bluuebunny/crossref_metadata_2025 huggingface dataset:
The histology of inhibition of limb regeneration in the newt, Triturus, by actinomycin D
Authors: Carlson Bruce M.
Published: February 2005

Adult newts, Triturus viridescens, were treated with from 1.0–10.0 μg/g body weight of actinomycin D one day before amputation of both forelimbs. Mean survival times ranged from over 50 days in newts treated with 1.0 μg/g to 13.2 days in animals given 10.0 μg/g body weight of actinomycin. Low doses little altered the course of regeneration, but animals treated with over 2.0 μg/g never formed blastemas. In another series, animals were given doses of 2.5 μg/g body weight of actinomycin D at intervals from 14 days before to 30 days after amputation. It was found that certain signs of toxicity (loss of equilibrium) are related to the time of administration of the drug whereas others (hemorrhage into the limb stumps) are restricted to a definite phase of the regenerative process. Early administration of actinomycin completely inhibits regeneration whereas later treatment results in a considerably lessened effect. The postamputational stages which are basically destructive in nature are not noticeably affected by actinomycin D, but the phases of dedifferentiation, blastema formation and redifferentiation are strongly inhibited.
The morphogenesis of the stomach and intestine in the salamander Ambystoma maculatum
Authors: Harris Thomas M.
Published: February 2005

The major events associated with the morphogenesis of the amphibian alimentary tract are described and illustrated with a series of photomicrographs that present a continuous account of the differentiation process from its onset at stage 38 until the initiation of feeding at stage 46. Histological evidence is presented for the normal disappearance of the midgut region of the archenteron and the de novo formation of the intestine through the yolk mass. The mechanics of intestinal lumen formation are discussed in terms of the dynamic autonomous actions and interactions of the endoderm and the splanchnic mesoderm. The opening of the intestinal lumen as a consequence of cytolysis or cellular digestion is discounted. The relation of the present observations to the previously described polar endoderm cells is considered.
Lympho‐myeloid organs of amphibia I. Appearance during larval and adult stages of Rana catesbeiana
Authors: Cooper Edwin L.
Published: February 2005

The bullfrog, Rana catesbeiana, possesses lympho‐myeloid and epithelial structures that are morphologically similar in some respects to lymph nodes of mammals. These organs are present during the entire life cycle of the frog, however, the structures that are present during larval stages do not appear to be morphological precursors of adult organs. According to certain terms used previously by other investigators, two major organs are present throughout the larval stages: the lymph gland and the ventral cavity body. In the adult, the jugular body, the epithelial body, the precoracoid and propericardial bodies are found in the ventral neck region in contrast to the lateral and ventral arrangement of the lymph gland and ventral cavity body in larvae. The function of these organs is not known but it is believed that they play a role in the production of certain blood cells, particularly lymphocytes, and they may be involved in some aspects of the differentiation and maintenance of the immune response capacity.
Studies on regeneration in the creeping ctenophore, Vallicula multiformis
Authors: Freeman G.
Published: February 2005

The ctenophore, Vallicula multiformis (V. multiformis) (Rankin), can reproduce asexully by segregating pieces of tissue from its periphery. These pieces of tissue then differentiate to form new individuals. In 99% of the cases the pieces of tissue form normal animals; however in 1% of the cases they form “half animals” which have only one set of tentacles (the animal normally has two sets of tentacles). V. multiformis can also regenerate its apical organ, and one or both sets of tentacles.

By cutting V. multiformis in half through the apical organ along the sagittal plane it is possible to produce “half animals” in 30% of the cases. “Half animals” can reproduce asexually. In 6% of the cases the new individuals which form from them differentiate as “half animals.” A part of a “half animal” that contains an apical organ will regenerate as a “half animal” while a part that does not contain an apical organ will regenerate as a normal individual. If one removes the apical organ from a “half animal,” it will regenerate it. A part of this animal containing the regenerated apical organ will regenerate as a “half animal.” If one removes the apical organ from a “half animal” and replaces it with the apical organ of a normal individual, the part containing the apical organ will regenerate as a normal individual. The results of these experiments are discussed in terms of possible mechanisms that control the process of regeneration.
Cytodifferentiation of the chick pancreas. II. Ultrastructure of the acinar cells
Authors: Przybylski Ronald J.
Published: February 2005

The ultrastructural changes occurring during the differentiation of the pancreatic acinar cell were studied in White Leghorn chick embryos from the onset of pancreatic morphogenesis on day 3 of incubation (day 3) to hatching. Generally, the changes included a loss of some structures, the addition of others and modification of existing structures. Numerous cytoplasmic filaments which were present in the early migrating cells of the pancreatic bud were no longer present on day 5. The nucleoli enlarged temporarily on days 5–6 and then resumed a reduced size. The Golgi apparatus enlarged by day 6 and remained this way throughout the embryonic period. Associated with these changes was the initial appearance of the zymogen granules on day 5. The endoplasmic reticulum was present initially in both the smooth and the rough forms. The rough form and the outer nuclear membrane were both initially studded intermittently with aggregates of ribosomes. Subsequently, there was an increase in the number of attached ribosomes, an increase in the amount of rough reticulum and a decrease in smooth membranes. The ribosomes attached to the membranes appeared to augment the large free ribosome population characteristic of the early cells. Mitochondria did not appear to increase in number but there was an increase in size. The granules varied in kind, number and size with developmental age. The first granules formed (days 3–5) appeared to be miniatures of the mature type. Subsequently, a heterogeneity of granule morphologies was present.
Ultrastructural differentiation of the epithelium and mucous glands of the esophagus in the chick embryo
Authors: Hinsch Gertrude W.
Published: February 2005

