bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuromuscular organization of feline anterior sartorius: I. Asymmetric distribution of motor units
Authors: Thomson B. , Scott S. H. , Richmond F. J. R.
Published: February 2005

The neuromuscular organization of feline anterior sartorius was examined using three experimental approaches. First, the branching pattern of the nerve supplying anterior sartorius was inspected in muscles taken from a large number of feline cadavers. All muscles were found to be supplied by two major nerve branches, one directed proximally and the other directed distally, and most muscles (42/51) had a third distinct branch that entered the muscle centrally. Second, the motoneuronal populations supplying the three nerve branches were investigated by electrophysiological techniques. Motoneurons that supplied axons to the distally‐directed branch did not appear to have collaterals in more proximally‐located branches. In contrast, other motoneurons supplying the proximally‐directed branch also appeared to supply axon collaterals to the centrally‐directed branch. This result suggested that the motoneuronal population of the distally‐directed branch was largely separate from that supplying the proximally‐ and centrally‐directed branches. Third, the motor unit territories supplied by different nerve branches were mapped using glycogen‐depletion methods. Muscle fibers supplied by the distallydirected nerve branch were mostly distributed to the medial portion of anterior sartorius, whereas the fibers supplied by the other two branches were generally found more anteriorly. Further, the muscle fibers supplied by an individual nerve branch were present in greater numbers at the end of the muscle closest to the entry point of that branch. Thus, the motor units supplied by discrete nerve branches were found to be distributed asymmetrically within anterior sartorius, but were arranged neither strictly in‐parallel nor strictly in‐series.
Cell behavior during early development in the South American annual fishes of the genus Cynolebias
Authors: Carter C. A. , Wourms J. P.
Published: February 2005

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.
Ovary of the golden crab, Chaceon fenneri: I. Post‐spawning and oosorption
Authors: Hinsch Gertrude W.
Published: February 2005

Oosorption has been considered an important strategy in many invertebrate species which occurs in response to behavioral, ecological, or physiological factors. In crustaceans, the early light microscopic studies of the ovary attributed a role in oosorption to follicle cells, hemocytes, or phagocytes. In this study, ovaries were collected from female golden crabs following spawning and processed for examination by electron microscopy.

Following spawning, several unspawned oocytes which had become dissociated from their follicle cells were found in the ovaries. They appeared to be lodged within the lumen. Such oocytes were observed undergoing various stages of autolysis. At no time were hemocytes or recognizable phagocytes found in the lumen of the ovaries or in contact with the degenerating oocytes. Follicle cells which had surrounded the oocytes prior to the time of spawning exhibited disrupted membranes. Resorption of unspawned eggs appears to occur by autolysis of the individual oocytes.

Several of the females who had recently spawned had numerous sperm in their ovaries. Such sperm may have been pressed into the lumen at the time of spawning or during the fixation process.
Oleospheres of the cave‐dwelling shrimp Troglocaris schmidtii: A unique mode of extracellular lipid storage
Authors: Vogt Günter , Štrus Jasna
Published: February 2005

The cave‐dwelling shrimp, Troglocaris schmidtii, has a unique mode of lipid storage. The lipid lies extracellularly in specialized compartments of the hepatopancreas, named oleospheres. The lipid is synthesized in the R‐cells of the hepatopancreatic epithelium and accumulates in lipid droplets which fuse to form bigger globules. Mature lipid globules display moderately electron dense centers probably comprising triglycerides, and a broad electron dense boundary presumably consisting of lipoproteins. The globules are discharged into the lumen of the hepatopancreatic tubules by a kind of apocrine secretion. There, they coalesce to form larger masses. Finally, these lipid masses are transported into the oleospheres through a valve‐like structure. The continual accumulation of lipid results in a drastic expansion of the oleospheres up to 500 μm in diameter. The absence of food in the digestive tract and the inactivity of the digestive enzyme producing F‐cells indicate that digestion is suspended in the period of oleosphere formation. The curious mode of lipid storage in T. schmidtii may represent an adaptation to the extreme environmental conditions of a cave.
Comparative anatomy and phylogeny of the cloacae of salamanders (amphibia: Caudata). III. Amphiumidae
Authors: Sever David M.
Published: February 2005

