bluuebunny/crossref_metadata_2025 huggingface dataset:
Post embryonic development of the central nervous system of the spiderArgiope aurantia(Lucas)
Authors: Babu K. Sasira
Published: February 2005

Volumetric and histological changes of the central nervous system were studied during post embryonic development of a spider,Argiope aurantia.

The neural mass ofArgiopegrows allometrically with respect to volume of the cephalothorax and body weight. In the first instar 46% of the cephalothoracic volume constitutes the neural mass and this is reduced to 4% in the female (9th stage) and 12% in the male (7th stage) spider.

Growth curves for the cephalic ganglion, measured at all stages, represent a straight line. The neural mass of females is two and a half times larger than that of the males. The ganglion increased 24 fold in female and 10 fold in male spiders. Addition of neural mass occurs in all stages.

The brain volume is greater than that of the subesophageal ganglion in the first two instars. In subsequent stadia, the subesophageal ganglion grows faster, and in females it is finally three times and in males two times larger than the brain.

Growth of cortex and neuropile depict exponential curves. Comparison of growth patterns of these shows an inverse relationship during development. While the volume of the cortex is higher in the first two or three stages, the volume of the neuropile is higher in the remaining stadia. The causes for this growth pattern are discussed.

Counts of cell numbers show that there is a constant population of neurons throughout the post‐embryonic development. The number of nerve cells in females is higher than in males, 11% in the subesophageal ganglion and 58% in the brain.

The growth of the cortex is partly accomplished by an increase in cell volume. In male and female spiders the increase in Type‐B cells is 20 and 50 fold, while that of large motor neurons is 200 and 600 fold respectively. The motor neurons of 20 μ and above number 63 in male and 916 in female adult spiders.

The growth of neuropile occurs through an increase of dendritic arborization and axonal branching. The largest axons measure 1 μ in the first and 16 μ in adult stages. An increase of incoming sensory fibers is also noticed during development.

Invasion of neural lamella into cortex and neuropile increases during development. Neural lamella which are 1‐2 μ in the first stage grow to 40–100 μ thickness in adult female spiders, near the origin of the main nerves. One type of astral cells, counted in neuropile, increases 10 fold.

The appearance of a central body and the beginning of web construction coincide during the second instar. The relationship between these two is discussed.
Cytological differentiation in the uropygial gland
Authors: Wagner Roger C. , Boord Robert L.
Published: February 2005

Ultrastructural changes were studied in the cells undergoing secretory differentiation in zone I of the tubules of the uropygial gland of White Plymouth Rock chickens. A layer of basal cells and four secretory stages are recognized as the cells migrate from the periphery to the lumen of tubules and progressively elaborate a secretion product.

Basal cells, containing rough endoplasmic reticulum and free ribosomes, rest on the basement membrane and are the source from which secretory cells arise. Dilated perinuclear cisternae and the proliferation of smooth endoplasmic reticulum in the form of vesicles, invaginated sacs and cusp‐shaped cisternae indicate the onset of lipogenesis in stage I cells. The perinuclear cisternae are more dilated and the endoplasmic reticulum is composed of saccules and cisternae in stage II cells. Stage III cells are characterized by concentric lamellae of endoplasmic reticulum surrounding secretory droplets. Dilated cisternae of endoplasmic reticulum and secretory droplets both contain a reticular substance. The perinuclear cisternae of stage III cells have returned to normal dimensions. Large mature lucent secretory droplets, lined with electron‐dense material, fill the cytoplasm of stage IV cells which degenerate and release their secretory product into the tubule lumen.

Spherical membrane‐bound compartments containing a mottled substance of moderate electron density occur in basal cells and all subsequent secretory stages. These mottled bodies are surrounded by saccules of endoplasmic reticulum in stage II cells and are intimately associated with secretory droplets in stage III cells, but there is no evidence that they give rise to secretory droplets and their role in secretory differentiation is unknown.
The fine structure of the lateral ocellus of the dobsonfly larva
Authors: Yamamoto Koji , Toh Yoshihiro
Published: February 2005

The lateral ocelli of the dobsonfly (Protohermes grandis, Neuroptera) larva have been examined with light and electron microscopy. The larva has six ocelli on both sides of the head, each containing a single corneal lens. A conical crystalline body, of some 10–20 cells is situated immediately posterior to the lens. From 100 to 300 elongated retinular cells are arranged perpendicular to the crystalline body except at the innermost surface of the lens, where they are absent. The distal process of each retinular cell is enclosed by a tube‐like rhabdom formed by the close association of microvilli from the same and adjacent distal processes. The distal process contains many mitochondria, multivesicular bodies, microtubles and pigment granules. In the dark‐adapted ocellus the pigment granules are concentrated near the nucleus which lies under the rhabdomic layer. The granules diffuse toward the rhabdomic microvilli during light adaptation.

