Studies with Ostertagia circumcincta in Sheep. I. The epidemiology of mature adults and arrested larvae

1967 ◽  
Vol 41 (2-3) ◽  
pp. 137-150 ◽  
Author(s):  
P. S. James ◽  
I. L. Johnstone
Keyword(s):  
Adult Population ◽  
Post Mortem ◽  
Fourth Stage ◽  
Mature Adults

By means of egg counts, faecal cultures and post-mortem examinations of sheep the course of an infestation of Ostertagia circumcincta was followed from March until the following January in a flock of 100 twelve-months-old wethers at Wellington, N.S.W. The highest adult infestations and egg counts occurred in March and January, while during the winter months there was a continual accumulation of inhibited fourth stage larvae in the abomasal mucosa. The data suggest that the adult population observed in January arose from the inhibited population observed during the previous winter and that one of the factors controlling the development of the inhibited population was larval intake.

Post mortem vitreous magnesium in adult population

2018 ◽  
Vol 284 ◽  
pp. 46-52 ◽  
Author(s):  
R. Tse ◽  
J. Garland ◽  
K. Kesha ◽  
P. Morrow ◽  
L. Lam ◽  
...  
Keyword(s):  
Adult Population ◽  
Post Mortem

scholarly journals Population status and demographics of Lake Sturgeon in the Bad and White rivers, Wisconsin

2019 ◽  
Vol 10 (2) ◽  
pp. 442-457 ◽  
Author(s):  
Joshua T. Schloesser ◽  
Henry R. Quinlan
Keyword(s):  
Sex Ratio ◽  
Adult Population ◽  
Lake Superior ◽  
Return Time ◽  
Lake Sturgeon ◽  
River Population ◽  
Mature Adults ◽  
Rehabilitation Plan ◽  
Population Trajectory ◽  
Spawning Run

Abstract Lake Sturgeon Acipenser fulvescens rehabilitation efforts in Lake Superior are guided by a rehabilitation plan that sets goals and criteria for a self-sustaining population, including a minimum of 1,500 mature adults, roughly equal sex ratio, and annual exploitation rates < 5%. The Bad and White rivers, Wisconsin host a genetically unique Lake Sturgeon population that is utilized by state-licensed recreational anglers and tribal subsistence fishers. Our objectives were to 1) determine if the Bad River population meets rehabilitation plan targets for a self-sustaining population, 2) assess harvest of Lake Sturgeon by recreational anglers and tribal subsistence fishers for compatibility with rehabilitation goals, 3) determine population trajectory from annual spawning runs, and 4) describe population demographics given the unique physical features of Lake Superior. We sampled Lake Sturgeon in the Bad and White rivers with gill nets over a 17-y period (2001 to 2017). The observed sex ratio in spawning runs was 2.2:1 (male : female), but calculated at 1.6:1 for the entire adult population on the basis of abundance estimates. Weight–length relationships converted to a standardized modified form factor indicated lower condition and possibly lower female fecundity compared with other large North American populations. Annual spawning run size estimates over time indicated that the population trajectory was stable to slightly increasing, and during 2016 was 739 and 241 individuals in the Bad and White rivers, respectively. Total population size (including nonspawners) exceeded 1,500 individuals, which met Lake Superior rehabilitation criteria for a self-sustaining population. Estimates of 1,426 males and 882 females were considered conservative because 472 unknown-sex fish could not be accounted for in return time and abundance models. Spawning return times were 2 or 3 y for males and 4 to 6 y for females, longer than many other populations. Exploitation by recreational anglers and tribal subsistence fishers was 1.3% or lower and met the rehabilitation plan target of < 5%, but we recommend exploitation not exceed 3.1% to maintain a self-sustaining population. These findings help gauge rehabilitation progress in Lake Superior and better describe the demographics of a remnant self-sustaining Lake Sturgeon population in Lake Superior.

Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

2007 ◽  
Keyword(s):  
Deterministic Model ◽  
Adult Population ◽  
Fish Passage ◽  
Adult Longevity ◽  
Bull Trout ◽  
Catastrophic Events ◽  
Mature Adults ◽  
Trout Population ◽  
Lake Washington ◽  
Adult Abundance

