publication as a separate memoir, without waiting for the completion of my work on the pineal organs. The blood-vessels have been investigated partly by dissection and partly by means of serial sections, and such completeness of detail as I have been able to attain is very largely due to the adoption of a method of fixing and hardening which I have found to have many advantages both for the study of the vascular system and of the brain itself. By this method the entire contents of the cranial cavity are fixed and hardened in situ , and are then in excellent condition either for dissection or for histological purposes. The application of the method in the case of Sphenodon is greatly facilitated by the fact that the brain does not occupy nearly the whole of the cranial cavity, a large subdural space being left, especially above the brain, across which numerous blood-vessels run, together with delicate strands of connective tissue which connect the dura mater with the pia .


2021 ◽  
Vol 11 (22) ◽  
pp. 8-28
Author(s):  
Zsuzsanna Kutasi

Based on the knowledge of ancient Greek philosophers, medieval Arabic theoretical anatomy describes the organs, their roles and function as well as their mutual relationships on a philosophical basis wherever there are organs with higher and subordinate roles. According to Ibn Sīnā Abū ‘Alī al-Ḥusayn b. ‘Alī (Avicenna) (370-428 AH or 980-1037 AD), everything in nature is connected with everything else, and the main operator of the body is the immortal divine soul (rūḥ). While breathing, a part of the divine soul enters the lungs, and then the heart as its mixture with blood where 'pneuma' is formed, which spreads out along the arteries throughout the body. The soul part of the inhaled air (al-hawāʼ) regulates the heat of the heart and nourishes it. According to Ibn Sīna, the heart has three cavities: one on the right side, one on the left side, and the third in the middle, which serves as a kind of blood store. The liver governs the right side, the spleen governs the left one. The heart is located in the middle of the chest maintaining a kind of balance between the two vascular systems. The left side has been exalted by the fact that the divine soul comes from the air to the left side of the heart, and from here it floods the whole body through the arteries. The right side of the body is dedicated to bodily functions like turning food into blood, nourishing the organs, and removing the excess. The right half of the body is operated by the left half through nerves originating from the brain. In the brain, the two sides merge. The source of the veins in the liver, while the arteries originate from the heart. As part of a close reading of the text, I created a diagram of branches of the blood vessels to facilitate their identification. In many passages of the anatomical description, we only learn that the vessel in question branches in three, four or five directions and travels in a certain direction or towards certain parts of the body. There is always a branch among them, indeed the largest one, and by connecting these largest branches, we get the full path of a given blood vessel from the beginning to the end. Such as the route v. cava superior from the right ventricle (branches in two directions) - v. brachiocephalica (branches to five) - v. subclavia (branches towards 4) - v. axillaris (branches towards 3) - v. basilica (2 branches branch to 4 at the forearm) - v. mediana cubiti (branches towards 2) - v. salvatella from the heart to fingers. In some cases, erroneous conclusions can be identified in Ibn Sīna's description wherever he connects blood vessels with different origins. Sometimes Ibn Sīna begins to describe a route of a blood vessel and then continues to describe another blood vessel as if it were a continuation of the previous one. Alternatively, he also assigns branches belonging to one blood vessel to branches belonging to another one, such as the v. jugularis interna in the description of branches of the v. jugularis externa.


Impact ◽  
2018 ◽  
Vol 2018 (3) ◽  
pp. 26-28
Author(s):  
Jonathan Dawson ◽  
Richard Oreffo