Each retinular cell has a single axon, which extends from the ocellus as an ocellar nerve fiber into the optic lobe, where it frequently synapses upon second order neurons. In addition to these afferent synapses, there are two other synaptic combinations: (1) a feedback synapse from a second order neuron to a retinular axon, and (2) a synapse between second order neurons. These results suggest that photic signals reach the more proximal part of the brain via second order neurons after some degree of integration in the optic lobe.
The epithelium of the gastro‐intestinal tract of Polypterus senegalus (Pisces:Brachiopterygii)
Authors: Magid A. M. Abdel
Published: February 2005

Light and electron microscopic studies revealed ciliation of the epithelium of the entire gastro‐intestinal tract of Polypterus. Acidophil cells were found in the different regions of the alimentary canal, including its derivatives (the lungs and hepato‐pancreatic ducts). Compared to other primitive forms and modern teleosts, the extreme fusion of the intestinal caeca in Polypterus, the ciliation and the overall dispersion of acidophil cells may represent a special organization inherited from a palaeoniscoid ancestor. Attention is also drawn to a possible channel of early evolution and function of the stomach diverticulum.
Functional anatomy of the heart of the harbor porpoise, Phocaena phocaena
Authors: Rowlatt Ursula , Gaskin David E.
Published: February 2005

Thirty‐six harbor porpoises, Phocaena phocaena, were caught off the coast of Southern New Brunswick and Nova Scotia as part of a study of the biology and ecology of these animals. The formalin‐preserved heart was examined first in situ, then measured and studied in detail. If the weight of the thick layer of blubber is discounted, the heart is heavy relative to the total body weight as may be expected in an animal capable of fast swimming, great agility and frequent emergence from the water to breathe. The shape of the heart, the relative size of atria and atrial appendages, the morphology of the ventricular septum, the thickness of the walls of the sinus and conus of the right ventricle and the anatomy of the pulmonary veins were found to be constant for this animal and unlike that of non‐cetaceans. It is suggested that the absence of respiratory movements during diving may lead to these modifications of cardiac structure in an animal that is particularly well adapted to a totally aquatic existence.
Sex steroids and epidermal glands in two species of gekkonine lizards
Authors: Chiu K. W. , Maderson P. F. A. , Alexander S. A. , Wong K. L.
Published: February 2005

In vivo and in vitro experiments on the endocrine relationships of epidermal glands in the tokay Gekko gecko, and the common house gecko Hemidactylus bowringii are reported. The results show that certain aspects of ß‐gland differentiation involve a synergistic action between androgens and those hormones responsible for controlling the normal shedding cycle, while other aspects are solely under androgenic control. Pre‐anal organ activity appears to be solely under androgenic control.
Morphology of lymphoid organs in a cichlid teleost, Tilapia mossambica (Peters)
Authors: Sailendri K. , Muthukkaruppan Vr.
Published: February 2005

In Tilapia mossambica organized lymphoid tissues are present in the thymus, head‐kidney and spleen, whereas they are lacking in pericardial tissue, liver, mesonephros, intestine and rectum. No lymphoid tissue was observed in the chondrocranium and cartilaginous viscerocranium of young adults.

The thymus in Tilapia is encapsulated by thin strands of collagen fibers and consists of outer, middle and inner zones. While middle and inner zones are comparable to the thymic cortex and medulla of higher vertebrates, the homology of the outer zone is not clear. At the anterior end of the thymus, a loose aggregation of lymphocytes without a definite boundary has been observed.

The head‐kidney is characterized by the presence of lymphoid follicles, a subcapsular sinus, a hilus‐like area and lymphatic vessels. The spleen is grossly divisible into white pulp and red pulp; the white pulp contains only a reticular area without definite lymphoid centers and the latter contains predominantly erythrocytes. Morphological changes in the lymphoid organs associated with immune response have been discussed.
Structure and function of the head in flabelligerid polychaetes
Authors: Spies Robert B.
Published: February 2005

The functional anatomy of the head of Flabelliderma commensalis is described and compared to other flabelligerid polychaetes. Prostomial parts include the dorsal lip, the palps, two pairs of nuchal organs, four eyes and the prostomial lobe and ridge. The eyes are inverse pigment cup types with the medial portions of the sensory cells expanded to form a clear lens‐like body. Peristomial parts include the median and ventral lips, the branchial membrane and the branchiae. The derivation of the nephridiopore is unknown. The spiraled branchiae of Coppingeria and the gill books of Diplocirrus are newly described variations in branchial structure. The head is retractable in some species and the anterior setigers are modified to form a protective setal cage. Two methods are employed for feeding: one for host fecal pellets and the other for detrital materials. Chemoreception, respiration, feeding and cleaning rely on a complex pattern of ciliary currents.
Chelonian mental glands
Authors: Winokur Robert M. , Legler John M.
Published: February 2005

A survey of 69 of the 74 currently recognized chelonian genera revealed that 21 genera in three families (Emydidae, Platysternidae and Testudinidae) possess paired integumentary glands or gland vestiges in the anterior throat skin. These glands are here termed mental glands; they are holocrine and may be classified morphologically as follows: Class I mental glands are large, complex, multilobed, have specialized ducts, and are found only in the genus Gopherus: Class II mental glands are small, simple sacklike invaginations containing secretory cells or keratinizing cells. The structure of Class II glands varies from distinctive and saccular to shallow keratinized invaginations having no glandular tissue; they are found only in the families Platysternidae and Emydidae.

