bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of Brunner's glands in the opossum. II. Postnatal development
Authors: Krause William J. , Leeson C. Roland 
Published: February 2005

AbstractThe postnatal development of Brunner's glands in the opossum has been traced, using 170 specimens divided into 21 groups according to snout‐rump length. The newborn opossum has a well developed small intestine, possessing villi and a differentiated intestinal epithelium with concentrations of PAS‐positive material in the apical cytoplasm. The ducts of the glands begin to develop within 24 hours after birth and, as they proliferate, two cell types appear. A tall, columnar cell type lines the excretory duct whereas the intralobular duct system is lined by pyramidal cells. Intralobular ducts undergo differentiation by the 50 mm stage and, after this event, secretory units appear as outgrowths from the intralobular duct system. Development continues into early adulthood.Duodenal glands appear to evaginate simultaneously at localized foci, resulting in the formation of a duodenal sinus between glandular elements. The glands evaginate from the mucosa in the most proximal portion of the duodenum, involving both intestinal and gastric mucosal elements. That portion of mucosa lying between the forming glands is submerged and forms the floor of the duodenal sinus. Excretory duct epithelium often lines the sinus in part. The development of Brunner's glands in the opossum is completely independent both of pyloric and intestinal glands.
Factors influencing villus size in the small intestine of adult rats as revealed by transposition of intestinal segments
Authors: Altmann Gabriel G. , Leblond C. P. 
Published: February 2005

AbstractAs an index of villus size, the number of epithelial cells per representative villus section was counted in longitudinal sections of the rat small intestine. Villus size was found to decrease gradually along the length of the small intestine, with villi being nearly three times as large in upper duodcnum as in terminal ileum. The influence of various surgical operations on villus size was then examined.In ileal segments inserted into the jejunum, villi enlarged to the size of local jejunal villi. In jejunal segments inserted into the ileum, villi decreased almost to the size of local ileal villi. Thus, villus size was influenced by the environment, that is, most probably by the different types of chyme in jejunum and ileum.In duodenal segments inserted into the ileum, villi did not decrease in size, and distally located ileal villi enlarged. This and other experiments indicated that the duodenum produced secretions which not only neutralized the villus‐reducing effect of the ileal environment, but also exerted a potent villus‐enlarging effect. Pyloric secretions had a similar villus‐enlarging effect.Segments of intestine were made into blind sacs by closing their proximal end and joining their distal end to the colon, so as to remove the influence of the chyme. Villus size decreased in sacs of jejunum and lower duodenum (without the duodenal papilla), but increased in sacs of ileum. Thus in the three types of sacs, there was a tendency for villi to acquire an intermediate size.In conclusion, an intermediate villus size, which is postulated to exist in chyme‐free, non‐functional intestine, would normally be modified by two types of factors: villusenlarging factors present mainly in pyloric and duodenal secretions, and villus‐reducting factors present in the ileal chyme. Interaction between these factors would result in the gradient of villus size along the small intestine.
The morphological effects of parathyroid extract upon the developing skeleton of the embryonic chick
Authors: Jones Helena S. 
Published: February 2005

AbstractThe in vivo effects of parathyroid extract (PTE) on the formation of the embryonic chick humerus and femur were examined. PTE had a considerable effect on mortality (increased) and ossification (inhibited). Group I embryos were injected with 0.1 ml PTE on day 4 of incubation; their survival rate was 71% which encompassed the experimental period through day 15. Group II embryos were injected with 0.1 ml PTE on day 6; only 32% survived through day 7 and none were alive after day 9. Until the effects of PTE were overcome as seen in Group I nine‐day embryos, PTE (1) inhibited ossification, (2) retarded development of the cartilage model and (3) caused chondrolysis of the capsular matrix in the zone of cellular hyperthrophy. PTE did not appear to cause (1) increased formation of osteoclasts, (2) formation of fibrous connective tissue instead of osteoid or (3) reversion of bone cells to a more primitive or multipotential bone type. It is suggested that the toxic effect of PTE on Group II embryos relates to its application at a critical stage of development.
Cytology of the pars anterior of the bovine adenohypophysis
Authors: Heath Everett 
Published: February 2005

