Participation of tissue basophils of the parathyroid glands in the regulation of the morphofunctional state of the organ

By means of cytometry estimation of mitotic index and nucleo-cytoplasmic relation of parathyrocytes, parathyroid glands have been studied in 52 white rats and 28 white mice under conditions of intal inhibition (30 mg/kg of body mass twice a day intraperitoneally) of tissue basophils (TB) secretory activity. For stimulation of the glands, repeated injections of trilon B and hemiparathyroidectomy are used. The experiment lasts for 3.5 days. In the rat parathyroid glands, containing a considerable amount of TB, intal does not produce any important effect of quantitative parameters of the organ's structure in intact animals, nevertheless it prevents development of hypertrophy of the parathyrocytes in the stimulated glands, as well as makes weaker the proliferative response of the cells to hemiparathyroidectomy. In mice, their parathyroid glands containing single TB, under conditions of stimulation of the parathyroid function, intal does not produce any inhibitory effect to growth of middle size parathyrocytes. The results obtained demonstrate that the parathyroid TB actively participate in regulation of the organ's morphofunctional state, intensifying the stimulating effect of hypocalcaemia to the parathyroid parenchyma.     

Regeneration of the parathyroid glands in experimental hyperthyroidism

By means of morphological, morphometric and radioautographic methods, regeneration of mechanically traumatized parathyroid glands has been studied in 22 euthyroid and 22 hyperthyroid rats on the 1st-20th days after the operation. The thyroid gland is stimulated by daily injection of thyrotropin (1 ME/100 g of body mass). Twelve non-operated animals (6 hyperthyroid and 6 euthyroid rats) serve as control. In the regenerating parathyroid glands of the hyperthyroid animals in comparison with the euthyroid ones, certain increase of proliferative activity is noted in parathyrocytes and in cells of the granular tissue on the 2d-6th days, a more pronounced hypertrophy of epitheliocytes on the 2d-20th days, hyperplasia of their nucleolar apparatus on the 2d-5th days. The experimental hyperthyroidism stimulates manifestation of restorative processes in the regenerating parathyroid glands during development of active inflammatory reaction in them; however, it does not influence the parameters of the organ's structure studied in the nonoperated animals.     

Restorative processes in the parathyroid glands in experimental hypothyroidism

By means of morphological, morphometrical and autoradiographical methods restorative processes in the parathyroid glands in 41 euthyroid and in 41 hypothyroid rats have been studied during 1-24 days after mechanical trauma of the glands or after hemithyroparathyroidectomy. Seven hypothyroid and 7 euthyroid rats serve as a control. Hypothyroidism is produced with daily injection of mercazolil (6 mg/kg) 3 weeks before the operation and during the time of the experiment. In nonoperated hypothyroid rats development of hypertrophy in parathyrocytes is noted. Prolonged injection of mercazolil weakens (posttraumatic regeneration) or completely suppresses (compensatory hypertrophy) mitotic activity of the glandular cells (in comparison with the euthyroid animals). Manifestation of hypertrophy in parathyrocytes of the hypothyroid rats in comparison with the corresponding control is also less, than against the background of euthyreosis.     

Biosynthetic activity of parathyroid cells during different function of the parathyroid glands

By means of autoradiograph c and morphometric methods parathyroid glands of 31 rats after single injection of 3H-leucin (2,5 mc Cu/g of body mass 25 min. before killing) were investigated. Parathyroid glands were inhibited by multiple injections of calcium gluconate solution or by a diet with increased content of calcium and vitamin D2. Parathyroids were stimulated by multiple injections of Trilon B solution, by a diet with increased content of phosphates or by subtotal parathyroid resection. Straight correlation between parathyroid function, average section area of parathyrocytes and average number of silver granules per one parathyrocyte was revealed. Hence, average section area of parathyrocytes is objective morphometric criterion of parathyroid function.     

Cytological mechanisms of the growth and regeneration of the parathyroid glands

Contribution of proliferation and hypertrophy of the epitheliocytes to the growth and regeneration of the rat parathyroid glands was estimated using organo- and cytometry, cytophotometry of DNA content in the nuclei and determination of mitotic index. During postnatal development and in the case of hypertrophy of the adult glands following a moderate resection (50%), the gland growth is provided by mitotic divisions of the parathyroid cells, rather than by the increase in cell size. When up to 75 and 90% of the gland volume is removed, cell hyperplasia is accompanied by stable hypertrophy of the parathyroid cells unrelated to their polyploidization. The contribution of nonmitotic cell hypertrophy to the total increment of the organ volume amounts to 40-50%.     

