Organ-body Weight Ratio Research Articles

Chronic Toxicity Studies on Food Colours

New Coccine and Nigrosine, at levels of 0·03, 0·3 and 3·0 per cent in the diet, had no effect on mortality in male or female rats. In groups receiving Malachite Green at levels of 0·3 and 3·0 per cent in the diet there was 100 per cent mortality within the first week of the experiment. Female rats receiving Malachite Green at 0·03 per cent or Nigrosine at 3·0 per cent in the diet showed a significant decrease in growth rate. For the group on Malachite Green this was accompanied by a decrease in food consumption. In both male and female rats receiving Nigrosine at 3·0 per cent in the diet, there was an increase in the organ-body weight ratio for liver and kidneys. Histopathological changes attributed to the toxic effects of the colours were noted in kidneys and testes.

English

The effect of aqueous leaf and berry extracts of Phytolacca dioica administered at 50, 100 and 200 mg/kg body weight for 14 days was investigated on haematology and weight parameters of Wistar rats. The extracts at all doses had no significant effect on the red blood cells (RBC), haemoglobin (HB), parked cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) when compared with the animals in the control group. In contrast, the extracts at all doses caused a progressive significant reduction in the serum levels of platelets, white blood cells (WBC), neutrophils and monocytes. Also, there was dose-dependent significant increase in the serum levels of lymphocytes and a reduction in the level of eosinophils. Administration of the extracts at all doses investigated led to a significant reduction in the body weight, absolute organ weight and organ-body weight ratio. These observable alterations in some parameters were indications that the leaf and berry extracts of P. dioica possess slight toxicity. Therefore, the crude extracts from the leaf and berry may not be completely safe as oral remedies.   Key words: Phytolacca dioica, haematology, weight parameters, slight toxicity, oral remedy.

Immunotherapeutic effects of some sugar cane (Saccharum officinarum L.) extracts against coccidiosis in industrial broiler chickens

Present paper reports the effects of aqueous and ethanolic extracts of sugar cane (Saccharum officinarum L.) juice and bagasse, respectively on protective immune responses in industrial broiler chickens against coccidiosis. Immunotherapeutic efficacies of the extracts were measured by evaluating their effect on body weight gain, oocyst shedding, lesion score, anti-coccidial indices, per cent protection and elicited serum antibody responses against coccidiosis. Results revealed a significantly lower (P<0.05) oocyst shedding and mortality in chickens administered with sugar cane extracts as compared to control. Further, significantly higher (P<0.05) body weight gains and antibody responses were detected in chickens administered with sugar cane extracts as compared to chickens of control group. Moreover, ethanolic extract showed higher anti-coccidia index (227.61) as compared to aqueous extract (192.32). The organ body weight ratio of the lymphoid organs of experimental and control groups were statistically non-significant (P>0.01). These results demonstrated that both ethanolic and aqueous extracts of sugar cane possess immune enhancing properties and their administration in chickens augments the protective immunity against coccidiosis.

Pharmacological and Toxicological Studies of an Ayurvedic Formulation (“Lauhasava”) on the Biological System of Rats and Mice

In this study, the pharmacological and toxicological effects along with possible side effects of the classical ayurvedic formulation "Lauhasava" (LSV), which is used in anemia, were evaluated. During this study, various experiments on body growth rate, organ-body weight ratio, tissue hydration indices and body fat ratio were performed to evaluate its efficacy and toxicity. In the body weight study, the LSV treated rats, irrespective of sexes, showed significantly lower body weights than the control group rats. LSV treated mice of both sexes gained less weight than their control counterparts. The study involving comparison of the relative weights of the major organs of rats and mice revealed some significant results. The percentage of lung to the body weight is significantly increased in both sexes of rats. Liver weight in LSV treated rats of both sexes were observed to be increased. The percentage of kidney weight was increased in both sexes of rats, the result being significant in the case of female rats. The thymus weight was found significantly decreased in both sexes of rats. Significant increase in the weight of rats' ovaries was observed. In the tissue hydration index experiment, only the increase in the female kidney was significant. No significant result was found in the fat content of the whole mice and eviscerated mice.

