A study of digit fusion in the mouse embryo

Development ◽  
1979 ◽  
Vol 49 (1) ◽  
pp. 259-276
Author(s):  
Elaine Maconnachie
Keyword(s):  
Embryonic Development ◽  
Mouse Embryo ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
Epidermal Cells ◽  
Mouse Limb ◽  
Epithelial Fusion

During the embryonic development of the mouse limb separation of the digits is followed by their union. This is a true, though temporary, epithelial fusion, a fused layer of epidermal cells remaining intact until separation takes place after birth. The periderm cells in the line of fusion are displaced to the dorsal or ventral surface of the foot. On the dorsal surface these displaced cells form a prominent interdigital ridge of elongated, intertwined cells which remains until the periderm is shed. During the fusion of the eyelids, and also of the pinnae to the scalp, a similar ridge of periderm cells is formed.

Structure of the compensation sac in two ascophoran bryozoans

1970 ◽  
Vol 175 (1040) ◽  
pp. 235-254 ◽  
Keyword(s):  
Cell Proliferation ◽  
Growth Model ◽  
Dorsal Surface ◽  
Proximal Part ◽  
Ventral Surface ◽  
Body Cavity ◽  
Structural Differences ◽  
Frontal Wall ◽  
Epithelial Fusion

Harmer established two groups of ascophoran bryozoans on structural differences in the compensation sac (ascus) and the frontal wall, although both he and Silén believed that the frontal wall of both groups is deposited within a simple ventral fold of ‘frontal membrane’. Such a fold would be expected to secrete a wall consisting of mineral and/or organic successions disposed symmetrically on either side of the first-formed layer. A study of Schizoporella and Umbonula , typifying the two ascophoran groups, showed asymmetrical frontal walls and other deviations from the Harmer–Silén growth model. In both genera, ascus development is determined by the formation and rapid migration of generative zones which result from the fusion of epithelia secreting periostracum and carbonate respectively. Differences in the location and timing of these processes influence subsequent events. In Schizoporella , the first-formed layer of the frontal wall is secreted within an epithelial fold which is separated from the overlying ventral periostracum and associated epithelium by an extra-zooecial body cavity. Next follows a fusion of the carbonate- and periostracum-secreting epithelia just proximal to the orifice, and the migration of the more proximal part of the junction to the zooecial walls. Cell proliferation in the wake of this retreat leads to the formation of the ascus floor. Exposed primary calcite on the dorsal surface of the frontal wall constitutes the roof of the ascus and, contrary to the Harmer–Silén model, shows no trace of periostracum or associated epithelium. In Umbonula , epithelial fusion occurs just within the periphery of the ventral surface, and the roof of the ascus is secreted by cells of a generative zone as it advances towards a submedial position near the orifice. The roof consists of a thin but complete periostracum continuous with that forming both the floor of the ascus and the ventral cover of the zooid. The calcareous frontal wall is subsequently deposited on the roof periostracum by the dorsal or carbonate-secreting layer of the doubled epithelium.

A temperature-controlled physiological colour response in the grasshopper Kosciuscola Tristis Sjost. (Orthoptera: Acrididae)

1954 ◽  
Vol 2 (3) ◽  
pp. 309 ◽  
Author(s):  
KHL Key ◽  
MF Day
Keyword(s):  
Natural Habitat ◽  
Marked Change ◽  
Colour Change ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
Distal Portion ◽  
Epidermal Cells ◽  
Dense Layer ◽  
Dark Phase ◽  
Thermoregulatory Function

The alpine grasshopper Kosciuscola tristis shows a physiological colour change under the control of temperature. Males are a bright greenish blue above about 25�C and a dull near-black below about 15�C. Intermediate shades are developed at intermediate temperatures. A similar, but less marked, change occurs in the female. The colour change in the male was studied with the aid of a special colour chart, which enabled quantitative ratings of colour to be made. The histology of the integument is described. In the pale phase a dense layer of highly refractive, very small granules occupies the distal portion of the cells of the epidermis; these are underlain by a layer of larger dark brown granules. In the dark phase the position of these layers is reversed and the nuclei are raised above the basement membrane, on which they rest in the pale phase. At intermediate colour shades the granules show transitional distributions. It is concluded that the colour change is brought about by the migration of the two types of granule in opposite directions within the epidermal cells. The ecology of K. tristis in its natural habitat is discussed. On clear days the insects become pale 2-3 hr after sunrise and begin to turn dark again during the late afternoon; the night is spent in the dark phase. The colour follows closely the temperature given by blackened thermometers, but at any given temperature it differs from the equilibrium colour developed when that temperature is maintained constant, because of the lag in accommodation to the continuously changing temperature in the field. It is suggested that the colour change may have a thermoregulatory function. Two undescribed species of Kosciuscola show similar colour changes, but these are confined to the face and ventral surface. The same two types of granule are present in the epidermal cells, including those of the dorsal surface, where they are distributed as in the pale phase of K. tristis at all temperatures.