Esophagi of White Leghron chick embryos, six days to hatching, were fixed in 5% glutaraldehyde in a cacodylate‐sucrose buffer, postfixed in 1% OsO4, dehydrated and embedded in Araldite. Tissues were sectioned with glass knives and viewed with a Philips EM 100C. The epithelium in early stages of development is characterized by small intercellular spaces, few cell processes and few desmosomes. In contrast the differentiated epithelium contains numerous cell processes, large intercellular spaces and numerous desmosomes. Mucin appeared in the mucous glands at 17 days.
Histology, histochemistry, and emptying mechanism of the venom glands of some elapid snakes
Authors: Rosenberg Herbert I.
Published: February 2005

The venom glands of several species of elapid snakes are described. The main venom gland consists of many tubules which usually contain large amounts of secretion product. The accessory gland surrounds the entire venom duct and is usually composed of uniform mucous epithelium. The epithelium lining the tubules of the accessory gland of Naja naja is composed of two distinct types of cells. Histochemical tests indicate that the main venom gland reacts with mercury bromphenol blue and PAS but not with alcian blue. The accessory gland reacts with PAS and alcian blue, and not with mercury bromphenol blue. Treatment of sections with sialidase demonstrates the presence of a sialomucin in the accessory gland. Stimulation of the muscles associated with the venom gland offers an indication of the venom expulsion mechanism of Bungarus caeruleus. A comparison of the venom apparatus of elapid and viperid snakes emphasizes marked differences in the internal anatomy of the venom glands, muscles associated with the gland, and arrangement of glandular components. The morphological differences and dissimilar venom expulsion mechanisms support the recent view of the polyphyletic origin of venomous snakes.
Cytodifferentiation of the chick pancreas. III. The content and synthesis of ribonucleic acid and proteins in developing acinar cells
Authors: Przybylski Ronald J.
Published: February 2005

The content and synthesis of ribonucleic acid (RNA) and protein was studied by microphotometry and autoradiography in the developing pancreatic acinar cells of White Leghorn chick embryos. These findings were correlated with previously reported changes in ultrastructural components. Shortly before or concomitant with zymogen granulation, RNA synthesis increased, in association with increases in the amount of nucleolar and cytoplasmic protein. The cytoplasmic fraction was transitory, whereas the accumulated nucleolar protein was maintained and was soon followed by an increase in nucleolar RNA. Concomitantly, a decrease in chromosomal RNA was observed, with the total amount of nuclear RNA staying constant. When zymogen first appeared, nucleoli were greatly enlarged due to large amounts of RNA and protein; total cellular RNA and protein had decreased slightly, in association with a decrease in cell volume. Subsequent development presented smaller nucleoli with decreased amounts of RNA and protein. Total cellular RNA increased due to its accumulation in the cytoplasm, probably as ribosomes. The accumulation of zymogen and the enlargement of other cellular structures contributed to an increase in total cellular protein. Prior to hatching, total cell RNA and protein decreased in amount, probably due to a reduction in cell volume through cell division.
The relationship between cytoplasmic organization and the epithelio‐mesodermal interaction in the embryonic chick thyroid
Authors: Hilfer S. Robert , Hilfer Eva K. , Iszard Lawrence B.
Published: February 2005

Epithelio‐mesodermal interaction in mature thyroids of older chick embryos was tested by dissociation, monolayer culture to disrupt cytoplasmic organization, and reaggregation with heterologous and homologous mesoderm. Each combination formed a different histological pattern: with mesentery — islands of epithelial cells in a loose connective tissue; with heart — follicles at the ends of cords in a rich vascular bed, with perichondrium — a ring of follicles surrounding masses of cartilage; with thyroid capsule — normal thyroid organization. Electron‐microscopic examination of cells incorporated into follicles revealed reorganization of canaliculate endoplasmic reticulum in only the homotypic combination. Therefore, interactions occur in mature organs as well as primordia.
The fine structure of limb tissues of the adult newt, Diemictylus viridescens
Authors: Norman Wesley P. , Schmidt Anthony J.
Published: February 2005

The limb tissues of the adult newt investigated for their fine structure include epidermis, subcutaneous glands, dermis, striated muscle, peripheral nerves and blood vessels. This survey complements and extends previous observations, emphasizing intercellular junctions, and the ubiquitous “glycocalyx” (= polysaccharide‐protein lamella, around cells and adjacent to epithelia).

