QUANTITATIVE STUDIES OF HAIR GROWTH IN THE ALBINO RAT

1958 ◽  
Vol 16 (4) ◽  
pp. 360-368 ◽  
Author(s):  
ELIZABETH JOHNSON
Keyword(s):  
Hair Growth ◽  
Ovarian Hormones ◽  
The Body ◽  
Female Rats ◽  
Inhibitory Effects ◽  
Albino Rat ◽  
Adrenal Hormones ◽  
Quantitative Studies ◽  
Males And Females ◽  
Second Wave

SUMMARY 1. Adrenalectomy 2 weeks before the start of the second wave of hair growth advanced the beginning of the wave in female rats, and speeded its passage over the body in both males and females. The rate of loss of club hairs was slightly accelerated, but there was no effect on the definitive length of hair produced. 2. Adrenalectomy after the wave of hair growth had begun was less effective. 3. ACTH did not affect the time at which the wave of hair growth began but delayed its passage. ACTH had no effect on the loss of club hairs nor on the definitive length of hair produced. 4. Implantation of oestradiol retarded the start and rate of passage of the wave, and the loss of club hairs in both spayed and spayed adrenalectomized animals. Oestradiol must therefore have some action which is independent of the adrenals. Nevertheless, inhibitory effects of oestradiol on these aspects of hair growth were enhanced by the presence of the adrenals. The action of oestradiol in reducing the rate of hair growth was, on the other hand, unaffected by the presence or absence of the adrenals. 5. Adrenal hormones delay the passage of the growth wave to a greater extent than ovarian hormones, but they have no effect on the rate of hair growth, and, compared with ovarian hormones, affect the loss of club hairs only slightly. It is therefore suggested that these three main phases of hair growth may be controlled by mechanisms which are at least partially independent.

QUANTITATIVE STUDIES OF HAIR GROWTH IN THE ALBINO RAT

1958 ◽  
Vol 16 (4) ◽  
pp. 351-359 ◽  
Author(s):  
ELIZABETH JOHNSON
Keyword(s):  
Hair Growth ◽  
Female Rats ◽  
Male Rats ◽  
Hair Length ◽  
Inhibitory Effects ◽  
Albino Rat ◽  
Rate Of Growth ◽  
Quantitative Studies ◽  
Reduced Rate ◽  
Second Wave

SUMMARY 1. Spaying of female rats aged 7 weeks accelerated the passage of the second wave of hair growth. Longer hairs were produced as a result of faster growth, and the rate of loss of dead or 'club' hairs [cf. Johnson, 1958] was increased. 2. Oestradiol implanted into spayed females delayed the initiation and passage of the wave. Shorter hairs were produced by a reduced rate of growth, and loss of club hairs was inhibited. 3. Castration of male rats aged 7 weeks accelerated the passage of the second wave of growth, and implantation of testosterone slowed it down. Testosterone had no effect on the definitive length of hair produced or on the rate at which club hairs were lost. 4. Oestradiol implanted into castrated males produced the same effects as in spayed females except that it had no effect on the time of initiation of the wave. 5. Combined implantation of testosterone with oestradiol into castrated males did not off-set the inhibitory effects of the oestradiol on hair length or rate of loss of club hairs, but may have slightly speeded the hair wave.

QUANTITATIVE STUDIES OF HAIR GROWTH IN THE ALBINO RAT

1958 ◽  
Vol 16 (4) ◽  
pp. 337-NP ◽  
Author(s):  
ELIZABETH JOHNSON
Keyword(s):  
Hair Growth ◽  
The Body ◽  
Female Rats ◽  
Albino Rats ◽  
Albino Rat ◽  
Growing Period ◽  
Quantitative Studies ◽  
Rates Of Growth ◽  
Resting Period ◽  
Follicular Activity

