bluuebunny/crossref_metadata_2025 huggingface dataset:
Persistent urachus — an observation in miniature swine
Authors: Weaver Morris Eugene
Published: February 2005

The embryology and anatomy of the urachus has been described and documented in some mammals. Though rare, the anomalies associated with the urachus represent such a hazard to life that, in man at least, the incidence and treatment have been recorded regularly. Documentation of the presence of the persistent urachus in animals was not as complete. References in recent literature described the anomalous urachus in only a few dogs, cows, and horses.

This study reported an impervious urachal canal from the urinary bladder to the umbilicus in a female “miniature” pig of the Pitman‐Moore strain. The urachus observed was similar to previous descriptions given for domestic swine and other species but was reported because of the increasing use of swine as laboratory animals and the dearth of specific information in the literature concerning these animals.
Collection of mouse semen by electroejaculation
Authors: Snyder Robert L.
Published: February 2005

Liquid and coagulated ejaculates were collected separately from mice by electroejaculation. Sperm concentrations in the liquid ejaculates from 51 animals ranged between 25,000 and 2,228,000/mm3 and total number of spermatozoa per ejaculate between 60,000 and 5,464,000. This method is suggested as a practical means of obtaining ejaculated spermatozoa free of coagulum for reproduction research.
Ultrastructural and cytochemical changes in spermatogonia and Sertoli cells of whole‐body irradiated mice
Authors: Hugon J. , Borgers M.
Published: February 2005

Adult male mice of CBA/C57 B1 strain received a whole‐body x‐irradiation of 400 r. The ultrastructural and cytochemical changes of the spermatogonia and of the Sertoli cells were studied throughout the first 48 hours after this irradiation. Tissues were fixed in osmium tetroxide or glutaraldehyde. The acid phosphatase reaction was carried out using a slightly modified Gomori medium. The first changes observed in spermatogonia were: dilatations of the smooth endoplasmic reticulum, moderate enlargement of the mitochondria and swelling of the nuclear membranes. In a later stage, the injured spermatogonia were phagocytized by the adjoining Sertoli cells, where the complete involution took place. The study of the acid phosphatase localization showed that the numerous dense bodies, appearing in the Sertoli cells in the first hours after irradiation, were heavily loaded with reaction product. They seemed to take an important part in the resorption of the phagocytized spermatogonia. These results were compared with findings of other authors.
Glycogen content of preimplantation mouse embryos
Authors: Thomson Joan L. , Brinster Ralph L.
Published: February 2005

Preimplantation mouse embryos of various stages of development, from single‐cell zygotes to late blastocysts, were fixed on microscope slides and were stained using the periodic acid‐Schiff method. Half of the slides were treated with diastase before staining to determine whether the positive material was glycogen.

Glycogen was found in all of the stages studied, regardless of whether development had occurred in vivo or in vitro. Single‐cell zygotes were not as heavily stained as the two‐cell embryos, but this could be due to the decrease in volume which occurs between these two stages. Large amounts of positive material were found in the cleavage stages, from two‐cell to morula, but a decrease occurred during the growth of the blastocyst. By the late blastocyst stage, glycogen is no longer found in the trophoblast cells and is present only in small amounts in the inner cell mass.

The decrease in PAS‐positive diastase‐removable material during the blastocyst stages suggests that glycogen may serve as an energy source during the fifth day of development, when the blastocyst is undergoing expansion and hatching. Culture experiments and enzyme analyses have provided evidence that the cleaving embryo undergoes some basic changes in the pattern of energy metabolism, and it is possible that additional changes might occur in the blastocyst stage.
The development and structure of the choledocho‐duodenal junction in Balaenopteran whales
Authors: Boyden Edward A.
Published: February 2005

Three specimens from Balaenopteran whales have been available for study: a 20 mm embryo, a fetus 57 inches long and the ampulla duodeni of a 47‐foot adult. By reconstruction, dissections and histological preparations, it has been possible to show that the extrahepatic portion of the bile duct is really an elongated hepato‐pancreatic duct receiving ductules draining both rostral and caudal pancreatic lobes. After coursing through the pancreas, this duct pierces the intestinal muscle at the beginning of the pars descendens duodeni, then runs through the whole length of the longitudinal fold before emptying at the bottom of the pars descendens. In the adult, maceration methods have demonstrated that there is no vestige at all of a sphincter of Oddi. Presumably, this is a consequence of the absence of the gall bladder. Contrary to statements in the literature, a complete foramen epiploicum, vestibule and lesser peritoneal sac could be demonstrated as well as a long infracardiac bursa. Most interesting is the presence of a sizable valve in the portal vein at the point where it enters the liver.
Comparative observations of the eminentia cruciata in birds and mammals
Authors: Igarashi Makato , Yoshinobu Toshiko
Published: February 2005

The eminentia cruciata in vertical semicircular canals was observed in all birds and the turtle investigated. Minimal structural difference was observed among all birds utilized for their different flying activities. This eminentia cruciata was found even in a flightless penguin. A rudiment was found in the rat, cat, and dog, but not found in the guinea pig, flying squirrel, squirrel monkey, owl monkey, macaca monkey, or human.