Histological descriptions of female and male cloacae are presented for the three species of Amphiuma. Little interspecific variation occurs in either females or males. Females possess numerous spermathecae around the walls of the posterior cloacal tube and anterior cloacal chamber as well as rudimentary vent glands, of uncertain homology, in the caudal end of the cloacal chamber. Ventral glands such as those known from female salamanders in other families are absent, likely a secondary loss in the amphiumid clade. In a female A. tridactylum with large ovarian follicles (5‐ to 8‐mm diameter), the lips of the cloacal orifice are highly cornified, and stored sperm in the spermathecae appear in organized bundles, either free in the lumen or with the sperm heads seemingly buried in the spermathecal epithelium. Males possess some gland clusters present in other members of the suborder Salamandroidea (dorsal pelvic glands, vent glands, Kingsbury's glands, anterior ventral glands) but lack others (lateral pelvic glands, posterior ventral glands), resulting in the most plesiomorphic cloacal anatomy in the suborder. However, males possess an autapomorphic gland cluster, called the pit glands, in the posterior wall of the cloacal chamber. The pit glands consist of shallow infoldings of the cloacal epithelium unlike other cloacal glands, which are relatively tubular and elongate. The “pits” contain columnar eosinophilic cells that give positive staining reactions for acid mucopolysaccharides and proteins.
Pigment pattern formation in larval ambystomatid salamanders: Ambystoma tigrinum tigrinum
Authors: Olsson Lennart , Löfberg Jan
Published: February 2005

We have begun a comparative study of pigment patterns and their mechanisms of formation in ambystomatid salamanders in an attempt to elucidate the evolution of these traits in this family. In Ambystoma t. tigrinum, the migration of the prospective pigment cells was followed by using scanning electron microscopy and light microscopy combined with markers (dopa incubation for detecting melanophores, ammonia‐induced pterin fluorescence for detecting xanthophores). The pigment pattern resulting from the cell migration shares features both with the alternating vertical xanthophore and melanophore bars of A. mexicanum and the horizontal stripes of certain salamandrids and ambystomatids. The pigment pattern of A. t. tigrinum is interpreted here as an intermediate evolutionary step between a primitive horizontal stripe pattern and a derived vertical bar pattern. The initiation of pigment pattern formation resembles the situation in A. mexicanum, probably reflecting the close phylogenetic relationship between the two taxa.
Fine structure of the dorsal epithelium of the tongue of the freshwater turtle, Geoclemys reevesii (Chelonia, Emydinae)
Authors: Iwasaki Shin‐Ichi
Published: February 2005

Scanning electron microscopy shows that lingual papillae occur all over the dorsal surface of the tongue of the freshwater turtle, Geoclemys reevesii. The surface of each papilla is composed of compactly distributed hemispherical bulges, each composed of a single cell. Microvilli are widely distributed over the surface of cells. Histological examination reveals that the connective tissue penetrates deep into the center of papillae and that the epithelium is stratified columnar. Under the transmission electron microscope, the cells of the basal and the deep intermediate layers of the epithelium appear rounded. A large nucleus lies in the central area of each cell. The cytoplasm contains mitochondria, endoplasmic reticulum and free ribosomes. The cell membrane form numerous processes. The shallow intermediate layer contains two types of cell. The cytoplasm of the first has numerous fine granules, in addition to mitochondria, ribosomes, and endoplasmic reticulum. The other type of cell contains highly electron‐dense granules. The surface layer shows two cell types. One type consists of typical mucous cells. The other type of cell contains fine, electron‐lucent granules. The latter cells lie on the free‐surface side, covering the mucous cells, and have microvilli on their free surfaces.
Trunk movements during locomotion in the marsupial Monodelphis domestica (didelphidae)
Authors: Pridmore Peter A.
Published: February 2005

The small didelphid cmarsupial, Monodelphis domestica, uses a lateral sequence walk during slow treadmill locomotion and gradually shifts to a trot as speed increases. At higher speeds it changes abruptly to a half‐bound. Cinematographic records suggest significant lateral bending but no sagittal bending of the trunk during the slow walk and a reduced amount of lateral bending during the fast walk. There is slight lteral, but no sagittal, bending during the trot. Sagittal bending is obvious during the half‐bound, but no lateral bending is evident. Cineradiography confirms that the vertebral column of the trunk bends laterally during the slow walk. Bending occurs throughout the trunk region, but seems to be most pronounced in the anterior lumbar region. Associated with this bending of the trunk is substantial rotation of the pelvic girdle in the plane of yaw. Pelvic rotation is synchronized with the locomotor cycle of hindlimbs. Each side of the pelvis rotates forward during the recovery phase of the ipsilateral hindlimb and backward during the contact phase of this limb. Information on locomotor trunk movements in other limbed tetrapods is limited. The pattern of trunk bending found in Monodelphis, however, is consistent with that reported in the placental mammal Felis catus and in some lepidosaurian reptiles. This suggests that sagittal bending did not replace lateral bending during the evolution of mammals, as is sometimes suggested. Rather, bending in the vertical plane seems to have been added to lateral bleeding when the ancestors of extant mammals acquired galloping and bounding capabilities.
Morphology and glycoconjugate histochemistry of the palpebral glands of the adult newt, Notophthalmus viridescens
Authors: Reyer Randall W. , Liou Willisa , Pinkstaff Carlin A.
Published: February 2005