SUMMARY 1. The patterns of the first and second hair growth waves, forming the second and third coats, were followed in albino rats which had been dyed black before the start of hair growth. 2. The length of hair produced during the growth waves varies from region to region of the body. These regional differences are partly the result of differences in rates of growth, but mainly due to differences in the duration of the period of follicular activity. 3. The duration of the growing and resting periods varies in different areas of the body. For example, in the ventral region the resting period between the first and second waves lasts for about 14 days and the growing period of the second wave for only 12 days, whereas in the mid-dorsal region the resting period lasts for about 4 weeks and the growing period about 19 days. 4. As the growth wave spreads over each area every follicle produces a new hair alongside the dead or 'club' hair. Loss of club hairs then begins, and the rate of loss varies from region to region of the body. 5. In female rats the growth wave moves more slowly, the definitive length of hair is shorter, and the loss of club hairs is slower than in the male. The sexual differences in hair length are the result of differing rates of growth, and there is no difference in the duration of follicular activity between the sexes. 6. It is suggested that in assessing the effect on hair growth of any treatment the following aspects should be considered: (a) Time of initiation of the growth wave and its duration. (The length of the resting period in any region will depend on both these factors.) (b) Duration of the growing period. (c) Rate of elongation of the hair during the growing period. (d) Rate of loss of club hairs.

Deposition of fat in the body of the rat during rehabilitation after early undernutrition

1978 ◽  
Vol 39 (1) ◽  
pp. 201-211 ◽  
Author(s):  
Patricia M. Harris ◽  
Elsie M. Widdowson
Keyword(s):  
Complete Recovery ◽  
The Body ◽  
The Other ◽  
Female Rats ◽  
Stock Diet ◽  
Fat Cell ◽  
Fat Depots ◽  
Male And Female Rats ◽  
Unlimited Access ◽  
Males And Females

1. Male and female rats aged 3 weeks were divided into two groups. One group of each sex was allowed unlimited access to the stock diet, the other group was given the stock diet in restricted amounts for 10 weeks so that the males gained only 19 g and the females 21 g in comparison with 176 g and 116 g for the well-nourished males and females respectively. The undernourished animals were then rehabilitated by being allowed the stock diet ad lib.2. Five animals of each sex were killed at various stages of the experiment, their bodies analysed for fat and nitrogen, and the size and number of fat cells determined in specific fat depots.3. The undernourished rats failed to make a complete recovery and were significantly smaller than the controls of the same sex at 172 d of age when the experiment terminated.4. The previously undernourished rats deposited significantly more fat in their bodies during rehabilitation than the control animals in the same number of days and over the same gain in body-weight.5. There were no significant differences in the number of cells containing fat at the abdominal fat site between the undernourished and rehabilitated animals and the controls at any stage, nor were there any significant differences in apparent fat cell numbers between the control and rehabilitated animals at any of the other sites studied when the experiment ended at 172 d.

THE INFLUENCE OF SEX ON THE MATURATION OF THE CENTRAL NERVOUS SYSTEM IN THE ALBINO RAT

1951 ◽  
Vol 7 (3) ◽  
pp. 271-279 ◽  
Author(s):  
J. T. EAYRS
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
The Body ◽  
Female Rats ◽  
Male Rats ◽  
Albino Rat ◽  
Litter Mate ◽  
Male And Female Rats ◽  
The Central Nervous System

The growth of the body and central nervous system and the emergence of stereotyped behaviour have been studied in male and female rats during the first 24 days of life. The effects of daily injections of equine gonadotrophin on these measures have also been investigated. The weight of the body and of the central nervous system was significantly less in the female than in the male. The daily administration of 10 i.u. of equine gonadotrophin was without effect on either. The movements of the trunk and limbs concerned in the body-righting reflex became coordinated more slowly in the gonadotrophin-injected animals than in their litter-mate controls. At 15 days old, male rats were able to right in mid-air more successfully than litter-mate females. The placing reflex appeared earlier in the male than in the female. Its appearance was accelerated in the females given gonadotrophin, but not in the males. In the ventral funiculus of the spinal cord of 24-day-old experimental animals, the axis cylinders occupied more space relative to that occupied by myelin than did those of the controls. The total amount of myelin present was unchanged. There was no sex difference in the progress of myelination in the spinal cord. The significance of these findings in relation to the secretion of sex hormones is discussed. It is suggested that the secretion of androgen may be responsible for an acceleration of nervous maturation.

