ALBERT

Notes: In an attempt to determine the role in the immune responses of the typhlosole, a hematopoietic tissue along the ventral wall of the larval lamprey Lampetra reissneri, scanning and transmission electron microscopic observations were made on ammocoetes hyperimmunized with sheep red blood cells. Besides including the cells of the erythrocyte series, this tissue also contained the following leucocytes forming an amorphous parenchyma: the cells of the granulocyte series, the most predominant cell type, possessing a markedly lobed nucleus and membrane-bounded granules of various sizes; the macrophages possessing primary and secondary lysosomes and long lamellipodia on the cell surface; the lymphocytes of a large nucleocytoplasmic ratio with a number of long, spiky microvilli, constituting a major type of rosette-forming (antigen-binding) cells; and the plasma cells possessing highly extended cisternae of rough endoplasmic reticula that are characteristic of the higher vertebrates. The immunoperoxidase technique, which employs rabbit antibodies against lamprey immunoglobulin, proved that these plasma cells do contain immunoglobulin. These results strongly indicate that the typhlosole of the larval lamprey, besides functioning as a hematopoietic tissue, is actively involved in the antibody responses. It is also stressed that the plasma cell occurs in the most primitive vertebrates as an immunologically competent cell.

Notes: The regenerative capacity of limbs was investigated by amputation of limbs at the zeugopodium in postmetamorphic froglets and adults of various sizes in four species of Japanese frogs, all of which showed some regeneration at these ages. In Hyla arborea japonica and Rana brevipoda porosa most young froglets regenerated their limbs well; however, the rate of regeneration decreased with the age of amputation, and the limb became nonregenerative in adults. Limbs of adults in Rana rugosa and R. japonica, on the other hand, exhibited good regeneration. All of the regenerates in the four species were heteromorphic, consisting histologically of well-developed cartilaginous rods surronded by connective tissue and skin. Limited development of muscle was appartment in regenerates of the three ranid species. The relations between body size, innervation of limbs, and regenerative capacity are discussed.

Notes: The structure and mechanism involved in jaw movements are described for an inertial high-speed suction feeding fish, Chaetodon miliaris. Jaw biomechanics were studied by (1) manipulation of live and fresh-killed specimens, (2) electrical muscle stimulation of anesthetized live specimens, (3) connective tissue severance experiments of fresh-killed and live anesthetized specimens, and (4) cine photography of live unimpaired and surgically impaired specimens.Three couplings appear to be involved in jaw opening: a levator operculi-opercular-interopercular-mandible coupling; and epaxial complex and/or hypaxial/sternohyoideus complex-hyoid apparatus-uncontracted protractor hyoideus-mandible coupling. Jaw opening, protrusion, closing of the protruded mouth, and jaw retraction occur in 60-110 msec. Jaw protrusion coincides with mandible depression during opening of the mouth. Closure of the protruded mouth is apparently the result of contractions of pars A1 and A2 of the adductor mandibulae muscle. Pars A3 and Aw may induce retraction of the jaws in the closed-protruded state. Jaw closure in the retracted, nonprotruded state may involve all branches of the adductor mandibulae.The importance of these findings is discussed in light of previous studies as are some proposed functions of jaw protrusion in this species.

Notes: We have studied the comparative anatomy of arterial plexuses (retia mirabilia) related to supply of the central nervous system in two closely related species of toothed whales - narwhal (Monodon monoceros) and beluga Delphinaterus leucas). In both species, retia originate from major vessels in the neck, thorax, and lumbar regions, then extend into the neural canal and cranium to supply the spinal cord and brain. The system generally consists of arteries embedded in á matrix of fatty connective tissue. Constituent vessels are only occasionally reated to veins or venous sinuses. Though retial anatomy is similar in the two species, there are two related features that appear species specific: (1) amount of retia originating from the supreme intercostal arteries and (2) thoracic retial size. Both are larger in the narwhal, as are values for hematocrit and hemoglobin concentration, which, in this study, we use as indices of diving ability. Our data are consistent with the hypothesis that the retia are in some way linked to diving ability. The nature of this link is not known; however, we discuss our results in the context of the most popular hyotheses of retial function.

Notes: The reduced bone resorption characteristic of osteopetrosis is accompanied in the incisors-absent (ia) rat mutation by a significant increase in osteoclasts of inactive (mutant) phenotype. Restoration of bone resorption in ia rats by transfer of spleen cells from normal littermates is preceded by a transformation of osteoclasts from mutant to normal phenotype.In this investigation the proportions of osteoclasts of normal phenotype have been determined by light microscopy in untreated ia and normal rats and in ia rats treated with various cell populations from normal rats. Significant increases in numbers of osteoclasts of normal phenotype were seen in the mutant skeleton soon after cell treatments that eventually restored bone resorption and cured the disease. No changes in osteoclast phenotype were seen after cell transfers that did not cure the disease.These data establish transformation of osteoclast phenotype as an early event in the recovery from osteopetrosis and suggest that determination of osteoclast phenotype is a reliable predictor of the success of normal cell populations to restore bone resorption in this mutation.

Notes: The gross morphology, histology, and ultrastructure of Liolaemus gravenhorsti gonads prior to and after differntiation are described. Special emphasis has been given to characterization and changes of the germ cell line throughout intrauterine development and 3 days postpartum.During the pregonadal stage, the primordial germ cell migrates toward gonadal rudiments by way of the mesenchyme. These cells can easily be identified by their great size, voluminous and lobulated nucleus, great quantities of yolk platelets, microtubules, and numerous lipid inclusions. In the undifferentiated gonad, the germ cells (type 1 gonocytes) have an ovoid or spherical shape and autodigestion of yolk platelets, great development of Golgi complex, and mitochondrial aggregation, though fewer liposomes, pseudopodes, and microtubules were noted. Concomitantly with the beginning of mitosis, a third type of germ cell appears, the type 2 gonocytes, which are smaller, with poorly defined membranous systems in various degrees of involution. The seminiferous cords are organized when somatic cells of the medullar portion of the gonad surround type 1 gonocytes. Germinal cells are centrally localized in the cords. Near birth many gonocytes migrate toward the basal lamina of cords and differentiate into spherical prespermatogonia, with few organoids. Sertoli cells eparate them from the basal lamina. In advanced pregnancy, Leyding cells become numerous with morphology typical of androgen-producing cells.

Notes: A forebrain atlas and stereotaxic neurosurgical techniques were developed for use in anatomical and behavioral experiments on the green anolis lizard (Anolis carolinensis). Green anoles are convenient and robust experimental subjects with a rich behavioral repertoire, the social components of which are partly under hormonal control.The technique and atlas were devised to conduct neuroethological investigations of the effect of lesions on species-typical display behavior. The atlas consists of 12 transverse sections from an average size adult male. The figures (4-15) are based on Nissl material and supplemented with fiber-stained material from adjacent sections. They appear at the end of the article. Limitations on the accuracy of stereotaxic coordinates are discussed and tables of correlative nomenclature for principal telencephalic and diencephalic nuclei are provided.

Notes: Dissection and a variety of absorption and fluorescent cytochemical methods have demonstrated that Antrodiaetus unicolor females have only one type of silk gland and spigot and, consequently, the simplest silk production system of any spider yet investigated histochemically. The small spherical to pear-shaped glands are grouped into four clusters, each cluster serving one of the four spinnerets. The spigots are long, slender, and slightly bent distally. Although all gland cells are structurally similar, each gland simultaneously produces two different secretory products, the secretion of the distal hemisphere being rich in basic protein and sulfhydryl groups, and the proximal hemisphere secretion being an acidic protein containing a high concentration of histochemically demonstrable C-terminal carboxyl groups. The two products remain segregated as they pass through the duct, where the acidic protein forms a thin outer layer around a core of basic protein. It is suggested that this segregation may persist in the silk strand after it exits from the spigot and that the outer acidic protein may be an adhesive agent.

Notes: The organization of the vestibulolateral lobe of the cerebellum is described in electroreceptive and closely related nonelectroreceptive teleost fishes. The vestibulolateral lobe includes an eminentia granularis and a lobus caudalis. The eminentia granularis is a lateral line-recipient, granule cell zone which in weakly electric fish (i.e., electroreceptive fish with an electric organ) has anterior and posterior divisions associated respectively with a mechanoreceptive medial medullary nucles and an electroreceptive lateral line lobe. A lobus caudalis includes a separate granule cell zone - the pars medialis, a molecular layer, and large Purkinje-like cells. Compared with weakly electric mormyrids, the pars medialis is hypertrophied in weakly electric gymnotoids and electroreceptive silurids. However, the pars medialis is also hypertrophied in nonelectroreceptive teleosts, suggesting it is a granule cell zone not associated with electroreception and perhaps the lateral line system.

Notes: The fine structure of the fat body of the higher termite king and queen has been studied both in species with (Macrotermes bellicosus, M. subhyalinus) and without (Cubitermes fungifaber) tracheal rosettes. There is a very pronounced sexual dimorphism. The adipocytes of the queen are highly specialized for protein synthesis and secretion; they store only a small quantity of reserves. The adipocytes of the king are not specialized in protein synthesis, but accumulate large amounts of reserve substances. The previously proposed different functions of the termite queen's fat body are discussed; it appears to be mainly concerned with vitellogenesis.

Notes: Scanning and transmission electron microscopy, together with dissection and light microscopy, have produced heretofore unavailable structural detail of the ovary of Fundulus heteroclitus. Structural and functional interrelationships among developing follicles and other histological elements, particularly as they might relate to vascularization of follicles, oocyte development, and ovulation, are described and discussed. Mature eggs, ovulated into the ovarian lumen, accumulate in the posterior “ovisac” region of the ovary prior to oviposition. This “ovisac” region is thin-walled and apparently nongerminal. The temporary retention of ovulated eggs permits cyclical oviposition even though oogenesis and ovulation are asynchronous. The histological differences between the ovisac and the anterior ovigerous of the ovary are described. The lumenal epithelium of the ovisac displays a localized population of unusual cells with long cytoplasmic extensions. The ultrastructure of these cells suggests that they might function in the transport of ovulated eggs into the oviduct and/or in secreting the substance (“jelly”) which forms the surface coat of extruded eggs.

Notes: A scanning electron microscopy study was made of the male setiferous sex patches and analogous structures in 11 families of Coleoptera (Anthribidae, Bruchidae, Ciidae, Cleridae, Coccinellidae, Dermestidae, Leiodidae, Ptinidae, Staphylinidae, Tenebrionidae, and Ostomatidae). These secondary sexual characters appear to have several features in common including relatively long, often ridged, setae, cuticular ducts (frequently cribriform pore plates), and the production of a secretion. It is suggested that these structures may all be concerned with the production, release, and dissemination of pheromones.

Notes: Single esophageal and paired cheliceral, palpal, pedal (I-IV), and opisthosomal nerves enter the synganglion and form specific neuropilar ganglia. The ganglia are integrated by a complex series of commissures and connectives. Eighteen paraldehyde-fuchsin-positive neurosecretory regions, which vary greatly in size and amount of granular neurosecretory material, are each associated (one or more) with neuropilar ganglia. Presumably transport of neurosecretory materials to target tissues occurs through axonal pathways, perineurial-neural lamella associations, and the neurohemal retrocerebral organ complex.

Notes: The cupula of the supraorbital neuromast in the lateral line canal of the clown knifefish contains vertical columns. In the central region of the cupula overlying the macula, these columns are densely packed, are relatively constant in size, and run from the base of the cupula to the surface of the cupula which is exposed to canal fluid. There are two types of columns, dark and light, which form elliptical compartments in planes of section that cut across the columns; the cupula therefore has the appearance of mosaic tile in such sections. The dark compartments contain tubules that extend from the base of the cupula at the junction with the macula to the top of the cupula. Each tubule is associated with the kinocilium of a single hair cell. The lateral parts of the cupula, not overlying the macula, also contain compartments, but these compartments differ in size and structure from those in the central region. In addition to the compartments, the central region of the cupula also contains spherical aggregates of droplets. These small aggregates, termed mora, are found principally in a layer within the central region of the cupula, but are also found outside this layer. Because of their light-reflecting properties, the mora can be used for noninvasive optical measurements in vivo of the motion of the cupula.