Mental glands occur in 17 of the 22 genera in the subfamily Batagurinae (sensu McDowell, 64); only 2 of 9 genera in the subfamily Emydinae have these glands. The taxonomic occurrence of mental glands suggests that they are primitive structures. The loss of mental glands in most emydines is interpreted as a subfamilial trend toward integumentary simplification.
Techniques for estimating allometric equations
Authors: Manaster B. J. , Manaster S.
Published: February 2005

Morphologists have long been aware that differential size relationships of variables can be of great value when studying shape. Allometric patterns have been the basis of many interpretations of adaptations, biomechanisms, and taxonomies. It is of importance that the parameters of the allometric equation be as accurate estimates as possible since they are so commonly used in such interpretations.

Since the error term may come into the allometric relation either exponentially or additively, there are at least two methods of estimating the parameters of the allometric equation. That most commonly used assumes exponentiality of the error term, and operates by forming a linear function by a logarithmic transformation and then solving by the method of ordinary least squares. On the other hand, if the error term comes into the equation in an additive way, a nonlinear method may be used, searching the parameter space for those parameters which minimize the sum of squared residuals. Study of data on body weight and metabolism in birds explores the issues involved in discriminating between the two models by working through a specific example and shows that these two methods of estimation can yield highly different results. Not only minimizing the sum of squared residuals, but also the distribution and randomness of the residuals must be considered in determining which model more precisely estimates the parameters.

In general there is no a priori way to tell which model will be best. Given the importance often attached to the parameter estimates, it may be well worth considerable effort to find which method of solution is appropriate for a given set of data.
A gross and microscopic study of the respiratory anatomy of the antarctic weddell seal, Leptonychotes weddelli
Authors: Boyd Robert B.
Published: February 2005

Four species of Phocidae, or true seals, inhabit the waters surrounding the Antarctic continent. These animals are thought to have different diving capabilities. The Weddell seal, Leptonychotes weddelli, is known to be capable of attaining depths up to 600 meters.

The respiratory system of the Weddell seal shows the usual adaptations to an aquatic environment characteristic of other marine mammals. These include lungs that undergo compression collapse at depths greater than 70 meters; hyaline cartilage in the tracheo‐bronchial tree as far as the terminal bronchioles; and large amounts of smooth muscle surrounding the distal‐most bronchioles. The collapsible lungs provide a mechanism by which air is forced from the alveoli adjacent to the pulmonary capillary beds thereby preventing the absorption of nitrogen gas into the bloodstream. The presence of hyaline cartilage throughout most of the tracheo‐bronchial tree increases the effective dead air space that accommodates most of the air forced from the collapsed lungs. The smooth muscle surrounding the respiratory bronchioles prevents their collapse while under the pressures of a deep dive. Collapse of the respiratory bronchioles not supported by cartilage would trap air in the lung alveoli during a dive.

In addition, large‐sac‐like “diverticulae” are found in the submucosa throughout the tracheo‐bronchial tree. These diverticulae, which open directly into the lumen of the tree, appear to be modified glands whose cells, in most cases, do not appear to be specialized for secretory function. They are most numerous in the more distal bronchi and terminal bronchioles where they are situated on both the luminal and adventitial sides of the hyaline cartilage supporting the walls of the air passages. Diverticulae are not found in the respiratory bronchioles or in the respiratory portion of the lungs.
Electron microscope studies of spermatogenesis in Branchiobdella pentodonta whitman (Annelida, oligochaeta)
Authors: Bondi Carlo , Farnesi Wsalba Maria
Published: February 2005

In Brallchiobdella pentodonta Whitman meiosis begins in follicles containing 16 spermatogonia. In each follicle the spermatogonia are connected by cytoplasmic bridges to a central anuclear cytoplasmic mass or cytophorus. They develop synchronously. Synaptonemal complexes are present in the primary spermatocytes. Spermatids contain a large globoid paranuclear body consisting of an acrosomal granule and coiled tubules which evidently receive the contents of the acrosomal granule and are considered the acrosome carrier. The spermatids separate from the cytophorus only when differentiation is completed.

The ripe spermatozoon is relatively long. It has anteriorly the coiled tubules, followed by the nucleus, the mitochondrial sphere and the distal centriole from which the flagellum originates, A coiled ribbon‐like structure encloses the flagellum along its entire length while a manchette of microtubules surrounds all the other structures of the sperm.
The pectoral anatomy of selected ostariophysi I. The characiniformes
Authors: Brousseau (A.K.A. Prem Singh Khalsa) Raymond Allan
Published: February 2005

