bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure and growth of human limb mesenchyme (HLM15) in vitro
Authors: Kelley Robert O. , Baker Thomas I. , Crissman Harry A. , Henderson Carolyn A.
Published: February 2005

Human embryonic hand and foot plates (horizon XVI) exhibit localized differences in mitotic activity between developing digital and interdigital zones of mesenchyme. To investigate development of regulation of cell reproduction, mesenchymal cells from lower limb buds dissected from a human embryo (stage XV) were cultured. Electron microscopy reveals that HLM15 cells in situ are fibroblastic, exhibit euchromatic nuclei, one to two peripheral nucleoli, extensive granular ER, free ribosomes, and microfilaments and microtubules oriented in the long axis of cellular processes. Cells released from substratum with trypsin‐EDTA become rounded and microfilaments and microtubules become disoriented, perinuclear bundles. HLM15 has a mean generation time of 24 hours during logarithmic growth and karyotype analysis indicates that cells retain diploid chromosomal number after 17 passages. DNA‐fluorochrome analysis on the Los Alamos Flow Microfluorometer (FMF) demonstrates that HLM15 cells possess no detectable polyploidy. Computer fit of FMF distributions reveal that random populations of HLM15 during exponential growth contain 42.6% cells in G1, 45.9% in S and 11.5% in G2+M. As confluency is reached these data become 57.6%, 37.5% and 4.9% respectively. Disaggregated limb mesenchyme (in vivo) analyzed without culturing exhibit FMF distributions of 56.1% in G1, 36.7% in S and 7.2% in G2+M. Similarities in cell cycles between near‐confluent HLM15 cultures and limb mesenchyme in vivo suggest that regulation can be achieved by increasing or decreasing the traverse time through G1 (both in vitro and in vivo). The proportion of non‐cycling cells (G0) in the FMF G1 distribution is presently not known.
The migration of lymphocytes from bone marrow to popliteal lymph nodes demonstrated by selective bone marrow labeling with 3H‐thymidine in vivo
Authors: Brahim F. , Osmond D. G.
Published: February 2005

Guinea pig popliteal lymph nodes were examined by DNA radioassay and radioautography following the selective labeling of tibial and femoral marrow cells by intramyeloid injections of 3H‐thymidine. The DNA radioactivity of the node increased for the first four days and at four to seven days exceeded that seen after an intraperitoneal injection of the same total dose of 3H‐thymidine, indicating an export of radioactivity from the labeled marrow to the node. Simultaneously, radioautographic sections of the node revealed labeled cells indicative of an origin from marrow precursors. Small lymphocytes constituted 60–90% of the labeled cells and reached maximal numbers at four to six days. Most of them were observed in the cortex, including the subcapsular sinus, primary follicles, mantle zones around germinal centers, and the lumen and walls of post‐capillary venules. However, the highest labeling indices of small lymphocytes occurred in the medulla, including the medullary cords, medullary sinuses and efferent lymphatic vessels. Labeled large mononuclear cells, including large lymphoid cells, monocytes and large blast cells, were confined almost exclusively to the cortex. A small number of labeled plasma cells was observed in the medullary cords. It is concluded that newly‐formed bone marrow lymphocytes migrate continuously into immunologically quiescent lymph nodes and become widely distributed throughout the cortex and medulla, while some enter the recirculating small lymphocyte pool.
Distribution of thyroid, parathyroid, and ultimobranchial hypocalcemic factors in birds. II. Morphology, Histochemistry, and hypocalcemic activity of pigeon thyroid glands
Authors: Hoyt Richard F. , Hamilton David W. , Tashjian Armen H.
Published: February 2005

Thyroid lobes from five common and six White Carneaux pigeons were cut into fragments which were assayed biologically for their calcitonin content. Pooled, alternate tissue slices from the individual thyroid lobes of 18 additional White Carneaux pigeons were assayed; the remaining tissue slices were prepared for light and electron microscopy or for demonstration of histochemical properties associated with the APUD system of polypeptide hormone‐producing cells, including: α‐glycerophosphate dehydrogenase, acetylcholinesterase, nonspecific cholinesterase, esterase, argyrophilia, and production of fluorogenic monoamines. Calcitonin was present at all cephalo‐caudal levels within pigeon thyroid lobes and was concentrated in peripheral, as opposed to central areas of the lobes. White Carneaux left thyroid lobes contained 34–225 MRC U of calcitonin/g tissue. Twelve of 18 right lobes lacked detectable calcitonin; the remaining six lobes contained 12–46 MRC U/g. Microscopy revealed a population of granulated cells that were found only in peripheral regions of lobes containing measurable calcitonin. These cells resemble mammalian thyroid parafollicular cells ultrastructurally. They appear to be surrounded by amine‐containing, argyrophilic nerve fibers. Of the histochemical characteristics of mammalian “C” cells tested, only amine‐precursor uptake could be correlated with the presence of calcitonin and granulated cells in the thyroid gland of the White Carneaux pigeon.
Electromyography of the human cheeks and lips
Authors: Isley Charles L. , Basmajian John V.
Published: February 2005

