bluuebunny/crossref_metadata_2025 huggingface dataset:
The forebrain of the crossopterygian Latimeria chalumnae Smith
Authors: Nieuwenhuys Rudolf
Published: February 2005

In this paper the telencephalon of Latimeria chalumnae, the only surviving crossopterygian, is described and compared to that of other lower vertebrates. It is concluded that Latimeria cannot be related to a particular group of vertebrates, but stands intermediate between the dipnoans and the actinopterygians in its forebrain structure. With respect to the shape of the subpallium, the structure of the telencephalon medium, and the arrangement of its fiber systems, the latimerian forebrain closely approaches the dipnoan condition. The pallium and membranous structures of the telencephalon of Latimeria, on the contrary, are reminiscent in gross form and histological structure of their actinopterygian homologues.

However, not all the structural features of the latimerian forebrain can be related to either the actinopterygian or the dipnoan plan. The subpallium, for instance, is more primitive than that of either group mentioned; in fact, it is more simply organized than that of any other living gnathostome.

The forebrain of Latimeria appears to display no special structural affinities to the amphibian forebrain. This is not too surprising, since the Coelacanths, among which Latimeria is classified, represent only a side branch of the Crossopterygii, and are not in the main line of evolution to higher forms. It is known that members of the same class of lower vertebrates may vary considerably in their forebrain structure. Hence, the Rhipidistia, totally extinct Crossopterygii which are believed to have given rise to the terrestrial vertebrates, may have possessed a forebrain quite different from that of Latimeria.
The occurrence of cardiac muscle in the pulmonary veins of rodentia
Authors: Kramer A. W. , Marks L. S.
Published: February 2005

Cardiac muscle fibers have been found to extend from the left auricle along the pulmonary veins as far as the hilus of the lungs in man, in dogs, and in rodents such as the guinea pig. In other rodents, however, the cardiac muscle extends into the veins of the lung itself. To study the occurrence of cardiac tissue in the pulmonary veins, the lungs of selected rodents which represent nine superfamilies have been examined. Only the guinea pig, Cavia porcellus, was limited to having cardiac muscle in the extrapulmonary veins. All of the other 47 species examined had intrapulmonary extensions of cardiac muscle to various distances along the pulmonary veins. It is apparent that this morphological feature is not a specialization among a few families of rodents, but is probably a feature common to almost all of the rodents.
Labiopedia, a sex‐linked mutant in Tribolium confusum duval (Coleoptera: Tenebrionidae)
Authors: Daly Howell V. , Sokoloff Alexander
Published: February 2005

The genetics and anatomy of the homoeotic mutant labiopedia (lp) of Tribolium confusum is described. The mutant is the second known among the insects to affect the mouthparts. The two‐segmented labial palps of the larva are completely replaced by leg‐like appendages resembling the prothoracic legs and exhibiting the apex of the trochanter and all parts distal to the trochanter. The labial palps of the pupa and adult are likewise replaced by legs. The three‐segmented palps of the adult are replaced by appendages closely similar to the prothoracic legs in many characters and exhibiting the apex of the coxa and all other parts of a normal walking leg. The legs have never been seen to move although they are supplied with labial nerves and an almost complete, though highly reduced, set of muscles. The labial appendages are invariably leg‐like and well‐developed, failing to show the range of variability which is commonly observed in homoeotic mutants. The leg‐like form of the heteromorphic organ is in striking conformity with the appendicular origin of the palps.

The lp gene is recessive and sex‐linked, with lethal to semilethal effects. It is the third sex‐linked gene discovered in Tribolium confusum and the first sex‐linked homoeotic mutant known among the insects. Since the inheritance of lp is entirely in the manner of a sex‐linked gene, it most probably is located on the original X chromosome, unless the translocated autosomal portion attached to the Y has become inert.
The structure and maturation of the spermatozoa of Sciara coprophila
Authors: Makielski Sally K.
Published: February 2005

The axial filament of Sciara coprophila does not conform to the usual 9 + 2 filament pattern but consists, rather, of as many as 76 pairs of filaments which decrease in number from the anterior to the posterior region of the sperm. It is first seen at the base of the head in the shape of an indented oval. The axial filament varies in configuration along the remaining length of the sperm as one whorl or two connected whorls of filament pairs.

The other structures of the sperm revealed by the light and electron microscopes are a homogeneous, dense, spear‐shaped nucleus, a row of spherical dense bodies in the middle piece enclosed by the axial filament and of unknown nature and function and a single mitochondrial derivative.

The mitochondrial nebenkern derivative consists of a large electron transparent region bordered by cristae and a smaller paracrystalline region located adjacent to the axial filament. The derivative arises as paracrystalline material in a medial nuclear indentation. The electron transparent material is first seen at the anterior end of the middle piece.