Gels made from clay could provide an environment able to stimulate stem-cells due to their ability to bind biological molecules. That molecules stick to clay has been known by scientists since the 1960s. Doctors observed that absorption into the blood stream of certain drugs was severely reduced when patients were also receiving clay-based antacid or anti-diarrhoeal treatments. This curious phenomenon was realized to be due to binding of the drugs by clay particles. This interaction is now routinely harnessed in the design of tablets to carefully control the release and action of a drug. Dr Dawson now proposes to use this property of clay to create micro-environments that could stimulate stem cells to regenerate damaged tissues such as bone, cartilage or skin. The rich electrostatic properties of nano (1 millionth of a millimetre) -scale clay particles which mediate these interactions could allow two hurdles facing the development of stem-cell based regenerative therapies to be overcome simultaneously. The first challenge - to deliver and hold stem cells at the right location in the body - is met by the ability of clays to self-organise into gels via the electrostatic interactions of the particles with each other. Cells mixed with a low concentration (less than 4%) of clay particles can be injected into the body and held in the right place by the gel, eliminating, in many situations, the need for surgery. Clay particles can also interact with large structural molecules (polymers) which are frequently used in the development of materials (or 'scaffolds'), designed to host stem cells. These interactions can greatly improve the strength of such structures and could be applied to preserve their stability at the site of injury until regeneration is complete. While several gels and scaffold materials have been designed to deliver and hold stem cells at the site of regeneration, the ability of clay nanoparticles to overcome a second critical hurdle facing stem-cell therapy is what makes them especially exciting. Essential to directing the activity of stem-cells is the carefully controlled provision of key biological signalling molecules. However, the open structures of conventional scaffolds or gels, while essential for the diffusion of nutrients to the cells, means their ability to hold the signalling molecules in the same location as the cells is limited. The ability of clay nano-particles to bind biological molecules presents a unique opportunity to create local environments at a site of injury or disease that can stimulate and control stem-cell driven repair. Dr Dawson's early studies investigated the ability of clay gels to stimulate the growth of new blood vessels by incorporating a key molecular signal that stimulates this process, vascular endothelial growth factor (VEGF). In a manner reminiscent of the observations made in the 60s, Dr Dawson and colleagues observed that adding a drop of clay gel to a solution containing VEGF caused, after a few hours, the disappearance of VEGF from the solution as it became bound to the gel. When placed in an experimental injury model, the gel-bound VEGF stimulated a cluster of new blood vessels to form. These exciting results indicate the potential of clay nanoparticles to create tailor-made micro-environments to foster stem cell regeneration. Dr Dawson is developing this approach as a means of first exploring the biological signals necessary to successfully control stem cell behaviour for regeneration and then, using the same approach, to provide stem cells with these signals to stimulate regeneration in the body. The project will seek to test this approach to regenerate bone lost to cancer or hip replacement failure. If successful the same technology may be applied to harness stem cells for the treatment of a whole host of different scenarios, from burn victims to those suffering with diabetes or Parkinson's.


Parasitology ◽  
1924 ◽  
Vol 16 (1) ◽  
pp. 111-112
Author(s):  
Edward Hindle

In December, 1922, whilst dissecting a large female example of Bufo regularis, one of my students noticed a cylindrical structure extending along the ventral region of the body-cavity. A careful examination showed that this structure consisted of an elongated sac-like diverticulum of the right lung, containing an almost full-grown specimen of a dipterous larva, which could be seen through the membraneous wall of the diverticulum. The base of the latter, in addition to its point of origin from the lung, was also connected to the dorsal surface of the liver by strands of fibrous tissue, suggesting that the growth had been in existence some considerable time in order to cause such adhesions. Posteriorly, the diverticulum hung freely in the body cavity and extended to the extreme hinder end. Its dimensions were 5·5 cm. in length, by 0·5 cm. in diameter, but tapering towards each extremity.


2022 ◽  
Author(s):  
health not provided

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PEDIATRICS ◽  
1961 ◽  
Vol 28 (1) ◽  
pp. 65-76
Author(s):  
Peter J. Koblenzer ◽  
Martin J. Bukowski

A case is described of a diffuse, possibly generalized, abnormality of a hamartomatous nature of the peripheral vascular system. A number of cases from the literature, which also appear to belong in this category, are summarized. Histologic examination shows that lymph and blood vessels may both be involved, though this may be essentially an abnormality of the lymphatic system in which extensive venolymphatic communications occur. The clinical manifestations vary according to the site of involvement and the extent of dissemination and also according to whether the lesions are predominantly hemangiomatous or lymphangiomatous. The main features are osteolytic lesions, visceromegaly, cutaneous hemangiomas or lymphangiomas and massive effusions into any body cavity. The effusions are usually chylous, sanguineous or a mixture of both. Any or all of these features may be present in any one case. The disease frequently has its onset in childhood or adolescence and tends to be progressive. If the lesions are widely disseminated or an effusion into a body cavity is present the outlook is grave. Treatment so far has been unsuccessful. Surgery may occasionally have a place. The term angiomatosis is employed to denote this condition not only to underline its potentially extensive nature but also to avoid debate as to whether it is essentially hemangiomatosis or lymphangiomatosis.


2020 ◽  
Vol 19 (5) ◽  
pp. 933-960
Author(s):  
Harry Collins

Abstract Here I try to improve on the available answers to certain long-debated questions and set out some consequences for the answers. Are there limits to the extent to which we can understand the conceptual worlds of other human communities and of non-human creatures? How does this question relate to our ability to engage in other cultures’ practices and languages? What is meant by ‘the body’ and what is meant by ‘the brain’ and how do different meanings bear on the questions? The central answer developed here is that it is possible, given the right circumstances, for a competent human from any human group to understand the culture of any other human group without engaging in their practices though there are barriers when it comes to communication across species. This answer has important social and political consequences and consequences for the debate about artificial intelligence.