ABSTRACT A life cycle model was employed to identify the response of an adfluvial bull trout <em>Salvelinus confluentus</em> population to chronic and catastrophic losses of subadults. The model simulates the bull trout population within Rimrock Lake, Washington, a reservoir on the Tieton River impounded by Tieton Dam. Subadult bull trout are entrained during summer water releases for irrigation, and the dam has no fish passage facilities to enable those fish to return upstream. Suitable spawning and rearing habitat is primarily upstream of the dam. Tagging studies of adult bull trout passing weirs in the two major tributaries to the reservoir were used to estimate model parameters for survival, maturity rates, reproductive capacity, and initial abundance. Sampling data and the deterministic model simulations indicated that the population was capable of rebounding quickly from intermittent catastrophic events. Resilience of the bull trout population resulted from high adult longevity and repeat spawning. The accumulation of mature adults across multiple age-classes led to egg deposition that fully seeded rearing capacity of the natal tributaries, even when several consecutive broods of juveniles exhibited poor survival. Catastrophic events simulated to entrain 50% of the subadults every 15 years caused a 40% reduction in adult abundance within 4 years of the event, followed by a full recovery to maximum production within 9 years. Even during the low point of adult abundance, 15 times more eggs were deposited than were needed to fully seed juvenile tributary habitat. Because the population was already producing juveniles at capacity, simulations for opening fish passage over Rimrock Dam showed that the sustained spawner population would increase by only two adults. However, simulations for expanded juvenile habitat by 14% indicated that the sustainable adult population would increase by 14%. Thus, habitat improvements that target juvenile rearing capacity appear to have the greatest potential to increase population size.

Studies on the distribution and site location ofNippostrongylus brasiliensiswithin the small intestine of laboratory rats

Parasitology ◽  
1970 ◽  
Vol 61 (3) ◽  
pp. 449-460 ◽  
Author(s):  
Thomas J. W. Alphey
Keyword(s):  
Small Intestine ◽  
Primary Infection ◽  
Sexual Attraction ◽  
Adult Population ◽  
Migratory Behaviour ◽  
Fourth Stage ◽  
Site Location ◽  
Laboratory Rats ◽  
Anterior Half ◽  
Normal Site

The distribution ofN. brasiliensiswithin the small intestine of rats, following a primary infection, is described.The fourth stage larvae were found to inhabit the sections later parasitized by the adult population.Both the larval and adult worms were found to be confined to the anterior half of the small intestine. This aggregation is believed to be under the influence of stimuli (factor(s) 1), present in the lumen of the host gut.The adult worms also clumped within the already confined worm population. This behaviour is thought to be due to intrinsic behaviour patterns of the worm, sexual attraction and thigmokinesis.Larval and adult worms were surgically transferred to points, at varying distance from the ‘normally’ inhabited region, in the small intestine of fresh recipient rats. The resulting migratory behaviour of the worms was studied.The worm populations resulting from both the larval and the adult transfers showed the ability to recognize that they were in the wrong position of the small intestine and to be able to orientate, migrate and locate the ‘normal’ site.

Trichostrongylid infections of sheep in a winter rainfall region. I. Epizootiological studies in the Western District of Victoria, 1966-67

1972 ◽  
Vol 23 (6) ◽  
pp. 1113 ◽  
Author(s):  
N Anderson
Keyword(s):  
Haemonchus Contortus ◽  
Seasonal Distribution ◽  
Post Mortem ◽  
Fourth Stage ◽  
Winter Rainfall ◽  
Merino Sheep ◽  
Region I ◽  
Low Levels ◽  
Rainfall Region ◽  
Previous Summer

Regular post-mortem counts from 'tracer' and flock sheep, together with faecal worm egg counts and plasma pepsinogen determinations, formed the basis of an epizootiological study of trichostrongylid infections of Merino sheep in the Western District of Victoria. Species from genera Trichostrongylus, Ostertagia and Nematodirus predominated in the worm counts; Haemonchus contortus was absent. Counts of Ostertagia and Trichostrongylus spp. from successive groups of 'tracer' sheep showed a pronounced seasonal distribution of available larvae in accordance with the temperature and humidity components of the prevailing weather. Mean worm counts ranging from 2000 to 32,000 per fortnight were recorded between May and October, whereas at other times the counts were consistently less than 500. When the availability of larvae was high, faecal worm egg counts of weaners and adult sheep were less than 150 epg. At this time the majority of the worms in the abomasum were early fourth stage larvae. Some weeks after availability had decreased to low levels, mean egg counts increased from 100 to values over 700 epg. It was concluded that the high levels of larval availability were derived from worm eggs deposited in the previous summer and autumn. Resistance to the establishment of worms was evident in both young and mature sheep. It was found that raised plasma pepsinogen levels, indicative of severe abomasal lesions, were closely related to the numbers of newly ingested larvae. Liveweights and fleece weights of weaners treated with 88 mg thiabendazole per kg every 14 days and those from untreated weaners did not differ significantly until the availability of larvae decreased to low levels, after which the treated sheep were heavier and produced 0.52 kg or 14.6% more wool per head.