Notes: Light and electron microscopic examination demonstrated two types of non-endocrine agranular cells, cavity boundary cells and stellate cells, in the adenohypophysis of the South American lungfish, Lepidosiren paradoxa. The cavity boundary cells line the hypophyseal cleft and diverticulum and display few microvilli, occasional cilia, prominent junctional complexes, and many cytoplasmic microfilaments. The stellate cells are scattered in the glandular parenchyma and are devoid of microvilli and cilia. When adjacent, they are connected to one another by desmosomes. Pinocytotic vesicles or caveolae are frequently seen along the plasma membrane of the agranular cells adjoining the endocrine cells or abutting on the basement membrane. Possible roles of the agranular cells, physically and metabolically supportive functions, are discussed on the basis of their ultrastractural features.

Notes: The paired organ of Bellonci protrudes from the optic lobe of the giant Antarctic isopod, Glyptonotus antarcticus. It is linked to the cortex by a broad peduncle. No connection to the cuticle or “sensory pore organ” was found. A cluster of sensory-like cells forms two outer ciliary segments branching into numerous microvilli with microtubules. The putative sensory somata are irregular in shape and contain a very high density of glycogen granules. The two outer segments sprout from two pits of the soma in different directions, forming a right angle. Glial cells wrap around the sensory cells and also delimit lacunae into which bundles of microvilli project. These lacunae contain electron-dense granules of small size and with species-specific patterns. Lacunae and dense granules show features typical of a degeneration process in the sensory cells.This general morphology corresponds to the unilobular type of organ of Bellonci, known in other isopods; it differs from the plurilobular type with onion bodies found in other Crustacea.

Notes: Neuromast structure in Rana cancrivora larvae was observed by scanning and transmission electron microscopy. Neuromast units, each being composed of two or three neuromasts, are arranged in several well-defined lines in the head, body, and tail regions. The structure of neuromasts in these three regions is basically identical. The neuromast is composed of sensory, sustentacular, and mantle cells. The top of each neuromast has a hillocklike appearance, and is surrounded by four to six epidermal cells with tight intercellular junctions. Long kinocilia and many stereocilia occur in the apex of the neuromasts and are surrounded by numerous microvilli. Numerous granules are present on the apical portions of the mantle and the sustentacular cells. Four or five trapeziform mantle cells are connected closely with each other to form the shell of the neuromast. Large intercellular spaces occur between the mantle cells and the cells of the inner epidermal layers, and between the cells of the inner epidermal layer. Thus, at the apical parts of the neuromast intercellular junctions are tight and the intercellular spaces are more dilated in more basal areas. Morphologically the neuromasts of R. cancrivora larvae resemble those of generalized pond anurans, based on the grouping of Lannoo (Journal of Morphology 191:115-129, 1987a), although larvae of this species inhabit brackish water.

Notes: Orbital gland structure of the Atlantic bottlenose dolphin, Tursiops truncatus, was examined at the macroscopic, light microscopic, and electron microscopic levels. The gland completely encircles the ocular globe in a belt-like fashion near the conjunctival fornix but is considerably more developed medially. Duct openings are scattered throughout the fornix and over the surface of the palpebral conjunctiva. Microscopically, the gland has a tubuloalveolar arrangement; alveolar cells contain numerous secretory vesicles which can be interpreted as two structural types by light and electron microscopy. Histochemical staining demonstrates that both types contain glycosaminoglycans. Lipid analysis of the glandular secretion (dolphin tears) shows them to be non-oily and to contain only negligible amounts of cholesterol, triglycerides, phospholipids, and free fatty acids. The secretion is clear, slippery, and viscoelastic and well-adapted to protecting the eye and to reducing frictional forces between the eye surface and surrounding seawater.

Notes: The muscle fibers of the feline biceps femoris have tapered ends, across which tension is transmitted to the endomysium. The angle of taper of 11 ends, measured on scanning electron micrographs, varied between 0.16° and 1.18°. The muscle fibers are highly variable in cross-sectional shape. The shape of the fibers has been quantified as the ratio (form factor [FF]) of the measured perimeter to the calculated circumference of a circle having an area equal to that contained by the fiber perimeter. The FF for 173 terminal portions of fibers varied between 1.06 and 1.85 and was found to have a highly significant negative correlation with sarcomere length. The slope of the regression line suggests that the fibers maintain both volume and surface area as they change length. These studies suggest that isovolumic muscle fibers maintain a constant surface area by changing shape as they change length.

Notes: Salt glands of the domestic duck Anas platyrhynchos differ from those of the herring gull Larus argentatus and other birds. In ducks, each salt gland consists of distinct medial and lateral segments. Centrally located drainage ducts that extend along the entire length of these medial and lateral segments collect hypertonic fluid secreted by an array of lobules. Each lobule is formed by a single mass of branched tubules in which the direction of capillary blood flow is opposite to that of the secreted fluid. This fluid drains from the medial segment through an external duct that opens into the nasal cavity at the base of the vestibular fold. A duct from the lateral segment loops and opens onto the surface of the nasal septum. The structure and function of the secretory cells is reviewed briefly within the context of our study of the configuration of duck nasal salt glands.

Notes: A contrast radiographic study of pelvic fin drainage in rays reveals considerable differences in patterns of drainage among the species studied. The “typical” shark pattern of drainage, to the lateral abdominal vein, is also found in rays with shark-like morphology. However, variation in the connections of pelvic fin veins to muscular and cutaneous vessels of the pectoral fin occurs in the more “derived” batoid groups, with marked differences between rays of similar external morphology and mode of locomotion. There is a positive association between the pattern of fin drainage and the number of radial cartilages in the posterior (metapterygial) lobe of the pectoral fin. Variation in shark pelvic fin drainage may also be related to differences in pectoral fin morphology.

Notes: Dissections of Sudan black B stained specimens reveal that, of a complex of medial, intermediate, and lateral muscles of skates, presumed homologous to the cucullaris of sharks, only the lateral muscle is innervated by a branch or branches of the vagus and is inserted, in part, to the fused pharyngobranchials of the caudal visceral arches. The medial and intermediate muscles are supplied by separate branches of rostral spinal nerves and do not attach to the branchial skeleton. The lateral muscle therefore is the most likely homologue of the cucullaris (trapezius) of sharks and perhaps other fishes and tetrapods. The medial and intermediate muscles appear to be part of the axial musculature.

Notes: An immunocytological study of four different parts of the gut of Helix aspersa clearly demonstrates the presence of many cells and fibers immunoreactive toward antibodies directed to vertebrate (α, β-endorphin, α, β-MSH, ACTH 1-24 and ACTH 17-39, met-enkephalin, somatostatin, insulin, glucagon, P.P., serotonin) or invertebrate (FMRF-amide) peptides.These results are evidence of the presence of different substances related to known peptides or amines in the epithelial and connective tissue cells and nerve fibers of the snail gut. Immunocytochemistry may help to elucidate the morpho-functional characteristics of the enteroendocrine cells of H. aspersa.

Notes: A histochemical investigation of kidney and lower intestine of the European starling (Sturnus vulgaris) shows no carbonic anhydrase activity in proximal convoluted tubules, although activity is seen in similarly prepared sections of rat proximal tubules. Early distal tubule cells in the starling are stained throughout the cytoplasm and at the apical and highly infolded basolateral membranes. Late distal tubules lose apical activity and have reduced basolateral infolding, resulting in less intense staining. Darkly stained intercalated cells appear in the connecting tubules and cortical collecting ducts. Both of these segments also show intense basolateral staining. Medullary cones of the starling are highly organized, with central zones containing unstained thin descending limbs of loops of Henle, surrounded by both medullary collecting ducts with only scattered cells staining for enzyme, and by thick ascending limb segments. The latter contain many uniformly stained cells intermingled with occasional unstained cells. Scattered cells of the starling colonic villi demonstrate intense apical brush border membrane staining as well as cytoplasmic staining. Cells lining the cloaca stain less intensely. A biochemical assay for carbonic anhydrase was used to quantify enzyme activity in these tissues. Starling kidney contained 1.96 ± 0.33 (mean ± SEM) enzyme units/mg protein, less than half the activity seen in rat kidney. Stripped colonic epithelium contained 0.66 ± 0.15 enzyme units/mg protein. These quantitative results correlate well with the interpretations derived from the histochemical observations. The lack of proximal tubule carbonic anhydrase activity suggests that the avian kidney relies more on distal nephron segments to achieve net acidification of the urine.

Notes: The orientation of the fibers in the dermis of the tiger salamander, Ambystoma tigrinum, undergoes a dramatic repatterning at metamorphosis. The pre-metamorphic, larval dermis is a tight layer composed of crossed fibers that wind helically around the trunk. This condition is retained by neotenic adults which do not undergo metamorphosis. In contrast, the metamorphosed adult dermis consists of a superficial, loose network of fibers invested with large multicellular glands - -the stratum spongiosum - and a deeper tight layer of fibers - the stratum densum. However, unlike the crossed fibers of the pre-metamorphic dermis, there is no preferred orientation to the fibers in either layer of the post-metamorphic dermis.In order to evaluate whether these two distinctly different fiber patterns are constructed from biochemically similar fibers, the collagen types present in the pre- and post-metamorphic dermis were determined using SDS-polyacrylamide gel electrophoresis. Type I collagen is the predominant collagen of the dermis and the same major collagen types are present for all individuals, whether preor post-metamorphic. Thus, the major types of collagen that compose the dermal fibers do not change during metamorphic repatterning of the dermis.

Notes: In the first half of this century, several workers observed small, seemingly glandular structures attached to the ampullate glands of spiders. Hence, they were termed accessory ampullate glands. In juvenile Araneus cavaticus, two pairs of these structures are present (starting at least with third instars), one pair attached to the major ampullate (MaA) glands and the other pair attached to the minor ampullate (MiA) glands. In adults, two pairs of accessory MaA glands and two pairs of accessory MiA glands are present. The two latter-formed pairs of accessory ampullate glands are clearly the remnants of those ampullate glands which atrophy shortly after adulthood is reached. Morphological similarities between these accessory ampullate glands and those present in juveniles provide an indication that the latter also have their origin in functional ampullate glands.A reduction in the number of ampullate glands following the last molt occurs in many spiders. The reason(s) for these reductions is unknown. In penultimate spiders close to ecdysis, we have observed that while the larger pairs of MaA and MiA glands (those that are retained in the adult) are undergoing molt-related changes which apparently render them nonfunctional, their smaller counterparts are seemingly unaffected and functional. This raises the possibility that the principal role of the smaller ampullate glands may be to assume functions during the pre-ecdysial period which are normally in the domain of the larger ampullate glands. If true, then their degeneration after the last molt would make economic sense.The presence of cylindrical spigots in juvenile females starting with fourth instars is documented.

Notes: Three basic types of cells are distinguished in the rat vomeronasal epithelium at birth: bipolar neurons, supporting cells, and basal cells. Neurons at this time include both immature and differentiated cells. By the end of the first postnatal week, all neurons show morphological signs of maturity in their cytoplasm, including abundant granular and smooth endoplasmic reticulum, neurotubules, dense lamellar bodies, apical centrioles, and tufts of microvilli. During the third week microvilli are more frequently encountered and appear to be longer and more branched. Supporting cells appear well-developed by the second day after birth. During the first ten days of life, supporting cells lose their centrioles and all of the complex associated with ciliary generation in the apical zone. Basal cells appear to be more numerous in newborns than in older animals. Protrusions projecting into the lumen are frequently observed in the epithelium of newborn animals, both on the dendrites of neurons and on supporting cells. After the third week, such protrusions are only observed in the transitional zone between the sensory and the non-sensory epithelia of the vomeronasal tubes. In this transitional zone, a fourth cell type showing apical protrusions with microvilli differentiates. Cytoplasm in this type resembles that of neighboring ciliated cells but has no cilia or centrioles. These transitional cells are considered to be cells in an intermediate state of differentiation, between that of the differentiated neurons and supporting cells of the sensory epithelium and that of the predominate ciliated cells of the non-sensory epithelium. The results suggest that by the end of the third week the vomeronasal epithelium is morphologically mature.

Notes: The wall of the stomach of the tigerfish is described and compared with that of other vertebrates. Light microscopic and ultrastructural characteristics of the stomach wall correspond to a large extent to those of other vertebrates, although some differences are found. The mucosa contains (1) surface epithelium characterized by narrow columnar cells with abundant mucous granules; (2) gastric glands consisting of pepsinogenic cells of variable height, containing tubulovesicles and bearing microvilli; (3) five granulated cell types located basally in the epithelium (types 1-5); and (4) lamina propria and muscularis mucosae. Connective tissue separating smooth muscle fibers of the muscularis mucosae constitutes a stratum compactum. The submucosa contains a loose connective tissue, a tunica muscularis of inner circular and outer longitudinal layers, and a serosa of mesothelium and subjacent connective tissue. Immunocytochemical tests with antisera to five polypeptides show gastrin/cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP) immunoreactivities in some cells of the gastric glands, and somatostatin in cells lying among epithelial cells lining the gastric luminal surface or gastric pits.