Our survey touches on the characteristic tonofilaments, intercellular desmosomes and basal hemidesmosomes of the epidermis. The subcutaneous glands consist of secretory cells with a granular product, and myoepithelial cells; intercellular desmosomes are present. The adepidermal reticulum of collagen fibrils reveals periodic regions of intersecting fibrils ( = nodules), and fibril continuity with the underlying dermis: a striking feature is the adipose tissue closely applied to the adepidermal reticulum. The limb striated muscle displays typical banded myofibrils, and a triad system with centrotubules in the I‐band close to the Z‐band: terminal sacs of sarcoplasmic reticulum complete the triad system. A particularly prominent glycocalyx is applied to the surface of the sarcolemma. The peripheral nerves of the limb possess connective tissue sheaths with prominent vesiculation of the cell membranes, and an occasional intercellular desmosomal junction. Blood vessels typically have endothelial cells with prominently vesiculated plasma membranes.

This investigation serves as the basis for recognizing the fine structure of tissue responses to trauma, their repair, and regeneration.
The atrioventricular branches of the human coronary arteries
Authors: Didio Liberato J. A.
Published: February 2005

Branches of the coronary arteries of normal human hearts, supplying both atria and ventricles, were found by fine dissection and have been named rami atrioventriculares. They comprise atrial branches from ventricular arteries and ventricular branches from atrial arteries. Their incidence was 74% in the 50 adult individuals studied. The subjects had committed suicide with a poison which did not damage the coronary arteries. The atrioventricular branches constitute communications across the coronary sulcus, thus establishing a continuity between the atrial and the ventricular arterial supply. Therefore, there is not invariably a sharp demarcation of blood supply between atria and ventricles, as has been commonly taught. Neither atrial nor ventricular branches consist exclusively of ascending and descending branches of the coronary arteries, as has been assumed. Atrioventricular branches can play a role in collateral circulation and may, in individuals who are born with them, provide an explanation for some of the variability in signs and symptoms incidental to heart attacks.
Fine structure of the bone marrow of the chicken and pigeon
Authors: Campbell Ferrell
Published: February 2005

The structure of bone marrow from chickens and pigeons was studied with light and electron microscopy. Erythropoiesis occurs in the lumen of the medullary sinuses. Immature erythroid cells appear to adhere to the sinus wall and may thus be prevented from entering the peripheral circulation.

The wall of the medullary sinuses is formed by elongated lining cells, lacking a basement membrane, which are continous except at sites where blood cells are passing through them.

When viewed with the electron microscope, developing heterophil myelocytes, which occur only in the extravascular spaces, possess two populations of granules; one type is globular in content, the other is fibrillar in content. The globular type predominates during all stages of development and appears to be the specific granule. Specific granules originate from material which is formed in the Golgi complex, pinches off, and accumulates in expanded vesicles. The origin of the material in the fibrillar granules was not determined. Like the globular granules of heterophil leucocytes, granules of eosinophil leucocytes arise from material which is formed in the Golgi complex.
Fine structure of the functional mesonephros in the eight‐day chick embryo
Authors: Gibley Charles W. , Chang Jeffrey P.
Published: February 2005

An electron microscopic study of the functional mesonephros in the 8‐day chick embryo revealed the following features of the nephron:

Proximal tubule cells. Nuclei are spherical and basally oriented. Mitochondri are round or elongate with clear‐cut cristae. Intramitochondrial granules occur sporadically. The Golgi complex, lying adjacent to the nucleus in apical cytoplasm, consists of flattened lamellae and associated secretion droplets. The cytoplasm is filled with ribosomes which occasionally are spiral in arrangement. Characteristic microvilli project from the apical end of cells. Basal regions of the cells are bounded by a homogeneous basement membrane. Adjacent epithelial cells are separated at their base by wide intercellular spaces. Interdigitating processes between cells are common in this area. At their apices, cells are joined by junctional complexes.

Distal tubule cells. Nuclei are round and centrally located. Microvilli are sparse and usually absent. When present, they are short and blunt. Cells are closely allied at their base and joined tightly at their apices. Interdigitating processes are not as prevalent as in proximal tubules. Infoldings of the plasma membrane are prominent and compartmentalize mitochondria.

Glomerulus. Endothelial cells are elongate, bordering the capillary lumen, and their membranes contain definite slit‐pores. Epithelial pedicels extend from the cell body, intergiditate with each other and rest on the capillary basement membrane. The latter consists of three layers resembling those in adults.

The similarity in the fine structural characteristics between chick mesonephros and adult metanepros corroborates the holonephric theory of vertebrate kidney evolution.
Lymphomyeloid organs of amphibia. II. Vasculature in larval and adult Rana catesbeiana
Authors: Baculi Buena S. , Cooper Edwin L.
Published: February 2005

