bluuebunny/crossref_metadata_2025 huggingface dataset:
Fracture callus formation in young and old mice observed with polarized light microscopy
Authors: Tonna Edgar A.
Published: February 2005

The organized cartilaginous fibrous system which appears during growth of the fracture callus in traumatized femora was investigated in mice of five, 52 and 78 weeks of age. Histological preparations were stained with toluidine blue O and observed under polarized light using a first order red retardation plate.

Development and organization of the cartilaginous fibrous system was similar in animals of all age groups studied, however, its time of appearance was dependent upon the time of appearance of cartilage cells and in association with these cells. Alignment of cartilage cells followed very closely after appearance of the fibrous system. Initial orientation of the fibrous system was almost perpendicular to the bone surface. As the system became more extensive the slope of fiber direction became less acute, pointing towards the fractured end of the shaft. Orientation of the fibrous system is believed to be a consequence of the forces set up during growth of the fracture callus, e. g., the force of the growing cell mass due to postfracture, active cell proliferation of the osteogenic layer of the periosteum and hypertrophy of cartilage cells and the tension placed on the fibrous layer of the periosteum in response to the events taking place below this tissue layer. The importance of the cartilaginous fibrous system is believed to lie in the early temporary support of the fracture fragments and the proper alignment of the cellular elements of the fracture, necessary for proper architectural reconstruction. Formation of the cartilaginous fibrous system was independent of the existing periosteal fibrous system.
Fine structure of the seminiferous tubule of the Swiss mouse. I. The limiting membrane, sertoli cell, spermatogonia, and spermatocytes
Authors: Gardner Paul J. , Holyoke Edward A.
Published: February 2005

Studies of the ultrastructure of the seminiferous tubule of the Swiss mouse have shown the external limiting membrane to consist of internal and external lamellae enclosing a single layer of flattened cells. Both lamellae contain fibers, probably collagenous, running parallel to the long axis of the tubule. Superficially, a layer of connective tissue cells covers the external lamella. The nucleus of the Sertoli cell is typified by irregularity of size and shape, electron density of the nuclear membrane, and characteristic nucleolus. The cytoplasm contains mitochondria with vesicular cristae, and irregular dense bodies of possible secretory origin. Cytoplasmic processes extend between the germinal cells and in certain areas their surfaces are marked by periodic accumulations of fine granules which present a picture suggestive of desmosomes.

Two types of spermatogonia have been noted. One possesses a large spherical nucleus containing finely granular nucleoplasm and scanty cytoplasm. The second is characterized by an ovoidal nucleus containing numerous chromatin clumps and scattered nucleolar fragments. Primary spermatocytes exhibit the intercellular bridges and synaptinemal complexes characteristic of these cells. The spherical nuclei contain densely packed fine granules. The nuclei of secondary spermatocytes often exhibit centrally located clumps of chromatin material. Mitochondria appear vacuolated at low magnifications but high magnification micrographs show them to contain finely membranous cristae.
Ciliated fibroblasts from a human brain tumor
Authors: Schuster Frederick L.
Published: February 2005

Rudimentary cilia were found on fibroblasts of a human brain tumor examined in the electron microscope. These cilia apparently have their origin in the centrioles of the fibroblasts; both centrioles appear to be involved in formation of cilia in most instances observed. Because of their atypical appearance and confinement by adjacent cell processes, it is unlikely that these cilia can perform any useful motor function for the cell. The cilia may serve as an expression of the morphogenetic potential of centrioles.
Lead acetate as a marker of growing calcified tissues a modified method
Authors: Scheiman‐Tagger Etty , Brodie Allan G.
Published: February 2005

The pattern of growth of bone and dentin was studied in serial decalcified sections by the use of lead markings. The experimental animals (monkeys and rabbits) received repeated intravenous injections of 4 mg lead acetate/kg body weight. The tissues were decalcified in 1% HCl through which H2S was constantly bubbled. Serial frozen sections were cut at 15–20 μ embedded in 10% gelatin and mounted in polyvinyl pyrollidone. They were placed in a 0.1% solution of gold chloride for ten minutes and then immersed for the same length of time in a 5% solution of sodium bisulphate in order to tone the background tissues. The sections were transferred to distilled water until the tissues became pink. When the desired toning was obtained they were fixed in 5% sodium thiosulphate. The examination of the sections obtained by this method confirmed the data obtained by other vital marking methods. However, much finer detail could be observed due to the sharpness of the lines and the use of relatively thin decalcified sections.
Development of the external ear in the dachs rabbit
Authors: Crary Dorcas D.
Published: February 2005

Development of that part of the external ear which protects the external auditory meatus appears to be similar in all animals since the hillocks of His have been described for reptiles, amphibia, and birds as well as mammals. Disagreement exists as to the origin and fate of the various hillocks, especially tragus and antitragus. Most observations of the developing ear have begun with the formation of the hillocks at which time the tragus is situated on the mandibular arch. Because of the rapid early growth, transitional steps from the open branchial groove to this stage have not been described previously. The retarded growth of the dachs rabbit makes it possible to see intermediate steps. Here it is shown that the entire auricle arises from an intact and continuous primordium, with the tragus arising from the hyoid arch and migrating to the mandibular bar in the normal course of cell proliferation and differentiation. Variations in normal and heterozygous animals can be found in the relative rates of development of the surrounding areas.
The effect of testosterone on the morphogenesis of the chick thymus
Authors: King John E. , Ackerman G. Adolph , Knouff Ralph A.
Published: February 2005

Because of the inhibitory effect of testosterone on lympho‐epithelial nodule formation in the bursa of Fabricius, possibly through the suppression of alkaline phosphatase activity of the surrounding mesenchyme, there appears the possibility of a comparable inhibitory effect on the thymus.

