Renewal of Cell Populations

Leblond, C. P.; Walker, Bruce E.

doi:10.1152/physrev.1956.36.2.255

Cited by 540 publications

(147 citation statements)

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“…The thyroid belongs to that class of organs in which most of the adult parenchymatous cells survive the lifetime of the animal (Leblond and Walker, 1956). The human thyroid reaches adult size after puberty.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of the Weanling Rat Thyroid to Radiation

Doniach¹

1957

Br J Cancer

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RECENT surveys have established an association between the development of carcinoma of the thyroid in late childhood and a history of previous X-irradiation of the thyroid region in infancy or early childhood (Duffy and Fitzgerald, 1950; Simpson, Hempelmann and Fuller, 1955; Clark, 1955; Buckwalter, 1955). Radiation had been given to shrink an enlarged thymus or enlarged cervical lymph nodes or tonsils and adenoids; the dose to the thyroid was more than 200 and less than 725 rads in the majority of patients. Their ages varied from a few weeks to 6 years at the time of irradiation and 4 to 15 years at the time of histological diagnosis of thyroid carcinoma. In their survey of the subsequent history of 1400 irradiated children Simpson et al. (1955) found 9 thyroid adenomas and 6 thyroid carcinomas; they found 1 thyroid adenoma and no thyroid carcinomas in 1795 unirradiated control siblings.The dosage order of 200 to 725 rads is much smaller than that recorded in the majority of examples of the carcinogenic action of X-rays (Furth, 1954). Duffy and Fitzgerald (1950) and Simpson et al. (1955) suggested that the thyroid tumours might have resulted indirectly from an endocrine effect initiated by irradiation of the thymus. One must consider the possibility that growing thyroid tisue of an infant might be more radio-sensitive than that of an adult. This dosage of radiation to the infant thyroid might therefore, from the point of view of radiation damage done to the thyroid, be comparable with those higher ranges of radiation found to be carcinogenic to adult tissues. The experiment described below is an attempt to test whether the growing thyroid of the weanling rat differs from the thyroid of the adult rat in its sensitivity to irradiation from 1311. The test used was described by Doniach and Logothetopoulos (1955) who found in adult rats that 30 /,C 131i produced a striking inhibition of goitrogenic response to a short course of thiouracil given 4 months after the 1311. 10 /C 131I produced only a slight impairment of response.Following injections of the 1311, in vivo measurements were made of its uptake, distribution and turnover rate in the thyroids of weanling rats in order to ensure that the dose range of 1311 used was comparable with 10 and 30 ,uC l3lI in adult rats. MATERIAL AND METHODSThe animals were taken from a group of hooded black and white rats of the Lister strain, all born in the same week and pooled after weaning at 4 weeks.

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Section: Discussionmentioning

confidence: 99%

Sensitivity of the Weanling Rat Thyroid to Radiation

Doniach¹

1957

Br J Cancer

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“…Instead, an attempt was made to obtain an understanding of the growth and regression of Graafian follicles from measurements of the volume and mitotic index of the granulosa of follicles of all sizes. From these data and a knowledge of the mitotic time it is possible to make estimates of the time intervals involved in .follicular grow~h (Leblond and Walker 1956). …”

Section: Introductionmentioning

confidence: 99%

The Pattern of Follicular Growth and Atresia in the Ovine Ovary

Turnbull¹,

Braden²,

Mattner³

1977

Aust. Jnl. Of Bio. Sci.