The eyelids of the newt were studied in 10 μm serial paraffin and 1–2 μm plastic sections using standard histological stains and special stains for glycconjugates. The eylids contain four different glands. Simple acinar serous and simple acinar mucous glands occur in the skin; unicellular mucous glands occur in the conjunctiva; and convoluted tubular seromucous glands are present in connective tissue beneath the conjunctiva. The first two are identical to cutaneous glands found elsewhere on the head and body. The simple acinar serous glands are surrounded by myoepithelial cells and release their sectetion, which is composed largely of proteins with minimal glycoconjugate content, by a holocrine mechansm. The secretory product of the simple acinar mucous glands is composed of neutral glycoconjugates with a minor content of acidic glycoconjugates; the mucin exhibits strong PAS and PAPD staining and weak staining by AB and PAPS methods. The unicellular conjunctival mucous glands secrete both neutral and acidic glycoconjugates as shown by positive reactions with PAS, PAPD, PAPS, and AB methods. Convoluted tubular seromucous glands in the ventral eyelid synthesize both proteins and neutral glycoconjugates. The mucous secretions of the conjunctival glands probably provide lubrication and protection for the cornea.
Spermatozoon structure of eight species of South African holothurians (Echinodermata)
Authors: Hodgson A. N. , Bernard R. T. F.
Published: February 2005

Transmission electron microscopy of the spermatozoa of eight species (from seven genera) of holothurians has shown that each species has a sperm with unique dimensions, indicating that spermatozoon morphology can be used as a taxonomic character. However, although the structure of the sperm is species‐specific, all sperm have a similar appearance which is typical of holothurians. The sperm head is composed of a spheroidal nucleus (about 2 μm diameter) which has a large anterior fossa housing the approximately spherical acrosome. The acrosome is differentiated internally and surrounded by periacrosomal material. The mid‐piece consists of a single mitochondrion with lamellar cristae which surrounds the eccentrically positioned centrioles. The conservative form and arrangement of the sperm organelles suggest that sperm morphology cannot be used for phylogenetic investigations within this taxon.
Ultrastructure of otolith increments and checks in the teleost fish Oreochromis niloticus
Authors: Zhang Z.
Published: February 2005

An otolith increment is composed of an incremental zone and a discontinous zone. Observation of the otoliths of Oreochromis niloticus with transmission and scanning electron microscopy reveals that organic fibers are concentrated in the discontinuous zone and are relatively scarce in the incremental zone. On the other hand, calcium carbonate crystals are chiefly packed in the incremental zone and are less dense in the discontinuous zone. Both fibers and crystals are oriented perpendicular to the growth increments. Otolith checks, or discontinuities, contain even denser fibers and fewer fine crystals than does the discontinuous zone. A higher proportion of individual fibers is prominently stained in the discontinuous zone and check than in the incremental zone. Other features of individual fibers appear to be the same among the three zones. The crystals on either side of a check or a discontinuous zone resemble each other both in size and orientation. Zonation of protein and mineral components of otoliths can be understood in terms of both incremental growth and the daily cycle of deposition.
Development of the subdigital adhesive pads of Ptyodactylus guttatus (Reptilia: Gekkonidae)
Authors: Rosenberg Herbert I. , Russell Anthony P. , Cavey Michael J.
Published: February 2005

Subdigital adhesive pads play an important role in the locomotion of many species of gekkonid lizards. These pads consist of integrated components derived from the epidermis, dermis, vascular system, subcuticular tendons, and phalanges. These components become intimately associated with each other during the developmental differentiation of the digits and the sequence of this integration is outlined herein in Ptyodactylus guttatus. The pads initially appear as paired swellings at the distal tips of the digits. Subsequently, a fan‐like array of naked scansors develops on the ventral surface of each digit, at about the same time that scales differentiate over the surface of the foot as a whole. At the time of appearance of the naked scansors, the vascular sinus system of the pad also differentiates, along with subcuticular connective tissue specializations. At this stage the digits, along with the rest of the body, are clad in an embryonic periderm. Only after hatching and as the periderm is shed, do the epidermal setae and spines appear. The developmental sequence described here is consistent with predictions previously advanced about the evolutionary origin and elaboration of subdigital pads in gekkonid lizards. The paucity of available staged embryonic material leaves many questions unresolved.
Relationship of saccular ultrastructure to otolith growth in the teleost Oreochromis niloticus
Authors: Zhang Z.
Published: February 2005