1. A single dose of one tenth milliliter (2.5 mg) of testosterone propionate in sesame oil (Schering) was injected into chick eggs between the first and fifth days of incubation, i.e., before and during the time of differentiation of the thymus from the epithelial primordia and before the appearance of lymphoblasts. The thymuses of 195 chicks including 50 controls were examined after 18 days of incubation; grossly and microscopically the thymus gland was relatively unaffected in all but a few chicks.

Because the thymus appeared unaffected by testosterone as opposed to its complete inhibitory effect on the bursa of Fabricius; and because of the apparent relationship of testosterone‐labile alkaline phosphatase to epithelial nodule formation in the bursa, further investigations were carried out on thymic differentiation and the possible role, if any, of alkaline phosphatase activity in the surrounding mesenchyme.

2. Chick embryos between 5–10 days of incubation were fixed in 80% ethanol or absolute acetone, embedded in paraffin, serially sectioned and exposed to either Gomori's glycerophosphate or Burstone's naphthol AS‐MX phosphate procedures for alkaline phosphatase activity. The mesenchyme surrounding the developing thymus showed either a negative or a negligible reaction for alkaline phosphatase activity following these procedures. In contrast, the thymic primordium did exhibit slight phosphatase activity which appeared to be localized in the reticular‐epithelial cells.

The difference in demonstrable alkaline phosphatase activity of the capsule of the thymus and of the subepithelial mesenchyme of the bursa of Fabricius suggests a fundamental difference in the differentiation of the two organs in the embryonic chick.
The fine structure of the thymocytes of young rats
Authors: Murray Raymond G. , Murray Assia , Pizzo Anthony
Published: February 2005

Thymocytes of young rats were studied with the electron microscope to provide a base line for a comparative study of the fine structure of various types of lymphocytes. Fixation with OsO4 or glutaraldehyde, Epon embedding, and heavy metal staining were the principal techniques employed. Small thymocytes, with nuclei from 3.5 to 4.5 μ in diameter are in the vast majority. Our results, which in general confirm previous reports, show the thymocytes to be primitive, or undifferentiated in structure. Certain exceptions and additions were noted, however. There are no protoplasmic bridges between thymocytes and epithelial cells and no clear evidence of epithelial‐thymocyte transformations. The nucleus contains typical pores and in many cases a clearly defined finely granular nucleolus, although the latter is not evident in most of the smallest cells. Cytoplasmic fragments appear to be separating from thymocytes by a process similar to the separation of platelets from megakaryocytes. The existence of a special band of cytoplasm beneath the plasma membrane devoid of formed elements is described for the thymocytes. The possibility of the common occurrence of this zone in other cells, and its possible significance, are discussed.
Ventricular blood pressures and competency of valves in the early embryonic chick heart
Authors: Paff George Hugo , Boucek Robert Joseph , Gutten Georgia Sharon
Published: February 2005

By direct ventricular puncture involving use of a micro‐pipette and water manometer the ventricular blood pressures of 81 chick embryos ranging in age from 2 to 7 days of age were obtained. The mean ventricular diastolic, systolic and mean blood pressures in millimeter of water (given in the order) were as follows: 5 ± 1.4; 21 ± 2.4 and 10 ± 1.4 in two day hearts, 10 ± 1.58; 27± 6.68 and 14 ± 14.32 in three day hearts; 14± 1.41; 39 ± 6.22 and 19± 2.39 in four day hearts; 17 ± 5.89; 63 ± 15.49 and 32 ± 12.08 in five day hearts; 5.45 ± 8.59; 74 ± 17.94 ± and 34 16.76 in six day hearts. At seven days the mean ventricular diastolic pressure was 1.33 ± 2.36 mm of water.