The dividing and frictional effects from this structure against the endolymphatic flow are expected in these vertical semicircular canals. The ampulla of the vertical semicircular canal contains one complete crista with planum semilunatum on each side, due to the presence of the eminentia cruciata.

The phylogenetic significance is important; the existence of the eminentia cruciata is parallel to that of the sensura neglecta, and it is antagonistic to the development of the horizontal semicircular canal.
An engineering analysis of myocardial fiber orientation in pig's left ventricle in systole
Authors: Streeter Daniel D. , Bassett David L.
Published: February 2005

The concept of discrete layers and bundles of muscle as a basic structural arrangement in left ventricular myocardium was tested by measuring the helix angles at 1 mm intervals from endocardium to epicardium, using pig's heart in the contracted state. A fixed coordinate system was established which permitted measurement of corresponding sites in hearts of different dimensions.

The helix angle was found to change from somewhat less than 90° endocardially to about −90° epicardially in an almost linear clockwise sequence, like a Japanese fan opened up. Approximately the same pattern was observed in the interventricular septum and the anterior, left and posterior walls. Generally, there was no abrupt change between the helix angle of papillary fibers and that of adjacent wall myocardium. Where occasionally abrupt changes in fiber orientation were demonstrated, no intervening septum could be discerned. The deviant fibers seemed to co‐exist as part of the same gross structure.

The concept of a continuum more appropriately describes the basic structure of left ventricular myocardium. Lev and Simkins ('56) and Grant ('65) showed that there was no evidence of identifiable layers as defined by the presence of connective tissue septa. This study shows no evidence of identifiable layers as defined by (1) an abrupt change in fiber direction demarking the boundary of a layer and (2) a parallel fiber direction between such boundaries.
Fluorescent localization of catecholamine stores in the rat lung
Authors: Zussman William V.
Published: February 2005

To localize the stores of catecholamines present, normal rat lungs were examined with a histochemical fluorescence technique. Comparison was made with sections from animals infused with methylene blue to demonstrate the autonomic innervation usually observed. An extensive network of fine fluorescent fibers was seen in the mucosa of the entire bronchial tree. Coarse interstitial fibers adjacent to bronchi represented the largest monoamine stores observed, and communicated by delicate fibers with both the musculature and mucosa. Arterial fluorescence was less prominent, and a continuous subendothelial layer of coarse fluorescent material communicated with finer fibers in the muscular walls. The extensive fluorescent fibrous network visualized with the present method, demonstrating fine details of innervation, suggested an intimate relation between the bronchi and pulmonary arteries.
The effects of contraction and stretch of a muscle on morphology of its spindles
Authors: Bridgman Charles , Sweeney Susan , Eldred Earl
Published: February 2005

The effects of acute stretch, laterally applied pressure, and exterfusal contraction upon the morphology of spindles in cat muscles have been studied by making measurements from serial histological sections. Cross‐sectional areas of bag and chain intrafusal fibers were taken and the circumferences of spindle capsules measured at the equatoriallevel. From these area values the relative effects on length of the measured structures were inferred. 1. Stretch was found to lengthen the capsules and both bag and chain fibers. 2. Contracture induced by use of the drug ryanodine was accompanied by shortening of both bag and chain fibers. 3. Stretch was still effective in the presence of full contracture. 4. Pressure applied to the lateral surface of the muscle affectedboth bag and chain fibers.

These findings taken with other considerations demonstrate the anatomical basis for the mechanism that is commonly assumed to cause the acceleration in discharge from primary and secondary endings with stretch and the “pause” with contraction of the gross muscle. The relation to a possible pressure sensing mechanism for secondary endings is discussed.
Synaptic contacts at nodes of ranvier in central nervous tissue
Authors: Khattab Fahmy I.
Published: February 2005

Parietal cortex, hippocampus and reticular formation of the medulla of normal rabbits were primarily fixed by glutaraldehyde perfusion followed by phosphate buffered osmium tetroxide. In electron micrographs of this material the central nodes of Ranvier exhibitedmost of the features of peripheral nodes. Branching was observed at central nodes which resembled branching of the myelinated axons at peripheral nodes. Two types of synapses were observed at the node. In the first type the axon formed a process which ended in a bouton, synapsing with a dendritic spine, while in the other type the axon bulged at the node to form the bouton.
A light and electron microscopic study of Kurloff bodies in the blood and spleen of the guinea pig
Authors: Berendsen Peter B. , Telford Ira R.
Published: February 2005

The Kurloff body of guinea pig mononuclear leukocytes was studied by light and electron microscopy of blood and spleen. Electron microscopy disclosed the presence of extensively dilatedendoplasmic reticulum, clusters of small vesicles, and clumps of long parallel fibers in the cytoplasm. The osmiophilic inclusions contained many myelin figures, both around the periphery and free in the matrix. Evidence for motility of these cells was noted.