Notes: Previous studies by Stephens and McNulty and Strecker and Stephens have demonstrated that foil barriers placed between the mesonephros and lateral plate at stages 12 to 15 inhibited limb development, but foil barriers placed between the neural tube and somites at stages 11 to 12 resulted in limbs with normal skeletal patterns. It was concluded that some influence present in the paraxial region of the embryo at stages 11 to 15 is necessary for normal limb development. The present study was undertaken to localize that influence more precisely. Foil barriers were placed in the lateral edge of the somites or segmental plate of stage 10 to 15 chick embryos. Barriers placed into stage 13 to 15 embryos resulted in chicks with normal limbs, but barriers placed into stage 10 to 11 embryos resulted in chicks with defective limbs. Barriers inserted just lateral to Hensen's node at stages 6 to 8 resulted in embryos with defective or absent wings. We also grafted stage 4 to 9 presumptive limb territories with and without Hensen's node. Explants without Hensen's node formed limb-like structures in 1% of the cases. Explants with Hensen's node formed limb-like structures in 27% of the cases. When barriers were implanted and a node was placed on the lateral side of the barrier, limbs formed in 40% of the cases. These data suggest a medial to lateral progression of some as yet unknown morphogenetic influence necessary for normal limb development and we hypothesized that the influence may initially emanate from Hensen's node.

Notes: The limb bone skeleton of the moa, a family of extinct ratite birds endemic to New Zealand, is described with particular reference to the anatomical and functional significance of osteological landmark form variation. The results generally support the existing classification of moa. Four genera, Megalapteryx, Anomalopteryx, Dinornis, and Pachyornis, were found to be evolved within moa, with Emeus and Euryapteryx possibly being more primitive. Megalapteryx was found to be less mobile than other moa genera. The Dinornis species were found to be more cursorial and more mobile relative to other moa. They may also have had a different center of gravity. A marked development of the lower leg in Anomalopteryx suggested a digging habit associated with food procurement.

Notes: A detailed description of muscular and skeletal features of the pelvi-cloacal region of the amphisbaenian Blanus cinereus reveals that the species has real hind limbs articulating with a real pelvic girdle. Arguments support this homology: 1) a link with the vertebral column; 2) a movable articulation, showing all the features of a diarthrosis, between the femur and the acetabulum; 3) all the long bone characteristics for the femur which distally bears a horny element. The morphological peculiarities of the amphisbaenian pelvic girdle are generally close to those of lizards, but the pubis seems to be more reduced. For the same number of precloacal vertebrae, the amphisbaenians have more appendicular elements than lizards have, and this composition recalls that of the Leptotyphlopidae, Aniliidae, and Boidae. The account provides more information concerning the aponeuro-tendinous system associated to the skeleton of the girdle and the hindlimb, the musculature, and the interrelations between the different structures of the pelvi-cloacal region.

Notes: Programmed cell death is an integral and ubiquitous phenomenon of development that is responsible for the reduction of wing size in female moths of Orgyia leucostigma (Lymantriidae). Throughout larval and pupal life, cells of the wing epithelium proliferate and interact to form normal imaginal discs and pupal wings in both sexes. But at the onset of adult development, most cells in female O. leucostigma wings degenerate over a brief, 2-day period. Lysosomes and autophagic vacuoles appear in cells of the wing epithelium shortly after it retracts from the pupal cuticle. Hemocytes actively participate in removing the resulting cellular debris. By contrast, epithelial cells in wings of developing adult males of O. leucostigma do not undergo massive cell death. Wing epithelium of female pupae transferred to male pupal hosts behaves autonomously in this foreign environment. By pupation, cells of the female wing apparently are committed to self-destruct even in a male pupal environment. Normal interactions among epithelial cells within the plane of a wing monolayer as well as between the upper and lower monolayers of the wing are disrupted in female O. leucostigma by massive cell degeneration. Despite this disruption, the remaining cells of the wing contribute to the formation of a diminutive, but reasonably proportioned, adult wing with scales and veins.

Notes: We describe the localization of lipids in the wall and superficial ooplasm of the largest avian ovarian follicles by the use of different fixatives and light and electron microscopy. We demonstrate that each yolk globule is always accompanied by one or more highly osmiophilic and sudanophilic alcohol insoluble yolk masses, which we have called satellite yolk. Together with the protein containing yolk globule it forms an integral morphological part of a compartmentalized, bipartite yolk system. Cytochemical, histoautoradiographic, biochemical, and light and electron microscopical aspects of satellite yolk were studied. At the start of satellite yolk formation in the 3-4 mm diameter follicle (when the oocyte begins to yellow) the distribution of the microcirculation of the follicle wall becomes printed on the underlying superficial ooplasm of the oocyte. The oocyte then presents so-called yolk mountains (containing satellite yolk), only localized below the thecal capillary sinus and not below the efferent and radially perforating thecal veins (black hole regions). We also describe the structural continuity between the thecal intercellular spaces and the microvilli-associated extracellular spaces of the granulosa cells via the basement membrane. The thecal cells present centripetal extensions into the basement membrane and the basement membrane material extends centripetally into the granulosa microvillar channels. Therefore, at least two cellular barriers are crossed when fat or fat precursors are transported from the thecal capillary sinus to the ooplasm.

Notes: Embryos of the poeciliid Heterandria formosa develop to term in the ovarian follicle in which they establish a placental association with the follicle wall (follicular placenta) and undergo a 3,900% increase in embryonic dry weight. This study does not confirm the belief that the embryonic component of the follicular placenta is formed only by the surfaces of the pericardial and yolk sacs; early in development the entire embryonic surface functions in absorption. The pericardial sac expands to form a hood-like structure that covers the head of the embryo and together with the yolk sac is extensively vascularized by a portal plexus derived from the vitelline circulation. The hood-like pericardial sac is considered to be a pericardial amnion-serosa. Scanning and transmission electron microscopy reveal that during the early and middle phases of development (Tavolga's stages 10-18 for Xiphophorus maculatus) the entire embryo is covered by a bilaminar epithelium whose apical surface is characterized by numerous, elongate microvilli and coated pits and vesicles. Electron-lucent vesicles in the apical cytoplasm appear to be endosomes while a heterogeneous group of dense-staining vesicles display many features characteristic of lysosomes. As in the larvae of other teleosts, cells resembling chloride cells are also present in the surface epithelium. Endothelial cells of the portal plexus lie directly beneath the surface epithelium of the pericardial and yolk sacs and possess numerous transcytotic vesicles. The microvillous surface epithelium becomes restricted to the pericardial and yolk sacs late in development when elsewhere on the embryo the non-absorptive epidermis differentiates. We postulate that before the definitive epidermis differentiates, the entire embryonic surface constitutes the embryonic component of the follicular placenta. The absorptive surface epithelium appears to be the principle embryonic adaptation for maternal-embryonic nutrient uptake in H. formosa, suggesting that a change in the normal differentiation of the surface epithelium was of primary importance to the acquisition of matrotrophy in this species. In other species of viviparous poeciliid fishes in which there is little or no transfer of maternal nutrients, the embryonic surface epithelium is of the non-absorptive type.

Notes: The flagellum of the thysanopteran spermatozoon has been examined by electron microscopy and computer-aided image analysis. The flagellum consists of 27 microtubular elements that probably are formed as outgrowths from three separate basal bodies. Nine of the elements are normal microtubular doublets that carry dynein arms and nine are doublets without dynein arms. The remaining nine elements are microtubular singlets that apparently bear dynein arms and have the same appearance as A-subtubules of microtubular doublets. The 27 elements are arranged in a fixed pattern that consists of nine groups, each of which begins with a microtubular singlet and ends with an arm-less microtubular doublet. Computer-aided image analysis has shown that the A-subtubules of the doublets and the microtubular singlets have lumens with very similar patterns. The sperm tail is known to have some motility; it generates fast waves running along its length. The amalgamated axonemes hence act as a functional flagellum. The thysanopteran sperm tail is the only type of flagellum known to us that consists of microtubules in a highly asymmetric array.

Notes: Many arachnids lack extensor muscles at the femoropatellar (knee) joint of their legs and extend this joint with hydraulic pressure during locomotion. Pressure is generated through compression of the prosoma, but there is disagreement about which muscles are involved in this process. Many arachhnologists consider contraction of the musculi laterales, a group of modified extrinsic leg muscles, as the cause of high prosomal pressure and regard hydraulic extension as a derived feature. However, integration of results from phylogenetic and comparative anatomical studies supports the view that hydraulic extension is primitive in Arachnida and that fluid pressure is generated by contraction of endosternal suspensor muscles.The functional predictions of the musculi laterales and endosternite hypotheses were tested by measuring muscle activity and prosomal pressure during unrestrained locomotion in a primitively “extensorless” arachnid, the giant whipscorpion. The results corroborate the endosternite model and refute the musculi laterales model. Changes in the prosomal pressure baseline were correlated with changes in endosternal muscle activity, while the musculi laterales fired in a step-coupled pattern of discrete bursts that appeared to be incapable of generating the pressure observed during locomotion. Step-coupled fluctuations in prosomal pressure were observed but were apparently caused by rapid flexing of the femoropatellar joints of the fourth leg pair rather than contraction of the musculi laterales.

Notes: In the fungiform papilla of Rana esculenta (Anura Ranidae), the Ca++-ATPase is mainly distributed on the basolateral membrane of the sensory area cells (i.e., neuroepithelial, supporting, and mucous cells). Apical membranes of all cells facing the surface present a slight enzymatic activity. Lateral wall cells have a strong Ca++-ATPase activity on basolateral and apical membranes. Strong Na+, K+-ATPase activity occurs on the apical surface of neuroepithelial cells. Ca++-ATPase activity is absent on the surface of endothelial cells of the capillaries located under the sensory area. These observations lead us to conclude that the sensory area of fungiform papilla is the selective way for calcium influx. Furthermore the absence of ATPase activity on the surface of the endothelial cells indicates that there is no functional barrier to calcium influx into capillary, and that calcium can be removed by vessels from the sensory area.

Notes: Spermatogenesis and sperm ultrastructure were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) in the longidorid Xiphinema theresiae. All germ cell stages, except spermatogonia, are present in the testes of young adult males. The nonflagellated, slightly elongated sperm displays little intraspecific variation and, although never polarized into a head and tail region, has a remarkably precise form, with a high degree of internal organization. Incipient fingerlike pseudopodia appear in the young spermatid and increase to such an extent that the adult sperm has a conspicuous “woolly” appearance. Microfilament bundles encircle the perinuclear mitochondria in the spermatid, and seem to be closely associated with the evaginated plasma membrane, especially in the spermatozoon. A large nucleus with nuclear envelope is prominent in the spermatocyte, but the envelope is absent in the young spermatid. Mitochondria are present in all germ cell stages and undergo certain morphological changes (e.g., in size and number, presence or absence of cristae), as well as changes in intracellular movements during spermatogenesis. Membranous organelles are prominent in the spermatocyte, but disappear in the older spermatid. Annulate lamellae and a residual body (i.e., cytophore) are conspicuous in the spermatocyte and spermatid, respectively; the spermatozoon clearly lacks a refringent body (i.e., acrosome).

Notes: The morphology and distribution of muscle spindles of jaw and tongue muscles in the mallard were examined in serial transverse sections of single muscles and in horizontal sections of a whole head. Our observations on spindle morphology are in agreement with previous descriptions of spindles in birds. Some spindles differ in their innervation and the pattern of intrafusal muscle fibers. The spindles of individual adductor and pterygoid muscles are distributed unevenly. Some adductor muscles lack spindles, whereas those of other muscles are confined to limited areas. Jaw opening muscles and extrinsic tongue muscles lack spindles. The stretch of extrafusal muscle fibers could be estimated from the difference in sarcomere length for birds with the beak open and closed. Not all muscle fiber groups are stretched evenly over the whole range of jaw opening. Only those fiber groups that are continuously stretched during jaw opening contain spindles.