Prophylactic Dose of Neem (Azadirachta indica) Leaf Preparation Restricting Murine Tumor Growth is Nontoxic, Hematostimulatory and Immunostimulatory

Significant restriction of growth of Ehrlich's carcinoma was observed following prophylactic treatment on Swiss albino mice with neem leaf preparation (NLP-1 unit) once weekly for four weeks. Toxic effects of this particular dose (1 unit), along with 0.5 unit and 2 units of NLP doses, were evaluated on different murine physiological systems. One hundred percent of mice could tolerate 4 injections of 0.5 and 1 unit NLP doses. Body weight, different organ-body weight ratios and physical behavior of treated mice remained completely unchanged during treatment with different NLP doses. All of these NLP doses were observed to stimulate hematological systems as evidenced by the increase in total count of RBC, WBC and platelets and hemoglobin percentage. As histological changes as well as elevation in serum alkaline phosphatase, SGOT, SGPT were not observed in mice treated with three different doses of NLP, the nonhepatotoxic nature of NLP was proved. The level of serum urea remained unaltered and normal architecture of the cortical and medullary parts of the kidney were also preserved after NLP treatment. Increased antibody production against B16 melanoma antigen was detected in mice immunized with 0.5 unit and 1 unit of NLP. Number of splenic T lymphocytes (CD4+ and CD8+) and NK cells were also observed to be increased in mice injected with 0.5 unit and 1 unit of NLP. However, NLP dose of 2 units could not exhibit such immunostimulatory changes; NLP mediated immunostimulation was correlated well with the growth restriction of murine carcinoma. In other words, tumor growth restriction was observed only when mice were injected with immunostimulatory doses of NLP (0.5 unit and 1 unit).

Hypoglycemic Potencies of Crude Ethanolic Extracts of Cashew Roots and Unripe Pawpaw Fruits in Guinea Pigs and Rats

Adult guinea pigs and albino rats were given 2 mg/100 g-body weight of crude ethanolic extract of cashew root or pawpaw fruits, thereafter, tail blood films were collected to monitor postprandial glucose levels, thereafter, animals were thereafter maintained at 2 mg/ 100 g-body weight of extract 3 times daily for seven days. Organ body weight ratios and biochemical parameters in the plasma were determined. The crude ethanolic extract of cashew root and pawpaw fruits showed hypoglycemic potencies, however, the crude ethanolic extract of cashew roots showed more hypoglycemic potency than the crude extract of pawpaw fruits in both guinea pigs and rats. The ethanolic extracts reduced both plasma glucose as well as cholesterol and total lipids but showed no effect on plasma protein; pawpaw extract reduced glucose, liver glycogen, cholesterol and total lipid in guinea pigs from 46.50 +/- 3.50-14.30 +/- 0.29 (mg/dl), 5.51 +/- 1.5-1.52 +/- 0.50 (g/100 g); 189.09 +/- 5.91-162.50 +/- 2.95 (mg/dl); 705.00 +/- 46.06-630.00 +/- 15.06 (mg/dl), respectively; while in rats reductions were from 53.3 +/- 3.50- 32.25 +/- 3.25 (mg/dl), 4.28 +/- 0.50-2.3 +/- 0.78 (g/100 g); 203.85 +/- 2.95-171.23 +/- 5.78 (mg/dl) and 855.00 +/- 45.0-645.00 +/- 30.0 (mg/dl), respectively. Cashew extract reduced the same parameters in guinea pig from 46.50 +/- 3.50-7.00 +/- 0.10 (mg/dl); 5.51 +/- 1.5-0.15 +/- 0.50 (g/100 g); 189.09 +/- 5.91-162.50 +/- 0.04 (mg/dl) and 705.00 +/- 45.06-562.50 +/- 52.5 5.91-162.50 +/- 0.04 (mg/dl) and 705.00 +/- 45.06-562.50 +/- 52.5 (mg/dl). The reduction in rats were from 53.5 +/- 3.50-10.75 +/- 3.75 (mg/dl); 4.28 +/- 0.50-0.18 +/- 0.30 (g/100 g); 203.85 +/- 2.95-162.50 +/- 8.06 (mg/dl) and 855.00 +/- 45.0-557.50 +/- 37.5 (mg/dl), respectively. The work concludes that ethanolic extract of cashew root and pawpaw fruit contains natural substances that can be harnessed for the treatment and management of diabetes mellitus.

Subchronic inhalation toxicity of 3.5-microm diameter carbon fibers in rats.