There were no lymphatic vessels and lymph nodes demonstrable in adult and larval Rana catesbeiana by a method that adequately demonstrated the same in mammals. Although the parenchymal arrangement in the lymphomyeloid organs is not exactly the same as in mammalian hemal nodes, nonetheless the vascular patterns of the lymph glands and jugular bodies are prima facie evidence that they function as blood‐filtering organs among other probable functions. The vascular pattern of the lymph gland is that of a rete mirabile, particularly a venous portal system, inasmuch as the afferent and efferent vessels are venous in character and interposed between them is a labyrinth of sinusoids. This is not the case, though, in the adult organs. The vascular pattern of the jugular bodies is very much like the spleen, viz., artery‐capillary‐sinusoid‐vein sequence. It is doubtful, however, if the propericardial and procoracoid bodies ever filter blood, because the smallest blood vessels in them are capillary in type Because of the absence of a well‐defined capsule in some parts of the propericardial body, similarly to lymphoid follicles, especially in the mammalian gastrointestinal tract, it is probable that it filters tissue fluid. The last two organs are apparently mainly blood cell‐forming organs. It is inferred from the vascular connections of the larval and the adult lymphomyeloid organs that they are not genetically related. This aspect was analyzed from earlier developmental data, but actual follow‐up of the larval organs to the adult stage is still in progress.
Mean weights of chick embryos correlated with the stages of Hamburger and Hamilton
Authors: Davis J. E. , Garrison Norman E.
Published: February 2005

A total of 1125 normal chick embryos, representing 25 each of the 45 stages of Hamburger and Hamilton, were removed, fixed in Bouin's solution, stored in 70% ethanol and weighed with a semi‐micro analytical balance. Entire blastoderms of stages 1–8 were weighed, whereas only embryos‐proper were weighed in stages 9–45. As a consequence, results constituted two groups, each of which showed a geometric rate of growth marked only by minor deviations which were related to specific events of normal growth and development.
Quantitative studies of superior cervical sympathetic ganglia in a variety of primates including man. I. The ratio of preganglionic fibers to ganglionic neurons
Authors: Ebbesson Sven O. E.
Published: February 2005

Estimates of the number of ganglionic neurons of superior cervical sympathetic ganglia and the number of preganglionic axons in the trunks just caudal to these ganglia were obtained from a sample of primates that included: man, chimpanzee, baboon, stump‐tailed macaque, rhesus monkey, and squirrel monkey. The number of ganglionic neurons ranged from 63,625 in a squirrel monkey ganglion to 1,041,652 neurons in a human ganglion. Estimates of the number of preganglionic fibers varied between 2,285 in a cervical sympathetic trunk of a squirrel monkey and 12,008 in a human specimen. The resulting ratios of preganglionic fibers to ganglionic neurons ranged from 1:28 in a squirrel monkey ganglion to 1:196 in a human ganglion.

The data reported in this study reveal considerable variation in the ratio of pre‐ to post‐ganglionic neurons, and as was noted in regard to the number of cells in the ganglion, the ratios of ganglionic to preganglionic neurons appear to increase as a function of body size. In contrast, the number of preganglionic fibers does not increase as strikingly with body size, but varies greatly in the same species. The resulting ratio between the two orders of neurons is, therefore, less predictable than the number of ganglionic neurons in any given ganglion.
Further studies on the development of the eye of Drosophila melanogaster. I. The ommatidia
Authors: Perry Margaret M.
Published: February 2005

Electron microscope observations on the differentiating Drosophila eye show an extensive proliferation of parallel arrays of microtubules at periods preceding, or coinciding with, alterations in cellular morphology. In the retinular cells they are aligned in the direction of elongation and close to the developing rhabdomeres, forming a cylinder around the central ommatidial axis. At a later stage, in the cone cells, they are aligned in the direction of cellular contraction. Thus as in other developing systems microtubules appear to be directly involved in the morphogenesis of the Drosophila eye. In the retinular cells they gradually disappear during elongation, whereas they persist in the cone cells. The pigment cells contain few of these structures. The distribution of two types of specialised cell attachments, adhering zones and septate desmosomes is discussed in relation to intercellular morphogenesis and communication. The rhabdomeres originate from infoldings of the plasma membrane which later grow out into typical microvilli. Unusul cytoplasmic granules are described in the pigment cells of early pupae.
Studies of a primitive mammalian spleen, the opossum (Didelphis virginiana)
Authors: Hayes Thomas G.
Published: February 2005

Light microscopic sections of the adult opossum (Didelphis virginiana) spleen were observed to lack venous sinuses; this primitive mammalian spleen may be classified as non‐sinusal in nature. In the spleen of the opossum, the capillary segments of the penicillar arteries lacked ellipsoid sheaths characteristic of certain mammalian spleens.

Separating the lymphoid nodules from the surrounding red pulp was a distinct band of vascular tissue, the marginal zone. Arising from the central artery within the lymphoid nodule, vessels of capillary dimension were observed to terminate within the marginal zone and the area between lymphoid nodule and marginal zone. In addition to the vascular channels established by the terminal arterial vessels within the red pulp, the system of vessels within the marginal zone has been implicated as an important intermediate vascular channel within the spleen.
A light and electron microscopic investigation of the digestive system of the Ophiuroid ophiuroiderma panamensis (Brittle Star)
Authors: Schechter Joel , Lucero Juan
Published: February 2005