To clear up indecision and disparities in the literature of muscular functions in the cheek and lips, multichannel electromyography with fine‐wire intramuscular electrodes was used in eight subjects. Both facial expressions and musical performance were investigated. Intersubject variations were common in the various muscles and intrasubject variation also appeared. The production of specific notes at specific volume on the trumpet or trombone did not depend on exact patterns of activity in the muscles of the lips and buccinator. Gentle puffing out of the cheek produces little or no activity in any muscle, but when this is done forcefully the orbicularis oris activity is marked. Buccinator can be kept deliberately relaxed or active during puffing. Smiling always produces buccinator activity as does forceful retraction of the corners of the mouth. Levator anguli oris activity always recruits concurrent buccinator activity but the reverse is not true.
Fine structure of acinar cells of human parotid gland
Authors: Riva Alessandro , Riva ‐Testa Francesca
Published: February 2005

Acini of human parotid gland consist of pyramidal secretory cells and of flattened, basally placed, myoepithelial cells.

Since secretory cells show a cytological organization intermediate between that of exocrine pancreas and that of mucous glands, human parotid is considered to be a seromucous gland. Short intercellular canaliculi extend between apical portions of secretory cells; more basally intercellular spaces, constantly separated from the lumen, are seen. Variations observed in cytology of secretory cells are believed to be more likely related to the presence of stages of a maturative cycle rather than to the existence of different types of cells. Secretory granules often show a bipartite structure consisting of a main portion and of a dense body (or core) contained in it. On the basis of the appearance of the main portion, dark and pale granules are recognizable. Dark granules are quite dense and homogeneous while pale granules, which tend to coalesce, are formed by a clear flocculent material. Together with granules endowed with intermediate characters, dark and pale granules are often present even in the same cell. Discharge of secretion into the lumen seems to take place following the fusion of the membrane of the secretory granule with the plasmalemma. In fact, bulging secretory granules and subluminal clefts are frequently seen. The shape of nuclei and the pattern of their chromatin content vary apparently with the cell cycle. Inside the nuclei, a distinct fibrous lamina, nucleoli and nuclear bodies are present. In addition, some nuclei exhibit a laminated inclusion arranged concentrically.

Myoepithelial cells have an elongated body and thin processes extending among secretory cells. They are characterized by a filamentous cytoplasm poor in organelles.
The stomach gland patch of the koala (Phascolarctos cinereus)
Authors: Krause William J. , Leeson C. Roland
Published: February 2005

A large gland patch is found in the submucosa of the lesser curvature of the koala stomach near the entrance of the esophagus. It measures approximately 3 cm in diameter and is comprised of numerous invaginations continuous with the surrounding mucosa. The glandular invaginations drain into the lumen of the stomach by 25 to 30 large orifices. The mucosa of the gland patch invaginations differs from the mucosal lining of the stomach chiefly in thickness. The elongate gastric glands that comprise the invaginations exhibit an increased number of parietal and chief cells. Ultrastructural examination of the gland patch illustrates that the parietal, chief, and mucous neck cells are similar in structure to those of other mammalian species.
Inferior rectal nerve variations as it relates to pudendal block
Authors: Roberts Walter H. B. , Taylor William Holmes
Published: February 2005

The fact that the inferior rectal nerve may have an independent origin from the sacral plexus is acknowledged in most current anatomy texts. That it may pierce the sacrospinous ligament well medial to the ischial spine is no longer mentioned. This variation which may occur in as many as 20% of the sides examined, could present a problem in pudendal block.
Maturation of goblet cells of the mouse small intestine as shown by the uptake of 35S‐sodium sulfate
Authors: Merzel José , Almeida Maria Lúcia P.
Published: February 2005

Adult male mice fed “ad libitum” were given a single intraperitoneal injection of 35S‐sodium sulfate and sacrificed one, three and six hours after. Plastic embedded one micron thick sections from duodenum, jejunum and ileum were radioautographed and the uptake of the 35S by goblet cells was analysed. Goblet cells of the small intestine originate in crypts and migrate to villi reaching their tips where they are released into the intestinal lumen. Radioautographic reaction appeared over all goblet cells whether in the crypts or in the villi indicating continual synthesis of sulfomucins.

By determining the silver grain concentration over goblet cells at different levels of crypts and villi it was shown that the cells of duodenum and jejunum become more active in the synthesis of sulfomucin, when they reach the upper half of the villi. In the ileum, although a similar maturation may occur, the results were not statistically significant.
Fine structure of the urinary bladder of the bullfrog, (Rana catesbiana)
Authors: Strum Judy M. , Danon David
Published: February 2005

The urinary bladder of the bullfrog, Rana catesbiana has been studied by light and electron microscopy. Three epithelial cell types were found: (1) granular cells, (2) mitochondria‐rich cells, and (3) basal cells. The structure of the Rana catesbiana bladder differs from that of the toad Bufo marinus, in several respects: it lacks a mucous (goblet) cell type, its granular cells do not contact the underlying basement membrane, it has specialized, smooth‐muscle cell‐basal epithelial cell contacts, not previously described in amphibian bladders, and its mucosa is richly innervated. Mitochondria‐rich cells within the bullfrog bladder epithelium were occasionally observed touching the basement membrane. The specialized smooth muscle‐basal cell contacts provide anatomical evidence for how regulatory vasoactive substances such as neurohypophyseal peptides might alter epithelial geometry. Many nerve endings invest the mucosa just beneath the epithelial basement membrane in proximity to mitochondriarich cells and basal cells. The possible role of neural regulation in epithelial transport was discussed.
Banded spindle‐shaped structures in the notochord of Salmo irideus
Authors: Watanabe K.
Published: February 2005

