Serpentine Movement Research Articles

Serpentine Movement on Superposed Trains of Differential Mechanisms.

In this paper, a slender and cordlike differential mechanism is proposed, and the capability of its motion is examined. It has a high number of degrees of motion, many more than the number in the input required to drive it, since it is composed of many differential mechanism units, all of which are two-dimensionally connected to each other. Every unit is made up of a wired pulley which is free around the axis connecting two links. The mechanism is driven by three or more wires on which tension forces changing sinusoidally are applied by DC motors under feedback control using a personal computer. Consequently, progressive transverse wave motion similar to the serpentine movement of snakes has been successfully generated on the mechanism.

The gubernaculum shows rhythmic contractility and active movement during testicular descent

Androgens are postulated to act indirectly on the gubernaculum via the genitofemoral nerve, which contains specific neuropeptide transmitters. We examined gubernacula in vitro and in vivo to see if these neuropeptides affected the gubernacular development directly. Gubernacula (n = 272) from male rats (aged 0 to 3 days) were incubated in organ culture with various different neurotransmitters. The cultures were examined daily with a dissecting microscope connected to a video camera and tape. Some rats were anaesthetized and the inguinoscrotal skin was excised to expose the gubernacula for in vivo video recording. Of 181 gubernacula treated with calcitonin gene-related peptide (CGRP) at concentrations of 7 to 714 nmol/L, 92 showed rhythmic contractions. The number of responsive gubernacula was proportional to CGRP concentrations ( r = .685). This compared with 9 of 40 gubernacula treated with vasoactive intestinal peptide and 2 of 25 controls. Neither female gubernacula, skeletal muscle, nor umbilical cord showed CGRP-induced contractions. Gubernacula in vivo showed vigorous contractility and serpentine movements, which were accentuated by increased intraabdominal pressure. These studies demonstrate the gubernaculum to be highly motile during testicular descent. Rhythmic contractions suggest the presence of possible smooth muscle-like components that may be modulated by CGRP release from the genitofemoral nerve.

Dipetalonema viteae: Survival of Adult Females and Microfilarial Release in Both a Chemically Defined and Serum-Supplemented Medium

Studies were conducted on survival and microfilarial release of afult Dipetalonema viteae in culture, using worms of various ages derived from jirds. In chemically defined NI medium (a 1:1 mixture of NCTC 135 and Iscove's modified Dulbecco's medium) under a gas phase of 5% CO2 in nitrogen (pO2 of medium approximately 40 mm Hg), the peak of microfilarial release of several thougsand microfilariae per female per 24 hr occurred at approximately day 10. Thereafter, microfilarial release declined and generally ended about 1 mo after the start of culture. The adult females moved actively for about 50 days or more and survived up to 82 days in NI medium alone. The females in NI medium supplemented with fetal bovine serum showed serpentine movement for approximately 2 mo. Some of the worms survived more than 83 days. The total number of microfilariae deposited in culture by D. viteae increased as adult females grew in size (volume) over time. Microfilarial deposition continued to increase after worms reached maximum size, deposition reaching a plateau between approximately 300 and 400 days of age. Thereafter, microfilarial deposition decreased as females continued to age. Addition of fetal bovine serum to the NI medium increased the number of microfilariae released and extended the period of release.

Discovery of Stretch Receptor Organs in Nematodes–Structure, Arrangement and Functional Analysis

Filamentous organs, termed metanemes and interpreted as stretch receptor organs, have been discovered in nematodes of the order Enoplida. They have not been found in species of 11 other nematode orders. According to light microscopical observations, a metaneme consists of a 5–15 μm long scapulus, a 20–400 μm long frontal and a 30–170 μm long caudal cuticularized filament; the latter is lacking in some taxa. Metanemes are arranged serially in the lateral epidermal cords; they are parallel or at an angle of 10–30° to the longitudinal body line. The function of metanemes is likely to coordinate the serpentine movement and to control the actual body volume.