The regulation of populations ofOstertagia ostertagiin calves

Parasitology ◽  
1970 ◽  
Vol 61 (3) ◽  
pp. 435-447 ◽  
Author(s):  
J. F. Michel
Keyword(s):  
Infection Rate ◽  
Small Proportion ◽  
Post Mortem ◽  
Fourth Stage ◽  
Infection Rates ◽  
Ostertagia Ostertagi ◽  
High Infection ◽  
The Relationship

The course of the worm burdens of calves infected daily with larvae ofOstertagia ostertagiat five different rates was studied by making post-mortem worm counts on groups of calves killed after experiencing infection for different periods of time.The relationship between worm numbers and infection rates together with evidence that a turnover of worms occurred, led to the conclusion that burdens of adult worms were regulated primarily by a loss of worms at a rate proportional to the number present.Further, estimates based on the number of developing fourth-stage larvae indicated that the proportion of the larvae administered which became established decreased gradually as the experiment progressed.At very low infection rates, the rate of turnover of the worms was slower than at high infection rates but in all groups it remained constant through the 6 months duration of the experiment.The development of a small proportion of the larvae administered was arrested at the early fourth stage. At the highest infection rate used, the proportion of worms that became inhibited was somewhat greater.

Studies on Paratylenchus nanus. II. Population changes around apple roots

1967 ◽  
Vol 18 (2) ◽  
pp. 279 ◽  
Author(s):  
JM Fisher
Keyword(s):  
Soil Sample ◽  
Low Temperatures ◽  
Seasonal Changes ◽  
Adult Population ◽  
Sufficient Information ◽  
Parasitic Stage ◽  
Fourth Stage ◽  
Population Changes ◽  
High Moisture ◽  
Males And Females

The numbers of fourth-stage larvae, males, and females of Paratylenchus nanus in soil around apple roots have been examined and found to be partially correlated with seasonal changes in the trees. Bulking subsamples did not give sufficient information, and so trends were determined from individual samples. Numbers of females were assessed: (a) per soil sample; (b) per weight of apple roots in each soil sample. In soil, all stages showed a decline in numbers in winter and summer and an increase in spring (Sept.). At other times numbers remained stationary except for a decrease in larval numbers in October and an increase in numbers of females between November and January. Males always exceeded females in number and larvae always exceeded adults, but the proportion of females in the adult population increased from 27% in winter to 41% in summer. Numbers of females – the only parasitic stage recovered – per gram of apple root decreased in winter, increased in spring, and decreased again in summer. Survival of the different stages under an adverse environment suggested that high temperatures in summer and low temperatures with high moisture levels in winter were partly responsible for the decreases in number at these times.

Ultrastructural investigation of an adenoma of the pituitary post mortem

1987 ◽  
Vol 45 ◽  
pp. 622-623
Author(s):  
Shirley Siew ◽  
W. C. deMendonca
Keyword(s):  
Deleterious Effect ◽  
Anterior Lobe ◽  
Definitive Diagnosis ◽  
Pars Intermedia ◽  
Post Mortem ◽  
Close Apposition ◽  
Autopsy Material ◽  
Progressive Loss ◽  
Transmission Electron ◽  
Means Of Transmission

The deleterious effect of post mortem degeneration results in a progressive loss of ultrastructural detail. This had led to reluctance (if not refusal) to examine autopsy material by means of transmission electron microscopy. Nevertheless, Johannesen has drawn attention to the fact that a sufficient amount of significant features may be preserved in order to enable the establishment of a definitive diagnosis, even on “graveyard” tissue.Routine histopathology of the autopsy organs of a woman of 78 showed the presence of a well circumscribed adenoma in the anterior lobe of the pituitary. The lesion came into close apposition to the pars intermedia. Its architecture was more compact and less vascular than that of the anterior lobe. However, there was some grouping of the cells in relation to blood vessels. The cells tended to be smaller, with a higher nucleocytoplasmic ratio. The cytoplasm showed a paucity of granules. In some of the cells, it was eosinophilic.

Post-mortem Peyer’s patches: Their potential application in forensic medicine

2009 ◽  
Vol 00 (00) ◽  
pp. 090513010017019-7
Author(s):  
Biagio Solarino ◽  
Giancarlo Di Vella ◽  
Thea Magrone ◽  
Felicita Jirillo ◽  
Angela Tafaro ◽  
...  
Keyword(s):  
Forensic Medicine ◽  
Potential Application ◽  
Peyer's Patches ◽  
Peyer’S Patches ◽  
Post Mortem
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