Ventricular diastolic pressure increased from the second through the fifth days, underwent a marked drop at six days and fell to near zero at seven days of development. Since in fully developed hearts ventricular diastolic pressure approaches zero if the valves of the outflow tract are competent, the following conclusion concerning valvular action was drawn; the valvular mechanism of the outflow tract in the developing embryonic chick heart is incompetent at two, three, four and five days of development. It begins to become competent between the fifth and sixth days and attains competency at seven days.
Differential staining of bone tissue elements by silver nitrate staining of blocks of decalcified bone
Authors: Tappen N. C.
Published: February 2005

Bone can be differentially stained en bloc by fixing in 10% formalin, decalcifying in dilute nitric acid, and placing in an ammoniacal silver nitrate solution. The block is then infiltrated and embedded in gelatin for serial sectioning while frozen. Structures range from colorless to yellow, through different shades of brown or reddish brown, to black. This range is seen among different osteones, and even within a single osteone. Color changes within the same structure can be observed easily in serial sections. Collagen fibers, Sharpey's fibers, and assorted cell nuclei are also stained, but cement lines are not. Canaliculi usually do not stain, but occasionally stain vividly. Very darkly stained areas show little histological detail. Some of the characteristics of bone stained by this technique suggest that a relationship exists between the extent of mineralization and degree of staining. Similar features of x‐ray photomicrographs of undecalcified bone sections support such a relationship.
The fine structure of the rat umbilical cord at various times of gestation
Authors: Leeson Charles Roland , Leeson Thomas Sydney
Published: February 2005

The morphology of the umbilical cord of the rat has been investigated in fetuses of 17,19,20 and 21 days gestation. The development and differentiation of three major features of the cord, the covering amniotic epithelium, the mesenchyme of Wharton's jelly, and the major umbilical blood vessels, were studied. At 17 days gestation, the epithelium is composed of a simple layer of flattened cells without obvious specialization and later becomes bilayered and shows considerable irregularity at the surface and at cell‐interfaces, where desmosomes are a prominent feature in the stages just prior to birth. Within the underlying mesenchyme, there is a decrease in cellularity throughout the period under study. Mesenchymal cells are characterized by the presence of a well developed endoplasmic reticulum containing an electron dense homogeneous material. Ribosomes in association with the endoplasmic reticulum are in the form of polysomal aggregates by 17 and 19 days gestation which later become less marked. Unit fibrils of collagen increase in number in the days prior to term and in later stages appear in definite bundles. In the umbilical blood vessels, there is differentiation of a muscle coat from an aggregation of mesenchymal cells. No nerves in relation to the blood vessels and no vascular supply to the umbilical cord itself could be identified in any stage of the present study.
The Ureter, ureterovesical junction, and vesical trigone
Authors: Woodburne Russell T.
Published: February 2005

The musculature of the ureter has a layered arrangement in which the internal layer is mainly longitudinal and the external layer is largely circular. There is, however, intermingling and migration of fascicles between layers. At the passage of the ureter through the bladder wall this layering is lost and all fascicles become oriented longitudinally.

At the ureterovesical junction fibers of the detrusor muscle of the bladder, interspersed with delicate connective tissue, reflect onto the ureter over a distance to 2 to 3 cm. This “sheath” of the ureter, as it has been designated, is a reflection of bladder wall muscle onto the ureter. At its passage through the bladder wall, the ureter is loose and an injectable space exists around it. This is properly termed “Waldeyer's separation” since he called attention to it in 1892.

Within the bladder, the ureteric wall flattens and widens, allowing the lumen to migrate to the surface to constitute the ureteral aperture at the angle of the vesical trigone. Delicate muscular decussations occur proximal and distal to the aperture.

Ureteric muscle mainly forms the vesical trigone. Most fascicles run to the midline and blend with those of the opposite side in the interureteric fold. Others spread through the trigone, its lateral margin being formed of somewhat more numerous fascicles directed toward the vesical orifice. Very few fibers actually descend into the urethra. The principal fixation of the ureter into the bladder is to the mucous membrane of the trigone area and to the deeper lying muscle and connective tissue.
Sequence of action of the diaphragm and quadratus lumborium during quiet breathing
Authors: Boyd W. , Blincoe H. , Hayner J. C.
Published: February 2005

A series of 15 rabbits had multiple intercostal clip electrodes implanted in the diaphragm and quadratus lumborum at open operation.

Leads from the electrodes were passed to the back of the animals and soldered to a junction band. Simultaneous recordings of electromyographic activity and spirometry were made following recovery.

The study revealed that the quadratus lumborum, acting simultaneously with the diaphragm, is an effective inspiratory muscle stabilizing the twelfth rib, converting it into a fixed point from which the diaphragm act. Very possibly the action of the quadratus pulls down the lower rib helping to increase the costo‐diaphragmatic recess. Like the sternal, crural and costal portions of the diaphragm, the quadratus exerts a braking action to oppose the normal elastic recoil of the lungs during expiration.
Further studies on the development of the lateral motor column in anuran larvae. I. Normal development in Rana temporaria
Authors: Race James , Terry Robert J.
Published: February 2005

A study was made of the normal development of the lateral motor column (LMC) in the lumbo‐sacral region of the European grass frog, Rana temporaia. The results were then compared with the development of the LMC in Rana pipiens (Beaudoin, '55), in order to determine if the difference in life cycle between the two species would result in differences in development of the column. The results show that the overall developmental pattern in R. temporaria is no different from that found in other anura. There is a general decrease in the large number of cells present early in the larval period and a concomitant increase in the size of the remaining cells during development through metamorphosis. During metamorphosis, at least 80% of the original population of cells are lost. Immediately following forelimb emergence, nuclear area is at least 52% larger than the nuclear area of cells found at the earliest stage. In both species, the largest decrease in cell number and increase in cell size is at the time the circulating thyroid hormone concentration is at its highest level. Although the pattern of development in the two species is similar, the number and size of the LMC cells differ significantly between the two species during the late larval stages. This difference can be attributed to the difference in life cycle between R. pipiens and R. temporaria.
Prevention and reversal of glycogen infiltration in the pancreatic islets of fetuses from diabetic rats
Authors: Kim Jae Nam
Published: February 2005

Fetuses removed by Caesarean section (between days 17 and 21 of pregnancy) were compared with litter‐mates removed at autopsy (between days 21 and 23).

