Membranous Sac Research Articles

VERTEBRATE RETINAL CELLS AND THEIR ORGANIZATION

Summary1. Electron microscopy has added numerous details emphasizing the kinship of the retina with the central nervous system. The space between the receptors and pigment epithelium resembles neural tube lumen in that all cells facing this lumen possess terminal bars at their margins. The receptors, glial cells of Müller and cells of the pigment epithelium all appear to be derivatives of ependymal cell varieties. As is the neural tube and mature central nervous system, the entire optic cup derivative in the eye is jacketed in a basement membrane. Blood vessels run through glial tunnels lined by this membrane. The choroid capillaries and pigment epithelium resemble the choroid plexus.2. The choroid capillaries have endothelial cells which possess numerous focal attenuations or perhaps pores where they oppose the cells of the pigment epithelium. The latter show deep membranal infoldings and an extensive endoplasmic reticulum. Some species possess spindle‐shaped aggregations composed of stacked pairs of membranes which are continuous with the reticulum. The melanin pigment granules lie within microvilli which drape the receptors.3. The receptors are derived from ciliated ependymal cells. Their outer segments contain stacks of flattened membranous sacs which are apparently formed by ingrowth or infolding of the plasma membrane. The connexions of the resultant sacs to the membrane may be very narrow or perhaps absent in most rod sacs, but are generally persistent in cone sacs. Rod sacs possess one to many incisures, depending on the group of animals examined. Details of the molecular architecture of these membranes are highly speculative since they are based upon the appearance of the membranes after various techniques involving empirical fixation procedures and little fundamental research.4. Receptors are in intimate relation with processes of cells of the pigment epithelium and microvilli of the glial cell of Muller. The apex of the receptor inner segments may be reflected, calyx‐like, over the base of the outer segments.5. Receptor inner segments are joined to the outer by narrow stalks which contain nine pairs of filaments or microtubules like those of cilia, except for the absence of a central pair. The filaments end in relation to a centriole and a second centriole is also present. Rootlets run from the centrioles through the inner segments.6. The ellipsoid of the inner segment is a cluster of mitochondria. The paraboloid, when present, is seen to be an ellipsoidal configuration of expanded tubules of the endoplasmic reticulum with clusters of granules dispersed in the cytoplasm outside the tubules. In double cones, the inner segments and nuclear areas of two independent cells are closely applied to one another. Golgi regions overlie the receptor nuclei.7. The receptor synaptic area is highly complex. Processes, presumably from bipolar cells, end in pits in the receptor base. Above these pits specialized organelles are found in the receptor cytoplasm. Other processes terminate superficially. These may include processes from certain receptors ending on others, a situation possibly analogous to that existing between receptors of Limulus.8. The neural retina as a whole exhibits a paucity of extracellular space, with estimates of intercellular distances made precarious by our ignorance of the molecular composition of the light areas intervening between the osmiophilic lines partially representing the cell membranes but probably not the cell surfaces! However, more extracellular space must exist in areas where cell processes are small and numerous owing to geometric factors. Receptors and retinal neurons and their processes may have broad surfaces of contact, but glial processes, particularly of the cells of Muller, are rather pervasive, and fill in spaces not otherwise occupied.

Seasonal Changes Occurring in the Pectinesterase Activity and Pectic Constituents of the Component Parts of Citrus Fruits.

SUMMARYPectinesterase activity, 3 pectic fractions, and other characteristics were determined periodically on 5 component parts of Valencia oranges during a 7‐month maturation cycle for 2 seasons. Usually, PE activity for peel, membrane, and juice sacs was least in December, when the Brix/acid ratio was low, and highest in June, when this ratio was greatest. The order of component parts for PE in most cases, from highest to lowest activity, was juice sacs, membrane, peel, seeds, and juice. Water‐soluble pectin generally remained constant in peel and juice sacs, increased slightly and then remained constant in the membrane, and was irregular throughout the cycle in the seeds. The trend of ammonium‐oxalate‐soluble pectin in the components was to increase during maturation. Protopectin in the component parts usually increased to a peak and then gradually decreased for the remainder of the season, except that protopectin in the juice sacs decreased throughout the sampling period. In this component, protopectin evidently was at its maximum by the first picking in December. Total pectin remained constant in the juice and seeds, and slowly declined in the other 3 components with maturation. Membrane contained the highest source of protopectin and total pectin throughout the season.