Banded spindle‐shaped structures consisting of packed cylindrical units were observed among the typical collagen fibrils in the notochord sheath or in the intercellular space between notochord cells of Salmo irideus larvae. The banded spindle‐shaped structures showed a regular periodicity ranging from 750–1000 Å and cylindrical structures which appear to be packed in hexagonal arrays so that six cylinders surrounded a central cylinder. Both banded and cylindrical structures appeared to be the same bodies in three dimensions. These banded structures may originate from surrounding collagen fibrils.

On the other hand, comb‐shaped structures were found between the elastica externa and the collagen fibrils of the notochord sheath in newly hatched S. irideus larvae and in fry. The width of the structures was about 0.25 Å in the widest part. The banding showed a regular periodicity ranging from 500–600 Å. These structures may play a role in adhesion of the elastica externa to the underlying collagen fibrils of the notochord sheath.
Alterations in the fine structure of cardiac muscle mitochondria induced by hyperthyroidism
Authors: Callas Gerald , Hayes James R.
Published: February 2005

Chronic hyperthyroidism was induced in radiothyroidectomized adult albino rats by feeding a diet of 0.3–0.4% desiccated thyroid for four to ten weeks. The left ventricle from control and hyperthyroid animals was examined with the electron microscope after perfusion fixation with 3% phosphate buffered glutaraldehyde and postfixation in 1% osmium tetroxide. No differences were discerned in the appearance of the Golgi zone, glycogen, lipid, lysosomes, sarcoplasmic reticulum, or the sarcomere ultrastructure of the ventricle from hyperthyroid animals compared with untreated animals. Changes were noted in the mitochondria. These included marked hypertrophy without increase in numbers and localized areas of vacuolization and disorientation of the cristae. Apparently these changes are reversible since the ventricular mitochondria of previously hyperthyroid animals allowed to return to a euthyroid state were indistinguishable from those seen in the control group.
Ultrastructural differentiation of Leydig cells in the fetal and postnatal hamster testis
Authors: Gondos Bernard , Paup Donald C. , Ross James , Gorski Roger A.
Published: February 2005

Leydig cells appear in the hamster testis between 12 and 13 days gestation. The cells are round to oval, with prominent lipid droplets, abundant smooth endoplasmic reticulum, large mitochondria with tubular cristae and well developed Golgi complexes. Cells of this type are found in pairs and groups around interstitial blood vessels during the last three days of gestation and up to the fourth day after birth, when regressive changes begin to appear. During the second postnatal week, most cells in the interstitial regions are undifferentiated, with only a few scattered partially differentiated Leydig cells remaining. The time during which fully differentiated Leydig cells are present encompasses the period of sexual differentiation of the reproductive ducts and the critical period for differentiation of sexual behavior.
Pancreatic islets of the Coturnix quail. A light and electron microscopic study with special reference to the islet organ of the splenic lobe
Authors: Smith Phillip H.
Published: February 2005

The endocrine pancreas of the Coturnix quail consists of two major islet configurations. Islets containing B and D cells are found in all four lobes of the pancreas, but islets consisting of A and D cells occur with regularity only in the third and splenic lobes. Pancreatic islets comprise only a small percentage of the tissue volume in the ventral, dorsal and third lobes. In the splenic lobe, however, one or more A islets surrounded by numerous small B islets may constitute more than 50% of the total cellular mass.

Secretory granules of the B cells are aldehyde fuchsin‐positive and show three distinct profiles at the ultrastructural level. The PTAH‐positive A granules are usually round or teardrop shaped and are of uniform electron density. D cells are argyrophilic; their secretory granules are of heterogeneous densities. These cells are located at the peripheries of the B islets, but are freely dispersed in the A islets. At the electron microscopic level, Type IV cells, previously not reported in avian islets, are found mainly in the A islets of this species. This unusual cell type contains granules of differing densities, but, unlike those of the D cell, they are often rod‐shaped and biconcave in profile.

Because of the distinct segregation of islet types, and the peculiar arrangement of the D and Type IV cells within the two kinds of islets, it is suggested that the Japanese quail may serve as a model for investigations of avian islet function.
Sequential changes in weight, density, and percentage ash weight of human skeletons from an early fetal period through old age
Authors: Trotter Mildred , Hixon Barbara B.
Published: February 2005

The weight, density and percentage ash weight of the dry, fat‐free osseous human skeleton have been examined from 16 weeks of gestation to 100 years of age. Data were drawn from 426 skeletons of American Whites and Negroes of both sexes.

Weight increases exponentially in the fetus and continues to increase to early adulthood, most rapidly in the second decade. A decrease appears about the fourth decade and continues gradually. Estimated loss in skeletal weight throughout the adult period is, on the average, 15.6 gm per year. Proportionate contributions of divisions of the skeleton to its total weight change with age.

Densities of bones follow the changing weight pattern. Volume and weight increase concomitantly to adulthood, when weight decreases but not volume.

