Induction de la maturation sexuelle chez la Planaire scissipare Dugesia gonocephala (Turbellarié, Triclade)

Development ◽  
1974 ◽  
Vol 32 (1) ◽  
pp. 159-168
Author(s):  
Th. Lender ◽  
C. Briançon
Keyword(s):  
Genital Pore ◽  
Sexual Maturity ◽  
Caudal Region ◽  
Genital Apparatus ◽  
Experimental Induction

Induction of sexual maturity in a fissiparous Planarian, Dugesia gonocephala The planarian Dugesia gonocephala reproduces either sexually, or asexually by fission, according to the presence or absence of a genital apparatus. The experimental induction of sexual maturity in a fissiparous planarian can be obtained by grafting a piece of a planarian with a genital pore containing mature testes, whether they are testes existing in the graft before the operation (grafts of testes) or testes differentiated in the piece after grafting (grafts of ovaries). Grafts of cephalic or caudal region, and pieces of a planarian without genital pore, cannot induce this maturation and cannot differentiate testes. The induction of testicular structures seems to be dependent on hormones. The development of a genital apparatus in a planarian without genital pore is accompanied by the disappearance of fission.

Acetaminophen: Macula densa hypersecretory activity by induced hepatotoxicity

1987 ◽  
Vol 45 ◽  
pp. 934-935
Author(s):  
S.S. Poolsawat ◽  
C.A. Huerta ◽  
S.TY. Lae ◽  
G.A. Miranda
Keyword(s):  
Cell Proliferation ◽  
Liver Function ◽  
Chronic Inflammation ◽  
Foam Cell ◽  
Term Effect ◽  
Short Term ◽  
Drug Induced ◽  
Experimental Induction ◽  
Tissue Alterations ◽  
Toxic Responses

Introduction. Experimental induction of altered histology by chemical toxins is of particular importance if its outcome resembles histopathological phenomena. Hepatotoxic drugs and chemicals are agents that can be converted by the liver into various metabolites which consequently evoke toxic responses. Very often, these drugs are intentionally administered to resolve an illness unrelated to liver function. Because of hepatic detoxification, the resulting metabolites are suggested to be integrated into the macromolecular processes of liver function and cause an array of cellular and tissue alterations, such as increased cytoplasmic lysis, centrilobular and localized necroses, chronic inflammation and “foam cell” proliferation of the hepatic sinusoids (1-4).Most experimentally drug-induced toxicity studies have concentrated primarily on the hepatic response, frequently overlooking other physiological phenomena which are directly related to liver function. Categorically, many studies have been short-term effect investigations which seldom have followed up the complications to other tissues and organs when the liver has failed to function normally.

Developing an experimental induction of flow

2007 ◽  
Author(s):  
Arlen Moller ◽  
Mihaly Csikszentmihalyi ◽  
Jeanne Nakamura ◽  
Edward Deci
Keyword(s):  
Experimental Induction

THE »EARLY-ANDROGEN« SYNDROME; ITS DEVELOPMENT AND THE RESPONSE TO HEMI-SPAYING

1964 ◽  
Vol 45 (1) ◽  
pp. 1-12 ◽  
Author(s):  
H. E. Swanson ◽  
J. J. van der Werff ten Bosch
Keyword(s):  
Sexual Maturity ◽  
Compensatory Growth ◽  
Testosterone Propionate ◽  
Single Injection ◽  
Weight Increase ◽  
Corpora Lutea ◽  
Transition Stage ◽  
Adult Females

ABSTRACT The »early-androgen« syndrome in the rat – i. e. anovulatory ovaries in adult females after a single injection of testosterone propionate (TP) within a week of birth – may not become apparent until some time after the attainment of sexual maturity. Large doses (50 or 100 μg) of TP were effective earlier than lower doses (5 or 10 μg). Rats which received 5 μg TP were ovulating at 10 weeks of age, mated but were infertile at 13 weeks of age, and were anovulatory at 21 weeks. In rats between 10 and 13 weeks old there was a marked fall in the number of corpora lutea in the ovaries of animals which had been given 5 μg TP. Hemi-spaying was followed by compensatory growth of the remaining ovary which consisted of corpora lutea in ovulating, and of follicles in anovulatory rats; little or no compensatory weight increase occurred in animals which seemed to be in the transition stage from the ovulatory to the anovulatory condition.