No effects were seen when rats were exposed for 6 h day(-1), 5 days per week, for 16 weeks to an atmosphere of 20 mg m(-3) of carbon fibers (25 x 10(6) fibers m(-3)) and small amounts of fiber particulate resulting from preparation of the ultimate test material. The carbon fibers were made from polyacrylonitrile fiber. They were 3.5 microm in diameter and 72% were 10-60 microm long. Histopathological evaluations were made after each of 4, 8, 12 and 16 weeks of exposure and after 36 and 80 weeks of recovery. No effects due to the exposure were seen, as judged by clinical signs, body weight, organ weight, organ-body weight ratios, organ-brain weight ratios, gross and microscopic examination of internal organs, special stains of lung tissue for fibrous tissue, reticulin and fat and pulmonary function measurements. Non-fibrous particles were seen in the pulmonary lymphoid clearance system and in alveolar histiocytes (macrophages) at each histopathological evaluation period. Non-fibrous particles were seen in histiocytes in the mucociliary clearance system after 12 and 16 weeks of exposure. Fibers were seen in the nasal cavity at each histopathological examination. Fibers also occasionally were seen in tissue sections from the lower respiratory tract, but their exact location in life could not be determined. There was no indication of fibrosis.

Behavioral teratologic studies using microwave radiation: Is there an increased risk from exposure to cellular phones and microwave ovens?

The objective of the investigations presented in this review was to determine if there are adverse effects due to chronic prenatal microwave exposure in rats at term and/or alterations in neonatal and adult offspring psychophysiologic development and growth. Following the establishment of a nonhyperthermal power density level of microwave radiation, pregnant rats were exposed throughout pregnancy to continuous wave 915 MHz, 2450 MHz, or 6000 MHz radiation at power density levels of 10, 20, or 35 mW/cm 2, respectively. Teratologic evaluation included the following parameters: maternal weight and weight gain; mean litter size; maternal organ weight and organ weight body weight ratios; body weight ratios of brain, liver, kidneys, and ovaries; maternal peripheral blood parameters including hematocrit, hemoglobin, and white cell counts; number of resorptions and resorption rate; number of abnormalities and abnormality rate; mean term fetal weight. Mothers were rebred, and the second, nonexposed litters were evaluated for teratogenic effects. Exposed offspring were evaluated using the following perinatal and adult tests: eye opening, surface righting, negative geotaxis, auditory startle, air righting, open field, activity wheel, swimming, and forelimb hanging. Offspring were also monitored for weekly weight and weight gain. Animals exposed to 915 MHz did not exhibit any consistent significant alterations in any of the above parameters. Exposure to 2450 MHz resulted only in a significantly increased adult offspring activity level compared to nonexposed offspring. Offspring exposed to 6000 MHz radiation exhibited an initial slight, but significant, retardation in term weight, while mothers had a significantly reduced monocyte count. No changes in any of the other term parameters were observed. A few postnatal parameters were affected in offspring exposed to 6000 MHz. Weekly weights were lower in the exposed offspring, but they recovered by the fifth week. Eye opening was delayed, and there were changes in the water T-maze and open field performance levels. Several organ body weight ratios differed from those of the control offspring. These results indicate that exposure to 6000 MHz radiation at this power density level may result in subtle long-term neurophysiologic alterations. However, in the absence of a hyperthermic state, the microwave frequencies tested, which included frequencies used in cellular phones and microwave ovens, do not induce a consistent, significant increase in reproductive risk as assessed by classical morphologic and postnatal psychophysiologic parameters

Long‐term dietary study and development of no‐observed‐effect level (NOEL) of technical HCH to rats

Daily feeding of technical hexachlorocyclohexane (HCH) (0.5, 5, 25, 250, and 500 mg/kg diet/d) for a period of 360 d to male rats elicited a dose-dependent toxicity, while the dose of technical HCH (0.5 mg/kg diet/d) did not produce signs of intoxication, mortality, organ body weight ratio, enzymatic, and pathomorphological changes. Other doses (5, 25, 250, and 500 mg/kg diet/d) produced significant changes in one or the other parameters studied. Based on this study, it may be suggested that the lowest dose of technical HCH (0.5 mg/kg diet/d) could be considered as the no-observed-effect level in experimental rats.