AbstractSelected samples from the pars anterior of 2 lactating cows, 2 normal calves, 3 thyroidectomized calves, and 12 heifers at different stages of the estrous cycle or in early pregnancy were examined by electron microscopy. Adjacent thick sections were differentially stained and routinely examined by light microscopy.Two acidophilic cell types were distinguished. One had granules with maximum diameters between 350 and 500 mμ. The other, containing granules with maximum diameters between 550 and 750 mμ, was frequently seen in lactating cows and midcycle or pregnant heifers.Basophilic cell types were not so clearly distinguishable. PAS‐positive, Alcian bluenegative basophils were most frequently seen in proestrous heifers, but basophils with Alcian blue, PAS‐positive granules were also present, and in some of these the granules were morphologically similar to those of the PAS‐positive cell type. Globular bodies, morphologically similar to those reported in amphibia but negative for acid phosphatase, were routinely observed in some of the Alcian blue, PAS‐positive basophils.The most significant change in estrous heifers and thyroidectomized calves was the development of large chromophobes with an extensive dilated rough endoplasmic reticulum. It was not possible clearly to relate these chromophobes individual basophilic cell types.
The trigeminal mesencephalic nucleus. II. Electron microscopy
Authors: Hinrichsen Colin F. L. , Larramendi Luis M. H. 
Published: February 2005

AbstractThe fine structure of cells in the trigeminal mesencephalic nucleus was examined in adult mouse and cat. Cell surfaces were studed with small spinous processes which were free of synaptic contacts. Some cells in soma‐soma and axosomatic contact were joined by maculae and membrane fusions resembling in cross section the zonula adherens and macula occludens of epithelial cells. Synapses containing three distinct morphological types of vesicles contacted the cell soma. The possible functions of synapses and membrane fusions were discussed.
The small pyramidal neuron of the rat cerebral cortex. The perikaryon, dendrites and spines
Authors: Peters Alan , Kaiserman‐Abramof Ita R. 
Published: February 2005

AbstractThe small pyramidal neurons of layers II and III of the rat parietal cortex have been examined with both Golgi staining and electron microscopy. The cell body contains a large nucleus and only a thin rim of cytoplasm in which the Nissl substance is not well developed. A cap of Nissl substance occurs at the base of the apical dendrite, however, and a number of cisternae of the Golgi apparatus occur in this same location. A centriole is often found here too, so that this region of the neuron represents the cell center. Little Nissl substance occurs in the dendrites, which mainly contain well‐ordered arrays of microtubules.Projecting from the stem of the apical dendrite and from the secondary dendrites are spines. Basically, the spines are of three types. The most common ones have long, thin stalks and small end bulbs. The least common ones are mushroom‐shaped and have thick stalks ending in large bulbs. The other spines are short and stubby, and have no well‐defined stalk. The distribution of these three types of spines has been determined. Although they are rare, spines may also project from the cell body, which has very few synapses on its surface.
Ultrastructure of the amnion and amniotic plaques of the white‐tailed deer
Authors: Sinha Akhouri A. , Seal Ulysses S. , Erickson Albert W. 
Published: February 2005