Unlike other known insect sperm, but reminiscent of sperm capacitation in mammals, sperm maturation is completed in the spermathecae of Sciara 7 to 9 hours after insemination. It consists of the acquisition of sperm motility and elimination of the electron transparent region of the mitochondrial nebenkern derivative. The electron microscope reveals in mature sperm that the axial filament doublets have changed configuration and consist of a single whorl which encloses the paracrystalline rod. The process by which the major portion of the nebenkern derivative is eliminated occurs in four identifiable stages. Since sperm maturation does not appear to be intrinsically controlled, factors in the spermathecal fluid may play a role in its completion.
Endometrial vascularity during pseudopregnancy in the rabbit
Authors: Tsutsumi Y. , Hafez E. S. E.
Published: February 2005

The vascular architecture in the rabbit uterus was studied during pseudopregnancy. Uteri at 2, 3, 4, 6, 7, 8, 9, 11, 13, 16, 17, 18, 20, 24 and 28 days after sterile mating were subjected to one of four techniques: neoprene latex casts, transparent sections, frozen sections, and histological sections. Measurements were made microscopically of the thickness of myometrium and of the subepithelial capillary plexus in the different mucosal folds. In the estrous rabbit, the circular arteries in the uterine muscular layer give off arterioles which pass upwards, with a few branchings through the endometrium to the uterine lumen. These arterioles reach the surface of the mucosal folds and break up into the subepithelial capillary plexus. This plexus is connected to the tips of the venules which run down through the endometrium to the endometrial vascular plexus at the base of the endometrium: some of the venules connect with the circular venous vessels in the muscular layer. With advanced stages of pseudopregnancy, the capillaries among the glands become stretched and elongated. Maximal branching of the folds occurs at 4 to 9 days of pseudopregnancy. The “branching activity” was consistently higher in the placental than in the periplacental or in the obplacental folds. Such changes reached a maximum at 6 to 7 days p.c., after which the capillaries became gradually shorter and tortuous. The development of arterioles in the mucosa was marked at 3 to 6 days p.c. The thickness of the plexus in the periplacental fold and in the obplacental fold as a percentage of the thickness in the placental fold was highly correlated with the stage of pseudopregnancy. At 9 to 11 days p.c., these ratios reached a minimum of 70 to 80%.
The hemocytes of Hyalophora cecropia (Lepidoptera)
Authors: Lea Malcolm S. , Gilbert Lawrence I.
Published: February 2005

The hemocytes of selected stages of Hyalophora cecropia from first instar larvae to four‐day‐old adults were examined and compared with those of Samia cynthia and Antheraea polyphemus. Five classes and two subclasses of hemocytes are described in these moths: (1) prohemocytes, (2) plasmatocytes (of several morphological types), (3) spherule cells, (4) adipohemocytes (two subclasses), and (5) oenocytoids. All types except oenocytoids and subclass II adipohemocytes, are found in all stages examined. Mitotic figures were common among prohemocytes of most stages, but were seen only rarely among plasmatocytes and adipohemocytes, and were not seen among spherule cells or oenocytoids. Prohemocytes and plasmatocytes often contain lipid but rarely PAS positive material. Spherules of spherule cells are PAS positive, as are occasional cytoplasmic inclusions of oenocytoids. Adipohemocytes of both subclasses contain lipid and PAS positive materials in all stages examined. Adipohemocytes and plasmatocytes proved to be most active in phagocytizing ink. Relationships between hemocytes of these and other insects, and some possible functions of hemocytes are discussed.
Studies on the morphology and function of the skull in the boidae (Serpentes). Part II. Morphology and function of the jaw apparatus in Python sebae and Python molurus
Authors: Frazzetta T. H.
Published: February 2005

Heads of the boid snakes Python sebae and Python molurus were dissected and the arthrology, myology and dentition studied. Living specimens of these species were observed and their feeding behavior analyzed by means of high‐ and regular‐speed motion pictures. Camera speeds of up to 400 frames per second permitted examination of the jaw movements during the striking and seizing of prey. Motion picture studies conducted at regular speeds provided information on cranial movements during the swallowing of prey. The morphology of the head was correlated with observed movements in an attempt to analyze the functional and adaptive implications of the jaw apparatus.

The cranial apparatus was discussed in terms of a linkage or kinematic chain whose constrainment and degrees of freedom were examined and compared with the jaw linkage of lizards. It was concluded that the very rigidly constrained mechanism in lizards is in remarkably sharp contrast to the very loose apparatus in snakes.

Motions of various cranial bones were analyzed with particular attention given the mechanical factors involved. In full protraction the maxillae and palatines are lifted and rotated outward about a longitudinal axis. These movements are important in orienting the teeth with respect to the prey and are related to seizing and swallowing.
The histology and histochemistry of oogenesis in the water strider, Gerris remigis say
Authors: Eschenberg Kathryn M. , Dunlap Helen L.
Published: February 2005

In each ovariole of Gerris remigis, nurse cells arise by mitotic divisions at the anterior end of the germarium. These cells enlarge as they move posteriorly. This size increase is possibly caused by fusion of cells, but probably by endopolyploidy as well. The nurse cells then establish connections with a central trophic core, which receives the products of subsequent nurse cell degradation. Two possible pathways of nuclear degradation are suggested: one involves the condensation of chromatin within the nucleus; the other, the release of DNA as fine granules into the cytoplasm. Cytoplasmic areas containing such DNA are also rich in proteinaceous granules, but have a meager content of RNA. The remainder of the cytoplasm of the mature nurse cells contains a high concentration of RNA, as do the nucleoli.