Percentage ash weight increases slightly in the total skeleton and in some bones during the fetal period, with no significant trend thereafter, indicating that change in weight of a dry, fat‐free bone is accompanied by change in ash weight.

Race and sex differences are not evident in the fetal skeleton, but become marked by the second decade of life: Negro skeletons exceed White skeletons and male skeletons exceed female skeletons in mean weight and density and, to a lesser degree, in percentage ash weight.
Uptake of exogenous protein by the preimplantation rabbit
Authors: Hastings Richard A. , Enders Allen C.
Published: February 2005

A study of the uptake of exogenous proteins, peroxidase, ferritin, and myoglobin by rabbit blastomeres of different developmental stages was undertaken to determine some of the means by which these stages ingest protein. Exposure of embryos in preimplantation stages, ranging from fertilized ovum to late blastocyst, was carried out in vitro with selected in vivo controls. Blastomeres of early cleavage stages up to the morula show little uptake of peroxidase. However, the endocytosis of peroxidase greatly increases with the morula stages and continues at an elevated level through the blastocyst stages. The uptake of the tracer is initially accomplished via micropinocytotic vesicles and tubules and can have several subsequent fates. The tracer can pass into larger vacuoles and be transported into the cavity of the blastocyst, or can pass into multivesicular bodies where it is presumably degraded by the lysosomal system for cellular use. The use of myoglobin at selected blastocyst stages yielded results similar to those obtained with peroxidase. However, the response by the blastomeres to ferritin is different. Endocytosis of ferritin is scant at all preimplantation stages, even though the ferritin has no difficulty reaching the surface of the blastomeres. The experiment with mechanically denuded blastocysts indicated that ferritin did not adsorb to the cell surface.
Breeding activity, preimplantation development, and oviduct histology of the short‐tailed fruit bat, Carollia, in captivity
Authors: De Bonilla Hela , Raseiler John J.
Published: February 2005

The reproductive biology of Carollia was investigated histologically in 113 females sacrificed at timed intervals after mating in a laboratory colony. A high incidence (44%) of non‐pregnant animals could be partially attributed to occasional mating activity at times other than close to ovulation. Breeding success also improved as the males and females were housed together for increasing periods of time. At least 25% of the bats had adrenal cortical‐like tissue in the vicinity of the ovaries.

Ovulation of the single ovum usually occurred within 48 hours of the onset of female receptivity to the male. Both ovaries were functional, but there was a tendency towards the alternation of successive ovulations. The blastocyst stage was reached and the zona pellucida was lost in the oviduct between days 10 and 12 post‐coitum. Blastocysts entered the uterus between days 13 and 16. The slow tubal journey of the ovum is presumably related to the occurrence of mensturation close to the time of ovulation and to the fact that most uterine growth is deferred until after ovulation. Additional ovulations and a new conception were observed during the course of several preexisting pregnancies.

Differential stimulation of the two oviducts was evident both prior to and after ovulation. The oviductal secretory cells became engorged during the tubal journey of the ovum with a substance that was Alcian blue 8GX‐ and Giemsa (pH 4.5)‐negative. Occasionally this material could be stained by the PAS procedure.
Collagen remodelling by fibroblasts in wound repair. Preliminary observations
Authors: Cate A. R. Ten , Freeman E.
Published: February 2005

Connective tissue remodelling has been studied at the fine structural level at the periphery of skin wounds repairing by both first and second intention. The periphery of such wounds was studied as it was predicted that not only would remodelling between old and new connective tissue be taking place, but that the fibroblast would be involved. Excisional and incisional wounds were made in the skin of adult mice and biopsied 14 days later. Our results showed that numerous fibroblasts in the junctional zone between old and new connective tissue exhibited intracellular collagen within vesicles. These findings indicate that the fibroblast is capable of phagocytosing and degrading collagen and has a fundamental role to play in connective tissue remodelling.
Electromyography of pectineus muscle
Authors: Takebe Kyoichi , Vitti Mathias , Basmajian John V.
Published: February 2005

Using bipolar fine‐wire electrodes, we investigated the function of the pectineus muscle. Electromyography revealed that the main function of pectineus muscle is flexion, adduction and medial (not lateral) rotation of the hip joint. These functions suggest that the spasm of this muscle may be important in the cause of deformities in cerebral palsy.
Capacitation of boar spermatozoa: The influence of post‐coital separation of the uterus and fallopian tubes
Authors: Hunter R. H. F. , Hall J. P.
Published: February 2005

The minimum period of uterine exposure required by ejaculated boar spermatozoa as a preliminary to rapid capacitation has been determined after natural or surgical deposition of sperm samples directly into the uterine lumen. Twenty‐four oestrous gilts were mated or inseminated close to the time of ovulation, and 15, 30, 45 or 60 minutes later, the Fallopian tubes were separated from the uterine cornua. The tubes were flushed at pre‐arranged intervals during a second intervention, and the proportion of eggs penetrated and activated examined by phase‐contrast microscopy.