STUDIES ON THE RELATIONSHIP BETWEEN OVARIAN HORMONES AND UTERINE INFECTION

SUMMARY Bacterial cultures contained within semi-permeable membrane sacs placed in the uterus of cows or in one uterine horn of rabbits developed normally, and the rate of bacterial growth was not influenced by the ovarian activity of the test animal. Similar cultures placed directly into the control uterine horn of rabbits were eliminated in oestrous animals. This showed that bacteria grow satisfactorily in the uterine fluids of both oestrous and dioestrous animals provided they are isolated from the uterine endometrium. The ovarian status of the animal did not influence the growth of bacteria in washings obtained from the uteri of both cows and rabbits when tested in vitro. No differences could be detected in the rate of growth of bacteria in extracts of uteri from oestrous and pseudopregnant rabbits. Injections of pilocarpine to increase the rate of flow of uterine secretions failed to influence the susceptibility of pseudopregnant rabbits to uterine infection.

Production of the Milk Agent in Cultures of Mouse Mammary Carcinoma

Thin sections of tissue cultures grown from tumors of the RIII high-breast-cancer strain mice were studied in the electron microscope. These tissues contain an abundance of particles whose morphology is consistent with biophysical measurement of the milk agent. These particles, found only extracellularly in our cultures, are formed at the cell membrane. The process of formation, as reconstructed from sections, appears to include a thickening and protrusion of the cell membrane which then evolves gradually into a dense sphere and separates from the cell in much the same manner as does influenza virus. The contents of the newly formed body are later rearranged to form a nucleoid within a membranous sac.

The Roentgen Diagnosis of Pericardial Effusion

There is no single roentgenologic sign of pericardial effusion. Such errors in diagnosis as are frequently encountered are most often the result of an impression gained by inspection of the film alone, and a conclusion that the heart shadow resembles a “water-bottle.” Since the contour of an enlarged heart may, in some cases, simulate the outline of a pericardial effusion, every bit of available evidence must be sought and weighed. Observations by various investigators have contributed substantially toward the diagnosis of pericardial effusion since the report of Camp and White (1) in 1932, which stated that in only one of 49 patients studied roentgenologically was the diagnosis of pericardial effusion established antemortem. The purpose of this paper is to summarize the most useful signs commonly employed and to present our own observations as to the diagnosis and differential diagnosis of pericardial effusion. The pericardium is a membranous sac containing elastic fibers and consisting of a visceral and a parietal layer. While the visceral layer is more or less intimately adherent to the surface of the heart, the parietal layer is loosely applied. This creates an actual space between the two layers, which normally contains 15–20 c.c. of clear, straw-colored fluid. After rounding the inferior borders and surface of the heart, the pericardium becomes firmly attached to the central tendon of the diaphragm (Fig.1). Superiorly, the pericardium is reflected onto the coats of the great vessels, with which it blends intimately. Anteriorly, the outer layer is loosely attached to the pleura by fibre-areolar tissue—the pleuro-pericardial membrane. At times, however, this membrane may consist of firm, dense, fibrous tissue. Attachment to the sternum is by the superior and inferior sterno-pericardial ligaments. The superior and inferior venae cavae pierce the pericardium posteriorly, as do also the four pulmonary veins. The ligamentum arteriosum is usually enclosed by pericardium, though occasionally it lies outside the attachment of the pericardial sac to the great vessels. While fluid in the pericardium may, under certain circumstances, accumulate with startling rapidity, as for example in the case of trauma, the process is usually subacute or chronic, and it is with these forms that this paper is chiefly concerned. Fluid naturally gravitates to the most dependent portions of the sac. Most observers (2, 3) agree that amounts less than 250 to 300 c.c. may not be recognized roentgenologically. This may be due to the fact that the normal heart is subject to considerable variation in size before it may be considered enlarged, and unless a patient has been under roentgen observation for a sufficiently long period to show progressive increase in the size of the heart shadow, it may not be possible to tell, from a single examination, whether or not the shadow is abnormal.

A Study of the Ptilinum and Ptilinal Musculature of the Pomace Fly, Drosophila Melanogaster Meigen1 (Diptera, Drosophilidae)

The pomace fly, Drosophila melanogaster Meigen, is one of the flies of the group Cyclorrhapha and suborder Schizophora which in the pupal stage possesses on the cephalic aspect of the head an extensive membranous organ or frontal sac, the ptilinum. It serves by its alternate distension and contraction to rupture the puparium and assist in the emergence of the imago. After emergence the ptilinum is permanently retracted as an invagination within the head capsule. Although the function of the ptilinum has been known since it was first described by Reaumur (1738), it is not known, to the author's knowledge, whether the failure of the adults to emerge from the puparia, in lethal flies, is dependent upon the failure of the ptilinum to function or upon some other cause. This research was instigated to determine the role of the ptilinum and attached muscles in the emergence of the normal flies. The author hopes to make a study of the lethal flies at a later time.