Posteriorly the trophic core connects via nutritive cords with each developing oocyte in the prefollicular region and in the anterior vitellarium. RNA is apparently contributed to the ooplasm via the trophic stream. Patches of cytoplasmic DNA are present in the young oocytes; the origin and fate of this DNA is uncertain.

During early oocyte maturation chromosomal stainability decreases, and the nucleolus enlarges. In previtellogenic stages, numerous proteinaceous bodies appear in association with the nucleolus‐chromosome complex. These bodies, like the nucleolus, have only a low RNA content. They may pass to the cytoplasm, but cannot be traced with certainty. During the latter part of this period a complex population of small proteinaceous and lipid preyolk bodies accumulates peripherally in the oocyte. Definitive protein and lipid yolk are probably derived by the enlargement and inward migration of these bodies.

The oocytes are each surrounded by a layer of follicle cells proliferated in the prefollicular region. These become binucleate and enlarge as the enclosed oocytes grow and elongate. RNA also increases in the nucleoli and cytoplasm of the follicle cells as they move posteriorly in the vitellarium. There is no evidence of transfer of nucleic acids or protein from the follicle cells to the oocyte.

The nurse cells are therefore implicated as the major source of nucleic acids for the maturing oocyte.
The structure of the cochlea in chiroptera. I. Microchiroptera: Emballonuroidea and Rhinolophoidea
Authors: Pye Ade
Published: February 2005

The structure of the ears, especially of the cochleae, has been examined in two superfamilies, i.e. Emballonuroidea and Rhinolophoidea of the Microchiroptera. An intra‐vitam fixation method was used and gave good histological preparations. The following features of the cochlea have been measured: the general size of the cochlea, the width and thickness of the basilar membrane, the size of the spiral ligament and the height of the cells of Claudius. The interpretation of measurements is discussed in relation to the nature of ultrasonic sounds produced by bats. It is concluded that functional interpretation of specific cochlear modifications cannot be assessed at present.
Ophidian cephalic glands
Authors: Taub Aaron M.
Published: February 2005

A survey of the comparative morphology and histology of the twelve glands in the ophidian head was made. The nasal and Harderian glands are the only non‐oral glands. The premaxillary, supralabial, posterior, Duvernoy's and venom glands are serially homologous. The infralabial, sublingual and supralingual glands are not related to the other oral glands. The relationships of the temporomandibular and anterior temporal glands to the other oral glands could not be determined.

For each gland a synonymy of previously used names, its approximate location within the head and its distribution within the various groups of the Ophidia is given. The general histological picture of most of the glands is illustrated and available information on their embryology and innervation is summarized.
Erythrocyte replacement at metamorphosis in the frog, rana pipiens
Authors: Hollyfield Joe G.
Published: February 2005

Small crenulated erythrocytes appear in the circulation of Rana pipiens during metamorphosis, increases in number as metamorphosis proceeds and gradually lose their wrinkled appearance. At the end of metamorphosis the entire red cell population has been replaced by these new cells. Thyroxine induces the premature appearance of these new cells in young tadpoles.
Oviducal anatomy and sperm storage structures in lizards
Authors: Cuellar Orlando
Published: February 2005

Gross and histological examination of lizard oviducts was made in 11 species of the family Iguanidae, and in one species of each of the families Gekkonidae and Eublepharidae. Lizard oviducts are bound dorsally by a mesentery which is continuous with the peritoneum, and ventrally by a smooth muscle band which extends from the posterior segment of the vagina to the base of the infundibular ostium. The musculature of the vagina consists of an inner circular smooth muscle layer which is thickened posteriorly, and an outer longitudinal layer which is arranged into longitudinal folds at about the utero‐vaginal transition. In iguanid lizards the vaginal mucosa is arranged into longitudinal folds that extend the entire length of the vagina. Posteriorly, the folds are high and reduced in number. Anteriorly, they decrease gradually in height and become more numerous. In Phyllodactylus homolepidurus fold height and number remain essentially constant through the vagina. Seminal receptacles in the iguanids occur principally in the anterior segment of the vagina. Receptacles in P. homolepidurus (Gekkonidae) and Coleonyx variegatus (Eublepharidae) appear to be confined to the tube between the uterus and the infundibulum. Most receptacles are located adjacent to the oviducal mesentery and to the smooth muscle band.
Special cutaneous receptor organs of fish: The tuberous organs of Eigenmannia
Authors: Wachtel Allen W. , Bruce Szamier R.
Published: February 2005