Rods, filaments, and spheres seen in supravital preparations appear as myelin figures when seen with the electron microscope. Although historically considered, parasitism, nuclear extrusion and phagocytosis of cells are unlikely as causal in the formation of the inclusion. Being based on contradictable evidence, a lysosomal origin is doubted. The formative process isfelt to be either one of intracellular secretion or of a sequestering and concentration of a serum molecular component.
The relationship between the histological localization of alkaline phosphatase activity and appearance of lymphocytes in lymphocytic tissue of the embryonic and neonatal rabbit
Authors: Hostetler Jeptha R. , Ackerman G. Adolph
Published: February 2005

Various lymphocytic organs (thymus, spleen, appendix and lymph node) were removed from embryonic and neonatal rabbits between the eighteenth day of gestation and the tenth postnatal day. These tissues were studied morphologically and histochemically using a variety of procedures in order to determine the manner of lymphocyte formation in relation to the pattern of histochemical differentiation in these lymphocytic tissues. Of particular interest was the consistent development of alkaline phosphatase activity in non‐thymic lymphocytic organs one to two days prior to the appearance of lymphocytes in these tissues. The regional development of alkaline phosphatase activity in these non‐thymic lymphocytic organs corresponded with the sites of appearance of the first lymphocytes in these organs and with the regions of subsequent lymphocytic proliferation during the developmental stages of the spleen, lymph nodes and appendix of the rabbit.

Specifically, alkaline phosphatase activity localized in the mesenchymal cells surrounding the developing arteries of the spleen, in the developing cortical region of the lymph nodes and in the lamina propria of the domed elevations of the appendix. In contrast, neither the thymus nor the surrounding connective tissue of the thymus exhibited demonstrable alkaline phosphatase activity during the early development of the thymus into a lymphocytic organ. Significantly, the first cells of the lymphocytic series to develop in the spleen, lymph nodes and appendix in the embryonic rabbit were of small or medium size in contrast with the thymus where lymphoblasts were the first recognizable cells of the lymphocytic series.

These observations suggest that alkaline phosphatase is intimately associated with the development of lymphocytes in potential non‐thymic lymphocytic organs. The mechanisms of alkaline phosphatase action, although not clear, may act to induce the in situ transformation of lymphocytes, provide a suitable environment for lymphopoiesis or serve as a chemotactic agent, attracting blood‐borne lymphocytes to these regions.
Plasma membrane changes during keratinization
Authors: Farbman Albert I.
Published: February 2005

Numerous electron microscopic studies have demonstrated that the plasma membranes of keratinizing epithelial cells undergo striking morphological changes. From a more or less symmetrical, trilaminar structure similar to that described for most cells, the membrane undergoes a marked increase in thickness and becomes highly resistant and impervious to the action of strong reagents. In the present electron microscopic study on rat tongue epithelium, this membrane thicken‐ing was observed to begin by the appearance within cells of a moderately dense band of material, about 100 A thick, in the peripheral cytoplasm against the intracyto‐plasmic face of the plasma membrane. This peripheral dense band was observed in epithelial cells each of which still possessed a nucleus and all its usual cytoplasmic organelles. Following its initial appearance, this peripheral intracytoplasmic band increased in density so that it became indistinguishable from the inner layer of the plasma membrane. The electron microscopic image at this stage gave the impression that the inner layer of the plasma membrane had undergone a considerable increase in thickness, whereas the outer and middle layers had remained essentially unchanged. Finally, in fully keratinized cells, the outer layer of the plasma membrane was not always demonstrable, so that in these cells the plasma membrane seemed to be composed of a single thick, dense layer of membrane material. The possible implications of these membrane alterations in the total process of keratinization are discussed.
Distribution and fine structure of globule leucocytes in respiratory and digestive tracts of the laboratory rat
Authors: Kent John F.
Published: February 2005

Study of an unselected population of adult laboratory rats demonstrates the presence of globule leucocytes in the bronchioles, bronchi, trachea, larynx and oropharynx. In the digestive tract, these leucocytes are seldom found in the antral part of the stomach but are abundant in the glandular stomach where they have been confused with mast cells. Numerous globule leucocytes also occur in the large and small intestines. Although most of these leucocytes are located in the epithelium rather than the connective tissue of themucous membranes of these organs, this pattern is reversed in the small intestine of normal rats. Globule leucocytes are present in essentially normal numbers in the trachea and larynx of axenic rats, but are less abundant than normal in the small intestine of these animals. The fine structure of the globule leucocyte and its characteristic inclusions is compared with that of other similar or possibly related cells and with that of the globule leucocyte of the fowl described recently by Toner.
Maternal behavior in the rat: Survival of newborn fostered young after hormonal treatment of the foster mother
Authors: Zarrow M. X. , Grota L. J. , Denenberg V. H.
Published: February 2005

The 10‐day old natural young of lactating rat mothers were removed, and the mother was given newborn foster young together with hormone treatment. A single injection of prolactin or progesterone was sufficient to increase the survival perentage and body weight of the fostered rats. An hypothesis is presented to explain the action of the hormones and the possible relationship to placental eating which is noted in many mammals at the time of parturition.
The morphology of valves in cerebral arteries of the rat
Authors: Rosen William C.
Published: February 2005