Notes: Living embryos of three species of South American annual fishes, Cynolebias constanciae, C. nigripinnis, and C. whitei, were observed from fertilization through the 10-somite stage. A description of normal stages of development applicable to all three species of Cynolebias is presented. Cleavage (stages 1-10) is meroblastic and produces a typical teleost blastoderm. Following cleavage (stages 11-13) blastomeres segregate into two populations, viz., (1) a population of deep blastomeres that will disperse as single motile cells, and (2) a hemispherical shell of outer blastomeres that flattens to form an enveloping cell layer (EVL). When epiboly of the EVL and the yolk syncytial layer (YSL) commences (stage 14), deep blastomeres clump together as a consolidation mass and then migrate outward as single cells on the YSL. When epiboly is concluded (stage 19), deep blastomeres have completely dispersed. If diapause does not intervene, the dispersed phase lasts only a few days. Subsequently, the dispersed cells come together to form a definitive aggregate (stage 27). Embryogenesis within the reaggregated mass of previously dispersed cells produces a typical teleost embryo.Early development in Cynolebias resembles that of other South American annual fishes, such as Austrofundulus, in that a phase of deep blastomere dispersion and reaggregation spatially and temporally separates epiboly from embryogenesis. Several features of development markedly differ from Austrofundulus. There are far fewer (250 vs. 2,500) deep blastomeres. Deep cells of Cynolebias are flattened rhomboids with filipodial extensions in contrast to the amoeboid cells of Austrofundulus. Blastomeres of dispersion and reaggregation stages in Cynolebias send out numerous cell surface extensions onto the YSL and in contact with one another, and often line up in rows as do some African annual fishes, e.g., Nothobranchius. During Dispersion II (stage 21), Reaggregation I (stage 22), and Reaggregation II (stage 23), deep cells move in an oriented pattern with respective mean velocities of 3.48 ± 0.91, 1.28 ± 0.46, and 1.31 ± 0.31 μm/minute. Cells move toward a granular mass of unknown composition, located at the YSL-yolk interface in the lower hemisphere of the egg. This mass appears to coincide with the site of cell reaggregation.

Notes: Several surfperches (Embiotocidae), including the black surfperch, Embiotoca jacksoni, exhibit a specialized prey handling behavior known as winnowing, in which ingested food and non-nutritive debris are separated within the oropharyngeal cavity. Prey items are swallowed, and unpalatable material is ejected from the mouth. Winnowing is believed to play an important role in the partitioning of food resources among sympatric embiotocids. We present a mechanistic model for this separative prey processing based on high-speed video analysis, cineradiography, electromyography, and buccal and opercular cavity pressure transducer recording.Winnowing by embiotocids is characterized by premaxillary protrusions repeated cyclically with reduced oral gape. Protrusion is accompanied by depression of the hyoid apparatus and adduction of the opercula. Alternating expansion and contraction of the buccal and opercular cavities generate regular pressure waveforms that indicate bidirectional water flow during processing. Separation of food from debris by Embiotoca jacksoni occurs in three phases. The prey-debris bolus is transported anteriorly and posteriorly within the oropharyngeal cavity and is then sheared by the pharyngeal jaws. Mechanical processing is complemented by the rinsing action of water currents during hydraulic prey transport.The feeding apparatus of Embiotoca jacksoni is functionally versatile, although not obviously specialized relative to that of nonwinnowing surfperches. Protrusion of the premaxillae and depression of the hyoid apparatus are critical to both prey capture and subsequent prey processing. The pharyngeal jaws exhibit kinematic patterns during separation of food from debris distinct from those observed during mastication of uncontaminated prey. This behavioral flexibility facilitates resource partitioning and the coexistence of E. jacksoni in sympatric embiotocid assemblages.

Notes: Quantifying shape is a broad problem in the morphological sciences. Most techniques for numerically describing shape abstract the shape into the most logical ideal Euclidean dimension. The fractional, or fractal, dimension is a simple computation that expresses shape in real, rather than ideal, space. The structured walk technique developed for the fractal analysis of rugged boundaries is applied here to the contour of the human sagittal suture in order to discriminate the separate morphological patterns of interfingering and interlocking. These attributes contribute differentially to the suture's “complexity,” a concept often used in biomechanical hypotheses. Previous techniques for estimating sutural complexity do not isolate small-scale from large-scale morphological patterns. Results indicate that despite the visual appearance of great variation, human sagittal sutures are remarkably consistent in the degree of complexity expressed separately by large-scale interfingering lateral excursions and small-scale interlocking ruggedness. There is no significant correlation between the absolute or bregma-lambda chord length of the human sagittal suture and its degree of complexity as determined by the structured walk technique.

Notes: Spermatophores in a squid, Todarodes pacificus, were observed by light and electron microscopy and were further analyzed by X-ray microanalysis (XMA) of frozen thin sections. Each spermatophore consists of a sperm mass, a cement body, an ejaculatory apparatus, and some fluid materials, all of which are covered by an outer tunic. The outer tunic consists of about 20 membranous layers, each containing straight, parallel microgrooves. Each layer's microgroove pattern is roughly in an orthogonal arrangement with respect to the next layer's pattern. The sperm mass, which is the only cellular component, consists of a sperm rope which is coiled more than 500 times. Most of the spermatozoa in the rope are arranged regularly and are enveloped in materials which are well-stained by Alcian blue. The cement body is located between the sperm mass and ejaculatory apparatus and has a hard outer shell with an arrowhead-like structure, presumably for penetration into the tissue of the female. Calcium and phosphorus are present in the shell of the cement body, which also has an affinity for alizarin red. The ejaculatory apparatus consists of two tubes, designated as the inner tunic and the inner membrane.After the spermatophoric reaction, a sperm reservoir is formed at the anterior end of the extruded and inverted ejaculatory apparatus. The sperm reservoir, which encases the sperm mass, is composed of the cement body at the anterior end and the inner tunic of the ejaculatory apparatus at the posterior end.

Notes: Spermiogenesis in the South American leptodactylid frog Odontophrynus cultripes was analyzed ultrastructurally. The spermatids undergo morphological modification while still enclosed in microtubule-rich processes of Sertoli cells. Electron-dense plates resembling junctional structures appear in regions at which the spermatids lie in close contact with the surface of Sertoli cell processes. Spermatid differentiation can be divided into five distinct stages based mainly on chromatin condensation. In the late stages, the densely compacted chromatin loses reactivity to ethanolic phosphotungstic acid (E-PTA). Helical arrangements of microtubules appear in the cytoplasm that surrounds the spermatid nucleus after the second stage. The acrosomal vesicle differentiates into a cone-shaped acrosome that caps the anterior region of the nucleus. The connecting piece, located in the flagellum implantation zone, has transverse striations, and is continuous with the axial rod. The tail is formed by a 9 + 2 axoneme, an undulating membrane, and an axial rod that is rich in basic proteins as demonstrated by E-PTA staining.

Notes: Morphology of the chromaffin cells of Triturus cristatus during a complete annual cycle has been investigated. General ultrastructural characteristics are similar for all chromaffin cells, including numerous small mitochondria, well-developed Golgi apparatus and rough endoplasmic reticulum with short cisternae. The primary difference among cells is the type of the chromaffin granules they posses. These are of two kinds: adrenalin (A) and noradrenalin granules (NA). Both types are simultaneously present in the chromaffin cells but with different ratios during the year. During December-January and May-August, NA granules largely prevail, while in September-November and February-April, A and NA granules are present in about equal quantities. The total quantity of catecholamine granules, however, is relatively constant throughout the year. These findings suggest that T. cristatus has a single type of chromaffin cell, the granule content of which varies according to different functional states. The catecholamines are apparently discharged by exocytosis.

Notes: The palatoquadrate and associated dermal bones have significant evolutionary transformations among teleostomes and provide numerous features that characterize teleostomian subgroups. The palatoquadrate forms the upper part of the mandibular arch and is present as a single cartilaginous element in the early ontogeny of teleostomes, except for some advanced teleosts such as siluroids where it is divided into pars autopalatina and pars pterygoquadrata. During ontogeny, the palatoquadrate may ossify as a unit, with a pars autopalatina (absent in Acanthodii), pars quadrata, and pars metapterygoidea in teleostomes (e.g., primitive acanthodians and actinopterygians, onychodonts, and rhipidistians). However, the palatoquadrate may remain cartilaginous (e.g., chondrosteans) or it may ossify as separate elements (e.g., autopalatine, metapterygoid, and quadrate) as occurs in advanced acanthodians, Polypterus and advanced actinopterygians, and advanced actinistians. From the single-unit pattern, separate autopalatine, metapterygoid, and quadrate evolve in parallel in the three teleostomian subgroups. Therefore, it is necessary to distinguish between actinopterygian and actinistian autopalatines and among acanthodian, actinopterygian, and actinistian metapterygoids and quadrates. A palatoquadrate fused with the neurocranium occurs in parallel in dipnoans.There are differences in the timing of ossification of the autopalatine, metapterygoid, and quadrate. The autopalatine ossifies late in ontogeny in Polypterus, Amia, and primitive teleosts (absent in lepisosteids and osteoglossmorphs), whereas both metapterygoid and quadrate ossify early in ontogeny. The early ossification of the autopalatine is characteristic of clupeocephalan teleosts. During ontogeny, tooth plates (not forming a separate dermometapterygoid) fuse with the metapterygoid in actinopterygians.Pars autopalatina, pars metapterygoidea, and pars quadrata are regions at the three corners of the single-unit palatoquadrate present in primitive teleostomes; there are no clear limits among these regions, but they may be identified by their processes, articular facets, and topographical relationships with surrounding bones and the orbit. Autopalatine, metapterygoid, and quadrate are chondral bones, perichondrally ossified. Dermal elements such as dermopalatine(s), entopterygoid, ectopterygoid, and tooth plates may cover the palatoquadrate medially. The predermopalatine that originates in front of pars autopalatina in Cladistia and the “dermopalatine” that lies medial to the ectopterygoid in Ginglymodi are specializations of these groups. A dermopalatine fused with the autopalatine is characteristic of clupeocephalan teleosts. Highly specialized tendon bone pterygoids are found in some teleosts (e.g., siluroids). The presence of both maxilla and lacrimal lateral to the pars autopalatina is synapomorphous of osteichthyans. The eye supported by the bony palatoquadrate is a teleostomian synapomorphy. Dermal elements support the eye in actinopterygians, the entopterygoid in advanced actinopterygians, but the ectopterygoid in lepisosteids.A quadratojugal is a synapomorphy of osteichthyans but exhibits a number of transformations in connection with the vertical pit-line and the preopercular canal; a quadratojugal bearing the vertical pit-line is the primitive condition for osteichthyans. Ontogenetic evidence does not support the homology of the membranous posterior process of the teleostean quadrate with the quadratojugal. The lack of a quadratojugal and the presence of the elongate posterior or posteroventral process of the quadrate is a synapomorphy of teleosts.

Notes: The events associated with premolt reformation of the cuticularized ductule in the underdeveloped (immature) branchial rosette glands, which are common in the gills of small (14-18 mm, total length) grass shrimp, are described and contrasted with the events of ductule reformation in the fully developed (mature) resette glands most common in larger shrimp. In immature rosette glands, two ciliary processes emerge from each of the component secretory cells and ascend into the basal luminal region of the old ductule. Subsequently a new ductule is formed around the old ductule, and the ciliary processes disappear, either because of degeneration or retraction. The transitory ciliary processes appear to prevent the old ductule from collapsing during the formation of a new ductule. Such transitory ciliary processes, however, are not found in association with premolt ductule reformation in the mature rosette glands; in their place are seen a number of microvilli-like cytoplasmic processes, which emanate from the apices of the secretory cells and from the channels of the central cell. These cytoplasmic processes in mature glands, like the ciliary processes in immature glands, are transitory and appear to prevent the collapse of the old ductule.Cytoplasmic processes comparable to those in mature glands, but relatively few in number and originating only from the secretory cells, are seen together with ciliary processes in some immature glands. The relative abundance of cytoplasmic processes in the mature glands, coupled with the observation that transitory ciliary processes occur in immature glands but not in mature glands, suggests that, during glandular maturation, transitory ciliary processes are replaced by transitory cytoplasmic processes.

Notes: The spermatozeugmata (sperm bundles lacking a distinct wall) from the spermathecae of Tubifex tubifex are composed of two different zones: an internal axial cylinder containing conventional spermatozoa and an external cortex composed of modified spermatozoa, tightly packed together. The conventional spermatozoa conform to the classical clitellate scheme: very long and thin with a complex acrosome, a filiform nucleus, small mitochondria, and a flagellum with Y links and β glycogen granules as accessory structures. The modified spermatozoa show “empty” acrosomes, degenerating nuclei, and tails which contain γ glycogen granules. The tails are helically wound around the spermatozeugma and are connected to each other by junctional complexes. The tips of the cortical tails are free and move with a metachronal wave. The presence of two sperm types in tubificids is discussed and a protective function for the modified cortical spermatozoa is proposed.