The special cutaneous receptor organs of the fresh water weakly electric fish have previously been proposed to be electroreceptors. In the gymnotid, E. virescens, two types of special cutaneous receptor organs, ampullary and tuberous, are distinguished from each other, as well as from the ordinary lateral line receptor organs, by their characteristic distribution and size. The tuberous organs usually contain 25 to 35 elongate nonciliated receptor cells within a cellular capsule. A single layer of supporting cells is present between the base of the receptor cells and the base of the capsule. A single thin myelinated nerve fiber innervates each group of organs and branches so that the base of each receptor cell is supplied with a single nerve ending. Synaptic contact is made at many points on each nerve ending. The synapses are characterized by fingers of receptor cell cytoplasm which contain dense presynaptic rods. The organ capsule is open toward the surface of the fish. A cellular plug partly obscures the opening, but continuity is maintained between the intracapsular fluid and the external water. Microvilli, projecting from the surfaces of the receptor cells, maintain an open gap between adjacent receptor cells. About 95% of the surface area of these cells is therefore in contact with the fluid. The functional implications of some of the ultrastructural observations are discussed.
The terpene‐producing glands of a phasmid insect cell morphology and histochemistry
Authors: Happ George M. , Strandberg John D. , Happ Christine M.
Published: February 2005

The defensive glands of Anisomorpha buprestoides produce the terpene toxicant anisomorphal. Each gland consists of a cuticular secretion reservoir surrounded by the secretory epithelium and the musculature which serves to compress the gland and expel the secretion. Two types of cells make up the secretory epithelium: a squamous layer next to the cuticular reservoir and a layer of larger secretory cells responsible for production of the toxicant. The microvilli‐laden plasma membrane of each secretory cell is invaginated to form a central cavity. It appears that secretory products pass into the central cavity and then flow out to the gland reservoir via an efferent cuticular ductule contained within the squamous epithelial cell.

Histochemical techniques demonstrate lipid reserves, carboxylic esterases, a variety of phosphatases, and an alcohol dehydrogenase, within the secretory cells. It is suggested that the lipid reserves are precursors of the terpenoid toxicant, that a mevalonic kinase has been histochemically demonstrated by the phosphatase test, and that an unusual alcohol dehydrogenase is active in the final steps of toxicant synthesis. The histochemical evidence is consistent with the hypothesis that anisomorphal is produced via the mevalonic acid pathway.
The origin and early differentiation of the egg chamber of Drosophila melanogaster
Authors: Koch Elizabeth A. , King Robert C.
Published: February 2005

The egg chamber of Drosophila melanogaster consists of 16 interconnected cells surrounded by a monolayer of follicle cells. Each 16 cell cluster (from which the oocyte and 15 nurse cells differentiate) arises within the germarial region of an ovariole. To study the ultrastructure of the early stages in the formation and differentiation of egg chambers, a three dimensional reconstruction was made from serial thin sections through a germarium from a 24‐hour old, virgin female. The germarium was found to be subdivided into three regions: (1) The mitotically active area where clusters of 16 cells originate from a series of cystocyte divisions, (2) the region where these cells interact with mesodermal cells, and (3) the region where the germarial cyst is transformed into the first egg chamber in the vitellarium. Since cystocytes were found to decrease in size with each division, the possibility exists that cell size may determine when the divisions cease. Models are presented which mimic with varying degrees of success the developmental changes the germarial cells undergo with time. Hypothesis are developed to explain why stem line oogonia are restricted to the anterior portion of the germarium, why mesodermal cells first interact with cystocytes in region 2, and why the oocyte is oriented posteriorly. The nuclear differentiations of the component cells of the chamber are described and correlated with observed differences in radiosensitivity. Symbionts were observed in the germaria of several strains of Drosophila, and the bearing of these findings upon nutritional studies is discussed.
The ganglion‐connective junction in the central nervous system of the leech, Hirudo medicinalis
Authors: Coggeshall Richard E.
Published: February 2005

Classical studies of the nervous system of the leech revealed that there were specific types of very large glial cells associated with various parts of the neuron. Recent microelectrode studies demonstrated that there was a low resistance to the flow charge from any one of these large glial cells to another. The present study describes a previously unreported type of glial cell, the glial cell of the fascicles. These cells, which resemble the glial cells of the connectives but are smaller, are found in the fascicles of axons that unite the connectives to the neuropil. Thus, these cells are located between the glial cells of the connectives on the one hand and the glial cells of the neuropil and packets on the other and must be taken into account in considerations of the low resistance to the transfer of charge from one glial cell to another.
A comparative investigation of neuroglia in representative vertebrates: A silver carbonate study
Authors: King James Sargent
Published: February 2005

The phylogenetic development of neuroglia (astrocytes, oligodendrocytes) was investigated in homologous cortical and subcortical forebrain regions of selected vertebrates. Microglia were not considered in the current study.

Four to seven brains from each species were used. Scharenberg's modification for astroglia of del Rio Hortega's silver carbonate technique was used. The analysis of neuroglia cells was based on (1) the characteristic cellular morphology found in each species, (2) a comparison of the selected regions in each animal, (3) the interrelationships of astrocytes and their relations to neurons, blood vessels, and oligodendrocytes.

The predominant type of neuroglia found in the fish, frog, and lizard was the ependymal cell; however, non‐ependymal glial cells were also present. The bird represented a transitional phylogenetic stage from a predominance of ependymal glial to a predominance of non‐ependymal glia. A progressive increase in the morphological relationships of glial cell bodies and processes to neurons was found with ascension of the phylogenetic scale from fish through primate.