The Brittle Star digestive system is composed of buccal, pharyngeal, esophageal and stomach cavities. The buccal and pharyngeal cavities are lined by columnar cells covered by a cuticle, and are apparently concerned with mucous production. Coelomocytes and tall columnar cells are described in the esophagus and stomach epithelia. The columnar cells are adapted for nutrient absorption, enzyme synthesis, and lipid storage. Nerves are found beneath the epithelia within a connective tissue layer. Smooth muscle and coelomic layers lie external to the connective tissue layer. The coelomic layer lines a perivisceral space and has diverse modifications of its perivisceral surface; a pedicle‐cuticle modification perhaps having general significance in echinoderms.
Formation of septa in the bulbus cordis of a turtle and a lizard
Authors: Hart Nathan H.
Published: February 2005

A total of 54 embryos of Chrysemys (Chelonia) and 29 embryos of Aristelliger (Lacertilia) were used in examining septation of the embryonic bulbus cordis. Division of this region of the heart includes a period of cushion or septal primordia formation and a period of physical partitioning. In both reptilian genera, the physical configuration of the early bulbus, the temporal sequence of appearance of the endocardial cushions, the number of major endocardial cushions, the primordia composing the two primary bulbar septa, and the mode of descent of the bulbar septa are strikingly similar. The two genera differ primarily in the pattern of the endocardial cushions and consequently the rotation of the two bulbar septa. In both the turtle and the lizard the aortico‐pulmonary septum passes through an angle of about 120° in its descent toward the ventricle. In Aristelliger the aortic septum rotates through an angle of approximately 120°. By contrast, the same partition in Chrysemys spirals through an angle of about 90°. The lesser spiral of this septum in the turtle is interpreted as the result of a decrease in the rotation of distal endocardial ridge 4. The pattern of the two bulbar septa in the turtle appears to represent an advanced phylogenetic feature in terms of the evolution of the reptilian bulbus cordis.
Anatomical changes in the neuromuscular complex of the proleg of Galleria mellonella (L.) (Lepidoptera: Pyralidiadae) during metamorphosis
Authors: Randall Winnifred C.
Published: February 2005

The lateral and ventral external surfaces of the third and fourth abdominal segments were described and muscle attachments were correlated with surface indentations of the larva. The proleg of this species has a symmetrical planta with a complete circle of crochets. Furthermore, it differs externally from the grasping type of proleg in having a largely membranous coxal region confluent with the body wall, and a relatively large subcoxal lobe.

The body wall musculature and innervation of the third and fourth abdominal segments are similar in many respects to those described for other lepidopteran larvae to which they are here compared, but differ from most because of the simpler structure of the prolegs which lack highly developed adductor muscles. Like most muscles innervated by the ventral nerve, the principal plantar retractors of these two segments cease to function in the first day of the pupal stage and have completely degenerated by the forty‐fifth hour of pupal life. The ventral nerve retains its four primary branches in the adult, in which many smaller rami can be traced to the cuticle and to the neoblastic body wall muscles.
Epidermal keratinization in the salamander and a comparison with other amphibia
Authors: Spearman R. I. C.
Published: February 2005

In a variety of amphibians examined the stratum corneum was one cell in depth, although in Xenopus it was up to three cells deep. The flattened horny cells were closely fused together along their lateral membranes to form a continuous sheet. Disulphide bonds of keratin were most concentrated in the peripheral cytoplasm, but the interiors of the cornified cells were sufficiently well keratinized to prevent more than slight enzymatic cytolysis of the normal cell components. Characteristically large, weakly stainable, non‐shrunken nuclear remnants were found in the salamander and frog horny layers, but the clawed toad had small pyknotic (parakeratotic) nuclei. The mature amphibian keratinocytes contained free fats, bound phospholipids, calcium and sulphydryl groups, together with acid phosphatase and non‐specific esterase. Cornification appears to begin by a process of separate individual cell keratinization and lateral membranes of neighbouring cells only later become fused together. This differs from the process in higher vertebrates in which the cells undergoing keratinization form a uniform transitional layer in the epidermis. In the amphibian epidermis neighbouring cells occur in different stages of keratinization.
Fine structure of the down feather during its early development
Authors: Kischer C. Ward
Published: February 2005

The down feather of the chick embryo has been examined by electron microscopy during three distinct stages of its early development; the presumptive stage, represented by dorsal skin of an area from which the feather organ will arise; the thickening stage, during which areas of the basal epidermis form spurs projecting into the mesenchyme, and the latter condenses under a thickened area of the epidermis; the elevation stage, at which time the basal epidermis flattens, the entire epidermis increases in thickness, and the underlying mesenchyme becomes more compact.

As development proceeds the rough endoplasmic reticulum of the epidermal cells dilates, but during the elevation stage begins to flatten, and Golgi is observed with increasing frequency. The mitochondria do not appear to differ except for those in the periderm during the presumptive stage, in which case they reveal a vacant matrix and irregular cristae.

Evidence is presented for actual contact between basal epidermal spurs and filopodia of cells within the mesenchyme, some of which contain numerous vesicles. The basal epidermal spurs are also seen in intimate association with collagen and anchor filaments and a network of reticulin.