Acute and subacute inhalation toxicity studies of a new broad spectrum insect repellent, N, N-diethylphenylacetamide

N, N-Diethylphenylacetamide (DEPA) is an inexpensive, long-acting and broad spectrum insect repellent. The acute LC 50 for a 4-h exposure of DEPA aerosol was found to be 1.451 mg l −1 (1.290–1.633) in male and 1.375 mg l −1 (1.307–1.447) in female rats. DEPA did not cause delayed deaths. Acute exposure to 0.9 LC 50 revealed that liver might be a target organ for DEPA toxicity. On subacute exposures to 0.2, 0.6 and 0.8 LC 50 for 6 h per day, 5 days a week for 2 weeks, there was no significant change in the 0.2 LC 50 group, as evaluated by the body weight gain and organ body weight ratio. The minimal changes observed in the 0.6 LC 50 group were of reversible type as the animals recovered on cessation of exposure. A massive concentration of 0.8 LC 50 produced lethal effects. The study shows that DEPA has a low mammalian toxicity by inhalation as was found earlier with cutaneous application of the insect repellent.

A Chronic Inhalation Toxicity Study of Diesel Engine Emissions and Coal Dust, Alone and Combined

To evaluate the potential health hazards of diesel engine emissions in underground coal mines, inhalation studies were performed using three species of animals. A wide range of toxicological responses was measured. Exhaust was provided by a 425 in.3displacement four-cycle, water-cooled, naturally aspirated diesel engine (Caterpillar Model 3304) equipped with a water scrubber. Exposures were 7 h/day, 5 days/week, for periods up to 24 months. Micronized coal dust was generated using a Wright dust feeder. Four exposures were evaluated: (1) filtered ambient air, (2) 2 mg/m3diesel particulate, (3) 2 mg/m3respirable coal dust, and (4) 1 mg/m3each of 2 and 3. Gaseous and vapor concentrations were similar in both exposures employing diesel exhaust. Male cynomolgus monkeys, Fischer-344 male and female rats, and female CD-1 mice were the experimental subjects. Monkeys were sacrificed at 24 months, rats at 3, 6, 12, and 24 months, and mice at 1, 3, and 6 months.Gross morphology and histopathology demonstrated that both diesel and coal dust particles are deposited in the lungs and retained in alveolar tissue. Alveolar type II cell hyperplasia and pulmonary lipidosis occurred in rats, being most evident in rats exposed to diesel exhaust alone. There was, however, no evidence of emphysema or chronic bronchitis, and only minimal fibrosis was seen in association with the retained particulate. Both particulates affected the defense mechanisms of the lung. Exposure to coal dust activated responses associated with phagocytosis, whereas exposure to diesel exhaust depressed them. Severity of influenza challenge increased concomitantly with decreased interferon production in diesel-exposed mice. Exposure to diesel emissions did not result in genotoxic effects as measured by increases in sister chromatid exchange, chromosomal aberrations, micronucleus testing, and urine genotoxic assays. Pulmonary function studies in monkeys showed mild obstructive airway disease in coal dust, diesel exhaust, and the combined exposed animals. This effect was most pronounced in monkeys exposed to diesel exhaust. Evidence of restrictive lung disease was not seen in any group. Clearance of F3O4particles appeared to be stimulated by exposure to diesel exhaust in the first 3 months, but long-term clearance of diesel particulate appeared to be inhibited. No evidence was found for increases in tumorogenicity (rats) or induction of xenobiotic metabolizing enzymes in the lung or liver (rats). Humoral and cellular immunities were not significantly affected by exposure (rats). No adverse seminal effects were observed in monkeys exposed for 2 years. There was no frank evidence of chronic toxicity as demonstrated by changes in mortality, body weight gains, organ-body weight ratios, or clinical parameters in rats or monkeys. Synergistic effects between diesel exhaust and coal dust were not demonstrated.

Response of rats to repeated oral administration of endosulfan.

Male and female albino rats given different oral doses (0.75, 2.5, 5.0 and 0.25, 0.75, 1.5 mg/kg/D) of endosulfan respectively for a period of 30 days elicited signs of toxicity such as hyperexcitability, tremor, dyspnea and salivation for a brief period. At the tested dose levels, endosulfan produced no significant change in the organ body weight ratio, biochemical, histological, haematological and fertility indices. Residue analysis using GLC techniques of different organs revealed a higher level of α isomer in the fatty tissue of male and female rats, than in other organs. There was no significant accumulation of the α and β iso-mers of endosulfan in the vital organs inspite of repeated exposure which seems to be the reason for the absence of a severe toxicological response in the rats. The lower doses of endosulfan, however, showed none of the toxicological effects in male (0.75 and 2.5 mg/kg/D) and female (0.25 and 0.75 mg/kg/D) rats.