Interrelations were observed between adjacent astrocytic processes and cell bodies, and between astrocytes and oligodendrocytes. The processes of adjacent glial cells also appeared to show an increase in thickness at the point of approximation. A variety of astrocytes were observed ranging from small, round‐oval shaped cells to large polygonal or stellate forms. Variations in the number of astrocytic processes, their thickness, and degree of secondary branching were described, and their possible functional significance was discussed.
Studies on the embryogenesis of Aulocara elliotti (Thomas) (Orthoptera, Acrididae). I. External morphogenesis
Authors: van Horn Saralee Neumann
Published: February 2005

The growth and morphogenesis of embryos of Aulocara elliotti (Thomas) at constant temperature are described in terms of 27 discrete morphological stages with four stages designating blastokinesis. The developmental variability of two series of embryos reared from a single wild population in two different years is compared. A bibliography to studies on other embryos of the Acrididae is included.
Morphogenesis and histochemistry of the developing mouse kidney
Authors: Redempta Vetter Sister M. , Gibley Charles W.
Published: February 2005

A morphological and histochemical investigation was conducted on the pronephros and mesonephros of the mouse embryo from 8.5 through 16.5 days. The pronephros appeared between days 8.5 and 9.5 as a thickening of the somatic layer of the intermediate cell mass. It consisted of three small clusters of cells on either side of the midline dorsally between the somite and the coelom, at the level of somites 8 and 9. The mesonephros arose during day 9 and persisted until day 16. In the male the anterior three tubules were incorporated into the testis at 15.5–16.5 days. The mesonephros consisted of approximately 11 tubules located between somites 10–17. The tubules possessed lumina and connected with the Wolffian duct. Indications of internal and external glomeruli were noted on day 11. The Wolffian duct reached the cloaca at ten days.

Strong alkaline phosphatase activity was noted in the differentiating tubules. Cytoplasmic and luminal enzyme activity was observed between 9.3 and 12.5 days indicating possible function at this time. Acid phosphatase was demonstrable in the tubules and duct only on day 11. Ribonucleic acid was observed in the nuclei and cytoplasm of the mesodermal cells as they differentiated into tubules and duct. A decrease in RNA was noted after differentiation was complete. Periodic acid‐Schiff material (diastase‐stable) was localized in the basement membrane of the tubule and duct cells. A faint positive reaction was also found at the luminal border of the tubules. The strongest reaction was noted in the luminal border at 11.5–12.5 days. Those tubules being incorporated into the genital system in the male were also PAS positive. Morphological and histochemical evidence suggested that the mouse mesonephros, though quasi vestigial, may function for a short time.
Choroid plexus and paraphysis in lower vertebrates
Authors: Shuangshoti Samruay , Netsky Martin G.
Published: February 2005

Cytoarchitecture of the choroid plexus of the third ventricle and the paraphysis was investigated in some lower vertebrates to compare the histologic characteristics of these organs. Both epithelia are similar in appearance in the same class. Minor microscopic variations exist in the different classes of vertebrates, but do not provide a fundamental distinction between the two organs. The epithelia, moreover, have similar staining properties, contain mucicarmine‐ and PAS‐reactive materials, and are derived from a common neuroepithelium. Tubules are identified in the choroid plexus and in the paraphysis; all are similarly formed by simple folding of epithelium on the surface into the stroma. The paraphyses in all vertebrates studied contain villi similar to those seen in the choroid plexus. Cilia are identified in both choroidal and paraphyseal epithelia, and are not an indication of degree of epithelial differentiation. Many types of epithelium are noted in both organs during histologic differentiation as well as in the mature stage. Functionally, the choroid plexus is active in both secretion and absorption. Accumulation of particulate material within the epithelial cytoplasm may indicate phagocytic as well as absorptive activity of cells. Based on a common neuroepithelial origin and similar histochemical properties, we conclude that the paraphysis is a modified choroid plexus. The velum transversum is an arbitrary boundary between diencephalon and telencephalon, and is itself formed of choroid plexus. The medial telencephalic ventricle is the rostral portion of the third ventricle. All neuroepithelial infoldings at the rostral end of the diencephalic roof including the velum transversum are intraventricular choroid plexuses; the neuroepithelial outpouchings in this region are the extraventricular choroid plexuses (paraphysis) of the diencephalon.
The structure and development of the digital lamellae of lizards
Authors: Ernst Valerie , Ruibal Rodolfo
Published: February 2005