Evidence is also presented for the presence of neuronal elements within the mesenchyme during the thickening stage. Cross sections of cell processes within the condensations of the mesenchyme resemble unmyelinated nerve fibers, and cross sections of filopodia similar to arborizing axons abound at and within the basal lamina of both the thickening and elevation stages. Further support for the presence of nerve fibers within the mesenchyme comes from positive staining results with Bodian's and Ungewitter's methods.

This comparative study of three stages of early development of the feather organ serves as a basis for more detailed investigations of each stage.
The structure of the antennae of the Florida Queen butterfly, Danaus gilippus berenice (Cramer)
Authors: Myers Judith
Published: February 2005

Interest in the structure of the antennae of the Florida Queen butterfly arises from the finding that a pheromone is active in their courtship. Light and electron microscopic techniques were used to study the sensilla on the antennae and three types of sensilla with perforated walls were identified. The most common of these are short, thin‐walled pegs which are distributed over most of the antennal surface. Long, curved, thin‐walled pegs occur in patches on the inner medial antennal surface. Multiple coeloconic sensilla are present having up to 50 pegs in one sensillum. On the outer 28 flagellar subsegments there are two such sensilla per subsegment. In addition there are on the antennae long, thick‐walled hairs which are mechanoreceptors and probably also contact chemoreceptors. Sunken pegs, the function of which is not known, occur on the antennae. Grooved sensilla were found with the electron microscope but could not be identified with the light microscope. There was no indication of sexual dimorphism in sensilla types or numbers on the antennae.
Embryonic development of the heart. I. A light and electron microscopic study of myocardial development in the early chick embryo
Authors: Manasek Francis J.
Published: February 2005

Embryonic chick myocardium (stages 8+ to 12−) was studied by light and electron microscopy. The myocardium, which is initially comprised of radially oriented cells with large intercellular spaces gradually becomes more tightly packed. Intercellular spaces decrease and the cells assume a circumferential orientation. Myocardial cells remain epithelial throughout formation of the functional tubular heart and specialized epithelial junctions (apical junctional complex or terminal bars) undergo modification to form intercalated discs. Embryonic myocardial cells contain large amounts of free ribosomes and particulate glycogen, the latter often associated with portions of granular reticulum. Unlike developing skeletal muscle. The amount of granular reticulum contained in the myocardial cell cytoplasm is large and, along with a hypertrophied Golgi apparatus, suggests that these cells may have a secretory function. These organelles persist during the initial period of fibril formation. Myofibrils apparently form from non filamentous precursor material and not by alignment of sequentially synthesized components.
Electron microscope studies on developing oocytes of a coelenterate medusa with special reference to vitellogenesis
Authors: Kessel R. G.
Published: February 2005

In a hydrozoan jellyfish, the female gonad is differentiated from a specialized region of the epidermis near the manubrium. Changes in the oocytes during growth and vitellogenesis are described as observed with electron microscopic and cytochemical techniques. Three major types of yolk are formed; these include lipid, glycogen, and membrane‐bound granules consisting of both protein and carbohydrate. The latter first appear evident within vesicular and cisternal elements of the numerous Golgi complexes. The orientation and structural variations noted between the endoplasmic reticulum and forming face of the Golgi complexes suggest that the protein component of the yolk granules may be transferred from the cisternae of the endoplasmic reticulum to the Golgi complex where it is joined to carbohydrate perhaps synthesized by the Golgi complexes. Stages in the release of the precursor yolk material sequestered in cisternal elements of the Golgi complexes are illustrated. The presence of coated and uncoated vesicles in the Golgi regions and their possible role in intracellular transport are described and discussed. The presence and possible method of morphogenesis of vesiculate yolk bodies are also described. What appear to represent invaginations of the oolemma extend into the ooplasm and display a special orientation with respect to lamellae of the rough‐surfaced endoplasmic reticulum. Intraooplasmic synthesis appears to constitute the major pathway for protein‐carbohydrate yolk deposition.
The architecture of the shoulder in some mammals
Authors: Oxnard Charles E.
Published: February 2005

A series of nine features of the shoulder girdle, chosen as having functional significance in relation to the movements of the shoulder in arboreal locomotion, have been studied in 1188 specimens of 194 genera of mammals. The features were defined metrically and examined by means of a multivariate statistical technique: viz. canonical analysis. The study has shown that those mammals which are nonarboreal differ considerably among themselves and form the arboreal forms. But the myriad shapes of the shoulder girdle in a wide range of mammals (e.g. some marsupials, edentates, rodents, carnivores and primates) which climb or forage in trees, can be summarized mathematically by a very small number of similar canonical variates. This information correlates well with that of a previous series of studies carried out on the primates alone.

The biological information that was postulated as being reflected by the individual canonical variates for the primates is also apparent for the arboreal mammals. The different variates separate the forms in ways which are consonant with what is known about the function of the shoulder in locomotion. Aspects of the shape of the shoulder defined by the analysis appear to be discernible from an examination of the contribution of the original variables to each individual canonical variate. This seems to confirm that the shape of the shoulder girdle within a very wide range of mammals is limited by a very small number of underlying factors of biological significance.