Valves associated with major arterial branches at the base of the brain in rats were studied after fixation by perfusion with buffered aldehydes. These endothelial covered structures are entirely intimal. All cellular and non‐cellular elements of their core are laminated, including the PAS positive ground substance. Smooth muscle and nerve endings are not demonstrable. Reticular fibers form a substantial sheath around the base of each valve. Their location and morphology suggest that they may serve a regulatory function in maintaining proper intracerebral blood flow.
Cell proliferation in the mammary gland during late pregnancy and lactation
Authors: Traurig Harold H.
Published: February 2005

Nulliparous, CFW mice were injected with 25 m̈c of tritiated thymidine on day 19 of pregnancy, and days 1, 2, 3, 5, 7, 10, 15 and 20 of lactation. The animals were killed one hour after injection. The inguinal mammary glands were removed and processed for paraffin sectioning. Radioautographs were prepared, using the dipping technique.

Quantitation of mammary epithelial cell proliferation for the intra‐ and interlobular (ducts) epithelium was performed by determining the percent of labeled epithelial cells in a large sample of cells (labeling index). It was concluded that epithelial cell sample sizes of 1,000–2,000 cells were adequate to measure mammary epithelial proliferation. A wave of epithelial proliferation was observed during early lactation. In the intralobular epithelium, a peak labeling index of 11.1% was attained on day two of lactation whereas a peak labeling index of 7.9% was observed on day three of lactation in the interlobular epithelium. Cells of the connective tissue and vascular bed proliferated in response to the growth of the mammary epithelium. Myoepithelial cells were frequently labeled on days two and three of lactation.
A radioautographic study of proliferation in brown fat of the rat after exposure to cold
Authors: Hunt Thomas E. , Hunt Eleanor A.
Published: February 2005

Radioautographs of the interscapular brown fat of six weeks old animals showed that within 24 hours after cold exposure at 4°–5°C, proliferation increased in endothelium of the already profuse capillary network and also that of arterioles and especially that of venules. This continued at a high level for 48 hours then declined. Extravascular fat precursor cells but not fat cells showed an increased proliferative activity at 48 hours cold exposure which continued until 96 hours. By eight days, adaptation to the cold occurred and proliferative activity was not increased thereafter nor did it occur significantly in animals seven months old. Animals exposed to cold 48 hours, given thymidine‐H3, and then returned to a temperature of 23°C for a week or more showed a considerable number of labeled fat cells which presumably were precursor cells when the thymidine‐H3 was given. When the interscapular brown fat was denervated on one side, there was no loss of lipid nor increased proliferative activity in the vascular or extravascular cells on that side after 48 hours cold exposure. The normally innervated opposite side, however, had more proliferating cells than usual, especially in the endothelium.
Interneocortical connections in the opossum, Didelphis virginiana
Authors: Martin George Franklin
Published: February 2005

Discrete neocortical lesions were placed in the brains of 12 opossums. After a survival time of 1 to 3 weeks, the brains were subjected to the Nauta‐Gygax technique for degenerating axons or to the Swank‐Davenport modification of the Marchi technique for degenerating myelin. A partial hemispherectomy was performed on the brains of two additional animals. The entire intact hemisphere opposite the lesion was then subjected to the Nauta‐Gygax technique.

The results of histological examination indicate that fibers cross extensively in the anterior commissure from all areas of the neocortex. Degenerating fibers passed from each of the neocortical lesions into the ipsilateral external capsule. It was by means of the external capsule that they entered the anterior commissure. After crossing in the anterior commissure, the degenerating fibers passed into the contralateral external capsule and subsequently terminated on cells in the homotypic cortex opposite the lesion. Some fibers, however, terminated in non homotypic cortical areas. Fibers, particularly from the more dorsally placed lesions, also crossed in the hippocampal commissure. The results support the concept that a portion of the anterior commissure of certain marsupials is homologous to the corpus callosum of higher forms.
Regeneration of resected calcaneal tendon of the rabbit
Authors: Conway Anna M. , Dorner Robert W. , Zuckner Jack
Published: February 2005

A connective tissue growth model based on the regeneration of rabbit calcaneal tendon following surgical excision is described. Tissues allowed to regenerate for various periods of time from two days to 240 days were studied histologically and compared with mature tendon.

Rabbit calcaneal tendon regenerating for 14 days or longer was found to represent a rapidly grown, normal connective tissue obtainable in quantities sufficient for biochemical microanalysis and thus to provide a valuable connective tissue growth model. By allowing growth to proceed for 56 days, the model could be used to provide normal tissue morphologically approximating mature tendon.
Electrophoretic patterns of proteins in the blastocoelic fluid of the rabbit following ovariectomy
Authors: Sugawara S. , Hafez E. S. E.
Published: February 2005