AbstractThe ultrastructure of the aminon and aminotic plaques of the white‐tailed deer was studied throughout pregnancy. The single layered amniotic epithelium had short, blunt, club‐shaped microvilli, tortuously folded lateral plasma membranes enclosing an intercellular space, and basal foot‐procsses. Wherever lateral plasma membrane processes abutted, desmosomes occurred. Hemidesmosomes were observed only in association with the foot‐processes. The epithelium contained granular endoplasmic reticulum, rod‐shaped mitochondria, free ribosomes, Golgi complexes, tonofibrils, tonofilaments and glycogen granules. The epithelium was supporte by a basal lamina. The subjacent connective tissue layer contained mesenchymal cells, fibroblasts and collagenous fibers.The amniotic plaques varied in size from microscopic to 4 mm in diameter. The small plaques were formed by mitotic activity of the aminion cells. their sites of formation appeared randomly distributed. Each microscopic plaque had one to three layers of basal columnar to cuboidal cells, and a single layer of covering cells next to the amniotic cavity. Further mitotic activity of basal columnar cells led to the formation and differentiation of large plaques which contained over 15 cell layers. The main mass of a large plaque showed four zones: stratum basale, stratum spinosum, stratum granulosum and stratum corneum. Cytoplasmic organelles were plentiful in the basal and spinous cells, but were sparse in the granular and cornified layers. Keratohyalin granules and dense tonofibrils were usually found in the granular cells, but only occasionally in cornified cells. Each plaque contained varying amounts of PAS‐positive glyucogen granules. The tortuously folded lateral plasma membranes enclosed intercellular spaces which extended from basal to cornified layers. Small portions of amniotic cells and layers of cornified cells sloughed throughout pregnancy and thus contributed to the composition of amniotic fluid. The homology of the plaques with mammalian skin and their distribution in the eutherian mammals is discussed.
Experimental studies on the dorsal nerve of the penis of the rat
Authors: Calaresu Franco R. 
Published: February 2005

AbstractDorsal nerves of the rat penis were studied in osmium tetroxide‐treated sections for number and diameter distribution of myelinated fibers. The mean count in four nerves was 1423 fibers. The percentage distribution of diameters was unimodal with the peak at 5‐6 μ. Counts taken at different levels of the nerve showed a proximo‐distal decrease in the number of fibers but no difference in the percentage a distribution of fiber diameters. The compound action potential of the dorsal nerve exhibited potential waves with conduction velocities between 62 and 10 meters/second, which correlates well with the histological data. Counts of myelinated fibers in the dorsal nerve of four animals 14, 26, 38 and 70 days after section of the ipsilateral pudendal nerve revealed complete degeneration at 14 days, progressive regeneration at 26 and 38 days, and complete recovery at 70 days. The percentage distribution of diameters in the nerves at different stages of regeneration was essentially the same. The rate of regeneration expressed as percentage of the total number of fibers from day 14 to day 36 was approximately 1.2% day and from day 36 to day 70 approximately 2.2% /day.
Regeneration of the rat gastrocnemius muscle from sibling and non‐sibling muscle fragments
Authors: Carlson Bruce M. 
Published: February 2005

AbstractRegeneration of the gastrocnemius muscle from minced transplanted muscle fragments was studied in 46 rats. The jumping complex of muscles (gastrocnemius, soleus and plantaris) was removed from the donor and minced into 1 mm3 fragments. In one experimental series minced muscle was orthotopically implanted into sibling animals, and in the other series minced muscle was implanted into non‐sibling animals of the same strain. During the first week after implantation, regenerative activity in the homotransplanted muscle fragments was intense and did not differ histologically from that occurring in autotransplanted muscle. Staritng in the second week, areas of regenerating homotransplanted muscle fibers became infiltrated with small lymphocytes. Despite relatively massive cellular rejection in the regenerates, individual skeletal muscle fibers regenerated to maturity. Regenerates from homotransplanted muscles often attained the same gross from as regenerates from auto‐transplanted material, but in no case was the amount of muscle fibers in homografted regenerates greater than 50% of that seen in regenerates arising from autografted muscle fragments. About half of the advanced regenerates were reduced to broad bands of connective tissue containing no muscle fibers.
Electron‐dense material within sarcoplasmic reticulum apposed to transverse tubules and to the sarcolemma in dog papillary muscle fibers
Authors: Walker S. M. , Schrodt G. R. , Edge M. B. 
Published: February 2005

AbstractThe space between the sarcoplasmic reticulum (SR) apposed to the transverse (T) tubules and the sarcolemma in dog papillary muscle fibers is traversed by structures of varying densities. The distance between apposed membranes is about 70 Å at the level of densities and about 100 Å at the level of less dense areas that alternate with the densities. The apposed SR shows a marked increase in electrondense material when comparison is made with the SR not apposed. The electron‐dense material is located in a dense layer parallel to and about midway between the membranes of the apposed SR and in numerous projections from the inside surface of the membranes. With appropriate staining procedures the central dense layer and the projections are as thick as membranes and they frequently show paired densities separated by a distance about equal to the distance between the outer dense layers of trilaminar membranes. The paired densities in the central dense layer and in the projections indicate that the electron‐dense material within apposed SR has structure. The projections are frequently in register with scallops or serrations in the SR membranes and they also appear to contribute to a waviness in the central dense layer. The serrations and waviness are interpreted as evidence that the projections exert a holding force because they project from the SR membranes and connect with the central dense layer.
Human choroid plexus: Morphologic and histochemical alterations with age
Authors: Shuangshoti Samruay , Netsky Martin G. 
Published: February 2005