On the basis of 166 eggs recovered from eighteen mated gilts, a period of uterine exposure as brief as 30 minutes, when followed by a tubal residence of approximately three hours, permitted 30.3% of the eggs to be activated; this proportion increased to 51.6% and 60.5% if the tubes were isolated 45 or 60 minutes, respectively, after mating (p < 0.001), as did the mean number of spermatozoa associated with the eggs. When the cornua were separated from the tubes 15 minutes after semen deposition into the uterus of six animals, 11.3% of 62 eggs were fertilized during the ensuing three and one half hours, but very few spermatozoa had reached and/or attached to the eggs in this group.

It is concluded that a population of boar spermatozoa potentially capable of effecting fertilization may enter the tubes within 15 to 30 minutes of mating near the time of ovulation, and that such vanguard spermatozoa can activate a proportion of the eggs within a further two to three hours. Thus, from a temporal point of view, the major components of the capacitation process in oestrous pigs are inferred to take place in the Fallopian tubes.
Enzymatic liberation of myogenic cells from adult rat muscle
Authors: Bischoff Richard
Published: February 2005

Five different proteolytic enzymes, trypsin, pronase, collagenase, papain and ficin, were tested for their ability to liberate mononucleated myogenic cells from adult rat muscle. Fragments of leg and thigh muscle from 350–400 gm rats were incubated with enzyme for one hour and mononucleated cells were separated from the partially digested fragments by centrifugation. Myogenic capacity of the isolated cells was tested in culture using procedures known to support differentiation of embryonic rat muscle. Although all the enzymes released viable cells from the muscle, myogenesis in vitro was obtained only from cells liberated by trypsin or pronase. The other three enzymes released fibroblasts, macrophages and fat cells but no presumptive myoblasts. Light and electron microscopic examination of the digested muscle revealed that the enzymatic release of myogenic cells is dependent upon removal of the basement lamina surrounding the fibers. Trypsin and pronase dissolve the basement lamina, whereas collagenase, papain or ficin do not. These findings demonstrate that a population of myogenic stem cells exists in fully mature, non‐regenerating adult muscle. The frequency of these cells and the conditions required for their release suggest that they are identical with the muscle satellite cells.
The repair of fractured membrane bones in the newly hatched chick
Authors: Hall B. K. , Jacobson H. N.
Published: February 2005

Repair of a fractured membrane bone, the quadratojugal (QJ), has been studied in the newly hatched chick. Complete open fractures never united by bony fusion, even in birds maintained for six months post‐fracture. Extraperiosteal connective tissue invaded the fracture gap and formed thick fibrous bundles which stabilised the fracture. Cartilage of two types formed on these bones. One was derived from periosteal cells and the other from osteoblasts or osteocytes. Considerably more cartilage formed in bones partially fractured than in those completely fractured. The “periosteal” cartilage did not form if the periosteum was removed at the time the bone was fractured. This was because, although the fibrous layer of the periosteum regenerated, the cambial layer did not. Metaplastic cartilage did form in the absence of the periosteum.

Isolating fractured bones within polyethylene or glass tubes prevented accumulation of a blastema between the bony fragments. Cartilage did not form in side the tubes but did form where the ends of the tubes abutted onto the bones.

Large defects in the bones (4 mm gaps, 4 mm of bone in the place of the QJ) healed via fibrous union with minimal osteogenesis and no chondrogenesis.

Severing M. depressor mandibulae at the time the bone was fractured inhibited chondrogenesis, favoured osteogenesis and resulted in development of a pseudarthrosis.

The potential for differentiation of the cells of the QJ and the role of adjacent tissues as they related to repair of the fracture was discussed, and the ability of cells from membrane bones to become chondrogenic emphasized.
The blood‐brain barrier of the rat choroid plexus
Authors: Davis Donald A. , Milhorat Thomas H.
Published: February 2005

Following intravenous injection, cytochrome c traverses the capillary endothelium of the rat choroid plexus and permeates the perivascular space and the extracellular space between epithelial cells. The tracer is incorporated into pinocytotic vesicles adjacent to the lateral and basal plasmalemmas. There‐after, cytochrome c is incorporated into multivesicular and dense bodies. Tracerladen vesicles were not found to fuse with the apical plasmalemma and cytochrome c was not discharged into the cerebral ventricles. Acid phosphatase activity of the choroidal epithelium after the administration of cytochrome c was greatly increased and localized in the same intracellular sites shown for cytochrome c. These data suggest that cytochrome c and possibly other proteins that penetrate the choroidal stroma are taken up by the choroidal epithelium and subsequently degraded in lysosomal vesicles. This heterolytic mechanism may be an important means for preventing the entry of certain substances such as proteins into CSF and subsequently into nervous tissue.
The development of proline‐containing extracellular connective tissue fibrils by chick notochordal epithelium in vitro
Authors: Lauscher Cristina K. , Carlson Edward C.
Published: February 2005

Notochords were isolated from Hamburger‐Hamilton stages 13–15 chick embryos by trypsinization and microdissection. These were shown by electron microscopy to be completely devoid of extracellular materials or mesenchymal contaminants. Cultivation of notochordal isolates was carried out on a non‐collagenous (Falcon Plastic) substratum for 0 to 48 hours. At 12 hours of in vitro incubation, a discontinuous basal lamina could be demonstrated on the surface of notochordal cells. This was followed by the appearance of microfibrils of various sizes and other components of the extracellular matrix. By 48 hours of in vitro incubation, the same extracellular materials which surround the notochord in vivo (notochord sheath) could be demonstated in vitro.