A total of 286 blastocysts were recovered 6 to 8 days post coitum (p.c.) from untreated or ovariectomized rabbits. The weight of the blastocyst and the volume of the blastocoelic fluid increased at a linear rate from seven to seven and one‐half days p.c., thereafter they increased more rapidly. The weight of the embryonic tissue did not change appreciably between seven and eight days p.c. The appearance of protein in the fluid was dependent on the stage of development, albumin being first detectable at six days p.c. Seven days p.c., β‐globulin was detectable, followed by α‐ and γ‐globulins (seven and one‐quarter days p.c.) and fibrinogen (seven and one‐half days p.c.). Seven and one‐half days p.c., the electrophoretic distribution of proteins was qualitatively similar to that of the maternal serum and peritoneal fluid, however, quantitatively different. Ovariectomy at six days p.c. had no effect 24 hours later on blastocyst growth or blastocoelic fluid volume. In contrast, ovariectomy at six and one‐half days p.c. had a negative effect 24 hours later on blastocyst growth, blastocoelic fluid enhancement and albumin accumulation in the fluid. These latter three phenomena were alleviated by administration of progesterone.
Electron microscopic observations on the membrane systems of the rat blood platelet
Authors: Behnke O.
Published: February 2005

Rat blood platelets have two membrane systems in their cytoplasm. One, named the surface connected system (SCS), consists of vacuoles and large cavities which are in continuity with the plasma membrane. The inner surfaces of the membranes of this system have, in common with the plasma membrane, a thin coat of an amorphous substance which probably consists of acid mucopolysaccharides.

The other system, named the dense tubular system (DTS), consists of slender membrane‐bound tubules which contain a homogeneous, rather electron dense substance. The DTS is not continuous with the plasma membrane or the SCS.

Rat blood platelets incorporate various foreign substances in vivo and in vitro; these substances are first adsorbed to the amorphous cell coat and subsequently taken into the SCS.

It is suggested that the uptake of material by rat blood platelets reflects a membrane flow from the surface membrane to the SCS, and that the process is not phagocytic in nature since segregation and digestion of the incorporated material do not seem to take place.
The junctional specializations of sertoli cells in the seminiferous epithelium
Authors: Flickinger Charles , Fawcett Don W.
Published: February 2005

Attention is directed to an unusual type of junctional complex between Sertoli cells in the seminiferous epithelium. The space between the membranes of adjoining cells is narrowed to 70–90 Å over large areas of their contact surfaces. In the superficial cytoplasm of each cell is an extensive cisterna of the endoplasmic reticulum, parallel to the membrane and 400–600 Å from it. Spaced at more or less regular intervals in the thin layer of cytoplasm between the cisterna and the cell membrane are periodic densities that appear to be band‐like aggregations of fine filaments. The sub‐surface cisternae are smooth‐contoured on the side toward the cell membrane but bear ribosomes on the side facing the cytoplasm. The possible significance of these distinctive junctions is discussed in relation to the support of the germ cells and the coordination of the developmental events in the cycle of the seminiferous epithelium.
A technique for the light microscopy of tissues fixed for fine structure
Authors: Rosen William C. , Basom Charles R. , Gunderson Leonard L.
Published: February 2005

Young adult female rats were perfused with buffered aldehydes. Selected tissues were prepared for light microscopy by standard techniques. The only procedural modifications permitted were those required by the special physical and chemical characteristics of the tissue. Extreme brittleness called for special precautions in all manipulative steps from excision to final embedment. Turbulence during the early stages of dehydration was lessened by drop‐by‐drop addition of the next concentration of ethanol. High melting‐point paraffins and celloidin‐paraffin embedments were used to accommodate the hardness of the tissues and to prevent disarrangement during mounting. Steel knives specially sharpened with fine abrasives on plate glass were fitted with fluid reservoirs. Four micron sections were obtained routinely. Sections were transferred individually from the reservoir to glass slides. The common dyes used in light micoscopy tended to overstain these tissues. This tendency was overcome by using shorter exposure times, lower concentrations and blocking agents. The chromatic staining techniques familiar to histologists and pathologists were useful after minor modifications.
Homology of form in plant and animal Golgi apparatus
Authors: Mollenhauer H. H. , Morré D. J. , Bergmann Louise
Published: February 2005

In both negatively stained and sectioned preparations, Golgi apparatus of mouse spleen, liver and kidney consist of dictyosomes having cisternae with tubular peripheries. The extent of the tubular portion varies among tissues and among cisternae of a given dictyosome. Animal dictyosomes closely resemble those from plants in both form and sedimentation characteristics. In these respects, plant and animal Golgi apparatus are homologous structures.
Morphology of the specialized conducting tissue in the atria of the equine heart
Authors: Bishop Sanford P. , Cole Clarence R.
Published: February 2005

The gross and microscopic anatomy of the sinus node (SN), atrioventricular node (AVN) and specialized fibers in the atrium were studied in 19 horses and eight mules. The SN is supplied with blood by a branch from the left circumflex artery which subdivides within the node. The SN has a body and long tapering cranial and caudal crura which encircle the lateral margin of the precaval orifice. The AVN, which has no large artery consistently present within its structure, is located within the fibrous septum above the septal leaflet of the tricuspid valve and anterior to the coronary sinus.

Histologically most of the fibers in the SN and AVN are similar to those in other species. They are smaller, paler staining and much more interwoven than ordinary myocardial fibers. In the caudal crus of the SN, the fibers are clumped together with loss of individual characteristics.