The sacculus of Oreochromis niloticus is anatomically separated from the utriculus and semicircular canals. The saccular wall is composed of the sensory epithelium, transitional epithelia, and squamous epithelium. Cellular granules are abundant in the sensory and transitional epithelia but scarce in the squamous epithelium. Over the dorsal side of the dorsal transitional epithelium there exists an oval patch of cells with distinctive microvilli. New finding is a shallow groove which extends from the anterior end of the sensory epithelium approximately halfway down along the ventral perimacular transitional epithelium. Small vesicles, which appear “empty” under transmission electron microscopy (TEM), are aggregated in the posterior region of the groove. These small vesicles are also present in both the sensory and transitional epithelia. A second kind of vesicle is comparatively large and appears filled with stainable contents. These vesicles are restricted to the sensory region. Both kinds of vesicles appear to be involved in apical secretion and possibly provide the otolithic membrane with fibers. The otolithic membrane is composed of a gelatinuous layer and subcupular meshwork. The meshwork appears to contribute to the formation of the otolith. The small empty vesicles appear to originate in sensory and transitional epithelial cells and may form the subcupular meshwork. The larger filled vesicles are derived predominantly from sensory cells in the sensory epithelium and appear to contribute to the gelatinuous layer of otoliths. © 1992 Wiley‐Liss, Inc.
Unusual cuticle‐associated organs in the heterotardigrade, Echiniscus viridissimus
Authors: Dewel Ruth Ann , Dewel William C. , Roush Brenda G.
Published: February 2005

Echiniscus viridissimus possesses two organs that lie above the ventromedial body wall approximately at the level of the second and third pair of legs. Each organ is composed of one medial and two lateral cells and possesses a pair of convoluted ducts. The lateral cells produce and release profuse amounts of filamentous basement membrane‐like material into the body cavity. The proliferated material persists en masse adjacent to the lateral cells and is associated with disrupted droplets of pigmented body cavity material (BCM). The medial cell is larger than the lateral cells and possesses numerous tubular invaginations in which droplets of BCM are frequently found. Each duct originates as an infold that becomes a simple channel in the lateral cell and continues through the medial cell in a deep groove covered by a long process of the lateral cell. Although the ducts lie on the medial cell surface, they are “internalized” at the base of deep clefts and isolated from the body cavity by “tight” zonulae adherentes junctions. In the medial cell the ducts have a cuticle‐like lining and the associated plasma membrane is characterized by numerous saccular infolds containing flocculent material. The duct linings, which extend beyond the limits of the medial cell, project into the endocuticle and terminate on the lateral body wall. Because the lateral cells are producing and releasing profuse basement membrane and because material with an electron density similar to BCM is present in the saccules, the distal regions of the ducts and in the endocuticle, we propose (1) that the lateral cells are producing basement membrane to disassociate BCM and (2) that the medial cell is absorbing and via its ducts translocating that BCM to the endocuticle. Furthermore, because the medial cell exhibits characteristics of transporting epithelia, namely numerous tubular infolds of the outer surface, a layer of distended saccules surrounding the duct and a high density of mitochondria, we suggest that the medial cell also functions in ion or osmotic regulation. © 1992 Wiley‐Liss, Inc.
Morphology of the reproductive tract in a lizard exhibiting incipient viviparity (Sphenomorphus fragilis) and its implications for the evolution of the reptilian placenta
Authors: Guillette Louis J.
Published: February 2005

The morphology of the female reproductive tract and corpus luteum is examined in Sphenomorphus fragilis, a lizard from the lowland regions of New Guinea exhibiting incipient viviparity. Females oviposit eggs that hatch either immediately or within a few hours. Corpora lutea form from ovulated follicles and decrease in diameter as embryonic development progresses. The oviduct from vitellogenic females is sparsely populated with well developed uterine glands containing secretory granules. The eggs are covered with a relatively thin shell (10 μm thick) composed of an inner boundary layer and proteinacous fibers. The secreted shell is complete by early neurulation. Shell morphology does not change throughout the remainder of the in utero incubation period. A well vascularized uterus and chorioallantoic membrane provide simple placentation. These findings suggest that the reduction in shell thickness associated with the evolution of a placenta is due to a decrease in the number of shell glands in the uterus and is not a delay or inhibition of the shelling process per se. This hypothesis further suggests that the selective forces favoring shell gland loss act on the vitellogenic female during gland recruitment which occurs prior to ovulation and not on the pregnant female. © 1992 Wiley‐Liss, Inc.
Histology of the esophagus of the adult frog Rana perezi (Anura: Ranidae)
Authors: Gallego‐Huidobro J. , Pastor L. M. , Calvo A.
Published: February 2005

Study of the esophageal microscopic morphology of adult Rana perezi by light and electron microscopy discloses some large folds throughout the esophagus that are in themselves ringed. Glandular ostia open in the furrows of the luminal surface. The esophageal wall is made up of a connective adventitia rich in melanocytes, a muscular tunica, a connective and glandular subepithelial layer, and a pseudostratified ciliated epithelium. This epithelium basically consists of ciliated, goblet, basal, microvillous‐apex, and migratory cells. Two types of goblet cells are distinguished with regard to the granular ultrastructure. The microvillous‐apex cell has not been found in other amphibians. It shows a very differentiated morphology with a high number of mitochondria. The basal cells give the epithelium a pseudostratified morphology, and they have a proliferative function. Glands are branched and drain through an excretory duct that has a monolayered mucosecreting epithelium. The glandular units are formed by two principal types of cells: mucosecretory and serous. © 1992 Wiley‐Liss, Inc.
Middle‐ear development: II. Morphometric changes in the conducting apparatus of the chick
Authors: Cohen Yale E. , Hernandez Hector N. , Saunders James C.
Published: February 2005