Spatial organization of proliferative processes in the parathyroid glands upon acute stimulation of parathyroid function

A quantitative analysis on homogeneity degree in distribution of proliferating parathyrocytes in the parathyroid glands under conditions of an acute stimulation of their function, produced by bilateral nephrectomy (12 rats, 50-70 h after the operation) and by hemiparathyroidectomy (12 rats, 2-3 days after the operation) have been performed. Six intact animals serve as the control. In order to reveal proliferating cells, 1 h before sacrifice 3H-thymidine (1 mc Ci/g) is injected intraperitoneally, and to some animals--colchicine (1 mg/kg) is injected 6 h before the sacrifice. By means of successive investigation of the glands serial sections along their whole area the amount of the microscope field of vision, having various content of proliferating cells are calculated; using the criterion chi 2, the correspondence of the empiric distributions obtained to the Poisson distribution are estimated. In the hyperfunctioning parathyroid glands the proliferating cells form foci of clusters and rarifaction. A similar clustering appears when a definite level of mitotic activity of the parathyrocytes is reached (1-1.2%), probably reflecting certain regional peculiarities of their functional state.     

Ultimobranchial body and parathyroid gland of the parrot Psittacula psittacula in response to experimental hypercalcemia

Psittacula psittacula when subjected to long term hypercalcemia by intramuscular injections of vitamin D2 (20,000 I.U.) on alternate days and by increasing dietary calcium, exhibit a rise in the serum calcium level after 10, 20 and 30 days of treatment as compared to their corresponding controls. The ultimobranchial cells show progressive hypertrophy up to 20th day of the treatment. From 20th day till the end of the experiment (30 days) these cells show feeble staining response. The parathyroid glands suffer from degenerative changes due to its inactivity under chronic hypercalcemia.     

Structure and behaviour of ultimobranchial gland in response to vitamin D3--induced hypercalcemia in male Clarias batrachus

Hypercalcemia was induced in Clarias batrachus by treating them with vitamin D3 (5,000 I.U./100 g body wt.) and/or 0.5% solution of CaCl2. The animals were killed on 1st, 3rd, 5th, 9th, 13th and 17th days after the initiation of the experiment. Histological preparations of the ultimobranchial gland (UBG) were made. The gland exhibits nuclear hypertrophy, hyperplasia and loss of staining response corresponding to the rise in serum calcium levels. At later intervals, the UBG shows exhaustion and degeneration which is evident from vacuolization and nuclear shrinkage of the ultimobranchial cells after day 13 in groups B and C and day 9 in group D.     

Ultimobranchial body of Notopterus notopterus in relation to calcium and sodium rich environments

The UBB of Notopterus notopterus is a paired structure situated between the oesophagus and sinus venosus. Both right and left lobes of the gland are enveloped by a common thick connective tissue which gets constricted between the lobes and separates them. Numerous follicles of varying sizes are encountered in each gland. In N. notopterus the effects of hypercalcaemia (caused by keeping the specimens in 0.5% of CaCl2 solution and by injecting 4000 I.U. of vitamin D2 on alternate days) on UBB has been observed. The effects of NaCl rich environment (created by keeping the fish in 0.5% NaCl solution) on this gland has also been studied. In the UBB of N. notopterus the activity of the gland is observed in terms of: 1. increase in the blood supply of the gland and the dilation of the blood vessel, 2. increase in the height of the follicular epithelium, 3. cytoplasmic hypertrophy resulting in the increase in secretory processes, 4. appearance of pseudostratified epithelium in place of single layered cuboidal follicular epithelium and 5. nuclear and cellular hypertrophy. According to these characteristics it is evident that the gland from group II shows gradual activity from the 2nd day onwards and is maximum on the 6th day. From 8th day to the close of the experiment gradual inactivity of the gland is discerned--follicles get atrophied and the cells appear in clumps. The gland from group III shows a good response to its environment and is more hypertrophied as compared to that of group II. The activity of the gland closely parallels serum sodium levels which increase up to the 8th day when UBB shows the maximum activity. The serum sodium level rises from a normal of 110 m eq/l to a peak of 180 m eq/l on 8th day. After 10 days onwards the gland shows gradual inactivity and degeneration. The serum sodium level is 130 m eq/l on 12th day. These observations support the view that the main role of UBB in N. notopterus lies in sodium metabolism and it is only partially responsible for calcium regulation.     