153

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The ovaries of 21 2-year-old Merino ewes at various stages of the oestrous cycle were serially sectioned and all follicles > 0·5 mm in diameter were counted and measured. The mean number of normal follicles > 0·5 mm in diameter was 19· 9 per ewe, of which 8·7 were > 1 mm in diameter. The mean numbers of follicles > 0·5 mm in diameter in 'early', 'advanced' and 'late' stages of atresia were 4· 6, 9· 0 and 12· 3 respectively. Early atresia was rarely seen in follicles < 1 mm in diameter; the greatest incidence was in follicles of diameter 1· 5-2' 5 mm.Volumes of the granulosa, theca interna and antrum were calculated for all follicle sizes and the mitotic index of the granulosa and theca determined. Follicles were classified according to granulosa volume, each class having twice the volume of the preceding class. Estimates of the doubling time of the granulosa were made from the mitotic index and an estimate of mitotic time (0'43 h) obtained by use of colchicine on two other ewes. In all ewes, irrespective of day of oestrous cycle, the rate of growth was slow in follicles < 0·4 mm in diameter; above this size it accelerated to a maximum (doubling time 26-30 h) in follicles O· 7-2 mm in diameter. It was estimated that, on average, a follicle takes about 5 days to grow from 0·5 to 2·2mm diameter, and a further 4 days to reach 4·5 mm diameter. The number of follicles entering the rapid growth phase was estimated to be 3-4 per day. The present data do not support any particular 'wave' theory of follicular development, but indicate that follicles are growing or regressing asynchronously at any given time during the luteal stage of the oestrous cycle.At 48 h after treatment of two ewes with PMS gonadotrophin (PMSG), the number of follicles > 0·5 mm in diameter was increased, the greatest proportional increase being in those > 3·5 mm in diameter. Relatively few follicles were undergoing early atresia. At 18 h after RCG treatment (given 48 h after PMSG to two ewes) all follicles> 3·5 mm in diameter were undergoing luteinization and two-thirds of the follicles between 1 and 3·5 mm in diameter were undergoing early atresia.

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“…It has been reported that the normal matured salivary glands hardly showed mitotic figures (16). It was ob served that there were a slight increase in the mitotic changes of the enlarged acini during the treatment of ISO.…”

Section: Discussionmentioning

confidence: 93%

The Influence of Isoprenaline and Propranolol on the Submaxillary Gland of the Rat

Fukuda

1968

Japanese Journal of Pharmacology

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It has been pointed that adrenergic 8-receptor is greatly concerned in the salivary secretion of amylase, which is one of the main digestive enzymes (1).It has also been noticed that the repeated administrations of isoprenaline which has a strong affinity to 8-receptor for catecholamines show a marked enlargement of the salivary glands (2-11).On the other hand, it has been also demonstrated that dibenamine, one of the potent a-adrenergic blocking agents, and guanethidine, an antiadrenergic agent, show a gradual atrophy in the salivary gland after the chronic administration (11,12).Although there are many reports concerning the enlargement of the submaxillary glands treated with isoprenaline, little has been known whether this enlargement is due to the 9-action of isoprenaline and whether it produces an enzymatic alterations in the enlarged salivary glands. The present study deals with the effects of Q-adrenergic blocking agent on the development of the enlargement induced by the chronic administration of isoprenaline in rat submaxillary glands from the histological, histochemical, biochemical and pharma cological points of view. MATERIALS AND METHODSThe experimental animals were 250 female Sprague-Dawley albino rats weighting about 150 g. The experiments consisted of the following six groups were performed.Group I: A dose of 5 mg/kg of isoprenaline (ISO) was administrated once daily for 14 days. Group II : A dose of 30 mg/kg of propranolol was administrated once daily for 14 days.Group III: Doses of 5 mg/kg of ISO and 30 mg/kg of propranolol were admini strated once daily for 14 days. Group IV: Doses of 5 mg/kg of ISO and 20 mg/kg of nialamide were administrated once daily for 14 days.Group V : Distilled water was injected once daily as control for 14 days .The observations were made on the 7th day and 14th day respectively in the above five groups.

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Renewal of Cell Populations

Cited by 540 publications

References 0 publications

Sensitivity of the Weanling Rat Thyroid to Radiation

Sensitivity of the Weanling Rat Thyroid to Radiation

The Pattern of Follicular Growth and Atresia in the Ovine Ovary

The Influence of Isoprenaline and Propranolol on the Submaxillary Gland of the Rat

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