Notes: The intraembryonic reticuloendothelial response to phenylhydrazine-induced hemolytic anemia was studied embryonic chicks (days 13-16) by light and electron microscopy and histochemical and biochemical assays for acid phosphatase. Phenylhydrazine was given on day 13 and tissue taken at 2, 5, and 10 h and at 1, 2, and 3 days after injections. The response varied in the three major reticuloendothelial organs. The spleen first demonstrated an increase in erythrophagocytosis that was accompanied by increased acid phosphatase levels. Erythrophagocytosis occurred primarily in the red pulp resulting in increased numbers of macrophages, increased size of macrophages, and retention of erythrocytes, which together combined to enlarge the spleens. By 2 days after phenylhydrazine injection, greatly enlarged macrophages began to migrate into the venous system, where some erythrophagocytosis continued to occur. The liver was also a major erythroclastic organ in which Kupffer cells became increasingly erythrophagocytic. However, erythrophagocytosis began later than in the spleen, and as measured by acid phosphatase levels, the liver was not as effective in removing damaged erythroid cells. Marrow erythrophagocytosis was only slightly enhanced; however, the marrow responded by increasing its production of red blood cells. Thus, the intraembryonic reticuloendothelial organs of the embryonic chick responded to phenylhydrazine-induced hemolytic anemia in much the same manner as might be expected of the adult bird.

Notes: The siphuncle of the chambered nautilus (Nautilus macromphalus) is composed of a layer of columnar epithelial cells resting on a vascularized connective tissue base. The siphuncular epithelium taken from chambers that have not yet begun to be emptied of cameral liquid has a dense apical brush border. The great number of apical cell junctions (zonula adherens) compared to the number of nuclei suggests extensive interdigitation of these cells. The perinuclear cytoplasm of these preemptying cells is rich in rough endoplasmic reticulum. The siphuncular epithelium of both emptying and “old” siphuncle (which has already completed emptying its chamber) both show little rough endoplasmic reticulum but do contain extensive systems of mitochondria-lined infoldings of the basolateral plasma membranes. Active transport of NaCl into the extracellular space of this tubular system probably entrains the water transport involved in the chamber-emptying process. Both emptying and old siphuncular epithelium also show large basal infoldings (canaliculi) continuous with the hemocoel, which appear to be filled with hemocyanin. The apical cell junctions of emptying and old siphuncular epithelium contain septate desmosomes that may help to prevent back-flow of cameral liquid into the chambers.

Notes: Two types of exocrine rosette glands (called type A and type B), located in the gill axes of the grass shrimp Palaemonetes pugio, are described. The type A glands are embedded within the longitudinal median septum of the gill axes, whereas the type B glands typically project into the efferent hemolymph channels of the gill axes. Although both glands have certain common characteristics (i.e., a variable number of radially arranged secretory cells, a central intercalary cell, and a canal cell that forms the cuticular ductule leading to the branchial surface), they differ in the following respects. The type B gland is innervated, but the type A gland is not; axonal processes, containing both granular (ca. 900-1300 Å) and agranular (ca. 450-640 Å) vesicles, occur at a juncture between adjacent secretory cells and the central cell of the type B gland. The secretory cells of type A and type B glands differ in their synthetic potential and membrane specializations. These differences are more pronounced in well-developed, mature glands, most frequently encountered in larger (24-28 mm, total length) grass shrimp, than in the underdeveloped, immature glands that are most abundant in smaller (14-18 mm, total length) grass shrimp. Thus, in mature glands, the secretory cells of the type A rosette glands are characterized by extensive RER, abundant Golgi, and numerous secretory granules, whereas the secretory cells of the type B gland are characterized by extensively infolded and interdigitated basal plasmalemmas and by the presence of numerous mitochondria. In general, both types of glands exhibit increased secretory activity soon after ecdysis. The central and canal cells in both glands seem to have a role in the modification of the secreted materials. The possible functions assigned to the type A gland and the type B gland include phenol-oxidase secretion and osmoregulation, respectively.

Notes: The events in the transformation of the intestine of the larval lamprey into the adult intestine were followed through the seven (1-7) stages of metamorphosis in anadromous Petromyzon marinus L. Light and electron-microscope observations demonstrated that the processes of degeneration, differentiation, and proliferation are involved in the transformation. In the anterior intestine, degeneration of cells and the extrusion of others into the lumen results in the disappearance of secretory (zymogen) cells and the decline in numbers of endocrine and ciliated cells. Larval absorptive cells, with a prominent brush border, are believed to dedifferentiate into unspecialized columnar cells with few microvilli. Degeneration and removal of cells occurs by both autophagy and heterography and cells extruded into the lumen in the anterior intestine are phagocytosed by epithelial cells of the posterior intestine. The loss of epithelial cells during transformation results in the folding and degradation of parts of the basal lamina and in an extensive widening of the lateral intercellular spaces in all parts of the intestine. As metamorphosis is a nontrophic period of the lamprey life cycle, the possible morphological effects of starvation on the intestinal epithelium are discussed.The development of longitudinal folds is a consequence of the events of metamorphic transformation of the intestinal mucosa. Although an interaction between the epithelium and the underlying tissues is believed to be importent, the actual mechanism of fold development is unknown.The intestinal epithelium of adult lampreys develops from surviving cells of the larval (primary) epithelium. Unlike the situation in amphibians, there does not appear to be a group (nest) of undifferentiated larval cells which differentiate into the adult (secondary) epithelium. Instead, in lampreys, columnar cells that persist through the degradative processes seem to be the source of absorptive and ciliated cells and probably are responsible for mucous and secretory cells.Preliminary observations indicate that the intestinal epithelium of feeding adults is specialized into an anterior region which liberates a secretion, absorbs lipid, and possesses the machinery for ion transport. A posterior region absorbs lipid, secretes mucus, and likely is involved in some protein absorption.

Notes: The octavolateralis area of actinopterygian fishes can be subdivided into a dorsal lateralis area composed of first-order lateral line nuclei, and a ventral octavus area composed of nuclei receiving first-order input from the eighth nerve. Three patterns of organization of the lateralis area are recognized in the present study. The organization of this area in polypteriforms and chondrosteans is similar to that in chondrichthyans. On the basis of recent studies in chondrichthyans (McCready and Boord, '76; Boord and Campbell, '77; Bodznick and Northcutt, '80), it is hypothesized that this pattern reflects the subdivision of the lateral line system into mechanoreceptive and electroreceptive portions. As petromyzontid agnathans also share this pattern of organization, it is hypothesized that they are elecroreceptive. The lateralis area of holosteans and nonelectroreceptive teleosts exhibits a second organizational pattern that is hypothesized to reflect the loss of the electroreceptive portion of the lateral line system; it is suggested that electroreception was lost sometime between the chondrostean and teleostean radiations. Each group of electroreceptive teleosts is believed to have evolved electroreception independently (Bullock, '74), a situation that is reflected centrally by a third organizational pattern within the lateralis area, which is distinctly different from that of early radiations of electroreceptive fishes.The octavus area of actinopterygians exhibits two patterns of organization-that of polypteriforms, chondrosteans, and holosteans, and that of teleosts. The functional significance of these patterns has yet to be elucidated.

Notes: During initial stages of oogenesis, many nucleoli are adpressed to the inner membrane of the nuclear envelope. Small nucleolar fragments appear to traverse the pores of the nuclear envelope and accumulate in the perinuclear ooplasm as fibrogranular bodies. Mitochondria become closely associated with some of the fibrogranular bodies. In addition to ribosomes and polyribosomes that are present in small oocytes, lamellae of rough-surfaced endoplasmic reticulum (rER) increase greatly in number during early stages of differentiation. Some individual lamellae are attached at their ends to the outer membrane of the nuclear envelope. Many parallel lamellae of rER are then encountered as well as numerous circular profiles consisting of concentric loops of rER. Soon after the differentiation of the extensive system of rER, lipid droplets or spheres appear in the ooplasm and they are initially surrounded by many circular, concentric lamellae of rER. Initially, the number of concentric lamellae of rER surrounding a lipid droplet may vary from less than a dozen to more than two dozen. During middle and late phases of vitellogenesis, most of the lipid spheres that comprise the most numerous and significant component of the yolk are surrounded by only one or two concentric lamellae of rER (in some cases the lamellae are part rough-surfaced and part smooth-surfaced). In addition, annulate lamellae are then observed to be associated with a portion of the lipid droplet surface. The number of annulate lamellae that extend focally from the lipid sphere distally into the cytoplasm is variable; often two or three to more than a dozen lamellae. Small granules, many of which range from 6 to 12 nm and thin fibrils (approximately 2-3 nm in width) may be associated with the annulate lamellae. In addition, polyribosomes frequently appear to be continuous with the pore-associated material of the annulate lamellae. The ends of some annulate lamellae may extend as lamellae of the rER. The morphologic relationships and relationships and variations observed between the lipid droplets, rER, annulate lamellae, and polyribosomes during lipidogenesis in this oocyte are interpreted to support a recent hypothesis (Kessel, 1981a,b) that the pores of annulate lamellae may be involved in some manner with the processing of ribosomal subunits or precursors into functioning polyribosomes, and that their appearance in specific association with the surface of many lipid spheres and rER in the oocyte late in vitellogenesis may be related to the formation of additional functional polyribosomes necessary to complete the final synthesis of many lipid droplets that are present in the ooplasm of the full-grown oocyte.

Notes: Using transmission electron microscopy of thin sections we have examined neuronal concentrations at hypostome-tentacle junctions in Hydra littoralis. A total of 194 ganglion cells were counted in 587 serial thin sections of a single hypostome-tentacle junction. We found two distinct types of ganglion cells: those with and those lacking stereocilia. The majority of the neurons observed lacked stereocilia; in a single hypostome-tentacle junction only 37% of the ganglion cells possessed a kinocilium surrounded by rodlike stereocilia. Most of the ganglion cells (55%) were clustered together in the oral or upper epidermis of the hypostome-tentacle junction: Nineteen percent were in the lateral and 26% in the aboral or lower epidermis. The two types of ganglion cells did not differ significantly in their distribution. Both types of ganglion cell had synaptic contacts with other neurons and with epitheliomuscular cells. More than 85% of the neuroneuronal and 61% of the neuroepitheliomuscular cell synapses were located in the oral epidermis of a hypostome-tentacle junction. In addition, two-way chemical synapses and a gap junction between neurons were observed at hypostome-tentacle junctions. Our morphological evidence of synaptic connectivity in neuronal clusters at hypostome-tentacle junctions suggests that primitive ganglia are present in Hydra.

Notes: Ventral bars, cartilaginous projections from the ventral aspect of the synsacrum that contact and form a joint with the ilium, were found in all normal chick embryos of age E9 and older. Bars were absent in a number of embryos which had been paralyzed from age E4 by the use of the acetylcholine receptor blocker α-bungarotoxin. They were also absent in some embryos that had been paralyzed between ages E4 and E10 but allowed to move thereafter. The bars, already formed, remained present in a third group of embryos in which paralysis was initiated at age E10. Apparently, normal embryonic movements induce the formation of bars. In support of this conclusion is the observation that two of three embryos which had had their hindlimb buds amputated at age E3 lacked bars. In these embryos with amputations, the ilium was present at least in part, but the forces exerted on the region where the bars develop would have been greatly reduced because of the lack of hind limb musculature. It is concluded that the bars, which form part of the iliosynsacral joint, are induced epigenetically by normal embryonic movements.

Notes: The development of the crayfish retina was examined in embryos and first, second and third instars with both and light and electron microscope. Light microscopic observations indicate that differentiation begins at the posterior portion of the optic disc and progresses in an anterior direction. Development of screening pigment, dioptric elements, and rhabdoms all parallel this posterior to anterior gradient in the retina. Tracer studies in early embryos reveal that the retina is separated from the proximal neuropil regions by a distinct vascular space. This observation suggests that the source of new cells for the retina may not be the more proximal cell proliferation zone as previously indicated. It is proposed that mitotic activity within the retina and/or differentiation of cells from the anterior surface layer of the eye may be sources for addition of new cells to the retina. Proto-ommatidial clusters of seven retinula cells occur very early at the posterior region of the embryonic retina. Initially the receptor cells extend throughout the entire thickness of the retina, but later they withdraw from beneath the cornea to occupy only the proximal portion of the retina. Microvilli of the rhabdom arise from the centrally opposed membranes of the retinula cells in each cell cluster. Each new microvillus contains a core of fine filaments which extend out into the cytoplasm at its base. As development of the microvilli continues, the core filaments appear to be lost or altered, but the cytoplasmic bundles at the base of the microvilli persist.