Autoradiographic studies show that tritiated proline is taken up by notochordal cells and secreted to the extracellular space where label is associated with basal lamina, microfibrils and ground substance. When cis‐hydroxyproline, a known collagen‐specific inhibitor is added to the system, tritiated proline label is located primarily intracellularly and fewer areas of active fibrillogenesis are noted. This suggests that ultrastructurally recognizable materials produced by notochordal cells in vitro may be at least partially collagenous. Significantly, these materials are produced in vivo at the same time (following stage 10) that notochordal tissues actively induce somite differentiation and cartilage formation. It seems reasonable that a biochemically or ultrastructurally identifiable component of the extracellular matrix may possibly mediate such induction.
In vitro development of palatal tissues from embryonic mice. I. Differentiation of the secondary palate from 12‐day mouse mebryos
Authors: Tyler Mary S. , Koch William E.
Published: February 2005

Single palatal processes or homotypic paired palatal processes from 12‐day mouse embryos (strain C57B1) were grown in organ culture on Millipore filters. The epithelium along the medial edge of each palatal process became disrupted, and, by 72 hours of culture, paired palatal processes achieved mesenchymal fusion at the site of disruption. The nasal epithelium of paired palatal processes became a recognizable pseudostratified ciliated columnar epithelium by 96 hours of culture, and the oral epithelium became a recognizable stratified squamous epithelium by 120 hours of culture. These events correspond temporally to the differentiation of palatal tissue in vivo. Differentiative changes of single palatal processes followed the same schedule as double processes. Observations also suggest that the epithelium at the tip of the vertically oriented young palatal process corresponds to the medial epithelium of the more advanced horizontal process — these observations have bearing on the mechanism of palatal movement. In addition, the results suggest that a re‐evaluation of the terminology “potential for fusion” is necessary.
Light and electron microscopic study of the effects of ZnSO4 on mouse nasal respiratory epithelium and subsequent responses
Authors: Matulionis Daniel H.
Published: February 2005

The effects of ZnSO4 irrigation on mouse nasal respiratory epithelium (NRE) and subsequent responses of the tissue were studied at the light and electron microscopic levels in two different strains of mice (C57B1/6J and SWR/J).

The most marked effect of the ZnSO4 took the form of necrosis and sloughing of surface cells in both strains one‐half day after ZnSO4 irrigation. This treatment caused maximal change in a different cell type in each of the two strains. Ciliated cells were most noticeably affected in the C57B1/6J strain, secretory cells in the SWR/J strain. Subsequent manifestations of recovery differed accordingly in each strain. In the C57B1/6J mice numerous dividing surface cells and large areas of tall nonciliated and ciliating cells were prominent two to five days after treatment. Secretory cells appeared normal but were reduced in numbers during this time, indicating that they were also affected by the treatment. The NRE of this strain was normal by the fourteenth day following treatment. The NRE of SWR/J animals, on the other hand, contained no visibly dividing cells and no large areas of nonciliated cells during the first four days following treatment, although a few ciliating cells were present at this time. The secretory cell population in these animals was normal after five days but individual cells deviated from normalcy by containing numerous dilated cisternae of rough endoplasmic reticulum which persisted in the secretory cells during the remainder of the experiment.
The bony tentorium of the cat: Stereotaxic coordinates
Authors: Lucas E. A.
Published: February 2005

The cat's tentorium cerebelli is an osseous structure which overlies much of the brain stem. None of the current brain atlases list the coordinates of this bony projection. With a stiff wire and a stereotaxic apparatus, the location of its free edge and dorsal surface was mapped in 1.0 mm steps in the skulls of 16 cats. In the midline the dorsal surface meets the calvaria at a point 7 mm posterior and 15 mm superior to the atlas zero (intra‐aural plane + 10 mm horizontal). From this junction it slopes inferiorly and anteriorly between the cerebrum and cerebellum along a 50° slope to terminate along a curved line. In the midline this free edge is located 0.5 mm anterior, and 6.5 mm superior to the atlas zero. It recedes laterally along a curved line to a point 6 mm lateral, 6 mm superior and 3 mm posterior to the atlas zero. The free edge then curves forward and descends to pass through an imaginary line 3 mm anterior and 4.5 mm inferior to the atlas zero. Statistical comparisons between measurements made in male and female cats revealed no significant differences.
Parietal eye‐pineal morphology in lizards and its physiological implications
Authors: Gundy G. Craig , Wurst Gloria Z.
Published: February 2005

Pineal complexes in 85 species of lizards examined comprised seven morphological types. Members of the same family do not necessarily have the same pineal complex type. “Regressive” parietal eyes were not common except in certain arboreal lizards, primarily from the family Chameleontidae. The parietal eye is often retained in burrowing lizards, presumably because these animals are occasionally exposed to light and the parietal eye is a more suitable photoreceptor for a burrower than are lateral eyes. The pineal of certain lizards possesses a finger‐like projection that extends toward the parietal eye. This extension, along with pineal wall convolutions, results in more photoreceptor cells oriented for maximal absorption of light. It is rare to find convolutions and an extension in the same pineal. Cartilage deposits and blood sinuses may modify the intensity and wavelength of light reaching the pineal. These observations suggest that the intracranial pineal of lizards is a more important photoreceptor than was previously realized, a situation that may be a factor in the occasional “failure” of parietalectomy experiments.
Ultrastructure of the pars intermedia of pigmented rats: Observations of melanin‐like granules within secretory cells
Authors: Saland L. C.
Published: February 2005