The muscles and bones of the pectoral fin of Serrasalmus nattereri, the piranha, resemble those of generalized, lower teleosts with specializations related to a body shape adapted for high‐speed carnivory; the pectoral fins being highly mobile with strong ligaments to the rays. The presence of two occipital nerves appears primitive, while the emergence of the subclavian artery within the branchial cavity, as in Gasteropelecus sternicla, appears specialized. The muscles and bones of the latter fish, a fresh‐water flying fish, are specialized for self‐propelled, aerial flight in the fusion of the right and left girdles greatly expanded for insertions of complex appendicular (flight) muscles, and in the consolidation of the rays and radials into one functional unit moving vertically in flight though contraction of vertical, massive ventral flight muscles. The bony pectoral anatomy of Electrophorus electricus, the electric eel, is specialized in having a mobile joint between the primary girdle and the cleithrum, the former being suspended vertically from the cleithrum by ligaments. The proximal radials and rays are very numerous and vertically aligned. The cleithrum is shaped to accommodate the extensive sternohyoid and pharyngocleithral muscles. The sheet‐like appendicular muscles extend beyond the special joint and control its movement. The deeper muscles do not cross this joint. The arterial system is specialized in lacking a deep brachial artery.
Ultrastructure of the cement gland of Xenopus laevis
Authors: Picard J. J.
Published: February 2005

To establish a morphological baseline for experimental studies of differentiation using the cement gland as a model, the following observations are added to those on record. The elongated cells of Xenopus laevis cement glands have an internal organization displaying five distinct zones differing in structure and specialized function. The apical zone contains packed secretion vesicles apparently belonging to two different types. The transit zone appears to be devoid of major biosynthetic activity and contains secretion vesicles migrating toward the surface. The zone of biosynthesis is typically organized in concentric regions. The very elongated nucleus lies in the next zone. Finally, the storage zone is characterized by lipid droplets and yolk platelets.

Only quantitative differences are observed between cells of young and mature cement glands. Though all cells have the same general organization they may probably be divided into two subtypes according to the structure of their cytoplasm. The epithelial cells surrounding the gland differ according to their position along lateral or basal borders.
The fine structure of the sperm of a holothurian and an ophiuroid
Authors: Fontaine A. R. , Lambert Philip
Published: February 2005

The fine structure of the mature sperm of the holothurian, Cucumaria miniata, and the ophiuroid, Ophiopholis aculeata, is described with particular reference to their acrosomal and centriolar satellite complexes, and compared to the sperm of other echinoderms.

In Cucumaria, the acrosome is in the form of a diffuse acrosomal vesicle. It is unusual in that it apparently lacks an acrosomal membrane. A membrane separating the acrosomal vesicle from the periacrosomal material may not be equivalent to a typical inner acrosomal membrane. In Ophiopholis, the acrosome is dense, with some internal substructure, and is enclosed by a complete acrosomal membrane. In both species, the acrosome is partially surrounded by an amorphous periacrosomal mass. There is a notable absence of a subacrosomal depression and associated structures as found in other echinoderm sperm.

The centriolar satellite complex (CSC) is essentially identical in both species. A reconstruction of the CSC is presented. The CSC consists of nine satellites radiating angularly from the distal centriole, each bifurcating at a dense node before inserting on a marginal ring containing circumferential microtubules. The ring is probably a cytoskeletal element. Immediately below the satellites are nine Y‐shaped connectives. connecting each of the axonemal alpha doublets to the flagellar membrane.
The functional anatomy of the hindlimb of some african viverridae (Carnivora)
Authors: Taylor M. E.
Published: February 2005

The functional anatomy of the hindlimb of 12 species of viverrids was studied with relation to locomotion. The animals were allocated to primary locomotor categories on the basis of their anatomy and locomotion.

The climbing, arboreal walking category (Nandinia binotata) is characterized by a small sacroiliac articulation, the iliopsoas inserts onto a medially located lesser trochanter and the femoral condyles are not posteriorly placed. The hindfoot is plantigrade and its structure permits considerable movement. The pads are soft and the claws retractile.

Representatives of the arboreal and terrestrial walking and jumping category (Genetta genetta, G. servalina, G. tigrina) have a plantigrade forefoot and digitigrade hindfoot. The lesser trochanter is more posteriorly placed than in the climbing category. A previously undescribed muscle, the caudofemoralis profundus extends from several anterior caudal vertebrae to the femur. The tibio‐astragular joint restricts supination of the foot. There is little mediolateral movement in the digitigrade foot. The claws are retractile.

In the general terrestrial walking and scrambling group (Helogale parvula, Mungos mungo, Atilax paludinosus, Bdeogale crassicauda, Herpestes ichneumon, H. sanguineus) the animals have essentially similar hindlimbs except for size differences and modifications to the feet. Helogale and Mungos have large medial epicondyles on the humerus and large terminal phalanges. Bdeogale has a vestigial first metatarsal, while Atilax can splay its digits. In all species the distal phalanges are non retractile.

The trotting category (Civettictis civetta. Ichneumia albicauda) is characterized by longer epipodials and metapodials and a more proximal position of muscle bellies. Most of the adaptations minimize rotation, adduction and abduction of the leg and supination of the foot. The metatarsals are closely adjoined and the distal phalanx is stout and non ‐retractile.