Notes: A model is presented to express how effectively animals increase the exposed surface area of their food by chewing. It includes a coefficient of masticatory effectiveness (E) the value of which increases with effectiveness of exposing new food surface area with each chew. Humans and other species of primates differ significantly in their values of E; among the nonhuman primates studies, Lemur catta has a higher coefficient than Lemur fulvus, and both have higher coefficients than either Varecia variegatus or Galago crassicaudatus argentatus. The differences among the coefficients to these prosimians are correlated with variations in specific features of the molar morphology.Of six lower molar shearing crests considered, the relative length of the post-metacristid correlates most highly with the coefficient of masticatory effectiveness for the prosimian species. Also, among comparable-sized prosimians, E correlates significantly with the absolute postmetacristid length. Both these findings indicate that the relative size of molar shearing crests is related significantly to how effectively an animal chews its food. There are also implications for an adaptation to a high-fiber diet.

Notes: Freshly extruded spermatophores from the lobster, Homarus americanus, were examined using light microscopy and scanning and transmission electron microscopy. The tubular spermatophore is trifoil in shape with two lobes tapered laterally from a third lobe situated ventrally. It is comprised of sperm surrounded by three acellular investments: (1) a primary spermatophore layer, (2) an intermediate layer, and (3) an outer bounding layer. The sperm are packed into a continuous tube contained largely within the ventral lobe and are embedded in a matrix of moderate electron density. The primary spermatophore layer is uniformly thick around the sperm mass and contains at its peripheral margins both ring structures and crystals in an amorphous matrix. The intermediate layer is thicker dorsally than ventrally. Dense granules dominate the ventral half of the intermediate layer while inclusions populate the dorsal half; both react positively to the periodic acid-Schiff (PAS) technique. The innermost portion of the outer bounding layer is composed of parallel fibrils; a flocculent material is present peripherally. This flocculent substance is presumed to impart stickiness to freshly extruded spermatophores. These observations provide a basis for the future understanding of the mechanisms involved in long-term storage of sperm in spermatophores.

Notes: This paper describes the early embryonic development of Neomicropteryx nipponensis from oviposition to the formation of the inner layer. Newly laid eggs are covered with many hygroscopic, gelatinous masses. The chorion is composed of a porous, spongy exochorion of variable thickness and of a thin endochorion. The eggs have a very thin periplasm and contain large amounts of yolk made of proteid and fatty yolk droplets. The processes of maturation division, fertilization, and cleavage are similar to those commonly found in lepidopteran eggs. The blastoderm of Neomicropteryx is very thin in comparison with that of other lepidopteran eggs. The small circular germ disk is formed on the ventral egg surface. It then invaginates deeply into the yolk to form a sac-shaped germ rudiment. The formation of the germ rudiment and of the embryonic membranes resembles that of swift moths, Endoclita (suborder Monotrysia) and of the caddisfly, Stenopsyche (Trichoptera), but differs from that of ditrysian Lepidoptera. As in other lepidopteran insects, the formation of the inner layer begins after completion of the germ band, which has a bilobed protocephalon and a slender protocorm. Unlike the situation in most lepidopteran eggs, yolk segmentation does not occur in N. nipponensis. During formation of the germ band, hydropyle cells are formed in the dorso-posterior region of the serosa; these are here reported for the first time in the eggs of holometabolan insects.

Notes: Analysis of the feeding apparatus of the stone crab, Menippe mercenaria (Brachyura, Xanthidae), has demonstrated that substantial internal and external morphological alterations occur at metamorphosis and suggests that the mastication of food shifts from the mandibles to the gastric mill at that time. These changes correspond to the changes in environment and diet that take place at metamorphosis, when the previously planktotrophic larvae begin benthic life.A detailed account of the structure and development of the mandibles is presented. The mandibles of all zoeal stages are similar: The incisor process has a series of teeth and denticles and the prominent molar process appears to be well adapted for grinding food. Megalopal mandibles are transitional but have the form that is typical of all subsequent stages: The expanded incisor process is rounded and toothless and the molar process is less prominent and has lost its grinding denticles. The cardiac stomach of the zoeal stages has no gastric mill; the medial and lateral teeth of the mill first appear in the megalopa.A very simple procedure is described for preparing larval mandibles for scanning electron microscopy using the molted exoskeletons from larval rearing experiments.

Notes: The ultrastructure of the sensilla, and other structures, within the stylets and precibarium of Macrosteles fascifrons were examined by transmission and scanning electron microscopy. Precibarium is a new term, defined here, for the canal that precedes the cibarium inside the leafhopper head. Within the precibarium are found 20 chemosensilla and a previously undescribed structure, the precibarial valve. Twelve mechanosensilla, three in each stylet, are found within the maxillary and mandibular stylets. The relationship between all of these structures and feeding by the insect is detailed in a feeding mechanism hypothesis. It is concluded that leafhoppers (and probably all homopterans) utilize the precibarial chemosensilla alone for gustatory discrimination, the stylet sensilla for proprioception, and the precibarial valve for regulation of fluid uptake and compartmentalization of the sensilla.

Notes: The nephrons of carp (Cyprinus carpio) and goldfish (Carassius auratus) were examined histologically and also histochemically for enzymes. In both species the distal and collecting tubules have much wider lumens than do the other renal tubules; thus urine probably flows more slowly in these larger tubules. Enzyme histochemistry shows that epithelium of the neck and proximal and intermediate tubules respires anaerobically. whereas that of the distal and collecting tubules respires aerobically. The distribution of Na-K-ATPase in the distal and collecting tubules indicates that they also transport sodium actively. The slow flow of urine and the energy produced by aerobic metabolism probably increase the efficiency of active transport.

Notes: The effect of ovarian hormones on the activities of glucose-6-phosphatase and alkaline phosphatase in the vaginal epithelium was studied in immature and ovariectomized rats, using ultracytochemical techniques. Comparative studies were done on normal rats at the luteal phase and on day 14 of pregnancy.Various vaginal cells show different degrees of response to progesterone and diethylstilbestrol (DES) with regard to glucose-6-phosphatase activity. Intense glucose-6-phosphatase activity was observed in the cisternae of granular endoplasmic reticulum (rER), Golgi saccules and vesicles, and nuclear envelope of both basal cells and stromal cells of progesterone treated rats, whereas in the basal cells and stromal cells of DES-treated and control animals the enzyme was totally lacking. Detectable glucose-6-phosphatase activity was also observed, however, in the rER cisternae and Golgic complex of keratohyalin-secreting squamous intermediate cells of the vaginal epithelium of DES-treated rats. Alkaline phosphatase was observed in the plasma membranes of various cell types of vaginal epithelium in the normal, progesterone-, and DES-treated rats, Alkaline phosphatase was also found on the limiting membranes of secretory granules of mucocytes in animals at the luteal phase and during pregnancy. DES and progesterone in the doses used did not affect alkaline phosphatase activity in the rat vagina. Overall, progesterone enhances glucose-6-phosphatase activity in basal cells of the rat vagina prior to completion of mucification. Alkaline phosphatase was found in all cells involved in mucin secretion.

Notes: The distribution of the adrenaline and noradrenaline chromaffin cells in the adrenal glands of 10 members of the family Cordylidae have been examined. In the genus Gerrhosaurus, all the catecholamine cells lie on the surface of the adrenal gland, forming a continuous envelope of one or two layers of cells that mainly contain noradrenaline (NA). In the genus Platysaurus, the chromaffin envelope is intermittent. There are relatively large tracts of interspersed interrenal tissue containing some adrenaline cells (A). Islets of chromaffin cells are scattered between these interrenal tracts. In the genus Pseudocordylus and the genus Cordylus, the superficial chromaffin cells tend to gather into a multilayered dorsal mass, containing mainly NA cells. Inside the interrenal parenchyma, there are always numerous chromaffin islets, containing mainly A cells.

Notes: Muscle spindles were studied histochemically in serial transverse sections of 42 cat tenussimus muscle specimens. Staining for myofibrillar adenosine triphosphatase was employed to identify nuclear bag1, nuclear bag2, and nuclear chain intrafusal muscle fibers. The nuclear chain fibers were further subdivided into three categories according to their polar length and the intensity of their staining for nicotinamide adenine dinucleotide tetrazolium reductase. A total of 430 spindle poles were surveyed. The mean spindle content of bag1, bag2, and chain fibers was established. The mean polar length of intrafusal fibers as well as that of the intracapsular and extracapsular spindle regions was determined. A cholinesterase (ChE) staining technique was used to demonstrate the termination sites of motor axons along intrafusal fibers. Two types of circumscribed ChE deposits, the “rim” and the “plate,” occurred on the fibers. The nuclear chain fibers usually carried both the ChE rims and plates, while most nuclear bag fibers displayed only the plates. The ChE plates were assessed in term of their appearance, staining intensity, length, and location along the fibers. The mean number of ChE plates found along the fibers was established for each of the various intrafusal fiber types.These histochemical observations are discussed with regard to the current concepts of cat spindle morphology and motor innervation. The results suggest a degree of predictability in the spindle fiber content and in the distribution of motor nerve terminals along intrafusal muscle fibers, at least in the tenuissimus muscle.

Notes: Freshly harvested kidneys from New Zealand white rabbits, Sprague-Dawley white rats, rhesus monkeys, and transplant-quality human kidneys were used in this study. Minced renal cortical tissue blocks (〈2 mm3) were treated with 1 mM EDTA, 3% Triton X-100, 0.025% DNAse, and 4% sodium deoxycholate in an effort to remove all cellular elements and leave the extracellular matrix (ECM) intact. These preparations showed remarkable structural preservation and all components of the ECM, including basement membranes (BMs), maintained their in vivo histoarchitectural relationships. By light microscopy, at least four major BM types were recognizable, including Bowman's capsular BM (BCBM), tubular BM (TBM), glomerular BM (GBM), and peritubular capillary BM (PTCBM). Scanning electron microscopy demonstrated that, despite the lack of supporting interstitium, GBMs in human, monkey, and rat (and rabbit to a lesser degree) exhibit intrinsic structural rigidity such that their convoluted spheroidal shapes are maintained following cell removal. Transmission electron microscopy showed that major BM types are morphologically heterogeneous and vary markedly within and between species. Randomized measurements showed that isolated BM thicknesses (lamina densa only) compared favorably with those reported in cellular preparations. Mean thicknesses of GBMs were within normal ranges in all species with or without power transformations to reduce right-sided skew of distribution curves. In all species, thickness of BCBM 〉 TBM 〉 GGBM 〉 PTCBM. The striking morphologic heterogeneity of major BM types demonstrated in the acellular renal cortex is not surprising in view of recent biochemical analyses that show that BMs derived from different sources are compositionally disparate. We conclude that BMs should be evaluated and characterized individually and that morphologic definition of isolated BMs is necessary prior to further analysis.

Notes: The aedeagal gland of male Tenebrio molitor consists of numerous acini containing several secretory units (organules) of three epithelial cells in series. The distal cortical cell and intermediate cell are secretory cells. Secretory products are passed into microvilli-lined extracellular reservoirs. From these storage areas products flow through minute canaliculi and into the efferent ductule. Canaliculi, cuticular trabeculae, and fibrillar material are characteristic features of the efferent ductules within the extracellular reservoirs of secretory cells. After passing from the secretory cells, the efferent ductule penetrates the basal ductule cell. The thin epicuticle that comprises the wall of the ductule is confluent with the epicuticle of the cuticular sheath forming the wall of the genital pocket. Secretory products flow from the cortical cell ductule into the intermediate cell and eventually empty into the genital pocket. A chemical reaction apparently takes place in the intermediate cell ductule, resulting in a frothy secretion product. When released from the ductule, this frothy product forms a foam-like layer that coats the inner wall of the genital pocket. Ultrastructural and probable functional aspects of this gland are described and discussed.

Notes: For years teeth of tetraodontoid fishes generally have been considered coalescent even though “coalescence,” which also is found in fishes of other families, has never been well defined. This paper deals with some aspects of coalescence of the teeth in tetraodontoids and attempts to define this condition. The sites of osteodentinogenesis and the mechanisms by which hard tissues are formed, reabsorbed, and abraded during feeding were analyzed from semiserial decalcified sections and from ground sections, as well as from autoradiographs of the premaxilla and dentary bones of Sphoeroides greeleyi. The observations reported here, taken together with other data we have obtained on members of the Tetraodontoidei, permit clear definitions of “tooth” and “supporting bone,” and consequently the structural meaning of coalescence. From these data we hypothesize how coalesced masticatory structures may have evolved in this group.