The pars intermedia of non‐obese pigmented rats of the Zucker strain is described using transmission electron microscopy. Secretory cells appear similar to those described elsewhere in albino rodent hypophyses. Cells which may be equivalent to ACTH cells of non‐pigmented mice and rats are observed near theborder of the pars distalis. Melanocytes are observed to surround lobules of the pars intermedia and to penetrate among secretory cells. In addition, large granules which appear to be melanin are present within some pars intermedia cells. Portions of some cells near melanin or melanin‐like granules exhibit expanded rough endoplasmic reticulum and Golgi zones containing dense granules. Observations are discussed in relation to origin of the melanin, and its possible significance near cells known to produce melanocyte‐stimulating hormone (MSH).
Tridimensional reconstruction and histology of the intratesticular seminal pathway in the hamster
Authors: Cavicchia J. C. , Burgos M. H.
Published: February 2005

The present work reports a tridimensional reconstruction of the intratesticular seminal pathway in the hamster as studied with light microscopy of serial sections of the proximal pole of the testis. It has three portions: a “terminal segment” of the seminiferous tubules; the tubuli recti with three parts; and the rete testis with two parts, intratesticular and extratesticular.

Experiments using ductuli efferentes ligation show a marked dilation of the rete testis and tubuli recti without a corresponding dilation of the seminiferous tubules. This may be due to a valve‐like action of the cells in the terminal segment of the tubules.
Integrated actions of masticatory muscles: Simultaneous EMG from eight intramuscular electrodes
Authors: Vitti Mathias , Basmajian John V.
Published: February 2005

In 29 normal persons with complete dental arches, the muscular activity of the temporalis, masseter, medial pterygoid, anterior belly of the digastric, mylohyoid and geniohyoid muscles was studied electromyographically with bipolar fine wire electrodes during various mandibular movements – both resisted and unresisted. Action potentials were recorded on FM magnetic tape and each experiment was also videotaped. Temporalis muscle was active during centric closing of the jaw with either contact of the teeth, or against resistance; during free lateral movements to the ipsilateral side, either against resistance or occlusal contact; during incisor gum chewing, molar gum chewing on ipsilateral or contralateral sides, during normal mastication; and during forceful centric occlusion.

Activity occurred in the masseter and medial pterygoid muscles during the following movements: closing the jaw slowly either without occlusal contact or with occlusal contact and against resistance; free lateral movement to contralateral side, either against resistance or with occlusal contact; protraction of the jaw either without occlusal contact or with occlusal contact; swallowing either saliva or water; incisor gum chewing with either the ipsilateral or contralateral molars; normal mastication; and during forceful centric occlusion.

Activity occurred in the digastric, mylohyoid and geniohyoid muscles during the following movements; opening of the jaw either slowly or maximally against resistance; closing the jaw against resistance; free lateral movement to ipsilateral and contralateral sides, either against resistance or with occlusal contact; protraction against resistance of the jaw either without or with occlusal contact; swallowing saliva and water; and protraction of the tongue. They work in antagonism (reciprocally) during gum chewing and normal mastication.
An electron‐dense extracellular material in the nervous system of Aplysia
Authors: Coggeshall Richard E.
Published: February 2005

An electron dense material is found in the extracellular space of the nervous system of Aplysia, a marine mollusc whose ganglia are widely studied by neurobiologists. This material appears to consist of irregular electron‐dense granules, with diameters of approximately 600 Å. This material is found between the glial cells that surround the neuronal perikarya. It is not found in other regions of the nervous system. Because it is found in the ganglion cell layer of the nervous system and because the neurons contain what may be the precursor of this substance, the electron‐dense material is regarded as most probably being a neuronal product. The importance of this material is that it is one of the few examples of visible structure in the extracellular space of the nervous system.
Fine morphological changes in the penicillate nerve endings of human hairy skin during prolonged itching
Authors: Cauna Nikolajs
Published: February 2005

Morphological changes in cutaneous nerve endings were investigated electron microscopically in patients suffering from certain kinds of urticaria with associated itching and in normal skin in which wheals and local itching were induced either by application of nettle hairs or by intracutaneous injections of a timothy pollen extract. Skin samples were obtained with a high speed dermal punch without anesthesia from the wheal areas.

It was found that some subepidermal free nerve endings derived from nonmyelinated nerve fibers (penicillate endings) showed accumulations of extracytoplasmic glycogen which was localized in the distended spaces between the axolemma, the Schwann cell membrane and the nerve basement membrane. In some cases, the glycogen was found to be so abundant that it occupied most of the cross sectional area of the ending. No morphological changes were observed in the pappilary endings, in nerve endings of the hairs or in the autonomic terminals. The conducting segments of all cutaneous nerve fibers showed normal morphology.