Large, glycogen‐rich cells morphologically similar to ventricular Purkinje fibers are found in the right atrial subendocardium. The distribution of these fibers suggest that they may be concerned with intraatrial spread of excitation. Muscular pathways between the SN and AVN are composed of ordinary myocardial fibers. The large atrial myocardial fibers do not connect directly with SN or AVN fibers.
The ampulloglomerular organ: An unusual neurovascular complex in the suboccipital region
Authors: Parke Wesley W. , Valsamis Marius P.
Published: February 2005

A group of venous sacculations associated wth a system of glomerular arteriovenous anastomoses and numerous nerves lies adjacent to the vertebral artery. As thin walled extensions of a dural sinus, these ampullae are structurally capable of responding to changes in venous pressure. The function of their glomerular connections to branches of the vertebral artery is not apparent.
Developing boundary (basement) membranes in the chick embryo
Authors: Low Frank N.
Published: February 2005

The primordia of boundary (basement) membranes are present in the freshly laid egg along the basal surface of the epiblast. This location provides boundary membranes for all ectodermal derivatives including the central nervous system. Entodermal boundary membranes begin to form during the first half of the second day and eventually serve all entodermal derivatives. Mesodermal boundary membranes are slower to form. Those around the myotomes undergo considerable remodeling before the adult arrangement is reached. Endothelial boundary membranes are very slow to develop, not having appeared at 36 hours incubation.
A radioautographic study of cell proliferation in the mammary gland of the pregnant mouse
Authors: Traurig Harold H.
Published: February 2005

Proliferation of the mammary gland epithelium on days 2, 3, 4, 6, 8, 12, 16, and 19 pregnancy has been studied in mice, by means of radioautography. Each animal received an intraperitoneal injection of 25°c of tritiated thymidine and was killed one hour later. The inguinal mammary glands were processed for paraffin sectioning and radioautographs prepared using the dipping technique. The rate of mammary epithelial cell proliferation was quantitated for each animal by determining the percent of labeled epithelial cells in a large sample (> 2000 cells) of cells (labeling index).

The data showed that the proliferative activity of the mammary epithelium during pregnancy followed a bimodal distribution. The first evidence of a proliferative response to pregnancy was noted on day 3. By day 4, the labeling index reached a maximum of 25.3%. The labeling index declined on days 6 and 8 to 7.5% and 8.0% respectively. On day 12, the labeling index increased to 12.1%, then fell to 7.9% and 1.3% on day 16 and 19, respectively.

Separate labeling indexes were determined for the interlobular epithelium (ducts) on day 12, 16, and 19. The data showed that the labeling indexes of the interlobular and intralobular epithelium during these stages of pregnancy were not significantly different. The correlation of the hormones secreted during pregnancy with the data on mammary epithelial proliferation is discussed.
Congenital anomalies induced in normal and adrenalectomized rats by amniocentesis
Authors: Kendrick Francis J. , Feild Lee E.
Published: February 2005

Sprague‐Dawley rats, which are not susceptible to the teratogenic effects of adrenalectomy, adrenal corticoids, and corticotropin noted in other species, were subjected to amniocentesis and to amniocentesis plus adrenalectomy.

Amniocentesis was shown to be teratogenic when performed at any time between the fourteenth and eighteenth gestational days inclusive, but no malformations occurred either in control fetuses or when amniocentesis was performed on the thirteenth day of gestation. Fetal resorptions were increased following single amniocentesis on any gestational day from the thirteenth to the eighteenth inclusive. The predominant defects induced were cleft palate and limb deformity. Cleft palate occurred only after amniocentesis on the fourteenth, fifteenth, or sixteenth days of gestation, principally on the fifteenth day. However, limb deformity, consisting primarily of malrotation, syndactyly, and varying degrees of agenesis, occurred following single amniocentesis on any day of gestation from the fourteenth to the eighteenth inclusive, but principally on the fifteenth day. Adrenalectomy did not alter significantly either the nature or the incidence of the anomalies induced by amniocentesis.

The data indicate that amniocentesis is teratogenic in the rat, and that the adrenal glands are neither essential for, nor do they exert any detectable influence upon the induction of those malformations.
The effect of bilateral or unilateral adrenalectomy and bilateral thyroidectomy on the anterior pituitary of perinatal rats
Authors: Eguchi Yasunobu , Morikawa Yoshio
Published: February 2005

Measurements of volume of the anterior pituitary and diameter of pituitary cells and differential counts of acidophilic and basophilic cells were made under normal or experimental condition of bilateral or unilateral adrenalectomy or bilateral thyroidectomy in late fetal and newborn rats. The pituitary volume showed a consistent rise from the twentieth day of pregnancy to the third day after birth, but not as rapidly relatively as did body weight. Just after birth, the cell diameter declined. Acidophilic and basophilic cells increased in per cent and stained more intensely.

In fetuses, bilateral adrenalectomy caused an increase in both the “pituitary volume/body weight” ratio and the cell diameter. Unilateral adrenalectomy caused an increase in the cell diameter. Thyroidectomy showed an increase in both the cell diameter and the per cent of basophilic cells which were partially degranulated.