The ontogeny of various middle‐ear structures was examined in 11 groups of chicks between 10 days embryonic and adult. Measurements of the tympanic membrane surface area and height, columella length, and that of the columella footplate, annular ligament, and oval window area were obtained using video micrographs and computer digitization techniques. The oval window matures first at 53 days post‐hatching, whereas the columella achieves adult size at 74 days. The tympanic membrane surface area is the last middle‐ear variable studied to reach adult size (79 days post‐hatch). The columella increases its length from 0.63 mm (10 days embryonic) to 2.73 mm in the adult. The tympanic membrane area expands by 280% whereas the columellar footplate area increases by 11x. As a result, the pressure amplification of the middle ear due to the tympanic membrane/columellar footplate area ratio improves by over 400%. These data further contribute to our understanding of the functional development of the middle ear. © 1992 Wiley‐Liss, Inc.
Four forearm flexor muscles of the horse, Equus caballus: Anatomy and histochemistry
Authors: Hermanson John W. , Cobb Matthew A.
Published: February 2005

Two of the forearm flexors of the horse, the superficial and deep digital flexor muscles, are critical to support the digital and fetlock joints, exhibit differing insertions, and are passively supported by the proximal and distal check ligaments, respectively. These two muscles differ in histochemical composition and architecture. The differences are correlated with the different stress levels transmitted through their tendons, and the different frequencies of clinical breakdown that have been reported. Both muscles contain type I and type IIa fibers. A few type IIb fibers occurred in the deep digital flexor. The superficial digital flexor contained approximately 56% type I fibers, extremely short muscle fibers, and extensive connective tissue investment. In contrast, the deep digital flexor had three muscle heads: ulnar, radial, and “long” and “short” regions of the humeral head. The “long” and “short” regions of the humeral head contained 33% and 44% type I fibers, respectively, fiber lengths three to four times as long as those in the superficial digital flexor, and relatively less connective tissue investment. Flexor carpi radialis and flexor carpi ulnaris compared most closely with the humeral head of the deep digital flexor. These data suggest a correlation of the unique architecture of superficial digital flexor with its proposed elastic storage properties during locomotion in horses, and an explanation for the frequent breakdown of the superficial digital flexor in athletic horses. © 1992 Wiley‐Liss, Inc.
Spermiophagy by the spermathecal epithelium of the salamander Eurycea cirrigera
Authors: Sever David M.
Published: February 2005

The spermathecae of Eurycea cirrigera are exocrine glands in the cloaca that secrete a substance that bathes sperm stored in the lumen after mating and prior to oviposition. Many sperm remain in the spermathecae after oviposition, and the spermathecal epithelium becomes spermiophagic. Pseudopodia enclose sperm into endocytic vacuoles. The vacuoles become associated with primary lysosomes in the cytoplasm. Following formation of secondary lysosomes and resulting condensation of the sperm fragments, residual bodies are exocytized into the surrounding connective tissue stroma. By the start of the next breeding cycle, most sperm remaining from the previous mating have been degraded, but some sperm remain in the lumen, and the viability of these sperm is unknown. © 1992 Wiley‐Liss, Inc.
Seminal receptacula in the female reproductive tract of Opisthopatus cinctipes purcell (onychophora, peripatopsidae)
Authors: Walker Muriel H.
Published: February 2005

The presence of seminal receptacula in the female reproductive tract of Opisthopatus cinctipes (Purcell, 1900) has been disputed (Choonoo, '47; Ruhberg, '85; Herzberg et al., '80). However, they do occur and are described here from observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). No spermatozoa are associated with the surface of the ovary; in contrast the ovary of Peripatopsis capensis is covered with spermatozoa and numerous small rounded cells. The seminal receptacula of O. cinctipes are formed from a loop in the proximal region of the uterus and contain remnants of spermatozoa in their lumens. The epithelial cells lining the seminal receptacula contain numerous vesicles and residual bodies. It is suggested that these cells absorb those spermatozoa not required for fertilization, and that the seminal receptacula in the Peripatopsidae act as short‐term storage sites for spermatozoa. By contrast, the seminal receptacula of the Peripatidae are considered to act as long‐term storage sites for spermatozoa. © 1992 Wiley‐Liss, Inc.
Video‐enhanced microscopy of organelle movement in an intact epithelium
Authors: Karnaky Karl J. , Garretson Leon T. , O'Neil Roger G.
Published: February 2005