scholarly journals Morphology of Metzgeria conjugata Lindb. (Metzgeriales, Hepaticopsida)

1992 ◽  
Vol 6 (1) ◽  
pp. 65-69
Author(s):  
Denise Pinheiro Da Costa ◽  
Raul Dodsworth Machado
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Outer Surface ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
Epidermal Cells ◽  
Scanning Electron

Scanning electron microscopy and light microscopy were used to elucidate the morphology of Metzgeria conjutata Lindb. and confirm the presence of 2 rows of epidermal cells on the dorsal surface, (21-3) rows on the ventral surface, midrib with cells in (3-51-6) tiers; hirsute, short hairs, straight on the thallus-margin and on the ventral surface of midrib; marginal hairs paired, single or in groups of three; male branches globose or subglobose; female involucres obovate and hirsute at the margin, calyptra fleshy, pyriform to club-shaped, hirsute on the outer surface, hairs long and straight.

Scanning electron microscopy of the integument of schistosoma rodhaini

1986 ◽  
Vol 44 ◽  
pp. 132-133
Author(s):  
P. Evers ◽  
C. Schutte ◽  
C. D. Dettman
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Oral Sucker ◽  
Adult Male ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
Sensory Receptors ◽  
East African ◽  
Dorsal Midline ◽  
Scanning Electron

S.rodhaini (Brumpt 1931) is a parasite of East African rodents which may possibly hybridize with the human schistosome S. mansoni. The adult male at maturity measures approximately 3mm long and possesses both oral and ventral suckers and a marked gynaecophoric canal. The oral sucker is surrounded by a ring of sensory receptors with a large number of inwardly-pointing spines set into deep sockets occupying the bulk of the ventral surface of the sucker. Numbers of scattered sensory receptors are found on both dorsal and ventral surfaces of the head (Fig. 1) together with two conspicuous rows of receptors situated symmetrically on each side of the midline. One row extends along the dorsal surface of the head midway between the dorsal midline and the lateral margin.

The larval stages of the celery fly (Acidia heraclei L.) and of the braconid Adelura apii (Curtis), with notes upon an associated parasitic yeast-like fungus

Parasitology ◽  
1943 ◽  
Vol 35 (1-2) ◽  
pp. 27-36 ◽  
Author(s):  
D. Keilin ◽  
P. Tate
Keyword(s):  
Dorsal Surface ◽  
Ventral Surface ◽  
Host Larva ◽  
Yeast Cells ◽  
Stage Larva ◽  
Normal Type ◽  
Abortive Infection ◽  
Unique Case ◽  
Larval Stages ◽  
Adult Females

The larval stages of the celery fly, Acidia heraclei, have been described, and it is shown that this larva agrees with other biontophagous dipterous larvae in having the pharynx devoid of ventral ridges. The transparency of the larvae permits the internal anatomy to be seen clearly in the living larva, and by this means the structure of the perispiracular glands is clearly revealed.The braconid Adelura apii occurs as a parasite of Acidia heraclei larvae, and its first. stage larva is described in detail. This larva is densely hairy, has a long, curved, hairy, tail-like appendage and, by the more rapid growth of the ventral surface, it develops a dorsal curvature which obscures the true orientation so that the true dorsal surface appears externally to be ventral. In these respects the first stage larva of Adelura apii resembles that of A. gahani described by de la Baume-Pluvinel. The later larval stages of A. apii, of which there are at least two, are naked, lack the tail-like appendage and do not differ from the normal type of parasitic hymenopterous larvae.A yeast-like fungus occurs as a parasite in the blood of Acidia heraclei larvae. It is always found associated with existing or abortive infection of the larvae with Adelura apii. Dense mycelial masses sometimes occur in the gut of A. apii pupae and are probably derived from the yeast cells parasitic in the host larvae. It is suggested that this is a unique case of a fungus parasitic in a host larva (Acidia heraclei) undergoing part of its development in a parasitic braconid (Adelura apii), adult females of which transmit the fungus to the host larva during oviposition.