The epidermal setae and the spinules of the digital lamellae of anoline and gekkonid lizards are shed periodically along with the rest of the outer layer of the skin. These structures are developed within the lamellae prior to ecdysis. The setae are larger and more complicated than the spinules and begin their development first. The setae of Anolis start as aggregations of tonofibrils beneath the plasma membrane of the presumptive Oberhautchen cells. These cells are arranged in rows parallel to the surface, several cell layers beneath the alpha layer of the skin. The developing setae protrude into the clear layer cells as finger‐like projections, with the tonofibrils longitudinally oriented in the direction of growth. About 100 setae are formed by each Oberhautchen cells in Anolis. In late development, the clear layer cells lose their cellular contents and when shed along with all distal cells, retain a template of the new setae or spinules. The spinules and setae are formed before the fibrous and alpha layers of the new skin. The fibrous layer, which occurs only on the ventral (outer) layer of the lamellae, and the Oberhautchen with its setae and spinules, is considered the beta layer. The alpha layer, which occurs adjacent to the fibrous layer on the ventral surface and adjacent to the Oberhautchen on the dorsal (inner) surface, is morphologically identical to that of mammalian α keratin. The shed lizard skin consists of the alpha and beta layers as well as the degenerating cells of the outer epidermal generation, and the clear layer. The clear layer that is shed shows the template of the new setae and spinules developed in the new skin layer. The separation of the new from the old skin occurs along the intercellular space between the clear layer cells and the new Oberhautchen. The alpha layer of the skin is not fully keratinized at shedding. The setae of the digital lamellae of lizards represent unique epidermal structures — intracellular keratinized microstructures.
Fine structure and origin of the tunic of Perophora viridis
Authors: Deck J. David , Hay Elizabeth D. , Revel Jean‐Paul
Published: February 2005

The fine structure of the tunic of a typical ascidian was investigated because of the cellulose‐like polysaccharide known to occur in its substance. The glycoprotein mantle does contain filaments very much like plant cellulose in morphology. Tunicin filaments are 35–50 Å in diameter, often beaded, and of indeterminate length. Histochemical evidence that they are composed of cellulose is given here and past chemical and physical studies on the unusual ascidian polysaccharide are reviewed. Moreover, we present here for the first time direct autoradiographic evidence that epidermal cells are involved in the synthesis and secretion of tunicin. Tritiated glucose is immediately incorporated into the Golgi zone of epidermal cells and labeled product appears in the tunic at later intervals. The fine structure of the epidermal cell is described in detail. Unlike the rather moribund appearing vanadocyte that wanders through the tunic, the epidermal cell has well‐developed cytoplasmic organelles and a large vesicular nucleus. The granular endoplasmic reticulum is abundant and the Golgi complex is highly developed. It seems likely that the lamellae and vesicles of the Golgi complex are involved in the production of the tunic sugar and that tunic proteins of as yet unknown nature are produced by the ergastoplasm. Further investigation of the ascidian mantle should be of interest because of the possibility that cellulose is a more general component of glycoprotein surface coats in animals than has heretofore been recognized.
Fine structure of the formation and fate of the residual bodies of mouse spermatozoa with evidence for the participation of lysosomes
Authors: Dietert Scott E.
Published: February 2005

Routine electron microscopy in combination with subcellular localization of acid phosphatase has been employed to study the formation and fate of residual cytoplasmic bodies extruded into the tubular lumen shortly before spermiation. Prior to extrusion the spermatid cytoplasm contains lipid droplets, mitochondria, ribosomes, endoplasmic reticulum, the caudally migrated Golgi apparatus, and numerous multivesicular and multigranular bodies. These membrane‐limited bodies and the Golgi zone stain heavily for acid phosphatase. Following extrusion the residual bodies undergo a series of alterations: (1) disruption of multigranular bodies with release of free granules; (2) sequestration of granules, ribosomes, and reticulum inside double‐membrane‐limited vacuoles derived from Golgi lamellae; (3) appearance of numerous, single‐membrane‐bound, cytoplasmic vacuoles; (4) fragmentation; (5) peripheral migration toward the tubular wall; and (6) phagocytosis of these migrating fragments by the Sertoli cells. The demonstration of acid phosphatase activity within free granules, the sequestering Golgi lamellae, and both classes of vacuoles suggests that initial residual body degradation occurs through lysosomal cytoplasmic autophagy.
Histochemical observations on mucin secretion by subsurface epithelial structures in the canine ovary
Authors: O'shea J. D.
Published: February 2005

Histochemical methods for mucins were applied to the ovaries of 23 dogs.

Solid and hollow groups and cords of epithelial cells (subsurface epithelial structures, SES) in the outer part of the cortex regularly showed evidence of mucin secretion. Intracytoplasmic, sialic acid‐containing, acid mucin secretion droplets were seen in solid and hollow SES, and secretion was present in both closed lumina and those opening onto the surface.

Intracytoplasmic droplets in the cells of SES were distinctive, and similar droplets were not found in the cells of any other ovarian epithelial component. The secretion of SES was not shown to possess distinctive histochemical features.

Mucin production was also observed in follicles, corpora lutea and rete tubules.

The significance of ingrowth from the ovarian surface epithelium in adult life, and of secretory activity by the cells of SES, are discussed.
Ultrastructure of the crocodile kidney (Crocodylus acutus) with special reference to electrolyte and fluid transport
Authors: Davis Lowell E. , Schmidt‐Nielsen Bodil
Published: February 2005

The study of the ultrastructure of the kidney tubules of the crocodile was made to compare the cellular structure with the capacity for electrolyte resorption and the ability to create an osmotic gradient across the tubular wall. The crocodile tubular cells were found to differ from the mammalian tubular cells in that they do not have basal infoldings, but instead have open lateral spaces between the cells, similar in many aspects to those found in the mammalian gallbladder. The physiological role of these lateral spaces in solute and fluid transfer is discussed.
Embryology of the thoracic and abdominal ganglia of the large milkweed bug, Oncopeltus fasciatus (Dallas), (Hemiptera, Lygaeidae)
Authors: Springer Charles Anthony
Published: February 2005