In newborns, bilateral adrenalectomy caused the death of all operated rats. Unilateral adrenalectomy caused no significant change in all categories observed. Thyroidectomy showed an increase in per cent of basophilic cells, but not to the extent observed in fetuses. The basophilic cells were somewhat degranulated.

The observations support the views that in the rat the pituitary‐adrenal and pituitary‐thyroid systems begin to function before birth and that the functioning of both systems is slightly reduced just after birth.
Cellular dynamics in the jejunum of essential fatty acid deficient mice
Authors: Snipes Robert L.
Published: February 2005

The population dynamics of the jejunal epithelium of mice maintained on a semi‐synthetic diet deficient in the essential fatty acids (EFA) has been investigated. Colchicine was employed to collect mitotic figures for the determination of mitotic indices. Twenty‐five crypts in longitudinal section were counted per animal and the mean mitotic index computed as the number of mitoses per total number of crypt cells. EFA‐deficient animals had a mean mitotic index of 36.56 as compared with 26.51 and 16.74 for the linoleic acid‐supplemented and chow‐fed control animals, respectively. Counts of the number of epithelial cells on one side of a villus and crypt indicated that the height of the villi, but not the crypts, of the EFA‐deficient animals was significantly lower than either control group. In the EFA‐deficient animals the mean percentage of villi having extrusion zones exceeded that of both control groups. Radioautography demonstrated that 36 hours after injection of tritiated thymidine the majority of villi in the EFA‐deficient animals were labeled at their tips, whereas in control samples label was restricted to the lower one‐half to three‐fourths of the villus. Thus, EFA‐deficiency induces increased rates of mitosis, migration and sloughing, resulting in alterations in villous architecture.
The development of the human fetal adenohypophysis
Authors: Conklin James L.
Published: February 2005

Understanding the development of the human adenohypophysis is dependent on visualizing the growth of Rathke's pouch. This embryonic structure gives rise to bilateral anterior and posterior, superior and inferior segments. These segments differ in their potential to produce various types of hypophyseal chromophils. The potential differences are described in the text.

Further, by application of specific staining procedures it has been possible to determine the approximate time that specific chromophils appear in the adenohypophysis. The chromophils of the adenohypophysis develop in the order: cell type III, I, IV, II, V, VI and IX. There may be a relationship between the development of certain chromophils and the onset of function in target endocrine glands.
Special ultrastructural features of parathyroid cells from Swiss mice bearing Ehrlich's ascites tumor
Authors: Latta John S. , Rutz Timothy J.
Published: February 2005

As part of studies on Ehrlich's ascites tumor cells transplanted into Swiss mice some unique myeloid figures, were found with electron microscopy in parathyroid cells, consisting of electron dense rings partially or completely encircling the nuclei of many cells in 7 of the 30 treated animals examined. These dense rings were seen to be made up of tightly matted bands, which at free ends, spread out to become continuous with agranular endoplasmic reticulum. The nuclei of these altered cells were quite pleomorphic and were closer together than in normal tissue, indicating decreased cell volume. Rough endoplasmic reticulum was scarce, mitochondria were long and slender and free ribosomes were widely scattered in the cytoplasm. A possible explanation for the development of these focal areas of degeneration is given.
Lipofuscin pigment accumulationin the nervous system of aging mice
Authors: Samorajski T. , Ordy J. M. , Rady‐Reimer P.
Published: February 2005

This morphologic investigation was undertaken with an inbred strain of C57BL/10 male mice to examine the accumulation of lipofuscin in nerve cells of dorsal ganglia and the cerebellum at 4, 8, 20, and 30 months of age. Histological examinations revealed that at four months of age, cells contained only a few small sudanophilic bodies distributed fairly uniformly throughout the cytoplasm. By 30 months, pigment aggregations became very prominent cytoplasmic features of many nerve cells in the dorsal ganglia and cerebellum. A more detailed examination of neurons from the dorsal ganglia with the electron microscope revealed particles of variable size with a high electron density at four and 8 months. By 20 and 30 months, the pigment bodies appeared to be larger and were more concentrated near the nucleus. In Purkinje cells of the cerebellum the pigment granules were observed only rarely at four and eight months. By 20 and 30 months, the granules in the Purkinje cells appeared to be larger, considerably more numerous, and concentrated between the nucleus and the apical dendrite. The intracellular pigment concentration was also estimated by calculations of the per cent of area occupied by pigment granules as well as by the per cent of the cells that contained pigment bodies at 4, 8, 20 and 30 months. A progressive increase in the intracellular pigment concentration was readily noted.
Nerve endings in the temporomandibular joint of the Rhesus macaque
Authors: Keller Jack H. , Moffett Benjamin C.
Published: February 2005