There appear to be two levels of locomotory adaptation. Major adaptations affect the whole appendicular skeleton and are used to assign animals to primary locomotor categories. Minor adaptations occur mainly in the foot and indicate the more specific habits of the animal.
Tongue evolution in the lungless salamanders, family plethodontidae I. Introduction, theory and a general model of dynamics
Authors: Lombard R. Eric , Wake David B.
Published: February 2005

Plethodontid salamanders capture prey by projecting the tongue from the mouth. An analysis of theoretical mechanics of the hyobranchial skeleton is used to formulate a working hypothesis of tongue movements. Predictions that the skeletal elements of the tongue are included in the projectile and that the hyobranchial skeleton is folded during projection are central to the analysis, When decapitated in a particular way, salamanders project the tongue, and it is not retracted. When these heads are fixed and sectioned, examination confirms the predictions, In turn, these observations are used to refine the working hypothesis and to generate a general model of tongue dynamics for plethodontids. Muscles performing the major roles of projection (subarcualis rectus I) and retraction (rectus cervicis profundus) are identified. The skeleton is folded passively along a morphological track having the form of a tractrix, Predictions concerning the shape of the track and the exact configuration of the folded skeleton are confirmed by study of sectioned material. The skeleton unfolds along the track during retraction and is spread into the resting state, The model developed herein will be used as a basis for predictions concerning selection patterns in the family and for analytical purposes in comparative and evolutionary studies.
Studies on the formation of germ cells in a compound ascidian Botryllus, primigenus oka
Authors: Mukai Hideo , Watanabe Hiroshi
Published: February 2005

Gametogenesis of a compound ascidian Botryllus primigenus was studied histologically. On either side of the zooid (stage 9), in the gonadal space between the epidermis and the atrial epithelium, either a single testis or a complex of an egg follicle and a testis can be formed. The egg follicle consists of a single ovum (occasionally two ova) and its accessory cells and is connected with the atrial epithelium by the follicle stalk. The egg follicle is always accompanied by the brood pouch, a diverticulum of the atrial cavity. The testis is equipped with a vestigial spermiduct and is attached to the atrial epithelium.

Buds of stage 8 comprise, besides the developing testes and, egg follicles, loose aggregations of hemoblasts and oocytes of early developmental stages, which are already accompanied by primary follicular cells. Both the oocytes and the primary follicular cells seem to arise from the hemoblasts. The young oocytes are isolated in the gonadal space of the buds nnd are transferred to buds of the succeeding generations until they finally mature.

In the bud of stage 3, a compact mass of cells appears, attaching to tbe inner vesicle on either side of the body. It is derived from the hemoblasts lodged there in the preceding generation and presumably also from the circulating hemoblasts. When the cell mass receives a large oocyte derived from the preceding generation, part of the cell mass differentiates into egg envelopes, forming an egg follicle, and a follicle stalk and the remainder into a testis. When the cell mass receives no oocyte, it differentiate as a whole into a testis. In the egg follicle thus formed the outer and inner follicular cells increase in number by mitotic division. Subsequently, initial test cells are derived from the inner follicle by migration across the developing chorion; then they increas2 in number by mitosis. In the testis, meiosis and spermiogenesis take place.
The structure of the ovarian ball and oogenesis in Moniliformis dubius (Acanthocephala)
Authors: Tkinson Kristne H. A. , Byram J. E.
Published: February 2005

Seven to nine days after infection of the definitive host (rat) by cystacanths, the genital primordium of the female acanthocephalan is transformed from a fragmented mass of cells into discrete ovarian balls. This is accomplished by envelopment of free germinal cells by somatic tissue which originates from the ligament sac primordium. Germinal cell nuclei then undergo repeated mitoses until about 21 days of development, with concurrent formation of oogonial syncytia which occupy the interior of the ovarian balls. Oocytes, derived from these oogonia, move to the periphery of the germinal syncytia for differentiation, growth, fertilization, shell formation, and release from the ovarian ball. After oogonial proliferation ceases, continued growth of the ovarian ball apparently results from increase in size of already present cells.

Free‐floating mature ovarian balls are found in the dorsal ligament sac; each consists of germ cells in various developmental stages, enveloped and pervaded by a multinucleate matrix syncytium of somatic origin, which functions as a follicle. Spermatozoa pass through the matrix cell for the internal fertilization of mature oocytes. Myelinated structures of an undetermined nature were found to correspond to previously reported polar bodies. After 100 days post‐infection, the somatic matrix syncytium begins to manifest the degenerative effects of aging. The germinal tissue exhibits no subcellular signs of senescence by 154 days, but decreases in amount in older worms.
Secretion of embryonic envelopes and embryonic molting cycles in Hemioniscus balani Buchholz, Isopoda Epicaridea
Authors: Goudeau Marie
Published: February 2005

The fertilized egg of Hemioniscus balani, a viviparous isopod, is encased in two envelopes, I and II, the structure of which is described.

In the course of its development, the embryo secretes five successive sacs called embryonic envelopes. Both their structure and the means of secretion by the embryo are analyzed through thin sections. The presence of these successive secretion cycles together with exuviations involving these embryonic envelopes lead us to believe that during embryonic development in Hemioniscus balani, embryonic molting cycles exist.