長期ストレスによる高血圧と動脈病変

The purpose of this study is to report the effects of long-term stress to the rats on the blood pressure or the spontaneous hypertension, and on pathological changes especially in cardiovascular system. Methods of stress.Experiment 1: Male Wistar rats were stressed with thrushing unceasingly and harassingly with a bamboo stick for 20 min./day for three and twelve months. Experiment 2: Male Wistar rats were fed by high fat diet and stressed with the same manner as Experiment 1. for two months. Experiment 3: Spontaneously hypertensive rats (SHRs) and normotensive rats (WKYs) were subjected to combination of immobilization and electrical stress for three months.Results. 1. The blood pressure reached a high value (191±3mmHg) in twelve months in Experiment 1. The development of hypertension was accelerated in stressed SHRs when compared with unstressed SHRs. 2. Organ-body weight ratios of heart, kidney and adrenal gland were increased by stress. 3. Mean values of relative thickness of media to radius of small arteries were increased in heart of stressed group of twelve months in Experiment 1. and in kidney and mesentery of stressed SHRs in Experiment 2. 4. Myocardium of stressed SHRs in Experiment 3. disclosed severe degree of fibrosis.

Studies of the physiological effects of 2,6-bis-(1′-methylheptadecyl)- p-cresol (dioctadecyl- p-cresol) in the rat and dog

It has been shown that rats and dogs fed as high as 10,000 ppm of DOPC in the diet for 100 and 90 days, respectively, tolerated the compound with little untoward reaction except for a slight decrease in body weight in one group of rats. No effects were noted on behavior, utilization of food, appearance, and stools nor were there any dose-related effects on hemograms, blood chemistry values or urine composition. No dose-related effects were found in organ-body weight ratios nor were there any significant lesions detected at necropsy or upon microscopic examination of the tissues. It appears that the administration of as much as 1.0% DOPC in the diet has no adverse effect on rats and dogs.

Histological responses of the alternative or combined administrations of ACTH and GH to adrenal cortex

The hypophysectomized rats of Wistar strain receiving an operation in 60-90th postnatal day respectively were injected with ACTH and GH alternatively or in combination. The adrenal cortex of these animals was histologically examined in comparing it to that in control hypophysectomized rats and the results were as follows : A decided conclusion was not obtained as to the changes in weight of adrenal cortex, since the number of experimental animals was small, and the value presented was complicated with the animal difference. But the organ body weight ratio shows that the adrenal gland surely decreases in weight by the hypophysectomy, but cannot be recovered from the reduction by means of the maintenance test of ACTH (2.5 mg/day for 7, 10 days) or GH (2 mg/day for 7 days), and of the repair test of ACTH (the same dose for 5 days) or ACTH and GH in combination (the same dose for 5 days), begun from the 6th day after the removal. Therefore ACTH and GH would be uneffective to allow the animals to recover the loss of organ weight, so far as this admistration method is concerned.However, it was informed in present research that the hormones are able to modify the histological changes induced by the hypophysectomy. The control hypophysectomized rats (7th day) provided the partially broadened zona glomerulosa in which the cells containing a lot of fat granules arrange fascicularly without a formation of glomerulum. The transitional zone became thicker, representing a layer of the package of nuclei. The cell-strands in zona fasciculata were irregular in general, slender, anastomosed one another and atrophic in some degree. Their cell-bodies were submitted to be rich in fat granules instead of proteinic stainable granules. The cortex cells at the vicinity of medulla surrounded by the multiplied connective tissue were usually flat in shape. The finding in the 10th day after the removal resembled in many respects that of the 7th day, but tended to be shown as the more pronounced changes. When the hypophysectomized rats were administered for 7-10 days with ACTH, the zonation of adrenal cortex was precisely altered, although the whole thickness of it was not recovered. The elongation of cell fascicules in zona fasciculata presses the zona glomerulosa on the capsule. The disappearance of the transitional zone resulted in the mutual transformation between atrophic zona glomerulosa and broad zona fasciculata, where the former no longer consisted of independent glomeruli. The superficial area of adrenal cortex was scanty of fat granules, whereas full of stainable granules (stained with iron-hematoxylin). Despite the atrophic pattern and irregularity of fasciculata cell-strands was not restituted by the administration of ACTH, it was fairly demonstrated that the gross fused fat droplets decreased in number within the cellbodies, in addition the stainable granules increased. This fact may show that the improvement in the internal cell stracture fellow the replacement therapy. Also the connective tissue near the medulla became thoroughly indistinct. As above mentioned, ACTH is expected to have the sweeping ability of some obstacles in intracellular hormone synthesis by the hypophysectomy, and at least the changes by ACTH was akin, beyond the recovery, to the pattern of elevation in function of cortical cells, as is seen in intact rats exposed by the stressful stimuli.The repair test by ACTH showed the same improvement as by its maintenance test. Of course, the betterment may be restricted to zonation and cell internal structures in connection with the metabolic amelioration, but was not involved in the hyperplasia of cotical cells.In the event of repeated injections of GH for 7 days (maintenance test) to the hypophysectomized rats, the symptom of the ablation is almost irrecoverable. The changes is not utterly reconcile with the findings of hypophysectomized untreated group,