Methylene blue preparations and silver impregnated material were used to demonstrate the sensory nerve endings in the temporomandibular joint of the Rhesus monkey. Sixteen millimeter motion picture sequences of the various nerve endings were photographed while the microscope was slowly focused up and down through the entire thickness of the nerve ending. A 15‐minute film with descriptive sound track was prepared to demonstrate these nerve endings in three dimensions. The following types of nerve endings (listed in decreasing order of frequency) were seen in the articular capsule and peripheral portions of the articular disk: free, Ruffini, Golgi, and Paciniform endings. The sphenomandibular and stylomandibular ligaments in these monkeys gave no gross appearance of a ligamentous structure and did not contain any specialized proprioceptive nerve endings. Physiologic studies indicate that the nerve endings seen in the temporomandibular joint provide sensory mechanisms for the rception of pain, the autonomic control of vascular supply, and the recording of information concerning joint position and change in rate of movement.
Cell sizes and frequencies in the human nucleus intercalatus
Authors: Radmanesh H.
Published: February 2005

A considerable area of the floor of the fourth ventricle, extending from the facial colliculus down to the vagal triangle, is underlaid by the nerve cells of the nucleus intercalatus. Only a minor portion of this nuclear complex is actually “intercalated” this portion comprising about 2,500 cells or 6% of the total. The great majority of cells making up this nucleus, 80% or 32,000 are found in front of the oral pole of the hypoglossal nucleus. The remaining 14% of cells or about 6,000 form a third distinct group located opposite the medial vestibular nucleus. The mean cell sizes in the three parts of the nucleus are also different, they are 90 μ2, 135 μ2 and 190 μ2 respectively. These differences of cell sizes and of location were the basis for the division of this nucleus into three parts by some authors. In the three cases studied, this division was, however, not so complete as to permit a separate cell count for each part to be kept. The mean of the cell frequencies in the three cases is 36349 ± 4114 cells.
Formation of ceroid pigment in subcutaneous implants in mice
Authors: Winnail Douglas S. , Williams W. Lane
Published: February 2005

Mice of the RF and C57 black strains, fed an adequate diet, were donors and recipients of subcutaneous tissue implants. Abundant ceroid formed in implants of liver, heart, and adrenal. The pigment developed concurrently with degenerative changes in hepatocytes and myocardial fibers. Ceroid was intracellular in implants of adrenal gland and limited to cortical cells. Skeletal muscle and multilocular fat cells were next most productive sources of ceroid. Unilocular fat cells produced only traces. Isogeneic and allogeneic implants of corresponding tissues revealed comparable amounts of ceroid after two weeks of transplantation. Formation of pigment was correlated with the type of tissue transplanted rather than to specific host‐graft responses.

Implants of liver tissue were an ideal model for studying genesis of ceroid pigment. Granules of ceroid appeared first at the periphery of the implant in tissue adjacent to obviously degenerating cells of the graft. These small granules of pigment were then engulfed by macrophages. In most instances liposis preceded formation of ceroid. The presence of large amounts of lipid in the tissue at time of implantation did not augment ceroid formation. Hyper‐ and hypovitaminosis E, choline deficiency (to produce fatty livers), hyperestrogenism, and the administration of immunosuppressive drugs to recipients failed to influence appreciably the production of ceroid. In livers and other tissues containing little fat a relatively rapid post‐implantation liposis preceded ceroid formation.
The role of Spleen in development of lympho‐hemopoietic tissues: Effect of splenectomy on development of blood cells, bone marrow, thymus and lymph node
Authors: Kalpaktsoglou Pitsa K. , Yunis E. J. , Good R. A.
Published: February 2005

The effects of splenectomy at birth and two and four weeks of age on the development of lymphoid and hematopoietic tissues has been compared in C3H/Bi mice. During the neonatal period normal mice showed changes in total leukocyte count, and in absolute members of the specific cell types. The predominant changes included an initial fall of numbers of granulocytes and steady increase in numbers of lymphocytes during the first six weeks of life. Neonatal splenectomy interfered with the normal developmental pattern by interfering with normal growth of numbers of circulating lymphocytes while splenectomy at two and four weeks of age produced increases in numbers of both circulating lymphocytes and granulocytes. Neonatal splenectomy produced effects on development of bone marrow, peripheral lymph nodes and thymus. The major influence seemed to involve decrease in percentages of small, densely stained lymphocytes in thymus and peripheral lymph nodes.
Surgically induced hypertrophy in skeletal muscles of the laboratory mouse
Authors: Rowe R. W. D. , Goldspink G.
Published: February 2005

Two surgical techniques were used to increase the work load per fiber in mouse skeletal muscles. These were, part removal of the muscle and incapacitation of a synergetic muscle. Both techniques were used for the soleus muscle. They resulted in the fiber size distribution of this muscle, which was normally unimodal, becoming distinctly bimodal. The same effect was obtained for the part removal of the anterior tibialis muscle. For the above mentioned muscles the extent of hypertrophy was very considerable. The recorded increase in the mean fiber cross‐sectional area was in the region of 56% to 92%. Part removal of the biceps brachii however produced only a comparatively slight increase in fiber size (9%). In this case the normal muscle was bimodal and the effect of part removal was to slightly increase the size of the second peak. The reason for the two peaks occurring in the distributions of fiber size in some muscles was due to the presence of fibers at a basic level of development and also the presence of hypertrophied fibers. The increase in mean fiber size resulting from an increased work load was in all cases, due to a proportion of the basic fibers undergoing hypertrophy and not due to a gradual increase in the size of all the fibers.