The appearance and shedding of the envelopes of the fertilized egg and embryo allow determination of ten embryonic stages which are briefly described.
Collagen deposition on a preformed grid
Authors: Humphreys Susie , Porter K. R.
Published: February 2005

Appearance of collagen fibrils in the cuticle was seen by electron microscopy to be preceded by fonnation of a finely filamentous matrix material. At first, the fine filaments of the matrix are unorganized. However, signs of orthogonal ordering soon appear in the most superficial portion of the cuticle, and subsequently appear more basally and closer to the underlying epidermis. Meanwhile, fibrils of different staining properties and identifiable as collagen begin to be deposited in the superficial portion of the cuticle, the same region which first showed organized fine filaments. Then, like the fine filaments before them, the collagen fibrils polymerize more basally. Collagen appears to polymerize on the preformed skeleton of fine filaments as though the fine filaments caused the collagen to assemble. Neither the polymerization nor ordering of collagen fibrils seems to require direct cellular intervention but occur first in that portion of the cuticle which is furthest away from the underlying epidermis. The fine filaments may be self ordering, extracellular macromolecules which in turn determine the polymerization of collagen fibrils.
Morphology of the gills of larval and parasitic adult sea lamprey, Petromyzon marinus L.
Authors: Youson John H. , Freeman Peter A.
Published: February 2005

The general morphology of the gills is similar in larval (ammocoetes) and parasitic adult sea lampreys, Petromyzon marinus, despite different methods of ventilation necessitated by their feeding habits.

The gill lamellae are supported by randomly‐distributed pillar cells which enclose blood spaces and collagen columns. The distribution of these cells in lampreys is different from that of higher fishes and it may be inefficient for respiratory exchange. The presence of cytoplasmic microfilaments suggests that these cells have the ability to reduce the lamellar blood spaces through contraction. Marginal channels at the tips of the lamellae are lined only by endothelial cells.

The thickness of the water‐blood pathway in lampreys falls within the range described for higher fishes, with the most efficient gas exchange likely occurring at the lamellar tips where only a single layer of epithelial cells is present. The abrupt increase in height of the epithelium near the lamellar bases in adults, compared to the gradual transition in height along the lamellae in ammocoetes, is perhaps reflective of higher oxygen requirements during the parasitic stage. The consistent appearance of wide, lateral intercellular spaces within the respiratory epithelium of lampreys indicates possible involvement of these spaces in transport.

Mucous secretion appears to be an important function of the superficial platelet cells in ammocoetes. “Mitochondria‐rich” and “mitochondria‐poor” superficial cells are observed in both ammocoetes and adults, with the mitochondria‐rich cells more prevalent toward the lamellar bases. The possibility that at least some of these cells may be involved in absorption is discussed. Mitochondria‐rich cells in the interlamellar region are morphologically different in ammocoetes and adults but all possess an abundance of smooth endoplasmic reticulum and hence resemble “chloride cells” of higher fishes. The similarity of these cells in the parasitic adult lamprey to chloride cells of marine fishes may reflect the potential of the adult lamprey to osmoregulate in salt water. A scarcity of these cells in ammocoetes and their resemblance to chloride cells in freshwater fishes may reflect the restriction of larval lampreys to a freshwater habitat.
The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta. I. Sexual dimorphism in the distribution of antennal sense organs in five species
Authors: Schafer Rollie , Sanchez Thomas V.
Published: February 2005

Sexual dimorphism in the distribution of antennal sense organs is common among adults of the genus Periplaneta. In three out of the four strains of Periplaneta americana examined, adult males had more contact chemoreceptors than females. In the fourth strain of P. americana and in P. australasiae, P. brunnea, P. fuliginosa, and P. japonica, no statistically supportable sexual dimorphism of contact chemoreceptors was found. However, in all strains and species of Periplaneta examined, sexual dimorphism was found in the total number and/or density of olfactory sensilla. Male adults had nearly twice as many olfactory sensilla as female adults. These observations are consistent with the behavioral observation that males within the genus Periplaneta rely on the reception of an airborne pheromone for the initiation of courtship behavior. In P. americana, where sexual dimorphism was found in the contact chemoreceptors, contact stimuli release the full wing raising display and presentation in males during courtship.
The cranial arteries of turtles and their evolutionary significance
Authors: Albrecht Philip W.
Published: February 2005

In this paper the cranial arteries, cranial arterial foramina, and bony canals of the Cheloniidae, Chelydridae, Pelomedusidae, and Chelidae are described in detail. From skull studies and published material, the general cranial arterial patterns of all the turtle families can be inferred. Sea turtles, the Cheloniidae and Dermochelyidae, possess both a large stapedial artery and a large artery supplying the orbit, which is possibly similar to the primitive cranial arterial pattern for turtles. From a primitive pattern in which stapedial and palatine arteries supply the orbit, the Chelydridae and Testudinidae retained a large stapedial artery and reduced the palatine artery, while the Kinosternidae and Dermatemydidae developed a large palatine artery and reduced the stapedial artery. The Trionychidae and probably the Carettochelyidae evolved a complex arterial pattern in which the stapedial artery was reduced somewhat and the pseudopalatine artery was substituted for the palatine artery. Pleurodires in general retained a large stapedial artery and reduced or eliminated the palatine artery. The Podocneminae, including the Madagascar species, developed a highly modified carotid canal, which is found in no other turtle group. The facts which have been presented should aid in fossil skull studies and in understanding the evolutionary background of recent turtles.
The structure and formation of the byssus attachment plaque in Mytilus
Authors: Tamarin Arnold , Lewis Pathicia , Askey Joan
Published: February 2005