Impact of di-(2-ethylhexyl) phthalate on the uterus of adult Wistar rats

2016 ◽  
Vol 36 (6) ◽  
pp. 565-572 ◽  
Author(s):  
DB Somasundaram ◽  
K Manokaran ◽  
BC Selvanesan ◽  
RS Bhaskaran
Keyword(s):  
Body Weight ◽  
Human Exposure ◽  
Wistar Rats ◽  
Healthy Adult ◽  
Ovarian Hormones ◽  
The Body ◽  
Female Rats ◽  
Adult Rats ◽  
Structural Abnormalities ◽  
Ethylhexyl Phthalate

Di-(2-ethylhexyl) phthalate (DEHP) is the most common plasticizer used in polyvinyl chloride-based plastics. DEHP is not covalently bound to the plastics and is easily released to the environment, resulting in human exposure. In this study, the adult rats were exposed to DEHP and its effects on the uterus was evaluated. Healthy adult female rats were treated with DEHP orally (with dose level 0, 1, 10, and 100 mg/kg body weight/day) for 30 days. No significant changes in the body weight and wet uterine weight were observed. Ovarian hormones and their receptor levels in the uterus were increased. Histological studies exhibited the structural abnormalities such as decrease in diameter, thinning of the layers and disruption in the glandular epithelium.

Hair Growth and its Relation to Vascular Supply in Rotated Skin Grafts and Transposed Flaps in the Albino Rat

Development ◽  
1959 ◽  
Vol 7 (3) ◽  
pp. 417-430
Author(s):  
F. J. Ebling ◽  
Elizabeth Johnson
Keyword(s):  
Hair Growth ◽  
Vascular Supply ◽  
Albino Rats ◽  
Skin Grafts ◽  
Albino Rat ◽  
Growing Period ◽  
Rate Of Growth ◽  
Second Wave ◽  
Follicular Activity

Hair-Growth in the rat occurs in a series of waves which start ventrally and pass over the flanks to the back (Dry, 1926; Butcher, 1934). In our colony of randomly mated albino rats the first wave begins at about 5 weeks of age and is complete 3 weeks later; the second wave starts at 8½–9 weeks of age and is not complete until a further 12–14 weeks have elapsed. In both these waves dorsal hairs are longer than ventral ones, and this appears to be due to a longer growing period rather than to any differences in the rate of growth (Johnson, 1958a). Haddow & Rudall (1945) demonstrated that such waves of growth are accompanied by increased vascularization of the dermis, and suggested that follicles become active as a response to increased vascularity. Durward & Rudall (1949) seem to have modified this view to the extent of suggesting that vascularization cannot cause follicular activity until a required resting stage has been completed.

GONADOTROPHIN PATTERNS IN MALE AND FEMALE RATS:

1968 ◽  
Vol 58 (4) ◽  
pp. 600-612 ◽  
Author(s):  
Robert Boyd ◽  
Donald C. Johnson
Keyword(s):  
Ascorbic Acid ◽  
Testosterone Propionate ◽  
Female Rats ◽  
Female Rat ◽  
Feedback Effects ◽  
Male And Female ◽  
Prostate Weight ◽  
Male And Female Rats ◽  
Males And Females ◽  
Normal Males

ABSTRACT The effects of various doses of testosterone propionate (TP) upon the release of luteinizing hormone (LH or ICSH) from the hypophysis of a gonadectomized male or female rat were compared. Prostate weight in hypophysectomized male parabiotic partners was used to evaluate the quantity of circulating LH. Hypophyseal LH was measured by the ovarian ascorbic acid depletion method. Males castrated when 45 days old secreted significantly more LH and had three times the amount of pituitary LH as ovariectomized females. Administration of 25 μg TP daily reduced the amount of LH in the plasma, and increased the amount in the pituitary gland, in both sexes. Treatment with 50 μg caused a further reduction in plasma LH in males, but not in females, while pituitary levels in both were equal to that of their respective controls. LH fell to the same low level in partners of males or females receiving 100 μg TP. When gonadectomized at 39 days, males and females had the same amount of plasma LH, but males had more stored hormone. Pituitary levels were unchanged from controls following treatment with 12.5, 25 or 50 μg TP daily, but plasma values dropped an equal amount in both sexes with the latter two doses. Androgenized males or females, gonadectomized when 39 days old, were very sensitive to the effects of TP and plasma LH was significantly reduced with 12.5 μg daily. Pituitary LH in androgenized males was higher than that of normal males but was reduced to normal by small amounts of TP. The amount of stored LH in androgenized females was not different from that of normal females and it was unchanged by any dose of TP tested. Results are consistent with the conclusion that the male hypothalamic-hypophyseal axis is at least as sensitive as the female axis to the negative feedback effects of TP. Androgenization increases the sensitivity to TP in both males and females.