AbstractThe choroid plexus was studied in 217 necropsy specimens from human beings two months to 94 years of age. With advancing age, the height of the cuboidal epithelial cell gradually decreases, many becoming squamous. Cytoplasmic vacuoles increase in number. Focal stratification is not an artefact, and is evidence of proliferation. The proliferated cells eventually desquamate, becoming round, large and foamy as they accumulate intracytoplasmic lipid and degenerate. The findings indicate that cellular desquamation occurs during life. Filaments of mucopolysac‐charides are common in the choroid plexus of old people. Stromal alterations associated with increased age consist of a gradual increase in the amount of connective tissue, in number of meningocytes and psammoma bodies, and in severity of hyalinization, fibrosis, fragmentation of connective tissue fibers and calcification. Most psammoma bodies are found in the glomus choroideum. Non‐lamellar calcific foci occur mainly in the matrix of the choroidal villi and fronds. Formation of psammoma bodies is associated closely with the meningocytic whorls. Lipids, mucopolysaccharides and mucins are identified in both epithelial and stromal components of the choroid plexus. Lipids appear in the stroma later in life. It is suggested that lipid in the cytoplasm of desquamated choroidal eipthelial cells is one source of lipids in the cerebrospinal fluid.
Morphogenetic studies of the rabbit XLI. Gradients of correlation in the architecture of morphology
Authors: Sawin P. B. , Fox R. R. , Latimer H. B. 
Published: February 2005

AbstractSignificant sex and strain differences in correlation of bone, body and skeletal weights show significant localized effects of sex and strain and a combination of both. Individually they seem to lack biological meaning. However, when considered in relation to the ponderal correlations, of which they are a part, they fall into place at the distal ends of a graded linear correlation series, both within and between limbs; and similarly between mandible and sacrum, respectively, with each bone of both limbs. The pattern of these gradients reveals a linear decline in correlation of bones with distance (rule of neighborhood, Karl Pearson) in most cases, but the exceptions are such as can be related to the functions in which they cooperate. In this way they demonstrate at least two major unifying genetic influences. One associates sex and strain with locomotion and the other with the incipient upright investigative posture of the Lagomorphs (including the rabbit). The expected effect of sex on the pelvis is apparently not expressed by these ponderal measurements. The manner in which this correlation approach, based on well established genetic growth differences, converges with the phylogenetic and ontogenetic concepts of normal and abnormal growth of bone in limbs and cranio‐facial development suggests that a combination of correlation and epigenetic analysis would be helpful in establishing a sound genetic background for the newer biomechanic, functional matrix and architectonic approaches.
Afferent nerve endings in the urinary bladder of the cat
Authors: Fletcher Thomas F. , Bradley William E. 
Published: February 2005

AbstractIn five cats, sacral dorsal rhizotomies were performed, alone or in conjunction with sympathetic nerve transections. Urinary bladders, collected 7, 10, or 30 days following the nerve transections, were sectioned and stained by the Holmes silver nitrate and the Nauta and Gygax methods and examined under the light microscope. Degenerative changes occurred in bladders of all the cats permitting an assessment of the appearance and distribution of vesical sensory endings. Degenerated myelinated axons and nerve terminals were found bilaterally in bladders, although they were more numerous ipsilateral to the transections. Within the muscle coat, degenerated endings were found in the perifascicular connective tissue, and less frequently, on the surface of muscle fascicles; endings were not seen among the muscle cells within a fascicle. Sensory endings were identified in the subserosa and lamina propria but not in transitional epithelium. Except for an occasional Paccinian corpuscle, encapsulated endings were not found. Afferent endings in the bladder appeared to be non‐encapsulated and without terminal fiber modifications.
The litter effect as a variable in teratologic studies of the albino rat
Authors: Jensh Ronald P. , Brent Robert L. , Barr Mason 
Published: February 2005