Notes: The masticatory pattern of Sphenodon punctatus, the sole remaining rhynchocephalian, now restricted to islands off the coast of New Zealand, has been analyzed by detailed anatomy, cinematography, cinefluoroscopy, and electromyography. Food reduction consists of a closing, crushing bite followed by a propalineal sliding of the dentary row between the maxillary and palatine ones. The large, fleshy tongue can be protruded to pick up small prey, and also plays a major role in prey manipulation. The rotational closing movement of the jaw, supporting the basic crushing movement, is induced by the main adductor musculature. It is followed by a propalineal anterior displacement relying heavily on the action of the M. pterygoideus. The fiber lengths of the several muscles reflect the extent of shortening. The most obvious modification appears in the M. pterygoideus, which contains a central slip of pinnately arranged short fibers that act a period different from that of the rest of the muscle; their action increases the power during the terminal portion of the propalineal phase. This also allows the animal to use its short teeth in an effective shearing bite that cuts fragments off large prey.The action of single cusped dentary teeth acting between the maxillary and palatine tooth rows provides a translational crushing-cutting action that may be an analog of the mammalian molar pattern. However, this strictly fore-aft slide does not incorporate capacity for later development of lateral movement.

Notes: Force, velocity, and displacement properties of a muscle are determined in large part by its architectural design. The relative effect of muscle architecture on these physiological variables was studied by determining muscle weight, fiber length, average sarcomere length, and approximate angle of pinnation for 24 cat hind limb muscles. Muscle lengths ranged from 28.3 to 144 mm, whereas fiber lengths ranged from 8.4 to 105.5 mm. Generally, fiber to muscle length ratios were similar throughout a muscle. Estimated angles of pinnation of muscle fibers varied from 0 to 21° with most having an angle of less than 10°. The cross-sectional area of the knee extensors was similar to the knee flexors (16.43 vs. 16.83 cm2) whereas the cross-sectional area of the ankle extensors was more than six times greater than the ankle flexors (18.59 vs. 2.83 cm2). There was a 6.7-fold difference in the maximal force between muscles, when normalized to a constant weight, that could be attributed to architectural features. Rations of wet weight to predicted maximal tetanic tension for each muscle and group were calculated to compare the relative priority of muscle force versus muscle length-velocity for a given mass of muscle. These ratios varied from 0.4 to 4.84. The ratios suggest that velocity and/or displacement is a priority for the hamstrings, whereas force is a priority for the quadriceps and lower leg muscles. As much as a 12.6-fold difference in maximal velocity between muscles can be attributed to differences in fiber lengths. This can be compared to approximately a 2.5-fold difference in maximal velocity reported to occur as a result of biochemical (intrinsic) differences.

Notes: The surface receptors in Branchiobdella pentodonta consist of “sense buttons” prevalent on the prostomium, isolated sense cells all along the body of the animal, and free nerve endings. The “sense buttons” are uni- and multiciliated neurosensitive elements and supporting cells together with mucus glandular processes and muscle fibers. In the neurosensitive elements the cilia are always surrounded by cytoplasmic extroversion. The cytoplasm of the apical zone has abundant small dense granules, mitochondria, bands of tonofilaments, and microtubules. The cilium of uniciliated elements originates from three short roots. The highly vacuolated support cells surround the neurosensitive elements, separating them from each other. The “sense buttons” appear to be mechanoreceptors and chemoreceptors, and the isolated sense cells tactile mechanoreceptors, as are the free nerve endings. The surface receptors are compared with those of other Oligochaeta and Hirudinea.

Notes: Some sea anemones possess structures called acrorhagi at the base of the tentacles. The acrorhagi are utilized solely for aggression. Acrorhagial aggression involves very exquisite intra- and interspecific recognition. This study examined acrorhagi and putative acrorhagial analogues or homologues in four species of sea anemone. The morphology and ultrastructure of tentacles, pseudoacrorhagi, column vesicles, and verrucae (adhesive column vesicles) differed from that of acrorhagi. Coral capitate tentacles and acrorhagi have different surface morphology, nematocysts, and functions. Besed on morphology, acrorhagi seem more likely to be homologous to tentacles than to verrucae.Acrorhagial nematocyst discharge and ectodermal peeling, the culmination of the response, were shown to require prior acrorhagial expansion in Anthopleura krebsi and Bunodosoma cavernata. A mechanical mechanism is suggested where- by distention of the acrorhagus opens a ciliary pit on the nematocyte surface and exposes the pit wall and microvilli, which may contain the chemoreceptors for the peeling process, including nematocyst discharge. A similar system may also be responsible for changing the threshold of nematocyst discharge in sea anemone tentacles. A case of possible neurosecretion in an anthozoan was also shown in this study.

Notes: The fine structure of spermatogenesis is described for the marine calanoid copepod Labidocera aestiva. The mature spermatozoon is a slightly flattened, disc-shaped cell without a flagellum or an acrosome.Primary spermatocytes in first meiotic prophase are characterized by large nuclei showing progressive condensation of chromatin. The cytoplasm contains free ribosomes, numerous mitochondria, cytoplasmic vesicles, centrioles, and perinuclear nuage. Densely staining cisternae are associated with the nuage of pachytene and diplotene primary spermatocytes. This association may represent the temporary differentiation of an acrosome. Synaptonemal polycomplexes are frequently present in the nuclei of zygotene, pachytene, and diplotene primary spermatocytes. Many of the intercellular bridges which join the germ cells throughout spermatogenesis appear occluded by systems of transverse membranous cisternae. After the second meiotic telophase, spermatids are incorporated into nongerminal accessory cells that may facilitate the release of spermatids from the testis and regulate the rate of spermatogenesis by phagocytosis.During spermiogenesis the mitochondria become closely applied to the nuclear envelope, the nuclear envelope fragments and forms an elaborate membrane complex, a pentalaminar plasma membrane develops, and electron-dense material accumulates on the inner and outer surfaces of the plasma membrane in the mature spermatozoon.

Notes: This study examines the structure of mucosal glands in the walls of the hamster maxillary recess, compares the histochemical appearance of nasal glands to their sialic acid content, and determines the vulnerability of nasal glands to actinomycin toxicity. Observations were made on plastic-embedded tissue with light and transmission electron microscopes. Determinations of total sialic acid in mucosal samples were conducted with thiobarbituric acid. Experimental hamsters were administered 0.2 μg of actinomycin D (IP)/gm body weight/day for five days. Types of granules present in the lateral nasal gland (LNG) and glands of the maxillary recess (MRGs) include: 2.0 μm lightly basophilic, lightly electron-dense granules and 1.5 μm strongly basophilic, electron-dense granules in the same acinar cell type in both the LNG and MRGs; 1.5 μm metachromatic granules in some acinar cells of the LNG; 1.0 μm moderately electron-dense granules in cells of MRG ducts; and 0.7 μm electrondense granules in cells of LNG intercalated ducts. Acid glycoproteins, demonstrable by histochemistry, are present in the LNG but not in the MRGs. However, the total sialic acid content of tissues from MRG tissue is greater than that of other tissues measured. A minor number of LNG acini, those with metachromatic granules, have branching basal cytoplasmic projections. Many dark cells are present in striated ducts of the LNG. Histological alteration due to actinomycin-D toxicity, conspicuous in parotid salivary parenchyma, is greater in MRG than in LNG tissue.

Notes: The head kidneys of adult Periophthalamus koelreuteri contain many functional glomerular nephorns which on the basis of this histochemical study, are indistinguishable from those of the typical opistonephros of marine teleosts. The anterior lobes resemble, in location and in the presence of intertubular erythropoeitic tissue, the pronephros in other species. The single nephron found there, however, does not differ significantly from the other nephrons of the head kidney. It is suggested, therefore, that the nephrons of the head kidney in this species are opisthonephric in origin.

Notes: The eyestalk of the astacideans Orconects limosus, Nephrops norvegicus, and Homarus gammarus, and the palinuran Palinurus vulgaris, was examined with an antiserum raised against purified crustacean hyperglycemic hormone (CHH) of the astacidean species Astacus leptodactylus. A distinct immunopositive reaction occurs in a group of neurosecretory cells in the medulla terminalis ganglionic X-organ (MTGX), in the MTGX-sinus gland tractus, and in a considerable part of the sinus gland. The immunoreactive sites in the eyestalk of the investigated species correspond to the site of production, storage, and release of the CHH. Preliminary investigations with this antiserum also indicate that a positive immunoreaction can be obtained in the eyestalk of other decapod crustaceans, for example, of the brachyuran Macropipus puber and the caridean Palaemon serratus.

Notes: Shells from eggs of the tuatara (Sphenodon punctatus) are 0.2 mm thick and are composed of a layer of calcite and a multi-layered, fibrous shell membrane. Most of the calcareous layer is composed of roughly circular columns of crystalline material that extend deep into the shell membrane. The crystalline matrix of the columns is interwoven with fibers of the shell membrane except near the outer surface of the eggshell, where the calcareous material is more compact. Overlying the columns is a granular layer composed of blocks of crystalline material of random size, shape, and orientation. Disruption of this granular layer, perhaps through swelling of the eggs or as a result of environmental factors, gives the outer surface of the eggshell a coarse, weathered appearance. Removal of the calcareous material with a decalcifying agent shows that the outer surface of the shell membrane is composed of a meshwork of small fibers bound together by an amorphous matrix. No matrix was observed in inner layers of the shell membrane, and the fibers of these inner layers are arranged somewhat more regularly than the outer fibers. No structure comparable to the central cores of avian and certain chelonian eggs was observed in eggshells of the tuatara.

Notes: Leukocytic organs of Amynthas diffringens are aggregations of leukocytes contained within a smooth muscle and stromal cell framework suspended in the coelom. Elongate processes of stromal cells subdivide each organ into numerous cell-filled compartments and are perforated by 130-nm pores that may permit the exchange of humoral substances between compartments, or between the organ and the surrounding coelomic fluid.We divide leukocytes within the organs into four morphotypes. Phagocytic leukocytes have many lysosomelike vesicles and may possess phagosomes. Mature types I, II, and III granulocytic leukocytes share certain features but are readily distinguished by cell shape and by the size, shape, and electron density of the cytoplasmic inclusions. Immature as well as mature phagocytes and granulocytes occur within these organs, suggesting that they are sites of leukocyte maturation and storage. Concentrations of leukocytes within the organs result in extensive cell to cell contact, especially within islets and tightly packed cords. Phagocytosis of cell debris occurs throughout the organs.Immature stages of the four morphotypes are difficult to distinguish even at high magnification, raising the possibility that they may originate from a common precursor. Our inability to observe mitoses or to detect lymphocytelike stem cells suggests that immature leukocytes migrate to the organs via coelomic fluid from as yet unidentified primary sites of production.

Notes: Rickettsiae-like structures were found in the salivary gland cells of Drosophila auraria during different larval and prepupal developmental stages, from the early 3rd instar up to 14 hr after spiracle inversion. These microorganisms are surrounded by a membrane, are constantly intracellular, and occur singly or in groups. Their widespread occurrence in various tissues of other Drosophila species indicates that they can be considered as symbionts, but their actual functional significance (if any) is unknown.

Notes: Histology of each of the five segments of the oviduct of the female turtle Chrysemys picta was described for successive intervals throughout their annual cycle. Uterine and glandular segments showed marked seasonal variations in the extent and content of the submucosal and epithelial glands. Submucosal glands were most prominent in preovulatory and postovulatory animals (May to June), regressing in late summer (oviposited animals) and recrudescing the following spring. These changes correlated with variations in the muscularis layer, the number of uterine epithelial blebs, oviductal vascularity, and the presence of eosinophils in cervical segment cross-sections. These cyclic seasonal changes are discussed in relationship to reported seasonal changes in gonadal steroids in this species. Hormonal control was corroborated by oviductal response to estradiol-17β injected (1 mg/kg daily for 2 weeks) into mature, reproductively inactive (winter) animals. This treatment induced increases in glandular activity, vascularity, and distribution of eosinophils comparable to those of reproductively active (summer) animals.