In one diabetic group, all rats were treated with a large dose of insulin until Caesarean section when insulin treatment was stopped. No fetuses removed by Caesarean section showed glycogen infiltration when blood sugar was less than 240 mg/100 ml. At autopsy, glycogen appeared in all fetuses from mothers which had blood sugar levels above 240 mg/100 ml for two days or longer; no glycogen appeared in fetuses from mothers which had blood sugar levels below 240 mg/100 ml.

In another diabetic group, all rats were treated with insulin, but the insulin dose was increased immediately after Caesarean section. All fetuses removed by Caesarean section showed glycogen infiltration when the blood sugar level was greater than 240 mg/100 ml. At autopsy, glycogen had disappeared in fetuses from mothers which had blood sugar levels less than 240 mg/100 ml for 2 to 3 days; glycogen persisted in fetuses from mothers which had blood sugar levels above 240 mg/100 ml.

It is concluded that glycogen appears in fetal islets if blood sugar level is greater than 240 mg/100 ml for two days or longer. This change is both preventable and reversible and is influenced by the level of blood sugar and by the duration of hyperglycemia.
External morphology of the erect glans penis of the dog
Authors: Hart Benjamin L. , Kitchell Ralph L.
Published: February 2005

The external morphology of the erect glans penis was studied and compared to that of the nonerect organ. Morphological changes that occur with tumescence and detumescence were also reported. Some distinct parts of the erect pars longa glandis which are not distinguished in classical nomenclature are described and labeled. These structures are the urethral process, corona glandis and collum glandis. These distinct morphological areas coincide with areas which seem to be functionally distinct in both the erect and nonerect glans penis. The implications that these observations may have for considerations of comparative anatomy of the external male genitalia are discussed.
Bilateral asymmetry in weight and in length of human bones
Authors: Latimer Homer B. , Lowrance E. W.
Published: February 2005

The weights and lengths of right and left bones of each pair, from 105 human skeletons from Asia, were studied.

All of the long bones of the upper are heavier and longer on the right side. The left femur is heavier and longer. The right tibia and fibula are heavier while the left tibia and right fibula are longer. The right scapula is heavier and the os coxae, clavicle and the bones of the hand and foot are heavier on the left side.

Generally, the left bones are more variable in weight and length. The upper extremity and its individual bones manifest more asymmetry than the lower.

The proximal bone of upper and lower extremities and the scapula and os coxae show a greater degree of asymmetry in weight than the the more distal bones.

In general, the left bones have slightly higher correlations with total skeletal weight. These and the intercorrelations between right and left bones of the six pairs of long bones of the extremities are all significant and positive. The highest intercorrelations of the long bones are between right and left bones of a pair.
The weight and thickness of the two ventricular walls in the newborn dog heart
Authors: Latimer Homer B.
Published: February 2005

The weight and thickness of the two ventricular walls of the heart were measured in 80 newborn puppies. These puppies were born in the dog colonny, the descendants of a typical heterogeneous collection of dogs, for student use in the laboratory.

The hearts of these dogs average 2.07 gm in weight. The left ventricular wall is slightly heavier and also slightly more variable in weight than the right wall. The two free ventricular walls comprise 56% of the weight of the entire heart. The ratio of the weight of the left to the right ventricular wall, at birth, averages 1.0078.

The left wall is also slightly thicker than the right wall. The thickness of the right wall is more variable than the left. The ratio of the thickness of the left to the right ventricular wall is 1.036.

These data are compared with other available measurements on adult dog hearts and on human hearts.
A comparison of selected morphological and chemical methods for measuring neuron activity in the supraoptic nucleus of dehydrated rats
Authors: Ifft John D. , Berkowitz Wallace
Published: February 2005

A comparison of results of measuring supraoptic neuron activity was made in normal and in dehydrated rats by the following methods; (1) Measuring the nucleolar diameter of the neurons with a filar micrometer, with an image splitting eyepiece and, with the latter instrument, using the “comparative technique”—all three methods yielded statistically significant differences. (2) Measuring the concentration of cresyl violet in the nucleoli with a microspectrophotometer—a statistically significant difference was found. Also included for comparison were the results of a previous experiment in which the ribonucleic acid and succinic dehydrogenase content of the supraoptic nucleus was measured with a spectrophotometer following chemical extraction. The RNA was found to increase significantly but not the succinic dehydrogenase. Of the methods used for measuring nucleolar diameters the “comparative technique” appeared to be the most rapid from the practical viewpoint.
Dorsal roots of the rabbit investigated by freeze‐substitution
Authors: Malhotra S. K. , Van Harreveld A.
Published: February 2005

