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P. E. HARTMANN, A. T. COWIE and ZENA D. HOSKING

SUMMARY

Five groups of five lactating rabbits each were used. Milk yield was recorded from the 8th day of lactation onwards and on the 10th day of lactation the rabbits received the following treatments: Group S, sham-operation with saline (1 ml/12 h); Group P, hypophysectomy with sheep prolactin (1 mg/12 h); Group H, hypophysectomy with human growth hormone (1 mg/12 h); Group B, hypophysectomy with bovine growth hormone (1 mg/12 h) and Group C, hypophysectomy with saline (1 ml/12 h). The injections of saline or hormones were continued for 5 days and at the end of this period a blood sample was taken, the animals were killed and their mammary glands removed for histological examination and assay of the following enzymes: 6-phosphogluconate dehydrogenase (EC 1.1.1.44), phosphofructokinase (EC 2.7.1.11), phosphoglucomutase (EC 2.7.5.1), UDP-glucose pyrophosphorylase (EC 2.7.7.9), acetyl-CoA carboxylase (EC 6.4.1.2), acetyl-CoA synthetase (EC 6.2.1.1) and ATP-citrate lyase (EC 4.1.3.8). On the 5th day after surgery the concentrations of blood l-lactate and pyruvate and plasma free fatty acids and protein were similar in all groups, whereas plasma glucose was higher in groups S, B and H than in groups P and C. Although the weights of pituitary target organs (adrenals, thyroid and ovaries) were similar in all groups, the weights (g/kg body weight) of mammary tissue varied markedly, group S being the heaviest and group C the lightest. Milk yields, 5 days after surgery, for groups P and H were about 50% that for S, whereas those for B and C were 15 and 4% respectively. Where possible the enzyme activity was expressed as a ratio of the rate of synthesis of the end product of the pathway in which the enzyme occurred. With the exception of acetyl-CoA carboxylase which may have had a rate-limiting role in the synthesis of milk fat, enzymic activity in vitro was in excess of that required in vivo for the synthesis of either milk fat or lactose. It appeared that the rate of milk synthesis depended upon the degree of maintenance of the secretory epithelial cells within the mammary gland rather than a block in the synthetic pathways within these cells.

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K. KOVÁCS

SUMMARY

Homotransplantation of the anterior pituitary gland of rats was made into the anterior chamber of the eye. The centre of the grafts developed ischaemic necrosis, but the peripheral zone remained alive to a depth of about 100 μ. During the next 6 weeks there was no evidence of significant regeneration or atrophy of this live peripheral zone, and mitoses were not observed there. The gradual resorption and scarring of the central necrotic area led to a diminution of the overall size of the graft.

In the surviving tissue nearly all the chromophil cells became completely degranulated during the first week or two. After 6 weeks only very rare shrunken basophil cells remained, although a few acidophil cells could still be identified.

From previous work it is known that such intraocular grafts have very little functional activity. This may possibly be because of the absence of any direct connexion between the graft and the hypothalamus, but the reduction of the total amount of parenchyma may also be an important factor.

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D. N. CONS

SUMMARY

1. The account of the cells of the seminal vesicles of the mature bull given by Mann et al. [1949] has been confirmed.

2. Evidence is presented that cells of the inner layer of the alveolus undergo cyclic changes. These cells, at one stage of the cycle, contain much glycogen and are probably responsible for the secretion of fructose.

3. Fat, in large part phospholipid, is mainly confined to the cells of the outer layer of the alveolus.

4. Comparable cells in the calf and bullock contain no glycogen and virtually no fat, confirming that the secretion of these substances is dependent upon the presence of androgenic hormone.

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A. IANNACCONE and G. CICCHELLA

SUMMARY

Changes occurring in the rat anterior pituitary after daily subcutaneous injections of 0·5 ml. benzene/kg body weight for 22 days have been studied using histochemical methods.

The acidophil cells and the 'β' cells exhibit a closer relationship to the blood vessels and a reduction in their cytoplasmic granulation, associated with an increase in the chromidial substance and with enlarged and weakly stained nuclei. The most prominent change discernible in the 'δ' cells is the vesiculation of the cytoplasm, sometimes giving the typical appearance of 'signet-ring' castration cells.

These alterations have been interpreted as indicating an increased secretion of simple protein hormones (especially adrenocorticotrophic hormone) and thyrotrophic hormone by the rat pituitary, and a decreased discharge of follicle stimulating and luteinizing hormone.

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E. J. CLEGG

SUMMARY

Comparison of the findings in this investigation with those in naturally occurring cryptorchidism indicates that whereas under the latter circumstances degenerative changes only occur at puberty, in the experimental condition they may be seen at all ages. It is suggested that this difference is due to inherent defects of the testis in naturally occurring cryptorchidism.

Comparison of the abdominal testes of unilaterally and bilaterally cryptorchid rats indicates that the testes are developmentally more mature in the latter and it is suggested that this difference is due to the circulation of greater amounts of gonadotrophins. This assumption is supported to some extent by findings in the adenohypophyses of such animals: castration cells appear to be more frequent in bilateral cryptorchids.

The conclusion is drawn that although simple androgen deficiency may explain the various changes which occur in the reproductive system and adenohypophysis of cryptorchid animals, deficiency of a hormone produced by the seminiferous tubules cannot be excluded completely; the findings also indicate that this hormone is more likely to be produced by the germ cells than by the Sertoli cells.