Notes: Molluscan shells, including those of Gastropoda, are formed by accretionary growth at the mantle edge. The mantle is a thin membrane of skirt-like shape, which extends minutely beyond the aperture, and its edge adds a shell increment to the aperture margin so that each increment copies a configuration of the mantle edge at that time. Thus, regulation of shell morphogeny is almost equivalent to the factors which control the mantle form at the moment of shell growth. Form of the mantle skirt is considered to be kept in a state of balance between the force of its internal stress and forces acting on it such as fluid pressure or muscle contraction.The expansion behavior of the mantle skirt has been numerically analyzed by using an elastic model (DMS-tube), which represents the fundamental structure of the mantle tissue as a double membrane structure with internal springs (DMS). Four characteristic expansion patterns of the DMS-tube have been detected: (1) general outward expansion; (2) developing a ridge-like fold on an initial longitudinal protrusion of the tube edge; (3) drastic shift of the expanded state from a uniformly curved to an elliptical shape in outline, owing to the existence of a fixed boundary condition on the tube wall; and (4) constricted protrusion on the open region of the shell wall surrounding the DMS-tube. These results have the potential for answering the following questions relating to the morphogenesis of gastropod shells. How does the mantle skirt usually make contact with the inner surface of the shell wall so as to ensure continuous accretion of shell materials to the aperture margin? What is the cause of spiral ridges? Why do open coiling or minimally overlapping shells have generally circular apertures, while shells with apertures overlapped by whorls have non-uniformly curved apertural lips? What is the cause of long closed spines and why do they always appear on spiral ridges?

Notes: The larval antenna of Bombyx mori has 13 sensilla and about 52 sensory neurons in its distal portion. The axons form two nerve cords which unite in the cranial hemocoel to supply the brain as the olfactory nerve. The antennal imaginal disc, which is a thick pseudostratified epithelium continuous with the antennal epidermis, thickens markedly during the 5th instar by rapid cell proliferation. At the prepupal stage cell proliferation ceases and the disc everts to form a large pupal antenna. Simultaneously, an extensive cell rearrangement occurs in the antennal epidermis and the disc tissue becomes much thinner because of the abrupt expansion of antennal surface area. The two larval nerve cords thin down markedly by degeneration of axons, but they do not disintegrate totally even after the onset of pupation. The epidermis of the larval antenna forms the distal portion of the pupal antenna, while the imaginal disc forms the more basal portion. Development to the adult antenna occurs almost immediately after the onset of pupation; many adult neurons appear in the simple epidermis facing toward the thick outer side of the newly formed pupal cuticle. By 12 hours after the onset of pupation, these neurons align themselves in many transverse rows which are the first sign of the adult antennal configuration. Addition of these neuronal axons to the once-thinned nerve cords causes resumed thickening of the cords during the first 24 hours and thereafter. Differentiation of adult sensilla begins in the next 24 hours and is almost completed at the third day of pupation, which requires a total of 10 days.

Notes: Sensilla diversity and abundance were extremely high on the apex of the maxillary and labial palpi of two species of Gryllacrididae. The terminal segment of the maxillary palpi of these species had 9 and 15 sensilla types, respectively, and up to 2,834 sensilla. The labial palpi had 7 and 12 types, respectively, and up to 5,195 sensilla. Several types of multiporous smooth and ridged olfactory basiconic sensilla, and coeloconic, coelosphaeric, placoid, and multipapilliform sensilla occurred, as well as many trichoid sensilla and the more typical uniporous basiconic contact receptors. Two species of the closely related Stenopelmatidae were compared to the gryllacridids and found to have similar sensillar diversity and abundance, but three species of the more distantly related Tettigoniidae had only 4 or 5 sensilla types and a total number ranging from 320 to 960 on their maxillary palpi.

Notes: The results of volumetric measurements led Hanström ('28) to suggest that specialized neuropil in the brain, the so-called central body (CB), may be of particular importance in the nervous control of web building behavior in spiders. We compared the volumes of the various brain regions in four spider species clearly differing in lifestyle and web building behavior: an orb weaver (Nephila clavipes), a wandering spider (Cupiennius salei), a jumping spider (Phidippus regius), and a bird spider (Ephebopus sp.). Our results obtained in adult animals as well as our observations on the postembryonic development of the brain do not support Hanström's hypothesis. The relative share of the CB in the brain is very similar in all four species (ca. 3.1 to 5.1%). The differentiation of the CB into a clearly demarcated two-lobed structure does not coincide with the onset of web building behavior in Nephila. The CB of both Nephila and Cupiennius is already clearly recognizable in spiderlings which have not even left the egg sac.

Notes: The venom gland of Crotalus viridis oreganus is composed of two discrete secretory regions: a small anterior portion, the accessory gland, and a much larger main gland. These two glands are joined by a short primary duct consisting of simple columnar secretory cells and basal horizontal cells. The main gland has at least four morphologically distinct cell types: secretory cells, the dominant cell of the gland, mitochondria-rich cells, horizontal cells, and “dark” cells. Scanning electron microscopy shows that the mitochondria-rich cells are recessed into pits of varying depth; these cells do not secrete. Horizontal cells may serve as secretory stem cells, and “dark” cells may be myoepithelial cells. The accessory gland contains at least six distinct cell types: mucosecretory cells with large mucous granules, mitochondria-rich cells with apical vesicles, mitochondria-rich cells with electron-dense secretory granules, mitochondria-rich cells with numerous cilia, horizontal cells, and “dark” cells. Mitochondria-rich cells with apical vesicles or cilia cover much of the apical surface of mucosecretory cells and these three cell types are found in the anterior distal tubules of the accessory gland. The posterior regions of the accessory gland lack mucosecretory cells and do not appear to secrete. Ciliated cells have not been noted previously in snake venom glands.Release of secretory products (venom) into the lumen of the main gland is by exocytosis of granules and by release of intact membrane-bound vesicles. Following venom extraction, main gland secretory and mitochondria-rich cells increase in height, and protein synthesis (as suggested by rough endoplasmic reticulum proliferation) increases dramatically. No new cell types or alterations in morphology were noted among glands taken from either adult or juvenile snakes, even though the venom of each is quite distinct. In general, the glands of C. v. oreganus share structural similarities with those of crotalids and viperids previously described.

Notes: The organization of identified neurosecretory cell groups in the larval brain of the tobacco hornworm, Manduca sexta, was investigated immunocytologically. Computer-assisted three-dimensional reconstruction was used to examine the architecture of the neurosecretory cell groups. The group III lateral neurosecretory cells (L-NSC III) which produce the prothoracicotropic hormone are located dorsolaterally in the protocerebrum and extend axons medially that decussate to the contralateral lobe prior to exiting the brain through the nervi corporis cardiaci I + II. The group IIa2 medial neurosecretory cells (M-NSC IIa2) are located anteriorly in the medial dorsal protocerebrum. The axons of these cells also exit the brain via the contralateral nervi corporis cardiaci I + II. However, their axons traverse a different pathway through the brain from that of the L-NSC III axons. Each of the cell groups possesses elaborate dendrites with terminal varicosities. The dendrites can be classified into specific fields based upon their location and projection pattern within the brain. The dendrites for these two neurosecretory cell groups overlap in specific regions of the protocerebral neuropil. After the axons of these neurosecretory cells exit the brain through the retrocerebral nerve, they innervate the corpus allatum where they arborize to form neurohemal terminals in strikingly different patterns. The L-NSC III penetrate throughout the glandular structure and the M-NSC IIa2 terminals are restricted to the external sheath. A third group of cerebral neurosecretory cells, the ventromedial neurons (VM) which stain with the monoclonal antibody to prothoracicotropic hormone in Manduca, are located anteriorly in the medial region of the brain. The axons of these cells do not exit the brain to the retrocerebral complex, but rather pass through the circumesophageal connectives and ventral nerve cord. These neurons appear to be the same VM neurons that produce eclosion hormone. One dendritic field of the L-NSC III terminates in close apposition to the VM neurons. The distinct morphologies of these neurosecretory cell groups in relation to other cell groups and the distribution of neuropeptides within the neurons suggest that insect neurosecretory cells, like their vertebrate counterparts, may have multiple regulatory roles.

Notes: The micropylar apparatus (MA) in Rhagoletis cerasi (Diptera, Tephritidae) is located at the anterior pole of the egg and consists of two parts: an outer chorion and an inner vitelline membrane. Sperm entry takes place through the micropylar canal, 2.0-2.5 μm in diameter, which penetrates the micropylar endochorion and terminates in the thick vitelline membrane, thus forming the “pocket.” The pore of the micropylar canal, i.e., the micropyle, is covered by the exochorionic tuft.The formation of the MA is accomplished by 40 micropylar cells during oogenesis. These cells secrete the successive eggshell layers: the vitelline membrane, the wax layer, the innermost chorionic layer, the micropylar endochorion, and the exochorion. Two among 40 micropylar cells differentiate and form two tightly connected projections. The latter contain a bundle of parallel microtubules and participate in the formation of the micropylar canal and the pocket. At the tip of the projections there are two thin extensions full of microfilaments. In late developmental stages the two projections and the extensions degenerate and leave the canal and the pocket behind. We also discuss the structural features of the MA in relation to its physiology among Diptera.

Notes: It is uncommon to find acid phosphatase activity in mature secretory granules. This paper demonstrates by light and electron microscope cytochemistry an acid phosphatase in mature secretory granules in the cells of one region of the salivary gland of Bradysia hygida (Diptera, Sciaridae). These secretory granules increase in number during larval development up to the beginning of the pre-pupal period when they undergo massive exocytosis. Biochemical assays show that upon exocytosis of the majority of the granules the total acid phosphatase activity in the granular gland region drops to 10% of the maximum reached before exocytosis. During and after exocytosis, two other acid phosphatases, eletrophoretically different and much weaker in activity, become increasingly detectable in all gland regions. At the same time, in whole mount preparations, numerous tiny acid phosphatase-positive granules (probably secondary lysosomes) become evident in all major cell types of the salivary gland. These results indicate that the S2 region of the salivary gland has mature secretory granules containing an acid phosphatase destined for exocytosis which is different in molecular properties from other acid phosphatases (likely lysosomal) made by the gland.

Notes: The general histology and ultrastructure of the tongue and anterior process of the sublingual plica of four Taiwanese venomous snakes, the Chinese cobra (Naja naja atra), banded krait (Bungarus multicinctus), Taiwan habu (Trimeresurus mucrosquamatus), and bamboo snake (Trimeresurus stejnegeri stejnegeri) are described.The tongue fork exhibits a mid-dorsal invagination that broadens gradually toward its base. No mid-ventral invagination is observed. The epithelial cells on both dorsal and ventral aspects of the tongue fork have large and small microfacets, micropores and microvilli. The cell size, distribution pattern of the large microfacets, and the number of small microfacets present on both sides of the fork are essentially the same within a species, but vary among species. The function of these ultrastructures on the cell surface might be for the capture of chemical substances. The large microfacets are raised areas of the cell membrane, each with a pale granule contained within. The chemical nature of the pale granule is not yet known. The small pores surrounding the large microfacets are shallow hollows left after the release of the pale granules from the microfacets. The basic histological pattern of the tongue fork of these species is similar, being composed of a mucosal layer outside and dense musculature inside. No taste buds are discernible.The anterior processes are concave-like expansions of the anteriormost portions of the sublingual plicae. The oblique folds and micropapillae of this organ might be helpful for receiving the chemicals collected on the tongue, when the tongue makes contact with the elevated processes. The elevated processes may penetrate the ducts of Jacobson's organs to effect the final transfer.

Notes: The scaleless notothenioid Gymnodraco acuticeps is a bottom dweller beneath the sea ice of McMurdo Sound, Antarctica. Gymnodraco experience unusual environmental conditions, including highly oxygenated subzero water. Skin morphology is evaluated with reference to its potential as a barrier to ice propagation and as a surface for cutaneous respiration. Light and electron microscopy and histochemistry reveal skin structure that is generally similar to that of other teleosts. In the epidermis, epithelial cells are arranged in nine to fifteen layers, and two types of mucous cells are also present. Large mucous cells are most common on external epidermal surfaces, whereas small cells are more frequent on internal epithelial surfaces. Epithelial cell junctions have extensive areas of desmosomes as well as interdigitations of the cell membranes, especially in the basal and midepidermis. The dermis consists of an exceptionally dense stratum compactum. The skin is thicker than that of Bovichtus, a scaleless temperate notothenioid from New Zealand. Mean skin thicknesses at sites on the trunk are 371-711 μm. With the exception of fins that contact the substrate, epidermal thickness between rays of most fins is 70-118 μm. The epithelial surfaces of the oral and branchial cavities are 27-50 μm thick. An unusual type of connective tissue is present beneath the epidermis of the pelvic fin. It contains abundant ground substance and is similar to mucous connective tissue of the mammalian umbilical cord. Perfusions of a microvascular filling agent reveal a moderately developed cutaneous vasculature. These vessels have the dimensions of capillaries (mean external diameter 11 μm). They are confined to the dermis and are more prominent on the head than on the trunk. The skin is secondary to the gills as a respiratory surface in Gymnodraco.