Growth and Feeding of Newborn Price's and Green Rock Rattlesnakes

On August 9th, 1941, a 429 mm. female green rock rattlesnake, Crotalus lepidus klauberi, collected in Carr Canyon, Huachuca Mountains, Cochise County, Arizona, gave birth to four young, three males and one female. At 12 noon, when they were first found, three had already been born, but the fourth did not emerge until an hour later. All were irritable from the first, promptly broke the membranous sacs in which they were enclosed and struck violently at any passing object. All were marked and colored much like the adults except that the delicate pink along the venter of the latter was not in evidence; and the tails, which in the adult are salmon or terra cotta red (including the basal segment of the rattle) were brilliant sulphur yellow for at least their distal half and the pre-button of the rattle.

THE EFFECT OF SALINITY UPON THE RATE OF EXCYSTMENT OF ARTEMIA

1. The excystment of Artemia takes place in two principal stages: first, the quiescent nauplius emerges from the shell of the cyst within a membranous sac, and then later the nauplius hatches from the sac and swims actively about.2. The excystment of Artemia obtained from the margin of San Francisco Bay has been studied at 25° C. in diluted and concentrated sea water over a salinity range from zero (distilled water) to 225 per cent sea water (i.e., a solution in which the salt concentration is 225 per cent of the salt concentration of sea water. No salts precipitated out).3. The same percentage of embryos emerged from the shells in all of these salinities, including zero salinity (distilled water).4. In distilled water the emerged embryos are motionless and they do not hatch from the sac. Some swell and burst.5. In 12½ per cent sea water, 83 per cent of the emerged embryos hatch; in 25 per cent sea water 93 per cent hatch. In 50-225 per cent sea water 96-99 per cent hatch.6. In 12½-225 per cent sea water ...

TRANSPLANTATION (IMPLANTATION) OF THE LACRIMAL SAC IN CHRONIC DACRYOCYSTITIS

The various methods of treating chronic dacryocystitis by the creation of an artificial passage into the nose have been reviewed extensively within recent years. Noteworthy in this respect are the publications of Chandler 1 and of Kaleff, 2 in which the advantages and disadvantages of the modifications of the Toti operation (dacryocystorhinostomy) are fully discussed. These operative procedures can properly be classified into four groups, all being external in type : Group 1 consists of procedures in which the anterior and posterior flaps of nasal mucous membrane and lacrimal sac respectively are sutured together, such as the method of Ohm 3 or of Depuy-Dutemps and Bourguet. 4 Group 2 consists of procedures in which one or more flaps of nasal mucous membrane are sutured to the anterior or posterior wall of the sac, but without forming an exact or complete anastomosis (Basterra 5 and Kuhnt 6 ). Group 3 consists of procedures

Distribution of Murine Typhus Rickettsiae in Developing Chick Embryo

Following the method of Goodpasture, Zia cultivated successfully typhus Rickettsia of endemic and epidemic types in the chorioallantoic membrane of developing chick embryo. This was confirmed by Wenckebach with endemic typhus, Bengtson and Dyer with Rocky Mountain spotted fever, and Cox with endemic typhus fever and Rocky Mountain spotted fever. These authors made a special study of the distribution of the Rickettsia in the infected embryo and found that whole embryo, brain, liver, chorioallantoic membrane, and yolk sac were infectious for guinea pigs, thus proving the presence of Rickettsial bodies. On the other hand Bengtson was not able to demonstrate any Rickettsia by direct smear in any of the organs. In view of the fact that various viruses have a different distribution in the fertilized egg, it was considered of interest to study the distribution of Rickettsia of the murine typhus fever by cultural methods. The procedure employed was as follows: Growth of murine typhus Rickettsia in Maitland culture was inoculated on to the chorioallantoic membrane of fertilized eggs 10–12 days old. They were incubated at 34°C for 8–9 days after which the eggs were opened, and the membrane, liver, spleen, stomach, intestine, brain, lungs, heart, and kidney were aseptically removed and inoculated separately on to Zinsser's “tissue-agar” media and Maitland flasks. Direct smear of all tissues were negative except for a few organisms occasionally found in smears made from the membranes. The cultures were examined after 12–20 days of incubation, and Macchiavello's technic of staining was employed for demonstration of Rickettsia. Sections of brain, liver, and spleen were made and stained with eosin and hematoxylin. Result: It was found that about 80% of the 48 eggs so inoculated showed dead embryos on examination, of which approximately 10% was found to have died of bacterial contamination.