One interpretation of the results suggests that the genetic model of the mammalian shoulder may have been sufficiently fixed at an early stage in the evolution of the class as to place considerable constraints upon the subsequent evolution of the shoulder in the different Orders.
Evolutionary morphology of the caecilian urogenital system. I. The gonads and the fat bodies
Authors: Wake Marvalee H.
Published: February 2005

The comparative morphology of the gonads and fat bodies of members of 17 genera and 46 species of caecilians (Amphibia: Gymnophiona) is described and analyzed. Comparison is made with the morphology of salamanders and frogs in order to elucidate evolutionary trends and relationships within the order Gymnophiona and within the class Amphibia. The structure of the testis lobes and transverse and longitudinal ducts is described based on gross dissection and histological investigation. The pattern of spermatogenesis and interstitial tissue changes are described and compared with those of other amphibians. A trend toward fusion of testis lobes is analyzed. The characteristics of the seasonal reproductive cycle of male Gymnopis m. proxima are described, and evidence for cyclic reproductive activity in other forms is presented. The morphology of the ovaries and ova is described. Size of ovary and size and number of ova is dependent on the state of maturation of the ova. Some evidence for seasonal ovum production and breeding is presented. Fat body morphology is found to be correlated with size, nutrition, and gonad condition, as in other amphibians.
The fine structure of daphnid supraesophageal and optic ganglia, and its possible functional significance
Authors: Bohm Marguerite K. , Parker Richard A.
Published: February 2005

Neurosecretory activity and fine structure of the supraesophageal and optic ganglia of Daphnia schødleri Sars were studied. The relative amount of paraldehyde fuchsin stainable material present was determined at “daylight” and at one and three hours following for animals maintained under photoperiods of 7.5, 10.5, 13.5, and 16.5 hours. More material was found after one hour in both ganglia and there was a tendency for more in the optic ganglion under 7.5‐ and 10.5‐hour photoperiods.

Sections made at two levels in the supraesophageal ganglion and one level in the optic ganglion were examined with an electron microscope. Posterior and anterior parts of the supraesophageal ganglion contain apparent nerve processes at the edge of the ganglion, parallel to the anterior‐posterior axis; these have large granules. Neurons in both areas contain patches of presumed polysaccharide granules. In the posterior region are a dorsolateral and a ventrolateral glandular cell, presumably these occur on both sides of the brain. They have very well‐developed endoplasmic reticulum and some large granules. The dorsal cell is usually at the tip of a glial attenuation.

Concentric lamellar systems are located in dilated nerve processes of the first optic ganglion neuropile. Large whorls (about 3.5 μ) are composed of concentric lamellae. When lamellae do not form complete rings, they end in loops or in dilated tubules that are sometimes constricted as vesicles. Small whorls (1.5 μ) typically have lamellae joined into two or three thick layers. Mitochondria are frequently associated with the whorls. It is proposed that the whorls are active in synthesis, possibly neurohumor production.
The development of the copulatory organs (gonopods) of a spiroboloid milliped
Authors: Berns Michael W.
Published: February 2005

In the spiroboloid millipeds the male gonopods develop from rudiments of both pairs of legs of the seventh body segment. They are first evident as “lumps” on the sternum of the seventh segment following the molt to instar 5; they replace the functional walking legs of the seventh segment of earlier instars. These “lumps” go through progressive morphological changes in each instar until they attain the adult form. It is evident that in the spirobolid millipeds the gonopods do not develop as a gradual modification of functional walking legs; rather they pass through a progressive growth and differentiation of their own.
Lymphomyeloid organs of amphibia. IV. Normal histology in larval and adult Rana catesbeiana
Authors: Baculi Buena S. , Cooper Edwin L.
Published: February 2005

This report presents light microscopic descriptions of normal histology, including innervation, of the lymph glands and jugular bodies, of larval and adult Rana catesbeiana. A brief description of two other adult organs, the propericardial and procoracoid bodies, is also included. The parenchyma was studied by employing the May‐Grunwald‐Giemsa staining technique for better cytoplasmic differentiation; the Periodic Acid‐Schiff technique and hematoxylin and eosin yielded clearer nuclear and cytoplasmic delineations. The intercellular portion of the stroma was studied from sections stained with Masson's trichrome, Weigert's elastic stain, Periodic Acid‐Schiff and Wilder's reticulum stain. Demonstration of phagocytes was facilitated by intraperitoneal India ink injections followed by the above staining procedures. Innerrvation was observed in serial sections of silver impregnated whole organs as well as in the other serial sections. These organs are lymphocytopoietic and to a certain extent granulopoietic; they also serve, like the spleen, as graveyards for dead cells and most probably play a role in immunity especially in the synthesis of antibodies as indicated by the presence of plasma cells, macrophages and lymphocytes.
Development of zonular patterns in the human adrenal gland
Authors: Sucheston Martha E. , Cannon Marvin S.
Published: February 2005

Microscopic studies of human adrenal glands from 58 autopsy specimens, ranging in age from one month gestation to 69 years, revealed a pertinent developmental pattern in the establishment of definitive zonation. This pattern was established using the following criteria: (1) relationship of age to the developing zones; (2) times of formation of definitive zonation; and (3) the morphological determination of developmental patterns based on staining characteristics.