The unusual morphological changes that occur in some penicillate nerve endings during the wheal development indicate that these endings are involved in the skin reaction and therefore they may be the specific end organs that are associated with itch, at least in urticaria.
Pulmonary circulation—vertebral venous interconnections in the chicken
Authors: Burger R. E. , Estavillo J. A.
Published: February 2005

Injections of India ink colored blood, latex, and plastic followed by study of corrosion casts and dissections were used to determine the interconnections of the vertebral venous system and pulmonary circulation in the chicken. Multiple, minute connections are found to the intercostal veins, small mesenteric veins and others connected to the vertebral venous system. Thus, blood can flow in quantities between the vertebral venous system and the pulmonary circulation depending upon pressure gradients.
The vertebral level of origin of spinal nerves in the rat
Authors: Gelderd John B. , Chopin Suzzette F.
Published: February 2005

Several dissections were performed to determine the level of spinal cord termination and the vertebral level at which the dorsal and ventral roots of spinal nerves C1‐S4 emerged from the spinal cord in the rat.

These levels of emergence were then compared to the level of exit from the vertebral canal. The dissections demonstrated that the effect of differential growth between spinal cord and vertebral column begins in the lower cervical region and becomes progressively more pronounced throughout thoracic and lumbar levels. The disparity between the vertebral level of emergence of spinal roots from the spinal cord and their level of exit via intervertebral foramina was found to be considerably larger than was previously reported by Greene ('68). It was further noted that the spinal cord terminated at the level of the intervertebral disc between the third and fourth lumbar vertebrae, not between the fourth and fifth lumbar vertebrae as reported by Greene ('68).
Alterations in the endoplasmic reticulum and golgi complex of intestinal epithelial cells during fat absorption and after termination of this process: A morphological and morphometric study
Authors: Friedman Harold I. , Cardell Robert R.
Published: February 2005

Earlier investigations of intestinal fat‐absorption have stressed the importance of continued protein synthesis to provide membranes which are utilized for the intracellular transport of resynthesized lipid. The resulting membranes, when incorporated into the endoplasmic reticulum (ER) and Golgi complex, serve as vehicles for the movement of fat within the cell and for its release to the extracellular space. In the current study, attention was focused on the morphological changes in the ER and Golgi complex both during fat absorption and at successive time intervals after fat‐absorption termination. Morphological interpretations were confirmed by morphometric analysis. This investigation supports the interpretation that during fat absorption, membrane synthesis by the rough endoplasmic reticulum (RER) is insufficient to accomodate membrane utilization and intraconversion, resulting in a decrease of both ER and Golgi complex components. However, following fat‐absorption termination, the cell is able to replace previously depleted components of the ER and Golgi complex and regain the full membrane complement of the fasted state. Replenishment of cellular membranes is postulated as resulting from a continued synthesis of new membranes by the RER which eventually exceeds membrane utilized during lipid transport.
Investigations on the turnover of adrenocortical mitochondria VI. An autoradiographic study of the effect of acth on the radioactivity decay in the mitochondrial compartment from the zona fasciculata of 3h‐thymidine injected rats
Authors: Nussdorfer Gastone G. , Mazzocchi Giuseppina , Robba Claudia , Belloni Anna S. , Gambino Anna M.
Published: February 2005

The radioactivity decay of the mitochondrial compartment from the zona fasciculata of the adrenal cortex of 3H‐thymidine‐injected rats was followed by high resolution autoradiography. The number of days in which the radioactivity of the mitochondrial compartment was reduced to a half was calculated from the semilogarithmic plots of radioactivity versus time. Since DNA is a very stable molecule, it was assumed that this parameter can be an estimate of the half‐life of adrenocortical mitochondria. The half‐life of mitochondria from the zona fasciculata of the normal rat averaged 11.17 days, and ACTH was found to increase significantly this figure to about 15 days. It is hypothesized that the ACTH‐elicited stimulation of the growth of rat adrenal zona fasciculata mitochondria involves not only hypertrophy and proliferation of the organelles (Nussdorfer et al., '74b), but also the slowing down of the degeneration rate of mitochondria.
Ultrastructure of in vitro type 2 epithelial cell cysts derived from adult rabbit lung cells
Authors: Rosenbaum R. M. , Picciano P. , Kress Y. , Wittner M.
Published: February 2005

Fragments of adult rabbit lung, composed chiefly of terminal airway obtained by a trypsin digestion technique were maintained on collagen‐coated cellulose sponges in Ham's F12 medium. Cell‐sponge associations were examined with light microscopy, scanning and transmission electron microscopy over a period from 6 to 28 days. After an initial 24‐ to 48‐hour period of cell migration from the airway fragment, sponge matrices became lined with cells suggestive of alveolar macrophages. After one week in culture, cysts appeared to be composed entirely of type 2 epithelial cells. These were characterized by a microvillous apical border and an elaborate junctional complex. The lumen of these cysts contained both myelin‐like lamellar configurations and tubular my‐elin structures such as have been described from pulmonary washings. Consistent with the age of the sponge cultures, one or more cyst types described as young, middle and late could be found simultaneously. Middle aged cysts showed signs of active secretion into the lumen. Late cysts showed changes in the epithelium comprising the cyst wall suggestive of a cell type intermediate between type 1 and type 2 epithelial cells.