Digitally enhanced video microscopy has provided improved optical resolution in the study of intracellular organelle/particle movement, particularly in extruded axoplasm and certain thin single cell systems. We report here, for the first time, particle movement in an intact, isolated epithelium, the killifish proximal convoluted tubule. Cytoplasmic particles exhibited predominately unidirectional linear movement approaching several microns in length, sometimes with multiple turns. The velocities of 34 particles measured in 11 cells averaged 0.29 μm/sec (range, 0.007–3.1 μm/sec). Microtubules—the well‐established basis for organelle movement in cells—were present but were sparsely represented in electron micrographs of these cells. Video‐enhanced microscopic techniques can now be applied to the study of organelle/particle movement in an intact epithelium. © 1992 Wiley‐Liss, Inc.
Retinoic acid enhances monoclonal antibody WE3 reactivity in the regenerate epithelium of the adult newt
Authors: Tassava Roy A.
Published: February 2005

Monoclonal antibody (mAb) WE3 recognizes an antigen that is developmentally expressed in the wound epithelium during adult newt limb regeneration. Experiments were designed to determine whether retinoic acid (RA), dissolved in dimethyl sulfoxide (DMSO) and administered by intraperitoneal injection, would enhance the temporal appearance of the WE3 antigen. RA given on days 1 or 4 after amputation, when the WE3 antigen is not yet detectable, resulted in moderate reactivity to mAb 2 days after injection and strong reactivity throughout the wound epithelium 4 days after injection. DMSO alone had no enhancing effect. RA also caused limb skin epidermis to exhibit reactivity to mAb WE3, initially near the amputation level, but then also more proximally. By 4 and 6 days after RA injection, epidermis of the flank, eye lid, and unamputated hind limbs also became strongly reactive to mAb WE3. Outer layers of skin epidermis were shed, resulting in an epidermis only one or two cells thick. Epidermis of newts given DMSO alone remained non‐reactive to mAb WE3. When RA was given on days 7 and 10 after amputation, when a low level of mAb WE3 reactivity is already present in the wound epithelium, a considerable enhancement of mAb WE3 reactivity occurred through the next few days. No such enhancement was seen with DMSO alone. RA also greatly increased mAb WE3 reactivity in the wound epithelium of denervated limbs, in which case the wound epithelial reactivity to mAb WE3 is normally low. Retinol palmitate also increased mAb WE3 reactivity. The results raise the possibility that the WE3 antigen is a component of most if not all retinoid target tissues in newts. © 1992 Wiley‐Liss, Inc.
Neuromuscular organization of feline anterior sartorius: II. Intramuscular length changes and complex length‐tension relationships during stimulation of individual nerve branches
Authors: Scott S. H. , Thomson D. B. , Richmond F. J. R. , Loeb G. E.
Published: February 2005

The feline anterior sartorius is a long strap‐like muscle composed of short muscle fibers. Nerve branches that enter this muscle contain the axons of motor units whose constituent muscle fibers are distributed asymmetrically within the muscle. In the present study, twitch and tetanic isometric contractions were evoked by stimulating individual nerve branches while muscle force was recorded and intramuscular length changes were monitored optically by the movement of reflective markers on the muscle. Contractions elicited by stimulating the parent nerve produced little change in the positions of the surface markers. Contractions elicited by stimulating the proximally or distally directed nerve branches caused the muscle to shorten at the end closest to the nerve branch and lengthen at the opposite end. Some muscles were supplied by a centrally directed nerve branch whose stimulation produced variable effects: in some cases a portion of the muscle shortened whereas the rest lengthened, but in other cases, the positions of the surface markers showed little change. The intramuscular length changes produced by stimulating single nerve branches were greater during isometric contractions at short whole‐muscle lengths than at long whole‐muscle lengths. The twitch and tetanic length‐tension relationships obtained by stimulating the individual nerve branches were not congruent with the length‐tension relationship produced when the parent nerve was stimulated. At short whole‐muscle lengths, stimulation of a single nerve branch generated only a small fraction of the force that could be generated by the muscle when the parent nerve was stimulated. As whole‐muscle length increased, an increased fraction of total muscle force could be generated by stimulating a single nerve branch. The results suggest that a complex relationship between passive and active elements contributes to the total muscle force and depends on the distribution of active and passive muscle units throughout the muscle. © 1992 Wiley‐Liss, Inc.
Visual demonstration of the limb‐forming zone in the chick embryo lateral plate
Authors: Stephens Trent D. , Sanders Duane D. , Yap Clementine Y. F.
Published: February 2005