2003 ◽  
Vol 33 (1) ◽  
pp. 53-54 ◽  
Author(s):  
Bello B Shehu ◽  
Nasiru J Ismail

A 37-year-old woman, Para 5+0 presented with a 1 year history of recurrent convulsions and progressive weakness of the right side of the body. She had been treated for postpartum eclampsia in her last delivery but symptoms recurred 3 months later. Evaluation including computerized tomography scan of the brain suggested a parieto-temporal meningioma, which was completely excised at craniotomy. Histology confirmed this to be a meningioma. The patient was well at 8 months of follow up. The growth of meningiomas may increase during pregnancy due to presence of receptors for progestational hormones in the tumour and the meningioma may become symptomatic in pregnancy, presenting as eclampsia. Close follow up of patients with eclampsia is necessary to identify neurological features that may lead to a diagnosis of meningioma. Early diagnosis is essential if a good outcome is to be ensured.


It is customary for Croonian lecturers, after expressing their thanks to the President and Council for the honour that they have received in being asked to give this lecture, to devote some time to a justification of their subject in terms of Mrs Croone’s suggestion that the lecture should deal with the advancement of natural knowledge on local motion. The first of these tasks, Mr President, I perform humbly and with deep gratitude, but at the same time with some surprise that Council in its wisdom should have chosen one so ill-fitted for the honour you have laid upon him. The second task is easier since my lecture will deal with the nerves which control the muscles surrounding the hollow organs of the body, blood vessels and bowels, and further justification as a theme dealing with local motion the most captious critic could not desire. Three years ago my former colleague Bernard Katz gave the Croonian Lecture on ‘ Transmission of impulses from nerve to muscle’ in which he described our present knowledge of the mechanism of the chemical mediation interposed between nerve and skeletal muscle and summarized his own brilliant contributions to this, to me, fascinating subject. Today I am dealing again with transmission from nerve to muscle, but in a different system and, I am afraid, at a quite different and lower intellectual level than that of Katz. The idea of chemical transmission from nerve to effector cell came first to T. R. Elliott in 1904 as a result of his observation, in an extensive comparative study, of the close similarities between the actions of adrenaline injected intravenously and the effects of stimulating nerves belonging to the sympathetic system. These nerves we should now call in Dale’s (1933) terminology the adrenergic nerves, those transmitting their effects whether excitatory or inhibitory by the liberation at their endings of a ‘minute charge’ of the catecholamine adrenaline or one of its analogues. The cells upon which these nerves exert their action are the smooth muscle cells controlling the movements of the hollow viscera, intestines, reproductive tract and so on, and of the muscle cells of the vascular system that regulate the diameter of the blood vessels. These are processes that do not demand high precision of timing nor do they apparently require the instant turning on and off of transmitter action with which we have grown familiar in the junction between nerve and skeletal muscle. At this junction, as Katz showed, liberation and action of acetylcholine and its inactivation by the specific enzyme cholinesterase are over in a few milliseconds, and there is no reason to believe that the liberated transmitter in the untreated junction can ever diffuse more than a few microus from its site of action. It is hemmed in by barriers of specific cholinesterase, and these are reinforced by barriers of the non-specific enzyme in blood and tissue fluids. This narrow coarctation of the transmitter acetylcholine in space and time seems, however, to be confined to places where precise timing is required, such as at the neuromuscular junction and in the ganglionic and central nervous synapse. When it is liberated as the transmitter from nerves to blood vessels, or to secretory glands, it can escape some way from its site of liberation and persist long enough to be detected by skeletal muscles sensitized by denervation, as is seen in the Sherrington, Rogowitz and Vulpian-Heidenhain phenomena. I have laboured a little this question of diffusion and action at a distance of transmitter because it constitutes prima facie one of the most striking differences between the adrenergic and the cholinergic transmitters in at least the mammalian body. It was indeed because the liberated adrenergic transmitter escaped into the blood stream and could be detected by another tissue or organ, sometimes, but not necessarily, specially sensitized, that W. B. Cannon and his colleagues in the 30’s were able to add so much to our knowledge of sympathetic innervation. Nevertheless, in spite of the relative stability of the adrenergic transmitter and its ready detection in the blood stream, little had been discovered about the quantitative aspects of its liberation and metabolism some 50 years after its existence had been postulated, whereas we now have, and have had for 30 years, quite reasonably complete information about the liberation, storage and metabolism of the unstable and ephemeral acetylcholine.


2012 ◽  
Vol 86 (3) ◽  
pp. 462-469 ◽  
Author(s):  
Ronald L. Parsley ◽  
Sergei V. Rozhnov ◽  
Colin D. Sumrall

Maennilia estonica Rozhnov and Jefferies was first described as a stem-chordate but restudy shows it is an unusually large homoiostelean echinoderm. Its feeding structure, an erect ambulacrum, extending exothecally from the peristomial frame plates, bears a large internal tunnel that opens directly into the body cavity. This type of feeding appendage is now recognized to be unique to homoiosteles. It bears no evidence for water vascular system impressions adjacent to its food groove. The theca has poorly developed marginal plates and a narrow rim that, in contrast to some other homoiosteles, does not extend over either lower or upper thecal face. Maennilia appears to have inhabited the deeper portions of a near-shore environment in limey muds adjacent to a linear zone of bryozoan and microbial bioherms.


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