The byssus attachment plaque and the tissues responsible for its formation were studied in M. califomianus by light microscopy and by transmission and scanning electron microscopy. It was shown that the plaque consists of at least three phases which ultrastructurally resemble three secretions considered to be collagen, mucoid material and polyphenol. The mucoid and polyphenol appear to mix as a colloidal suspension in which the latter is the continuous phase and forms the definitive bonding surface. Plaque collagen represents an extension of thread material into the cementing substance.

Stimulated secretion within the ducts and distal depression of the mussel's foot shows a continuum of increasing heterogeneity from the inner toward the outer regions. This reflects the distribution of exocrine cell apices wherein exocytosis of polyphenol granules predominate deeply, mucous granules superficially and collagen granules in between.

It is proposed that the morphology of the plaque conforms to theoretical physical‐chemical requirements for adhesion under water.
Anatomy and ultrastructure of the excretory system of the lizard, Sceloporus cyanogenys
Authors: Davis Lowell E. , Schmidt‐Nielsen Bodil , Stolte Hilmar , Bookman Llnda M.
Published: February 2005

The anatomy and ultrastructure of the lizard kidney (Sceloporus cyanogenys) have been studied by light and electron microscopy. The number of glomeruli was counted' in serial sections and estimated to be 2,000 (in the two kidneys). Beginning with the glomerulus and Bowman's capsule the nephron segments are sequentially: (a) proximal tubule; (b) intermediate ciliated segment consisting of a proximal and distal part; (c) distal tubule, which can be divided into two segments, followed by (d) connecting tubule and (e) initial collecting duct. The initial collecting ducts from several nephrons open into the collecting duct. Tubular epithelium in this lizard has similarities to that of other reptiles, The lateral borders do not overlap like in mammals, but interdigitate by fingerlike projections. The length of the nephron segments was measured in disected tubules and the diameter was measured on light and electron micrographs. From these measurements estimates of inner tubular surface area were made. Together with data from physiological studies (Stolte et al., '76; Schmidt‐Nielsen, '76) the estimated surface area was used to calculate transport rates per unit area across the epithelium. Comparisons of structure and transport rates were made between S. cyanogenys and other reptiles and mammals.
The ultrastructure of the hepatopancreatic caeca of Gammarus minus (crustacea, amphipoda)
Authors: Schultz Terry W.
Published: February 2005

The hepatopancreatic caeca of the freshwater amphipod Gummarus minus are four tapered blind pouches lined with a simple columnar epithelium bearing an apical surface of regular microvilli and resting on a basement membrane. This epithelium is enclosed by a tonic, striated muscularis. Each caecum consists of three regions. The distal zone is formed of embryonic cells having a high nuclear to cytoplasmic ratio and giving rise to the other cell types. The second or differentiation zone consists of regular tall columnar cells of two morphological types:(1) light staining R‐cells which have a large number of lipid droplets and few Golgi bodies; (2) basophilic F‐cells which have numerous distended Golgi bodies. The more proximal secretory zone forms the majority of each diverticulum. This mature zone is formed from R‐cells and large, basophilic, vacuolated B‐cells which differentiate from F‐cells. The secretory cell sequence appears to be E‐cell — F‐cell — B‐cell with secretion being apocrine in nature. The exact relationship of Rcells to the other cell types is questionable, but the R‐, F ‐ and B‐cells all appear to be able to absorb and store nutrients. Within the Malacostraca the hepatopancreatic epithelium of Amphipoda more closely approximates that of Decapoda than that of the Isopoda.
An ultrastructural investigation of the striated subumbrellar musculature of the anthomedusan, Pennaria tiarella
Authors: Keough Ellen M. , Summers Robert G.
Published: February 2005

The presence of striated subumbrellar musculature in hydromedusae can be related to the development in hydrozoans of a free‐swimming life stage. The detailed ultrastructure of the striated subumbrellar musculature of the anthomedusan, Pennaria tiarella is presented. The striated musculature of Pennaria resembles vertebrate striated muscle in filament arrangement (L2 lattice pattern) and M line structure. The striation pattern, out‐of‐register myofilaments, filament structure as determined by rotational symmetry, Z line structure, types of intercellular junctions, and sarcoplasmic reticulum are more similar to structures found in other invertebrate striated muscle.
A staging system for forelimb regeneration in the axolotl, Ambystoma mexicanum
Authors: Tank Patrick W. , Carlson Bruce M. , Connelly Thomas G.
Published: February 2005