The present study was undertaken to determine whether a visible Wolffian ridge, distinct from the lateral fold, can be identified in chick embryos. Ectoderm thickness was measured in stage 11–17 chick embryos. There was a general trend, from thin ectoderm in the midline, to an ectodermal thickening over the somites, intermediate mesoderm, and lateral plate. Other embryos were cut from the yolk, pinned out, and photographed. The lateral fold was then eliminated, and the embryo was rephotographed. The photographs reveal a definite opaic zone, distinct from the lateral fold, in stage 11–18 chick embryos. Furthermore, there is a direct correlation between the opacity of this cellular band and the limb‐forming potential of grafted wing, flank, and leg regions (see Stephens et al., '89). At stages 11–14, the wing, flank, and leg exhibit a uniform opacity, and a uniform capacity for limb formation when grafted to a host celom. From stage 15 to stage 18, the opacity in the flank diminishes, and its limb‐forming capability disappears. This study demonstrates the presence of an opaic zone, which we have called the limb‐forming zone (LFZ) along the lateral side of early chick embryos, which is independent of the lateral fold, is not as extensive as the lateral plate, and is not simply associated with ectodermal thickening, but which is directly correlated with limb‐forming potential in the lateral plate. © 1992 Wiley‐Liss, Inc.
Vertebral development of the chick embryo during days 3–19 of incubation
Authors: Shapiro Frederic
Published: February 2005

Chick embryo vertebral development has been studied during the period from 3 to 19 days of incubation. Whole mount preparations stained with alcian blue for cartilage and alizarin red for bone show the vertebral bodies as cartilaginous at 5 days, with dorsal spinous processes at 6½ days, the onset of bone formation at the ventral and dorsal surfaces of the bodies at 13 days, ossification extending dorsally within the neural arches at 13½ days, and bone development occurring throughout the vertebrae at 16 days. Descriptions at each time period center on the thoracic vertebrae with occasional inclusion of adjacent lower cervical and upper lumbar vertebrae. Histologic development is correlated with the Hamburger‐Hamilton stages, which are based on external characteristics. The notochord and neural tube are well developed by 3 days and surrounded by sclerotome, myotome, and dermatome cells. Cartilage formation in the perinotochordal region of the vertebral body is seen at 5 days and precedes development of the neural arches and spinous processes. Separate centers of chondrocyte hypertrophy occur in the body (9 days), the lateral neural arches and the dorsal spinous process. Bone formation is under way at 13 days, beginning in the vertebral bodies. Intramembranous periosteal bone formation is seen adjacent to internal regions of chondrocyte hypertrophy. Vascular invasion of hypertrophic chondrocyte regions occurs, but the mechanism of endochondral ossification differs from that of mammals. The cartilage is resorbed by multinucleated chondroclasts and marrow round cells. Clumps of growth plate cartilage cells and matrix are surrounded occasionally by newly synthesized bone, but invasion of individual hypertrophic chondrocyte lacunae by vessels with bone deposition by accompanying osteoblasts on single trabeculae of cartilage does not occur. 3H‐thymidine autoradiography shows high uptake at 3 and 5 days in the germinal neuroepithelial cells of the neural tube (spinal cord) and notochord. By 7 days, notochordal uptake is markedly diminished, and no uptake of isotope occurs from 8 days onward. Spinal cord uptake is highest in the first 8 days but persists in lessened amounts to 19 days. From 5 days onward, both undifferentiated mesenchymal cells and differentiated chondrocytes show positive 3H‐thymidine uptake, but labeling is never seen in hypertrophic chondrocytes. © 1992 Wiley‐Liss, Inc.
Gill raker structure and development in indo‐pacific anchovies (Teleostei: Engrauloidea), with a discussion of the structural evolution of engrauloid gill rakers
Authors: Bornbusch Alan H. , Lee Melinda
Published: February 2005

The postlarval development of gill raker denticles is described for the engrauloid (anchovy) genera Coilia, Lycothrissa, Setipinna, Thryssa, Stolephorus, and Encrasicholina based on scanning electron microscopy. The raker structure of adult Papuengraulis is also described. In the coiliid genera Coilia, Lycothrissa, Setipinna, Thryssa, and Papuengraulis, denticle development is not confined to particular region(s) of the raker. With few exceptions, the proliferation of denticles with growth is greatest along the upper raker edge; denticles are smaller and less dense on the raker faces and along the lower raker edge. Some Thryssa and Setipinna have a derived condition of denticle clustering along the upper raker edge. In Stolephorus and Encrasicholina, denticle development is confined to the upper raker half and includes the development of a single row of denticles along each raker face. A phylogenetic analysis of engrauloid raker structure, incorporating data from Bornbusch ( 88: Copeia 1988:174–182) and based on outgroup comparisons, indicates that for the Engrauloidea: (1) the pattern of denticle development shared by coiliids is plesiomorphic; and (2) the pattern of denticle development shared by Stolephorus, Encrasicholina, and most other engraulids is synapomorphic for the Engraulidae. There is no evidence that the studied coiliids Stolephorus and Encrasicholina are suspension feeders. The engraulid pattern of raker denticle development which is retained in suspension feeding engraulids of the genus Engraulis was thus derived before the derivation of suspension feeding in Engraulis. Comparative morphological and phylogenetic studies of clupeomorph raker structures and feeding behaviors can infer the historical origins of morphology‐behavior associations, help define possible directions for analyses of raker denticle function, and thereby help elucidate the significance of structure‐function couplings in the evolution of such clupeomorph trophic behaviors as suspension feeding. © 1992 Wiley‐Liss, Inc.
Cytoplasmic droplets of painted turtle spermatozoa
Authors: Gist Daniel H. , Hess Rex A. , Thurston Ronald J.
Published: February 2005