In this study, the condensation of the three thoracic and 11 abdominal segmental ganglia to form a prothoracic and central nerve mass during embryogenesis is described. During katatrepsis, many changes occur in the organization of these ganglia; this study suggests that some of these changes are caused by mechanical forces acting on the ventral nerve cord at this time. The ventral nerve cord begins its anterior migration and coalescence ten hours after katatrepsis and is completed 63 hours later. The central ganglion is made up of the meso‐ and metathoracic ganglia and seven abdominal ganglia. Intrasegmental median cord nuclei are shown to form glial elements in the median sagittal plane of the neuropile and in the longitudinal connectives. Intersegmental median cord neuroblasts migrate into the posterior gangliomeres but, apparently, degenerate soon after katatrepsis. Lateral cord cells bordering on the neuropile form a glial investment that surrounds this fiber tract region. Peripheral lateral cord cells are shown to form the cells of the outer ganglionic sheath, the perineurium.
Histochemical studies on cell death and histolysis during regeneration I. Distribution of acid phosphomonoesterase activity in the normal, the regenerating and the resorbing forelimb of the larval spotted salamander, Amblystoma maculatum
Authors: Weiss Charles , Rosenbaum Robert M.
Published: February 2005

Histochemical methods, especially azo dye methods for detecting acid phosphomonoesterase activity were applied to normal, regenerating and denervated, amputated limbs from larval Amblystoma maculatum. Efforts were made to control inactivation of enzymic activity and diffusion of both enzyme and reaction product. “Base‐line” values for enzymic activity were determined for normal limbs. Activity appeared most intense in macrophages, less intense in epidermis and cartilage matrix. Some activity was detected in Schwann cells, peri‐ and endoneurium and muscle fibers form normal limbs. Enzymic activity in regenerating limbs was strongest within macrophages which appeared in increased numbers especially in early stages. Wound tissue showed little increased activity. As the blastema formed, increased enzymic activity was detected in epidermis and within increased numbers of macrophages. Chondrocytes showed increased activity especially during cartilage matrix deposition. Amputated, denervated limbs showed large numbers of active macrophages beneath and within epidermis and along muscle. As regression commenced, areas of cartilage matrix breakdown showed increased enzymic activity but, in general, greatest activity was in macrophages. The various possible roles of acid phosphomonoesterase activity in the specific biological situations dealt with are considered in light of such observations.
The development of neuromasts in Cirrhina mrigala Ham. Buch. (Cyprinidae) and Ophicephalus (Channa) punctatus Bloch (Channidae)
Authors: Srivastava M. D. L. , Srivastava C. B. L.
Published: February 2005

The development of neuromasts was studied in two species of teleosts, Cirrhina mrigala Ham. Buch. and Ophicephalus punctatus Bloch, and the findings are presented and discussed. It has been discovered, in the course of this investigation, that a neuromast arises by a process of invagination — a fact hitherto not reported. The occurrence of the dorsal lateral line and the accessory lateral line of the trunk, in addition to the main lateral line, has also been reported for the first time for teleosts, although known for other bony fishes.
The fine structure of developing bristles in wild type and mutant Drosophila melanogaster
Authors: Overton Jane
Published: February 2005

In an attempt to understand the factors involved in morphogenesis of a complex cell like a scale or bristle, the fine structure of the normal development of bristle cells in Drosophila melanogaster (Oregon R) has been studied and compared with that of the mutants sn3 and Sb. In the development of the normal bristle rounded bundles of longitudinally oriented fibrils lie just beneath the cell surface at regularly spaced intervals. Fiber bundles constitute about 20% of the cross sectional area. The cytoplasmic surface between these bundles is active in enveloping the nerve fiber associated with the bristle and in sending out cytoplasmic processes associated with which the longitudinally oriented bristle ridges form. Singed bristles are bent and twisted and the fiber bundles are present as flattened bands constituting only about 5% of the cross‐sectional area. In Sb mutants the total cross‐sectional area of fiber bundle material is the same as that in Oregon R, but fiber bundles are smaller and more numerous, being distributed over the larger surface of this thicker and shorter bristle. They constitute only 7% of the cross‐sectional area of the bristle. In Sn3Sb mutants characteristics of each gene are exaggerated and an extremely short, wide, and irregular bristle is formed.
The failure of exoskeletons and endoskeletons
Authors: Currey J. D.
Published: February 2005

A theoretical analysis is made of the mechanical advantages of exoskeletons and endoskeletons. More complicated and realistic loading systems are considered than have been by previous authors. For all cases involving static loading, an exoskeleton would seem to be advantageous, but sometimes the advantage is quite small. If impact is considered, the advantage of exoskeletons becomes very much reduced, even on theoretical calculations; and it is likely that in life the advantage may be converted to a disadvantage, particularly in large active animals such as vertebrates.
Development of the corpuscles of stannius in the anabantid teleost, Colisa lalia
Authors: Krishnamurthy V. G.
Published: February 2005

The development of Stannius corpuscles in the teleost Colisa lalia is described. Certain cells of the mesonephric tubules differentiate and proliferate to form buds which evaginate and finally become separated from the structure of origin. The separated cellular masses undergo further histologic differentiation to attain the adult structures.