Movements of Diatoms and Other Microscopic Plants

FEW subjects in the domain of cryptogamic botany have given rise to more speculation and conflicting theories than have the studies into the cause of the apparently voluntary movements of diatoms. From time to time for the past twelve years the author has been confronted with this seemingly fruitless subject, and only recently, almost by accident, has the problem been solved. It was early shown by examination in closed cells the phenomenon was not due to external currents set up in the surrounding liquid, but the poxver of motion came from the organism itself. Largely on account of these movements, which appeared to be spontaneous and voluntary, the diatoms were originally classed in the animal kingdom. The first theory which naturally presented itself was they move as do the Infusoria by means of vibrating hair-like cilia or flagella. Later certain authors claimed to have seen protoplasmic processes similar to those of the rhizopods protrucling from the small openings in the frustule of the organism. Then came the theory of Onderdonk 1 which described the progression as clue to a thin fluid mass in rhythmical motion covering the surface of the diatom. Ndogeli suggested the motion is due to enclosmotic and exosinotic currents, and H. L. Smith 2 after much study of the subject came to the conclusion that the motion of the Navicuke is cule to injection and expulsion of water, and these currents are caused by different tensions of the internal membranous sac in the two halves of the frustules.

I. On the source of free hydrochloric acid in the gastric juice

The long-disputed position of Prout that the gastric juice contains free hydrochloric acid, was at length established by C. Schmidt, who, in an absolute quantitative analysis of the juice, found about twice as much hydro­chloric acid as was required to neutralize all the bases present. The pro­longed discussion of this subject (now since 1823) has brought to light, through the researches of Lassaigne, Tiedemann and Gmelin, Berzelius, Blondlot, Claude Bernard, Schwann, and numerous others, the unmistakeable evidence of the presence of lactic acid and of acid phosphates in the gastric juice, which latter might or might not be due to the presence of lactic or hydrochloric acid. A point of special interest to the chemist and physiologist still remained, and was this: How couldfree hydrochloric acid be secreted from the bloody which is an alkaline fluid ? The blood freshly drawn consists of a fluid (the plasma) in which there are swimming myriads of exceedingly minute irregularly spheroidal bodies (the corpuscles). The plasma consists of two bodies, one of which, the fibrine, spontaneously separates from the other, the serum. The corpuscles are little sacs of delicate animal membrane enclosing a fluid. This fluid has an acid reaction, and its ash contains a monobasic alkaline phosphate. The fibrine of the plasma contains, according to Virchow, a glycero-phos-phate of lime, though the plasma, as a whole, has an alkaline reaction, and contains in its ash a great measure (11 per cent.) of chloride of sodium.

A case of the human fœtus found the ovarium, of the size it usually acquires at the end of the fourth Month. By A. B. Granville, M. D. F. R. S. In a letter addressed to Sir Everard Home, Bart. V. P. R. S

The body, of which the dissection is described in this paper, exhibited a considerable tumour, placed immediately above the region of the pubis. Upon opening the abdomen, a quantity of fluid resembling blood was found in its cavity, and a tumour, four times the size of a hen’s egg, obstructed the view of the internal parts of generation, resting upon the left portion of the anterior surface of the uterus; a blood-vessel, which proved to be a branch of the left spermatic artery, and of the size of a large crow-quill, penetrated the dense portion of this tumour, and a smaller vessel communicated with the spermatic vein. The inferior portion of the tumour presented diaphanous membranes, through which was seen a fœtus of about four months’ growth. The fact of an extra-uterine conception being thus made out, the author proceeded to examine the connection of the tumour with the neighbouring parts, and the condition of the uterus; whence it appears that the tumour was seated in the left ovarium, which had burst in three places, so as to suffer the membranous sac containing the fœtus to protrude into the cavity of the abdomen; and that by the growth of the fœtus that part of the covering of the ovarium was ultimately lacerated, which involved the placenta by which the adhesions of the latter were torn, producing the sudden and fatal hæmorrhage which killed the patient and filled the abdomen with blood.