PLASMA LH, TESTOSTERONE AND DHT IN THE PIG FROM BIRTH TO SEXUAL MATURITY

1973 ◽  
Vol 71 (4_Suppl) ◽  
pp. S148 ◽  
Author(s):  
F. Elsaesser ◽  
D. K. Pomerantz ◽  
F. Ellendorff ◽  
K. Kreikenbaum ◽  
A. König
Keyword(s):  
Sexual Maturity

Estimation of Sexual Maturity Based on Morphometrics of Genital Organs in Male Northern Fur Seals, Callorhinus ursinus

Mammal Study ◽  
2020 ◽  
Vol 46 (1) ◽  
Author(s):  
Yukino Hirakawa ◽  
Takanori Horimoto ◽  
Ippei Suzuki ◽  
Yoko Mitani
Keyword(s):  
Sexual Maturity ◽  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Northern Fur Seals

Rites of Passage

2018 ◽  
Author(s):  
Axel Michaels
Keyword(s):  
Life Cycle ◽  
Old Age ◽  
Sexual Maturity ◽  
Rites Of Passage ◽  
Life And Death ◽  
Transformational Process ◽  
Local Contexts ◽  
Vulnerable Community ◽  
History Of ◽  
The Individual

This chapter examines the classical Hindu life-cycle rites, the term saṃskāra and its history, and the main sources (Gṛhyasūtras and Dharma texts). It presents a history of the traditional saṃskāras and variants in local contexts, especially in Nepal. It describes prenatal, birth and childhood, initiation, marriage, old-age, death, and ancestor rituals. Finally, it analyzes the transformational process of these life-cycle rituals in the light of general theories on rites of passage. It proposes, in saṃskāras, man equates himself with the unchangeable and thus seems to counteract the uncertainty of the future, of life and death, since persons are confronted with their finite existence. For evidently every change, whether social or biological, represents a danger for the cohesion of the vulnerable community of the individual and society. These rituals then become an attempt of relegating the effects of nature or of mortality: birth, teething, sexual maturity, reproduction, and dying.

Isolating Gene E' for Early Sexual Maturity

1945 ◽  
Vol 79 (783) ◽  
pp. 372-377 ◽  
Author(s):  
F. A. Hays
Keyword(s):  
Sexual Maturity

Sex ratio and life history traits at reaching sexual maturity in the dioecious shrub Fuchsia parviflora: field and common garden experiments

2021 ◽  
pp. 1-6
Author(s):  
Jessica S. Ambriz ◽  
Clementina González ◽  
Eduardo Cuevas
Keyword(s):  
Natural Population ◽  
Sexual Maturity ◽  
Sex Ratios ◽  
Natural Populations ◽  
Common Garden ◽  
Common Garden Experiment ◽  
Trade Offs ◽  
Reproductive Biomass ◽  
Common Garden Experiments ◽  
Growth And Reproduction

Abstract Fuchsia parviflora is a dioecious shrub that depends on biotic pollination for reproduction. Previous studies suggest that the male plants produce more flowers, and male-biased sex ratios have been found in some natural populations. To assess whether the biased sex ratios found between genders in natural populations are present at the point at which plants reach sexual maturity, and to identify possible trade-offs between growth and reproduction, we performed a common garden experiment. Finally, to complement the information of the common garden experiment, we estimated the reproductive biomass allocation between genders in one natural population. Sex ratios at reaching sexual maturity in F. parviflora did not differ from 0.5, except in one population, which was the smallest seedling population. We found no differences between genders in terms of the probability of germination or flowering. When flowering began, female plants were taller than males and the tallest plants of both genders required more time to reach sexual maturity. Males produced significantly more flowers than females, and the number of flowers increased with plant height in both genders. Finally, in the natural population studied, the investment in reproductive biomass was seven-fold greater in female plants than in male plants. Our results showed no evidence of possible trade-offs between growth and reproduction. Despite the fact that female plants invest more in reproductive biomass, they were taller than the males after flowering, possibly at the expense of herbivory defence.

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