A staging system has been devised for normal regeneration from the upper arm in the mature axolotl. It consists of seven externally definable stages: (1) Wound healing (WH); (2) Dedifferentiation (DD); (3) Early bud (EB); (4) Medium bud (MB); (5) Late bud (LB); (6) Palette (Pal), and (7) Digital outgrowth (DO). Serial histological sections of 38 regenerating limbs were used to correlate gross stages with microscopic events in the regenerative process.
Development of butterfly scales. II. Struts, lattices and surface tension
Authors: Ghiradella H. , Radigan W.
Published: February 2005

An investigation of the structure of the iridescent scales of the green hairstreak, Callophrys rubi, reveals an internal lattice which is probably cubic close‐packed in form. We present a model which explains the formation of the lattice in terms of packing of spheres and surface tension forces and generalize these results to internal structures in other Lepidopteran scales.
The cytology of the testaceous rhizopod Lesquereusia spiralis (Ehrenberg) Penard. I. Ultrastructure and shell formation
Authors: Harrison Frederick W. , Dunkelberger Dana , Watabe Norimitsu , Stump Alex B.
Published: February 2005

Ultrastructure and shell formation in the testaceous ameba, Lesquereusia spiralis, were investigated with both scanning and transmission electron microscopy and X‐ray microanalysis. The nucleus, surrounded by a fibrous lamina, contains multiple nucleoli. The cytoplasm, containing a well developed granular endoplasmic reticulum, also contains remnants of starch granules in stages of digestion. Spherical aggregates of ribosome‐like particles may be seen. Golgi complexes seem to produce both a nonordered fibrous material and an electron dense vesicle. Only the latter appears to bleb off from the Golgi complex. X‐ray microanalysis demonstration of silicon in Golgi vesicles and in some dense vesicles suggests that the fibrous component of the cisternae may take up and concentrate silica to form the electron‐dense component of the vesicles. Membrane‐bound siliceous crystals are often seen adjacent to the Golgi, suggesting either a Golgi origin or platelet formation in vesicles after release from the Golgi complex. Both electron‐dense bodies and siliceous platelets are released from the cell by a process similar to apocrine secretion and may be seen outside the cell in route to the shell during shell morphogenesis. Shell development involves fusion of electron‐dense bodies to form a matrix, positioning of siliceous platelets in this matrix parallel to the shell surface, and development of a system of matrix chambers. A particulate glycoconjugate is released to the shell surface upon rupture of the matrix chamber.
Functional morphology of the feeding system in the ruff — Gymnocephalus cernua (L. 1758) — (Teleostei, Percidae)
Authors: Elshoud‐Oldenhave Mariette J. W. , Osse Jan W. M.
Published: February 2005

The ruff, Gymnocephalus cernua, is a European freshwater fish that feeds by sucking up small invertebrates from the bottom of ponds and slow flowing rivers. The feeding movements have been studied by simultaneous electromyography of seventeen muscles of the head and cinematographic techniques.

A theoretical model of movements imposes the functional demands of suction upon an abstraction of the form of a teleost head. Three phases in the feeding act, a preparatory phase, a suction phase and a transport phase, could be correlated with the observed movements and EMGs. Differences between the predicted and the actual movement are discussed. Two different types of feeding occur. The direction, magnitude and duration of the suction forces during feeding are modified, according to the position of the prey. A mechanism preventing early mandibular depression allows sudden and strong suction. Retardation of the suspensorial abduction during the overall expansion of the buccal cavity is ascribed to kinetic interrelations with the hyoid arch. Protrusion of the upper jaws also permits an earlier closure of the mouth and directs the food‐containing waterflow posteriorly. When the fish is feeding on sinking prey, protrusion occurs later in the sequence of movements than when it is feeding from the bottom. As the protruded jaws produce a downwardly pointed mouth this retardation aims the suction force.
Effects of incubation temperatures on sexual differentiation in the turtle, Chelydra serpentina
Authors: Yntema C. L.
Published: February 2005

Eggs of the common snapping turtle, Chelydra serpentina, were incubated at constant temperatures ranging from 20°C to 30°C, At hatching, the oviducts were absent or incomplete in males; the testes were differentiated. In females at hatching, the oviduct was intact hut in some cases the gonad retained bisexual characteristics. Three months after hatching, the ovary was differentiated and contained follicles. Eggs incubated at 20°C and at 30°C developed into females in 100% of the cases. At 26°C, 99% of the individuals were males; at 24°C, 100% were males. More males than females developed at incubation temperatures of 22°C and 28°C.
The characterization of granular amoebocytes and their possible roles in the asexual reproduction of the polystyelid ascidian, Polyzoa vesiculiphora
Authors: Fujimoto Hirokazu , Watanabe Hiroshi
Published: February 2005

The blood cells in the bud and the zooid of the polystyelid ascidian, Polyzoa vesiculiphora, were examined by means of light and electron microscopy to identify the cells that have been named trophocytes. The large blood cells were abundant in the mesenchymal space of the bud, but not in that of the functional zooid. They contained glycogen particles, lipid droplets, large protein granules and autophagosomes in their cytoplasm and were identified as granular amoebocytes. The majority of these cells were specifically phagocytized by phagocytes during bud development and disappeared. These results indicate that the granular amoebocytes virtually represent trophocytes in Polyzoa and may participate in bud development via nutrient supply to the developing tissues.