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E. H. D. CAMERON and J. K. GRANT

SUMMARY

The ability of cells from the zona fasciculata and zona reticularis of the horse adrenal cortex to transform [7α-3H]pregnenolone, [4-14C]progesterone, [7α-3H]17α-hydroxypregnenolone and [4-14C]17α-hydroxyprogesterone to cortisol in vitro was investigated.

It was found that: (1) Both types of cell form cortisol from these steroids. (2) The transformation is greater in fascicular cells. (3) The formation of 17α-hydroxyprogesterone from pregnenolone (via either progesterone or 17α-hydroxypregnenolone) is slower that the subsequent formation of cortisol from 17α-hydroxyprogesterone. (4) The formation of 17α-hydroxyprogesterone from 17α-hydroxypregnenolone is rate-limiting in cortisol formation, but is about 2·4 times faster in fascicular than in reticular cells. (5) 17α-Hydroxylation of progesterone is also faster in fascicular than in reticular cells.

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KATHLEEN HALL

During pregnancy in the mouse the pubic bones become separated, and the gap is bridged by a ligament which at parturition may be 5 or 6 mm. long [Gardner, 1936]. The normal course of separation of the two bones in pregnant mice has been described in a previous paper [Hall & Newton, 1946a]. The bones begin to separate on the 13th day of pregnancy, and the gap widens an average of 1 mm. per day until parturition, which normally takes place during the night following the 19th day. After this the gap rapidly closes, is usually less than 2 mm. on the 3rd or 4th day post partum, but does not completely return to the virgin condition.

The changes which occur during pregnancy can be produced in the spayed mouse by the administration of an extract of pregnant rabbit serum (shown by Hisaw [1926] to contain relaxin), accompanied by

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D. G. MONTEMURRO

SUMMARY

The effect of bilateral electrolytic lesions in the ventral hypothalamus at the coronal level of the posterior ventromedial nucleus and anterior premammillary nucleus on the weight and cytology of the pituitary gland of castrated male Lewis rats was investigated. All castrated rats were carrying successful intrasplenic isologous grafts of neonatal testes. The hypothalamic lesions resulted in a significant inhibition of pituitary hypertrophy in the castrated animals, but did not alter appreciably the cytology of the gland as compared with that of castrated rats without hypothalamic damage. The development of castration cells was not impaired by these lesions.

It is concluded that hypertrophy of the pituitary gland after castration and the development of castration cells are two manifestations of the pituitary response to a low concentration of circulating testicular hormone. The former requires the integrity of the posteroventral hypothalamus while the latter is independent of this hypothalamic region.

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P. GALAND, F. LEROY and J. CHRÉTIEN

SUMMARY

The duration of the phase of DNA synthesis (S-phase) and turnover times were measured by autoradiography in the vaginal and endo-uterine epithelium of spayed mice at different times after a single oestradiol injection. With three doses of oestradiol (0·3, 1·2 and 10·0 μg), changes of turnover time followed similar patterns in uterine epithelium, but maximal activation and subsequent levelling off of proliferation rates were reached sooner with higher doses. In the vagina, no significant dose-dependence was apparent with the same doses of oestradiol; maximal activation of cell proliferation was observed in every case 12 h after hormone injection.

Transient shortening of S-phase was observed in both tissues under oestrogen stimulation. The morphological changes in uterine epithelium appeared to be independent of mitotic stimulation. For vaginal epithelium, the results may be interpreted to indicate that oestrogen-induced keratinization starts by a differentiating action on pre-existing G1 cells.

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L. Cancela, P. J. Marie, N. Le Boulch and L. Miravet

ABSTRACT

Mineral, hormonal and skeletal changes were determined in vitamin D-deficient (−D) and vitamin Dreplete (+D) mother rats and in their litters on day 20 of lactation. These results were compared with those obtained in −D mothers and pups, after giving the mothers an oral supplement (10 i.u. vitamin D3/day) during the period of lactation (20 days). Compared to +D animals, both −D lactating mothers and their pups exhibited extremely low plasma levels of 25-hydroxyvitamin D3 (25-OH-D3), diminished 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and increased levels of immunoreactive parathyroid hormone (iPTH). Vitamin D-deficient mothers also had higher levels of calcitonin and lower levels of prolactin than +D mothers. All − D animals (mothers and pups) showed increased osteoclastic bone resorption and severe osteomalacia as shown by decreased bone ash, decreased calcification rate and increased endosteal osteoid surface, volume and thickness. In mothers treated with vitamin D3 during lactation, nearly all the plasma variables measured, as well as bone histomorphometric features, were normal. In contrast, their pups still showed rickets and osteomalacia, despite normal levels of 25-OH-D3 and calcium in the plasma. These pups had raised plasma levels of 1,25(OH)2D3 and iPTH associated with persistent stimulation of bone resorption. This study showed that (1) severe vitamin D deficiency in lactating rats produced marked osteomalacia and secondary hyperparathyroidism in both mothers and pups, and (2) vitamin D treatment of − D mother rats during lactation (10 i.u. vitamin D3/day) reversed the mineral, hormonal and skeletal abnormalities in mothers but not in pups.

J. Endocr. (1985) 105, 303–309