Size-At-Age Variability and Sexual Dimorphism of Morphometric Characteristics in the Late Ontogenesis of the Marsh Frog, Pelophylax Ridibundus (Anura, Ranidae), from Terrytory of Crimea

2019 ◽  
Vol 53 (4) ◽  
pp. 325-334
Author(s):  
V. N. Peskov ◽  
N. A. Petrenko ◽  
V. Yu. Reminnyi
Keyword(s):  
Age Groups ◽  
The Body ◽  
Adult Males ◽  
Morphometric Characteristics ◽  
Morphometric Characters ◽  
Mean Values ◽  
Marsh Frog ◽  
Males And Females ◽  
Size At Age ◽  
Linear Body

Abstract We study size-at-age and sexual variability of morphometric characteristics of the marsh frog. According to the size of the body, males were divided into three size-age groups (juvenis, subadultus, adultus), females — into four groups (juvenis, subadultus, adultus, adultus-I). We found that the chronological age of frogs (skeletochronology) does not always correspond to their biological age (size and proportions of the body). We noted that the semi-adult males are reliably larger than females by mean values of 26 studied morphometric characters. Males and females of “adultus” group do not differ by linear body size, significant differences were found in body proportions (7 characters). For the females of “adultus-I” group, the mean values of 26 characters are significantly larger than for “adultus” males. The results of our study showed that with the age of the marsh frog, the level of exhibition, directionality and structure of morphometric sex differences changes.

Inhibition of Yeast Growth by Tryptamine and Recovery with Tryptophan

2020 ◽  
Vol 16 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Chandrika Kadkol ◽  
Ian Macreadie
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Competitive Inhibition ◽  
Yeast Species ◽  
Inhibitory Effect ◽  
The Body ◽  
Inhibitory Effects ◽  
Trna Synthetases ◽  
Fermentative Growth ◽  
Biogenic Monoamine

Background: Tryptamine, a biogenic monoamine that is present in trace levels in the mammalian central nervous system, has probable roles as a neurotransmitter and/or a neuromodulator and may be associated with various neuropsychiatric disorders. One of the ways tryptamine may affect the body is by the competitive inhibition of the attachment of tryptophan to tryptophanyl tRNA synthetases. Methods: This study has explored the effects of tryptamine on growth of six yeast species (Saccharomyces cerevisiae, Candida glabrata, C. krusei, C. dubliniensis, C. tropicalis and C. lusitaniae) in media with glucose or ethanol as the carbon source, as well as recovery of growth inhibition by the addition of tryptophan. Results: Tryptamine was found to have an inhibitory effect on respiratory growth of all yeast species when grown with ethanol as the carbon source. Tryptamine also inhibited fermentative growth of Saccharomyces cerevisiae, C. krusei and C. tropicalis with glucose as the carbon source. In most cases the inhibitory effects were reduced by added tryptophan. Conclusion: The results obtained in this study are consistent with tryptamine competing with tryptophan to bind mitochondrial and cytoplasmic tryptophanyl tRNA synthetases in yeast: effects on mitochondrial and cytoplasmic protein synthesis can be studied as a function of growth with glucose or ethanol as a carbon source. Of the yeast species tested, there is variation in the sensitivity to tryptamine and the rescue by tryptophan. The current study suggests appropriate yeast strains and approaches for further studies.

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