Epididymal sperm from the painted turtle (Chrysemys picta) possess a cytoplasmic droplet which is located eccentrically on the sperm midpiece. The droplet contains a large quantity of lipid droplets in addition to hollow vesicles and degenerate mitochondrial fragments. Lipid droplets are closely associated with mitochondrial membranes and may function in the formation or degradation of mitochondria. Cytoplasmic droplets become detached from the sperm midpiece in a coordinated manner shortly before the commencement of fall mating and are not observed on sperm recovered from the oviduct of females. © 1992 Wiley‐Liss, Inc.
Malpighian tubules of Formica polyctena (Hymenoptera): Light and electron microscopic study
Authors: Garayoa M. , Villaro A. C. , Montuenga L. , Sesma P.
Published: February 2005

The study of semithin (1 μ in thickness) and thin sections of Epon‐embedded material reveals that Malpighian tubules of Formica polyctena are composed of a single cellular type throughout their length. No differentiated regions were observed. Ultrastructural traits of the epithelial cells are those of highly metabolic cells engaged in water and ion transport: large euchromatic nucleus, several nucleoli, abundant mitochondria, a conspicuous brush border, and basolateral infoldings. Lysosomes, smooth endoplasmic reticulum, and intercellular junctions are also well developed. Mineral concretions occur within the cells and in the lumen. However, the degree of development of these cytological traits is variable among the different cells. The tubules drain into the gut through a specialized posterior region of the midgut or ampulla. In this region, the epithelial cells, although usually taller and showing conspicuous basal infoldings, display cytological structures similar to those of the Malpighian tubules. © 1992 Wiley‐Liss, Inc.
Pigment pattern formation in the larval salamander Ambystoma maculatum
Authors: Olsson Lennart
Published: February 2005

As part of an ongoing comparative study of pigment patterns and their formation in embryos and larvae of ambystomatid salamanders, Ambystoma maculatum from two differnt populations, one in the northern (New York) and one in the central (Tennessee) United States, were investigated. Scanning electron microscopy was used to study early neural crest development. Light microscopy in combination with markers for the two pigment cell types (xanthophores and melanophores) made it possible to follow pigment cell migration before the pigment cells were fully differentiated. A bilateral pigment pattern consisting of two horizontal melanophore stripes surrounding an interstripe area populated by xanthophores formed in the larvae. In both populations, some variation was present in the form of a continuum ranging from clear horizontal stripes to extreme cases with a random pattern. Unlike the other ambystomatids that have been investigated, the neural crest cells in A. maculatum do not form aggregates and no vertical bars are formed. Instead, both the pattern and its formation are very similar to what has been reported for salamandrids. If pattern formation mechanisms can act as developmental constraints we would expect the A. maculatum pattern to be the primitive condition in the Ambystomatidae, using the Salamandridae as the outgroup. There is no strong support for this when aggregate formation is used as a character and mapped onto phylogenies for the group. The aggregate formation mechanism, and the pigment pattern that it leads to, have most likely been secondarily lost in A. maculatum. © 1993 Wiley‐Liss, Inc.
Early development of the chick embryo
Authors: Watt Jillian M. , Petitte James N. , Etches Robert J.
Published: February 2005

The ultrastructure of the early chick embryo was investigated, using scanning (SEM) and transmission electron microscopy (TEM). Eggs were obtained from the shell gland by injecting hens intravenously with a synthetic prostaglandin or arginine vasopressin. Embryos were examined during late cleavage (stages IV–VI, Eyal‐Giladi and Kochav, '76), formation of the area pellucida (stages VII–XI), and formation of the hypoblast (stages X–XIV). SEM highlighted the reduction in cell number at the underside of the embryo during formation of the area pellucida although it became apparent that the thickness of the embryo is not reduced to a single layer of cells at stage X. In addition, blastomeres at the perimeter of embryos (stages V–VI) project filopodial extensions onto a smooth membrane that separates the sub‐embryonic cavity from the yolk. During hypoblast formation, epiblast cells generate stellate projections at their basal aspect, thus providing a meshwork for the advancing secondary hypoblast cells. By stage XII the epiblast was one cell thick and reminiscent of a columnar epithelium when viewed transversely. Cells of the deep portion of the posterior marginal zone were distinguished morphologically in the stage XII embryo by their many cell surface projections and ruffled appearance. Blastomeres at the perimeter of stage V–VI embryos projected filopodial extensions onto a smooth membrane which separates the sub‐embryonic cavity from the yolk. This membrane is presumed to be confluent with the cytolemma. Evidence is presented demonstrating the presence of intracellular membrane‐bound droplets which are hypothesised to contain sub‐embryonic fluid. © 1993 Wiley‐Liss, Inc.