Dorsal roots from adult rabbits prepared by a freeze‐substitution technique and studied by electron microscopy have been compared with those obtained by standard fixation with OsO4. The essential features of myelinated and nonmyelinated fibers and their associated Schwann cells are similar in appearance after both types of fixation. There are, however, slight differences. The extracellular clefts between the nonmyelinated axons and their associated Schwann cells are wider in freeze‐substituted roots (200 to 250 Å versus 100 to 150 Å). The major dense lines in the myelin sheath are wider (45 to 55 Å versus about 30 Å) and their radial repeat period is larger (145 to 155 Å versus 100 to 120 Å) in freeze—substituted material than in routinely fixed nerves.
Fertilization and early development of dorset horn sheep in the spring and summer
Authors: Chang M. C. , Rowson L. E. A.
Published: February 2005

The estrous cycles of 34 Dorset Horn ewes were observed during the spring and summer in East Anglia. The majority of sheep (22 out of 34) came in heat fairly regularly. In 26 out of 37 estrous cycles the duration was between 14 and 25 days. Laparotomy performed soon after estrus did not prolong the subsequent estrous cycle in the majority of animals. Failure of ovulation following estrus was not observed; the observations were made either at laparotomy or at autopsy. The rate of ovulation was 1.55 per cycle as assessed by counting the number of corporalutea in the ovary. The time of ovulation was estimated at about 30 to 40 hours after the onset of estrus.

Following deposition of semen into the Fallopian tubes of nine ewes, either before or soon after ovulation, five eggs were recovered but none of these was found to be fertilized. Following intra‐cervical insemination or mating 21 fertilized eggs, at different stages of division, were found in 11 out of 29 ewes. In 13 ewes out of 26 which were examined 5–17 days after mating 15 normal embryos were found. Photomicrographs of early sheep embryos are presented and the low fertility of sheep in summer is discussed.
Differentially localized incorporation of amino acids in relation to epidermal keratinization in the newborn rat
Authors: Fukuyama Kimie , Nakamura Toshio , Bernstein I. A.
Published: February 2005

Incorporation of tritiated methionine, phenylalanine, leucine, glycine and histidine into protein in the epidermis of the newborn rat was studied by autoradiography.

Methionine, phenylalanine and leucine behaved similarly. Thirty minutes after injection, radioactivity was detected in both nucleus and cytoplasm of the basal, spinous and granular cells with a greater intensity over the cells of the lower layer as compared with that observed over the upper layer. The label appeared over the cornified cells at 24 hours after injection probably as a result of the migration of cells into the cornified layer. In the case of glycine and histidine, the label was detected in eachof the three layers at 30 minutes after injection but the labeling was higher in the upper part of the epidermis as compared with the lower part. The label appeared in the cornified layer six hours after injection. Processes possibly involved in formation of the cornified layer are discussed.
Rapid pinealectomy in hamsters and other small rodents
Authors: Hoffman Roger A. , Reiter Russel J.
Published: February 2005

Removal of the pineal organ from small rodents may be rapidly accomplished by (1) immobilizing the skull in a head mounting device and (2) by cutting and removing a circular disc of bone overlying the pineal area with the use of a dental machine and a specially designed circle cutter.
The sinus node artery in man
Authors: Ryback R. , Mizeres N. J.
Published: February 2005

Thirteen sinus node arteries from human material (2 months post partum to 68 years) were studied by various histologic techniques for connective tissue, muscle, and nerve distribution and arrangement. Its relationship to the sinus node is also emphasized. The outer longitudinal muscle coat of the artery is replaced with a thick adventitia. This loss of smooth muscle is not typically found in other coronary arteries. In addition, many nerve fibers, arranged both circularly and longitudinally, present the possibility of a pressoreceptor mechanism related not only to coronary blood pressure changes but also to the neurogenic control of the heart beat.
Propagation and prolongation of mitotic activity in the formation of injury‐induced lentomas in Rana pipiens
Authors: Rafferty Nancy S.
Published: February 2005

Autoradiography following labeling with H‐3‐thymidine was used to study the pattern of growth of injury‐induced lentomas in Rana pipiens. This reaction to injury was compared with the more controlled reaction in the rabbit lens, which has been extensively studied by others.

These studies show that, unlike that of the rabbit, the entire lens epithelium of the frog reacts within a day to the injury stimulus by disarrangement of its normal architecture. H‐3‐thymidine is incorporated between 24 and 40 hours post‐injury, followed subsequently by widespread mitotic activity. Peak thymidine incorporation occurs at three days and peak mitosis at five days post‐injury. However, the stimulus to mitotic activity is propagated after the first week largely among the superficial cells of the enlarging lentoma and adjacent normal epithelium; DNA synthesis and mitosis in the deeper cells of the lentoma diminish at a week and cease by two weeks post‐injury, and by three weeks in the superficial cells.