A new species of Glyptothorax (Teleostei: Sisoridae) from the Brahmaputra River basin, Arunachal Pradesh, India

Zootaxa ◽  
2021 ◽  
Vol 5023 (2) ◽  
pp. 239-250
Author(s):  
LAISHRAM KOSYGIN ◽  
PRATIMA SINGH ◽  
SHIBANANDA RATH
Keyword(s):  
River Basin ◽  
Indian Subcontinent ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
Northeast India ◽  
Arunachal Pradesh ◽  
Brahmaputra River ◽  
Body Depth ◽  
Pectoral Spine ◽  
Pelvic Fin

Glyptothorax rupiri, a new sisorid catfish, is described from the Brahmaputra River basin in Arunachal Pradesh, northeast India. It differs from its congeners in the Indian subcontinent by the following combination of characters: the presence of plicae on the ventral surface of the pectoral spine and first pelvic-fin ray; a posteriorly serrated dorsal-fin spine, its length 11.3–12.2% SL; body depth at anus 11.2–13.4% SL; a thoracic adhesive apparatus longer than broad, with a V-shaped median depression which opens posteriorly; an arrow-shaped anterior nuchal plate element; adipose-fin base length 10.9–12.6% SL; nasal barbel not reaching anterior orbital margin; 14–18 serrae on posterior margin of the pectoral-fin spine; body with two longitudinal pale-cream stripes; densely tuberculated skin; and the presence of numerous tubercles on the dorsal surface of pectoral and pelvic-fin rays.  

A New Delphinium-Infesting Aphid (Homoptera: Aphididae)

1958 ◽  
Vol 90 (11) ◽  
pp. 690-692 ◽  
Author(s):  
W. R. Richards
Keyword(s):  
Dorsal Surface ◽  
Ventral Surface ◽  
Apical Segment ◽  
Basal Diameter ◽  
Viviparous Female ◽  
Fourth Segment ◽  
Small Tubercle ◽  
Small Primary ◽  
Basal Portion ◽  
Large Primary

Apterous Viviparous FemaleHolotype.–Dorsum of head with six blunt or slightly clavate setae. Frontal tubercles well developed, smooth, diverging, each with one long, (blunt seta on dorsal surface and one or two on ventral surface. Antenna about as long as body, third segment expanded just distad of base to almost twice its basal diameter; 56 small, tubercle-like, secondary sensoria scattered along whole length of one third segment, 60 on other; one fourth segment with four secondary sensoria, the other with five; a single, large, primary sensorium near apex of each fifth segment, and one large one and five or six adjacent smaller ones near apices of basal portion of sixth segment; each small primary sensorium on sixth segment with a central papilla; all primary sensoria lacking marginal, cilia-like fimbriations. Antennal setae distinctly capitate and about equal in length to basal diameter of third segment. Lengths of antenna1 segments as follows: III, 0.85 mm.; IV, 0.4 mm.; V, 0.3 mm.; VI, 0.15-0.85 mm. Rostrum reaching slightly beyond middle coxae; apical segment 0.13 mm. long, with 17 slender pointed setae in addition to usual apical ones.

scholarly journals Tongue papillae morphology of brown-throated sloth Bradypus variegatus (SCHINZ, 1825)

2014 ◽  
Vol 66 (5) ◽  
pp. 1479-1486 ◽  
Author(s):  
D.M. Martins ◽  
L.L. Pinheiro ◽  
V.C. Ferreira ◽  
A.M. Costa ◽  
A.R. Lima ◽  
...  
Keyword(s):  
Dorsal Surface ◽  
Ventral Surface ◽  
Simple Type ◽  
Morphological Aspect ◽  
Fungiform Papilla ◽  
Wild Mammals ◽  
Deep Groove ◽  
Vallate Papillae ◽  
Filiform Papillae ◽  
Bradypus Variegatus