AbstractThis study was conducted to determine if there is a greater variation in fetal weight and/or placental weight among litters of rat fetuses than within a single litter. Three hundred and twenty‐seven litters comprising 1,979 fetal and placental weights were analyzed using analysis of variance within versus among litters. There was a definite litter effect, i.e., variation in fetal and placental weight was greater (p < 0.05) among litters than within litters. The variation in fetal and placental weights between litters became greater with increasing litter size. Experimentally limiting the litter size early in gestation does not reduce or eliminate the litter effect. This litter effect means that individual fetuses from several rat pregnancies cannot be considered to have come from a common universe and, therefore, the number of litters and their mean growth data are much more meaningful than the number of embryos in an experiment. When designing research programs in which embryonic and placental growth in rats are to be evaluated, it is more important to establish the experimental goal on the basis of the total number of litters rather than the total number of embryos per experimental or control group.
Histology of the subauricular and rump glands of the pronghorn (Antilocapra americana ord)
Authors: Moy Randall Frank 
Published: February 2005

AbstractSubauricular and rump glands of pronghorns (Antilocapra americana) collected during every month of the year, were examined histologically. In early spring the apocrine and sebaceous zones of the paired subauricular glands, which are found only in males, proliferate abruptly. These zones continue to enlarge and become highly secretory during the summer; they regress during the fall and are quiescent in December. During the peak of activity large sebaceous storage vesicles are present and copious amounts of secretory material occupy the apocrine lumina. Irregular clumps of cells that are associated with the apocrine tubules are numerous in summer and appear to be associated with apocrine secretory activity. The subauricular glands of castrated bucks are small and inactive compared to normal glands. Annual proliferation and regression of the subauricular glands follows similar activities of the testes. Thus, the cycle of activity in these glands is apparently controlled by gonadal hormones. Odors from the subauricular glands may serve for sex recognition, stimulation, and marking of territories. The paired rump glands consist of lobulated sebaceous units and coiled apocrine tubules that maintain limited secretory activity throughout the year. Contraction of large arrector pili muscles associated with hairs in the glands may cause accelerated secretion. The rump glands of normal males, females, and castrated males, are similar in all respects. Apparently these glands are not sexually influenced. The rump glands may serve for olfactory warnings in conjunction with the visual warnings of the white rump patch.
The prenatal development of the human femur
Authors: Gardner Ernest , Gray D. J. 
Published: February 2005

AbstractThe study reported here is the result of a detailed investigation of the changes in shape of the femur with growth and torsion, the type, rate and character of ossification, and the onset, subsequent course, and general features of remodeling.Forty pairs of femurs, from a series of embryos and fetuses ranging from 26 to 342 mm in crown‐rump length, were measured, radiographed, and sectioned for microscopic study.A primary bony collar was present before the end of the embryonic period, and in a 27 mm embryo it extended for about one‐fifth of the length of the femur. Erosion of the collar was evident at 34 mm. and invasion and destruction of calcified cartilage were occurring by 37 mm. Cartilage canals first appeared in the proximal epiphysis at 57 mm and in the distal epiphysis at 61 mm.Along with the progression of endochondral ossification proximally and distally and the establishment of growth zones, periosteal bone formation also proceeded in both directions, and, until 275 mm, extended about 1 mm beyond the zones of cartilage destruction. After 275 mm, the extents of periosteal and endochondral ossification were the same and at term occupied almost four‐fifths of the length of the femur.Trabeculation of the bony collar was first noted at 37 mm. Fusion of endochondral trabeculae with the inner aspect of the periosteal shell began by 61 mm. A central marrow cavity free of trabeculae was present at 86 mm and thereafter. Evidence of reconstruction appeared in both proximal and distal ends by 92 mm, and was consistently present in both ends in all specimens of 111 mm and larger.