It is concluded that the frog lentoma is formed by accretion from the surface as a result of extensive multiplication of cells throughout the injured epithelium. The reaction of frog and rabbit lenses to injury differs both in the extensiveness of the initial reaction and the duration of the stimulus to proliferation.
Normally occurring intraluminal projections in the arterial system of the mouse
Authors: Menschik Zygmunt , Dovi S. Frank
Published: February 2005

The arterial system of 27 ICR/Albino mice was studied by: (1) examining 8 μ thick serial histological sections, (2) observing under the dissecting microscope the interior of arterial segments split longitudinally, (3) making reconstruction models, 100 times magnified from serial sections and (4) applying various histological and histochemical stains to determine morphological details. Almost regularly at each point of origin of an arterial branch, a structure forming a specific anatomical entity was observed and referred to as an intraluminal projection. A typical projection consists: (1) of an elevation or cushion located at the proximal edge of the orifice, (2) of two collateral ridges running distally at the sides of the orifice and becoming gradually thinner and taller, and (3) of a union of collateral ridges into a semilunar, flap‐like, movable structure guarding the distal edge of the orifice. Imperfectly developed intraluminal projections were occasionally encountered at the origin of large arteries from the abdominal aorta. Histologically a projection is entirely luminal to the internal elastic membrane, has an endothelial covering of thickened endothelial cells and consists of a stroma containing polygonal elongated cells which have oval nuclei and resemble smooth muscle fibers. They are surrounded by a network of elastic and reticular fibers. The intraluminal projections may regulate the volume and pressure of blood entering the branch by sphincteric and valvular mechanisms.
The evolution of the mm. interossei in the primate hand
Authors: Lewis O. J.
Published: February 2005

Various conflicting views relating to the phylogenetic history of the interossei are reviewed. The primitive mammalian (marsupial) precursors of these muscles are shown to present a bilaminar arrangement: a dorsal layer of four bipennate abductor muscles (inserting into a proximal phalanx) is overlaid ventrally by a sheet of ten flexores breves, grouped in pairs, and inserting as wing tendons into either side of the extensor aponeurosis of the corresponding digit. The homologues of these muscles are identified in the hands of representative Primates including Homo. The dorsal abductors become the dorsal interossei proper; the flexores breves become the palmar interossei, which are therefore frequently more numerous than the four found in man. Certain of the flexores breves show a tendency to merge with those subjacent abductors with which they insert. Thus, the descriptive human dorsal interossei are composite muscles resulting from the amalgamation of a flexor brevis with a dorsal interosseous proper. Comparative morphology is shown to provide a logical basis for the understanding of the extensor apparatus of the human fingers.
The effect of bleeding and starvation on blood volumes and peripheral hemogram of the turtle, Pseudemys scripta elegans
Authors: Hirschfeld William J. , Gordon Albert S.
Published: February 2005

In assessment of some aspects of the erythropoietic system of a poikilothermic vertebrate, values were determined for red cell, white cell, reticulocyte and circulating erythroblast numbers as well as hematocrit, hemoglobin, the erythrocyte corpuscular constants and serum iron concentration in normal and in starved turtles. Starvation caused no change in the peripheral hemogram but resulted in a decrease in serum iron.

Bleeding of normal turtles decreased both the red cell and plasma volumes, while starvation resulted in only a slight lowering of the plasma volume. In addition, blednormal turtles showed decreases in hematocrit, hemoglobin concentration and serum iron concentration.

In the cellular response to bleeding, radioiron‐labeled erythroblasts appeared in the circulation by the second day after Fe59 administration. A sudden rise occurred on the fourth day which was associated with a high spleen radioactivity. Erythroblast levels were elevated in the blood of bled‐normal but not in bled‐starved turtles. Indeed, the bled‐starved animals appeared incapable of increased erythropoiesis as measured by any of the criteria used in these studies.
Cell number deficiencies in the nervous system of dwarf mice
Authors: Viola‐Magni Mariapia
Published: February 2005

A quantitative histologic investigation has been performed on the nervous system and striated muscle of the dwarf mouse (Snell's Strain).

The number of nerve cells in the spinal cord of the dwarf mouse is half of that seen in the normal mouse. These data are fully confirmed by separate counts of efferent and afferent fibers of the spinal roots. Spinal root fiber diameters are similar in both normal and dwarf mice. The number of muscle fibers in the peroneus longus muscle is about the same in both the normal and in the dwarf mouse; the diameter of each muscle fiber, however, is reduced in the dwarf.

At the muscular level the deficiency manifests itself as a volumetric reduction in the muscle fibers; whereas, at the level of the spinal cord there is a reduced number of nerve cells. It follows from these observations that in the dwarf mouse the ratio of nerve fibers to muscle fibers within a motor unit is altered so that each motor neuron innervates more muscle fibers than in the normal mouse. This fact could explain the peculiar movements of the dwarf mouse.
Effect on the weights of fetuses and fetal lymphoid organs of adrenalin given to rabbits at a critical period of pregnancy: Observations on spontaneous and induced runting
Authors: Wier Katherine
Published: February 2005

The effect of injecting adrenalin at a critical period in pregnant rabbits was investigated. This critical period is around the twenty‐second day of pregnancy, when the maternal blood supply to the uterus is naturally low. The relative weights of thymus, spleen and appendix and the total body weights of the fetuses were measured both one week after the injection and eight weeks after birth to examine long range effects. Controls consisted of saline‐injected and untreated rabbits.