ほふく(匍匐)運動の生物力学的研究

It is a well-known fact in morphology that static forms of living organisms are classified into several fundamental shapes. Some of them can be described by a geometrical function. On the contrary, the posture of a moving animal has scarcely been treated in morphology, with a few exceptions. But it seems that the posture could be represented with an idealized mathematical form if the animal's behavior is conditioned and maintained in uniform and stationary surroundings. The present paper shows one such typical case, discussing the shape of a gliding snake.In this paper the gliding shape of snakes during locomotion on a flat surface in stationary straightforward movement is treated. The authors conclude that two kinds of geometrical curves, Eq. (7) and (10), represent sufficiently the shape of a gliding snake. Especially the curve derived under the assumption that the muscle will repeat contraction and relaxation cycles harmoniously during serpentine movement, which we named as the “serpenoid curve”, is shown to be remarkably similar to that of a living snake. Thus the authors believe that research on the shape of animals is useful not only to zoology but also to the biomechanics of an artificial animal-like vehicle and its designing.

On an Immature Didymozoid Larva (Trematoda: Didymozoidae) in the Muscles and Swim Bladder of Anthias squamipinnis (Anthiidae) from the Gulf of Aqaba

An immature didymozoid larva, designated Immature Didymozoid H, is described from the dorsal muscles and swim bladder of Anthias squamipinnis (Peters), a coral-reef fish caught in the Gulf of Aqaba near Eilat. This larva is considerably larger than any didymozoid larva previously described. Protrusion of the larva from the muscles along the dorsal fin of the host fish, and its vigorous, serpentine movements, suggest that cleaner fishes may possibly serve as definitive host for the parasite. Among fishes caught 10 km south of Eilat, in the Gulf of Aqaba (Red Sea), six specimens of Anthias squamipinnis (Peters) (Anthiidae) harbored immature didymozoid larvae. These larvae were located in the dorsal muscles of the fishes and in some also on the swim bladder and in the muscles immediately above it. Larvae in the dorsal muscles were found singly, unencysted, protruding, and actively bending half or more of their body in serpen- tine fashion from the dermis near the dorsal

Embryonic behaviour in the lizard, Lacerta vivipara

The behaviour of embryos of the lizard Lacerta vivipara has been studied in cultured eggs, removed from the mother. Spontaneous movements begin at a time when the embryo is still unresponsive to touch, and about two days before the appearance of reflex responses. The earliest movements consist of lateral flexion which gradually gives place to dorsiventral flexion. Embryonic movements are not necessarily related to contractions of the amnion. The activity of the embryo, as measured by the number of times movements were initiated and the amount of time spent in activity during a half hour period, rises to a plateau and then decreases sharply as the time of hatching approaches. Activity of the tail is prominent, particularly at times when other movements occur in rapid succession. Serpentine movements were not observed in embryos younger than stage 39; some prematurely born animals showed such activity in response to contact with the substratum. During embryonic life any part of the animal may move individually or in combination with any other part, such combined movements being unco‐ordinated. In these respects the spontaneous motility of the lizard embryo closely resembles that of the chick. Statistical analysis of the embryonic movements provides evidence of rhythmic activity within the developing central nervous system.

The Mechanism of Locomotion in Snakes

ABSTRACT Among snakes four main types of terrestrial progression have been described: (i) serpentine movement which is observable in all, or nearly all, genera; (ii) concertina movement as briefly described by Wiedemann (1932) in Vipera and Coronella; (iii) crotaline or ‘side-winding’ as seen in Crotalus or Cerastes (Mosauer, 1932a,b); and (iv) rectilinear movement as exhibited by boas and other large types (Home, 1812). The observations described in the present paper have all been made on the common grass snake (Tropidonotus natrix); the evidence to be presented shows that serpentine, concertina or crotaline movements can all be elicited in this genus by appropriate modification of the external forces operating on the body of the moving animal.