The Bradypusvariegatus inhabits the forests of South America and feeds from leaves, branches and sprouts from different plants. Due to its diet and the lack of literature on the morphological aspect of Xenarthras, five Bradypusvariegatus tongues from animals which died from natural causes were evaluated, and they came from Pará State Museum Emílio Goeldi and were donated to the Laboratory of Animal Morphological Research (LaPMA) from UFRA, for revealing the different types of papillae and epithelial-connective tissue. Macroscopically, the tongues presented elongated shape, rounded apex, body, root, median sulcus in the root's apex, and two vallate papillae. The mucous membrane of the tongue revealed a keratinized stratified pavement epithelium, while the ventral surface of the tongue was thin and smooth, not provided with any type of papillae. However, the dorsal surface of the tongue was irregular with the presence of three types of papillae: filiform, fungiform and vallate papillae. The filiform papillae found were of a simple type, presenting a rounded base, irregularly distributed with a larger concentration and development on the tongue's apex and body. The fungiform papilla showed a practically smooth surface with irregular format, with the presence of gustatory pores; these were found all over the dorsal surface, with larger concentration at the rostral part of the apex. Only two vallate papillae were observed disposed in the root of the tongue, surrounded by a deep groove, and revealing several taste buds. The tongues from Bradypusvariegatus presented gustatory papillae similar to the ones described for other Xenarthras species and wild mammals.

scholarly journals The Eyes and the Photonegative Behaviour of Nephtys (Annelida, Polychaeta)

1956 ◽  
Vol 33 (3) ◽  
pp. 461-477
Author(s):  
R. B. CLARK
Keyword(s):  
Light Intensity ◽  
Light Beam ◽  
Linear Function ◽  
Posterior Part ◽  
Dorsal Surface ◽  
Epidermal Cells ◽  
Small Species ◽  
Accessory Cells ◽  
Vacuolated Cells ◽  
The Brain

1. The photoreceptors found in the Nephtyidae are: (a) Two pairs of vacuolated cells lying in pigment cups, with accessory cells, embedded in the posterior part of the supra-oesophageal ganglion. (b) One or two cells, which may or may not be vacuolated, on either side, lying a little anterior to the ganglion. (c) Undifferentiated epidermal cells surrounded by pigment granules may be photosensitive. 2. There are both morphological and behavioural grounds for concluding that the prostomial eyes of Nephtys are homologous with the eyes of Nereis, and that they are involved in the same types of behaviour. 3. The frequency with which Nephtys swims is, within limits, a linear function of the light intensity. Although the ganglionic eyes are directional receptors the worm does not orientate itself in a light beam; presumably the light reaching them is too diffuse. In the very small species N. cornuta, the eyes are close to the surface of the brain and the worm does orientate itself in a light beam. 4. Swimming is an essential prelude to burrowing, and the brighter the light the more frequently the worm swims and the sooner it is buried. Activity in light can be inhibited by stimulating receptors on the dorsal surface of the animal by contact.

scholarly journals The first data on the role of rhyncholites in the process of epibiota

2019 ◽  
pp. 5-9
Author(s):  
E. S. Gaponenko ◽  
M. A. Ulshin ◽  
V. N. Komarov
Keyword(s):  
Adult Worm ◽  
Dorsal Surface ◽  
Ventral Side ◽  
Ventral Surface ◽  
Clear Indication ◽  
Life Activity ◽  
Additional Food ◽  
Inner Surface ◽  
First Time

For the first time the role of rhyncholites in the process of epibiota has been figured out. Serpulidae inlay is detected in 39 rhyncholites of 979 specimens, representing 4% of the all studied material. This fact demonstrates that rhyncholites were used extremely rarely by encrusting species as a substrate. No other epibionts were found. Polychaetes were found in the genus Hadrocheilus (87%) and in the genus Akidocheilus. Size of the inlaid rhyncholites ranges from 7 to 23 mm. Serpulidae cover usually only the ventral side of rhyncholites, herewith, at 48,7% of the samples epibionts with different degrees of intensity are developed throughout the ventral surface, at 30,7% of the samples they are observed only on the ventral side of the hood and at 20,6% serpulidae are present only on the ventral surface of the arm. At four exemplars of the genus Hadrocheilus (10 % of the total amount) polychaetes are developed on the dorsal surface, but they are always and usually very wide developed on the ventral side of rhyncholites. No samples were found in which serpulidae were found only on the dorsal surface. Among the remains of polychaete worms, large and small tubes were identified and described. The presence of serpulidae on the handle of rhyncholites, that during the life of the cephalopod mollusk was located in a horny jaw, is a clear indication of the settlement’s epibionts on isolated skeletal structures of the already dead cephalopod. Cases when serpulidae are observed only on the ventral side of the hood in representatives of the genus Akidocheilus, suggest that planktonic trochophore – larvae of polychaetes can settle on the inner surface of the mandible of living ammonoids, where they turned into an adult worm. At the same time, polychaetes gained access not only to traditional prey, represented by various microscopic organisms, but also to additional food resources associated with the life activity of cephalopodas.

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