Using these criteria, development was divided into five phases: (1) condensation of coelomic epithelium; (2) secondary proliferation of coelomic epithelium; (3) finding of PAS‐positive material within the fetal cortex; (4) decline and disappearance of the fetal cortex; and (5) establishment and stabilization of the definitive zonular patterns.

Significant features occurring in this development were: (1) the origin of both permanent and fetal cortex from proliferation of coelomic epithelium; (2) the appearance of PAS‐positive granules surrounding a homogenous mass in the fetal cortex and the zona reticularis during maturation and organization; and (3) the gradual establishment of definitive zones by proliferation of the permanent cortex, maturation of the fetal cortex, and growth of the medulla; with the adult structure of the adrenal gland achieved by the eleventh to fifteenth year without any apparent major involution or hemorrhage.
The involvement of nurse cells in oogenesis and embryonic development in the marine sponge, Haliclona ecbasis
Authors: Fell Paul E.
Published: February 2005

Oogenesis and embryonic development in the marine sponge, Haliclona ecbasis, were studied using standard histological procedures.

When the oocytes reach a diameter of about 30 μ, nurse cells begin to aggregate around them. Then when the oocytes are about 36 μ in diameter, they begin to engulf the associated nurse cells. Whole nurse cells are engulfed; and although the nucleus of the nurse cells disappears either as or soon after the cells are engulfed, the cytoplasm remains essentially unchanged. The accumulation of these cells within the oocytes most of the cytoplasm is nurse cell cytoplasm.

During cleavage of the egg, the engulfed nurse cells are gradually fragmented, but otherwise appear unchanged. At the same time the cytoplasm of the nurse cells is progressively incorporated into that of the blastomeres by what appears to be fusion process. When the latter process is complete, the embryo develops into a typical parenchymula larva.
Cell proliferation in Xenopus tissues: A comparison of mitotic incidence in vivo and in organ culture
Authors: Simnett John D. , Balls Michael
Published: February 2005

Using the Colcemid technique, the mitotic incidence (MI) was measured in the epidermis, lung, spleen, liver, kidney and ovarian follicular cells of metamorphosed, immature Xenopus laevis laevis. The MI was higher at 25°C than at 20°C, and there was a significant ranking correlation between organs in respect of the MI in different animals. With the exception of the liver and kidney, organ cultures showed good preservation for up to six days in vitro using a medium supplemented with 10% fetal calf serum, and values for MI comparable with or even higher than in vivo were obtained.
Structure of the apical cells of the testis of the tenebrionid beetles: Tenebrio molitor and Zophobas rugipes
Authors: Menon Maya
Published: February 2005

The developmental cytology of the apical tissue of the testis of Tenebrio molitor and Zophobas rugipes was studied with light and electron microscopy. In the early larvae of both species the tisue was found to be a thickened protrusion of nongerminal cells appearing at the apical end of each testis follicle following gonadal differentiation. The cells persist through pupal and adult stages in both species, becoming more prominent at these stages in Z. rugipes, despite tracheal invasion in both species. In older adults the apical tissue regresses and ultimately distintegrates.

Ultrastructurally the apical cells are distinguished from adjacent germinal cells by their (1) small, rounded or oval nuclei, (2) highly convoluted plasma membrane, (3) electron‐opaque cytoplasm, (4) profuse concentrically‐stacked, granular endoplasmic reticulum, (5) large aggregates of glycogen‐like granules, (6) numerous small, tubular mitochondria, (7) well‐developed Golgi centers and (8) striking arrays of microtubules. These cells have many cytological features in common with the androgenic gland cells of crustaceans, but not with the steroidogenic cells of vertebrates. Evidence for the formation of protein granules is also lacking. As yet, experimental procedures have not indicated an endocrine function for these cells in tenebrionids. However, their cytology is consistent with secretory activity of some kind.
The cytology of submandibular glands of the opossum
Authors: Wilborn Walter H. , Shackleford John M.
Published: February 2005

Submandibular glands of the opossum have been studied by light and electron microscopy and compared with other mammalian salivary glands. The glands have four parenchymal segments which connect in the order named below to convey saliva toward the oral cavity.

Secretory units are elongated branching tubules exhibiting mucous and special serous cell types. Mucous cells predominate and resemble those in other salivary glands. Special serous cells differ from “typical” serous cells. They contain a preponderance of tubular or vesicular endoplasmic reticulum and secretory granules which vary from electron lucent to electron opaque.

Intercalated ducts are short segments lined by nonsecretory, cuboidal cells.

Striated ducts are numerous and lie in the center of the lobule. The duct epithelium has four cell types, designated light cells, dark cells, Type I basal cells, and Type II basal cells. Light cells possess basal infoldings associated with mitochondria, but the other cell types lack this characteristic.

Excretory ducts are also lined by four cell types which bear the same names as those of striated ducts. Three of the four cell types are virtually identical to those of striated ducts, but light cells differ. They do not always contain basal infoldings and the supranuclear cytoplasm lacks distinct inner and outer zones.

The glands resemble salivary glands of higher mammals in many respects while possessing certain unique cytological features which may reflect the secretory needs of the organism.