Comparative Examination for the Histological Pictures in Rat Thyroid Gland Following the Administrations of Mercazole and Thyroxine

Albino rats of Wistar strain were subcutaneously injected with mercazole (1-methyl-2-mercaptoimidazol) 2.5mg/day for 7 to 35 days, orally administered on free demand with 0.05% mercazole solution for 70-300 days, and subcutaneously administered with D. L.-thyroxine 10γ/day for 14 to 28 days, 30γ/day for 14 days respectively. The histological alterations were observed in thyroid glands of control and experimental animals. The organ-body weight ratio of thyroid gland was elevated by the administration of mercazole in spite of the dropped ratio by thyroxine. According to the complete serial sections in thyroid glands, comprehending their adhering tissues and neighboring organs, in three normal rats, it was able to be determined that there were neither destructions of follicles nor desquamation of gland cells followed by the colloid reduction in follicular lumina, although these degenerating or destructing signs would be constantly much or less found at the outer parts of thyroid glands upon a common preparation of the gland conventionally removed at autopsy. Following the administration of mercazole, the follicles became in general smaller, irregularly shaped; the gland cells were ellongated, contained abundant mitochondria instead of PAS-positive granules.The activity of apocrine secretion was prevented apparently by the chemicals, notwithstanding the occurence of various number of tiny vacuoles with the uniform size at the supranuclear regions. These vacuoles might be eliminated through the striated border-like structures newly formed on the free surface of the gland cells into the lumina, where being tranformed into circumference vacuoles which thereafter increased in number and size to fill the lumina. Otherwise, by the persistent oral introduction of mercazole, enormous gross faintly stained colloid substances, associated with the huge vacuoles seemingly resulted from their liquefaction, often appeared at the basal parts of many gland cells.The proliferation of follicles induced by mercazole was in a state of equilibrium with the advancing amount of the chemicals; it was initiated with a dominance in quantity of the common gland cells, followed by the plump formation which bulged like nodules into the interspace, with a consequent separation from the mother follicles by the intrusions of blood vessels at the constricted part of the plump. The nodules were provided with some pseudofollicles, whose colloid increased in amount to occupy the developing real follicular lumina. It was not apparent to discriminate a parafollicular cell from a common gland cell in mercazole administered rats.By the injections of thyroxine, the follicles composed of flattened gland cells were either large or small with irregular shapes. In their cytoplasm mitochondria and secretory granules were either scanty or almost disappeared; the cytoplasmic projections showing an apocrine secretion, as well as circumference vacuoles, were rarely seen; the lumina of follicles were full of deeply stained colloid substances. Whereas the parafollicular cells hypertrophied and were in hyperplasia that they arranged themselves compactly but confusedly to wholly mantle the atrophic follicles with extraordinarily flattened gland cells, and in their cytoplasm there were observed a number of vacuoles or PAS-positive granules concurrently stained with iron hematoxylin. Above alterations were augmented with increasing dosage of in fused thyroxine. This paper deals with a role of parafollicular cells in both metabolic and growth activties in thyroid gland and some links to their humoral control were discussed. The administrations of mercazole or thyroxine fairly caused to promote or prevent the release of TSH from the anterior lobe of the pituitary respectively, and in approaching the morphological response to the chemicals