The adrenalin injection reduced significantly the fetal weight compared with that of the controls. The relative thymus weight was found to be significantly correlated positively with fetal weight in both adrenalin‐treated animals and controls. However, there was no significant difference in relative thymus weight between the two groups.

Of the two litters raised to eight weeks, the young of the untreated litter showed a fairly constant growth rate. The pups of the adrenalin‐treated litter started out smaller than the controls but at about three and one‐half weeks the former overtook the controls; at eight weeks they were, on the average, larger. With this small sample size, the difference in weights cannot be shown to be statistically significant, but the litters show consistent differences.
Mammillary complex of cat brain—aspects of quantitative organization
Authors: Fry William J.
Published: February 2005

Accurate determination of the neuron populations of the medial and lateral mammillary nuclei in normal cat brains, and of the same structures (after quasi‐equilibrium of the cellular populations is achieved) in brains of these experimental animals modified by unambiguous lesion arrays, provides the foundation for deciphering features of the neuronal circuitry that cannot be elucidated on the basis of qualitative neuroanatomic knowledge. This paper is concerned first with the closeness of agreement of cell population values between bilaterally corresponding mammillary nuclei in the same brain and with the degree of reproducibility of the ratio of the populations of the lateral and medial nuclei of this complex from one brain to another. Second, it is concerned with illustrating in specific cases the usefulness of population ratios determined from normal and from modified brains in revealing important neuroanatomic relations: (1) clarifying the structure of the dorsal bifurcation of the principal mammillary tract into the mammillothalamic and mammillotegmental tracts for fibers projecting from the medial mammillary nucleus, and (2) deciphering the neuronal circuitry of the bilateral projection of each lateral mammillary nucleus to the anterior dorsal nuclei of the thalamus.
The hair follicle group in mice
Authors: Claxton J. H.
Published: February 2005

Initiation and development of the follicle population in mice were examined during embryonic and early postnatal life. The shape of the curve relating follicle density with age suggests that follicle intiation begins in the 14‐day‐old embryo and continues until about two days after birth. During the period of follicle intiation, groups of follicles are established in a regular and systematic way but at any particular age during this period, the stage of development of adjacent groups is not always synchronous so that when initiation ceases the composition and numerical size of different groups are highly variable. Although 75% of all groups contained three, four, or five follicles some were composed of only two and others as many as 11 folllices. In adult mice the most notable feature of the spatial distribution of follicles is often only the tendency for follicles to be arranged in rows. An examination of the follicle population about six days after birth showed that this feature is not incompatible with the earlier developmental grouping structure. A comparison of the proportions of different fiber types in the coat with the proportions of follicles occupying specific positions in the follicle groups was unable to establish any close relationship between follicle and fiber types. Evidently the type of fiber grown by a follicle is more dependent on the age when the follicle is initiated than on the position of the follicle in the follicle group.
The attenuation of elastic tissue in the aorta of the baboon, Papio doguera
Authors: Katzberg Allan A.
Published: February 2005

A histological study was made of the quantitative distribution of elastic elements in the aorta of the baboon, Papio doguera. Materials were obtained in East Africa from freshly sacrificed animals as well as from domestic stock, and represented all age groups from a fetus near term to 28 years. Verhoeff's elastic tissue stained sections were prepared from 4 zones from the arch to the bifurcation.

All specimens showed an attenuation of the thickness of the aortic wall as well as a decrease in the number of layers of elastic membranes from the arch to the bifurcation. The attenuation was less prominent in the older and heavier animals. The reduction in the number of elastic membranes at the lower end indicates a reduced requirement for the storage of ventricular energy by the elastic constituents for blood propulsion. Gravitational forces may be instrumental in maintaining blood flow to the lower extremities without additional expenditure of energy of ventricular origin.
Differences in internal structure and nerve terminals of the slow and twitch muscle fibers in the cat superior oblique
Authors: Pilar Guillermo , Hess Arthur
Published: February 2005

Measurements of nerve fiber size in the trochlear nerve indicate that many small nerve fibers are present which could serve as the small nerve motor supply for innervation of the slow muscle fibers in the superior oblique of the cat. Twitch and slow muscle fibers in the superior oblique muscle of the cat have been examined in the electron microscope. In twitch fibers, triads consisting of the transverse tubule and dilated sacs of the sarcoplasmic reticulum occur at the level of junction of A and I bands. In the slow fibers, the sarcoplasmic reticulum is reduced in amount and the transverse tubular system is completely absent. The junctional folds of the postsynaptic membrane of the muscle fiber under the nerve terminal of a twitch fiber are present, although not extensive; in slow fibers, these postjunctional sarcolemmal folds are essentially absent. Some physiological implications of these differences in fine structure of twitch and slow fibers and their respective nerve terminals are discussed.
Selective staining of chromatin in hematogenous lymphocytes in nodes
Authors: Tompkins Edna H.
Published: February 2005

Lymphocytes with “atypical nuclei” have been shown to increase in lymph nodes during afferent drainage ('64). This report concerns the selective staining of these nuclei with the MBL technique (exposure of methylene blue stained sections to alcoholic Lugol's solution).