The corpuscles in C. laha, in contrast to some other teleosts, develop only from mesonephric tubules. A possible explanation for the different types of distribution of Stannius corpuscles in teleosts is suggested, and the possible homology of these structures with part of the adrenal cortex or higher vertebrates is discussed.
Epidermal morphology and sloughing frequency in normal and prolactin treated Anolis carolinensis (Iguanidae, lacertilia)
Authors: Maderson P. F. A. , Licht P.
Published: February 2005

The morphology of the epidermal generations throughout the sloughing cycle of Anolis carolinensis is essentially the same as that described for other squamates, whether studied in control or hormone‐injected animals. Readily identifiable granules in the clear layer of this and other lizard species emphasize the eventual hardening of this layer prior to its separation from the subjacent Oberhautchen, which brings about sloughing. Eosinophils are described for the first time in the lacunar tissue of lizard, but their functional role remains problematical. Daily 25 μg injections of prolactin (alone or in combination with gonadotropins) raise the frequency of sloughing by shortening the resting phase as compared with controls and animals receiving 1.0 I.U./day injections of gonadotropins. The duration of the proliferation‐renewal phase and the pattern of histological changes occurring therein is unchanged by experimental treatments. The results show that neither endogenous nor exogenous gonadotropins affect the sloughing frequency, but exogenous prolactin produces a similar effect to that described for thyroxine. Although the mechanisms of action are unknown, the results provide another example of the cutaneous action of prolactin in vertebrates.
Studies on the rabbit appendix. I. Lymphocyte‐epithelial relations and the transport of bacteria from lumen to lymphoid nodule
Authors: Shimizu Yoshifusa , Andrew Warren
Published: February 2005

A correlated light and electron microscope study was made of lymphocyte‐epithelial relations in the appendix of normal rabbits, ranging in age from one week to ten months. The lymphocyte migration into the epithelium was very slight at one week. The lymphocytes were increased considerably in number from two weeks to three months, grouping into unique nests in the epithelium. The basement membrane began to be penetrated by migrating cells at one week and bacame discontinuous in older animals. At one and two weeks, the epithelial cells contained glycogen, which disappeared at three weeks. Degenerating cells as well as bacilli were found in the epithelial cells and in the macrophages of the nodules. The varied appearance of bacilli in the macrophages indicates that they were being digested. The lymphocytes in the epithelium were larger, having less crowded cytoplasm as compared with those in the lymph nodules. Many lymphocytes were in deep folds of epithelial cells. There was evidence favoring an intracellular position for some lymphocytes in the epithelium.
Cyclic changes in the ovary of the brook stickleback Eucalia inconstans (kirtland)
Authors: Braekevelt C. R. , McMillan D. B.
Published: February 2005

The ovarian cycle of the brook or 5‐spined stickleback was studied histologically. Specimens were trapped between July, 1965 and August, 1966 in a shallow pond near London, Ontario.

Spawning took place from mid‐April to mid‐July, when the water averaged 10°C. In early August, When the water averaged 20–22°C for prolonged periods, spawning ceased and the ovaries contained only oögonia, atretic mature oöcytes and empty follicles. Oögonia and immature oöcytes were found throughout the year but only in the spring did the mature stages begin to appear.

Oöcytes for each year's spawning appear to arise mitotically from a residual stock of lightly basophilic oögonia. As the oöcytes mature, their basophilia increases and they acquire a vitelline membrane and follicular layer. The deeply basophilic cytoplasm of the early oöcyte becomes frothy, as oily droplets of primary yolk are laid down. Finally, it becomes filled with eosinophilic secondary yolk in the mature egg.

Two types of atresia of developing eggs are common, especially during and after the spawning period. The first involves active phagocytosis of yolky material and hypertrophy of the follicular layer, leading to the formation of what could be called a “corpus luteum.” In the second type of atresia, neither phagocytosis nor hypertrophy was seen and nothing resembling a corpus luteum was formed.
The structure of developing muscle insertions in insects
Authors: Lai‐Fook Joan
Published: February 2005

The relationship between muscles and the components of the integument in muscle insertions have been studied with the electron microscope in two insects, Calpodes ethlius (Hesperiidae, Lepidoptera) and Rhodnius prolixus (Reduviidae, Hemiptera). The area of contact between the muscles and the epidermis is increased by interdigitating processes whose membranes are joined by intermediate junctions. The junctions occur at the level of a Z line so that actin filaments attach directly to them. Within the epidermis, microtubules extend from the junctions of the myoepidermal connection to the cuticle, where they attach to hemidesmosomes which line deep indentations of the membrane. The microtubules probably enable the tendinous epidermal cells to withstand the tensions exerted upon them by the muscles. The epidermis is anchored to the cuticle by tonofibrillae, homogeneous rods secreted in the deep indentations of the plasma membrane. Since the tonofibrillae of successive instars are continous, they penetrate and attach to the cuticulin, the outermost layer of the epicuticle.