Comparisons with other techniques, together with suitable extractive procedures, lead to the conclusion that chromatin throughout the hematogenous series of lymphocytes is subject to two general forms of selective response to the MBL technique during lymphatic drainage. These are distinguished by differences in: 1, time required for staining with the iodine solution; 2, morphology; and 3, ease of dedifferentiation.

The first response (unpatterned, coarse, intranuclear granules) occurs in older hematogenous lymphocytes only, after brief exposures, and varies in ease of dedifferentiation.

The second response (intranuclear, reticulated figures) occurs in hematogenous lymphocytes of any age, after long exposures to iodine, and is slow to dedifferentiate. The figures uniformly conform to the reticular patterns of inter‐ and prophase, and become condensed as cell volumes decrease.

The findings show that fluctuant, dynamic relationships exist among hematogenous lymphocytes in nodes :‐ unidentified factors become associated with their chromatin and result in selective nuclear staining; the chromatin becomes restricted to reticular positions and mitoses cease; cell volumes shrink progressively; nucleo‐cytoplasmic ratios increase; and intranuclear structures become condensed. Yet evidences of degeneration are not found.
Mucosal cellular populations and distribution in the normal canine stomach
Authors: Ritchie Wallace P. , Barzilai Ami , Delaney John P.
Published: February 2005

Mucosal cellular populations and glandular thickness in the corpus of the canine stomach was assessed in 30 dogs. The average number of mucous neck cells per “swath” of full thickness mucosa over a width of 0.223 mm was 41 (S.E. ± 2.09), of parietal cells, 95 (S.E. ± 8.71), of chief cells 205 (S.E. ± 12.63). The average glandular thickness was 557 μ (S.E. ± 24.71).

The distribution of cells in the stomachs of four additional dogs was determined. More mucous neck cells were noted in the glands of the juxta‐antral and cardiac zones than in those of the corpus. Few parietal and chief cells were noted in the cardiac zone. In the corpus, however, these cells were abundant and evenly distributed.

The data presented permit calculation of the total gastric mucosal cellular population of the stomach from an “average” 15 kg dog. The acid‐pepsin secreting area has a volume of 35 cm3, and therefore contains 4.3× 108 parietal cells, 7.2 × 108 chief cells, and 1.4 × 108 mucous neck cells.
Initiation of vagal control of heart rate in the embryonic chick
Authors: Legande Mary C. , Paff George H. , Boucek Robert J.
Published: February 2005

The objective was to determine on what day of development the vagal complex i.e., dorsal motor nucleus in the floor of the fourth ventricle, vagus nerve and post synaptic neuron assumes functional control of the heart rate in the chick embryo. Adapting a technique used by Armstrong ('35) for the Fundulus embryo, 0.003 ml of Tyrode solution containing 0.03 μg of acetylcholine was injected into the fourth ventricles of 16 chick embryos at four days of age, 25 at five and 15 at six days of age. Heart rates were taken before and after injection.

Analyzed statistically no significant changes in heart rate occurred following injection of acetylcholine into four day embryos but at five days a significant average drop from 106 to 95 beats per minute occurred. The same was true in six‐day‐old embryos where the average drop in rate was from 108 before to 84 after injection. As proof that the acetylcholine injected into the brain ventricle acted by stimulating the vagal mechanism and not by diffusing into cerebral blood vessels and being carried to the heart we found that corresponding amounts of acetylcholine injected into omphalomesenteric veins had no significant effect on heart rate. Also 0.003 ml of plain Tyrode solution injected into the fourth ventricle elicited no significant response. These observations justify the conclusion that the vagal pathway to the heart becomes functional between five and six days of development in the chick embryo.
Light and electron microscopic studies of pigment in human and rhesus monkey substantia nigra and locus coeruleus
Authors: Moses Harold L. , Ganote Charles E. , Beaver David L. , Schuffman Shirley S.
Published: February 2005

Neuromelanin pigment of the substantia nigra and locus coeruleus from nine human autopsy cases and from four rhesus monkeys was studied. Melanin and lipofuscin pigments from other anatomical sites were also observed for the purpose of comparison with the substantia nigra‐locus coeruleus pigment. Ultrastructurally, the neuromelanin pigment granule was composed of three distinct components. The first was a finely granular, medium dense matrix which occasionally had linear configurations very similar to those of neuronal lipofuscin granules from human cerebral cortex. The second component was a very dense, coarsely granular material which appeared to to be deposited on the finely granular matrix. This very dense component was apparently the reducing part of the neuromelanin granule, as it was the site of localization of silver deposits in formalin‐fixed tissue which had been stained with diamine silver prior to post‐osmication and examination in the electron microscope. No evidence of silver reduction was noted in lipofuscin pigment. The third component of the neuromelanin granule was a lipid globule which was not preserved in glutaraldehyde or formol‐permanganate fixed tissue. A lipid globule was not observed in melanin granules from the skin, eye, or pia mater.