Ultrastructural changes in the microcirculatory bed and filtration-reabsorption barrier of the kidney during temporary ischemia after unilateral nephrectomy

Ultrastructure of cellular elements of the microcirculatory bed and filtration-reabsorption barrier has been studied in 150 mature white rats, in which vascular fasciculus of the left kidney has been compressed for 30 min, 1-2 h with a subsequent restoration of the blood stream in the organ undergone ischemia on the 3rd, 7th, 14th, 30th, 60th, 180th, 360th days under conditions of the preliminarily right kidney nephrectomy. On the 3rd day after ischemia of the remained kidney for 30 min, structural components of the walls of the glomerular arterioles and those of the filtration-reabsorption barrier undergo certain ultrastructural changes, that with time elapsed (7, 14 days) gradually pass away, and amount of cells with hypertrophic processes increases. Ischemia for 1 h in the remained kidney with subsequent restoration of the blood stream on the 3rd, 7th days produces in the structures mentioned more pronounced destructive changes. During subsequent compensatory hypertrophy (the 30th, 60th days) of the remained kidney after its ischemia, in the microcirculatory bed elements and in the convoluted canal epitheliocytes intracellular regenerative and hyperplastic processes develop. However, ischemia for 2 h in the remained kidney produces severe destructive-necrotic phenomena in ultrastructure of the microcirculatory bed and of the filtration-reabsorption barrier.     

Ectodermal ablation of the third branchial arch in chick embryos and the morphogenesis of the parathyroid III gland.

The parathyroid glands have been classically considered to be derivatives of the third and fourth pharyngeal pouches in most species, including humans. Furthermore, the presence of neural crest-derived cells in the parathyroid glands connective tissue has been apparently established. However, our previous studies have provided a new hypothesis on the origin of these glands in human and chick embryos. To determine the origin of the parathyroid III (P3) gland, ectoderm of the third branchial arch was cauterized in chick embryos at Hamburger and Hamilton's stage 19 (embryonic day 3). Cauterization of the ventral half of the ectoderm was followed by the non-formation, on the same side, of the P3 gland. When the dorsal half of the ectoderm was cauterized, both the right and left P3 glands formed. Our observations suggest that the ectoderm of the ventral half of the third branchial arch is necessary for the organization of the P3 gland.     

'Suppressed' double adenoma--a rare pitfall in minimally invasive parathyroidectomy

Since the introduction of a quick intraoperative parathyroid hormone (QPTH) assay, complete removal of hyperfunctioning parathyroid tissue can be proven during surgery. We report on a scintigraphically and biochemically documented patient with persistent primary hyperparathyroidism (PHPT) caused by suppressed hyperfunctioning parathyroid tissue. A left lower enlarged parathyroid gland was resected by minimally invasive open parathyroidectomy. QPTH measurements confirmed complete resection of hyperfunctioning tissue and histology showed a tumorous enlarged left lower parathyroid gland. The patient was normocalcemic until 1 month after surgery, when serum calcium increased again. A MIBI scan 6 months after surgery showed no evidence of hyperfunctioning parathyroid tissue. After an increase of PTH, a third MIBI scan another 3 months later was performed. Increased tracer uptake behind the lower pole of the right thyroid lobe was seen and confirmed by ultrasonography. Another tumorous enlarged parathyroid gland was removed. These findings support the hypothesis that smaller yet abnormal parathyroid glands can be suppressed and may become hypersecretory if left in situ after surgical removal of the larger gland.     

Research on Intra-Operative Indocyanine Green Angiography of the Parathyroid for Predicting Postoperative Hypoparathyroidism: A Noninferior Randomized Controlled Trial

Objective: A noninferiority randomized controlled trial was undertaken to clarify whether the postoperative measurements of serum calcium and parathyroid hormone and oral supplementation of calcium and calcitriol could be omitted if patients had at least one well-perfused parathyroid gland evaluated by intra-operative indocyanine green (ICG) angiography.Methods: Patients with at least one parathyroid gland well-perfused by ICG angiography (ICG score >2) were randomized to the control group or test group. For the control group, oral calcium and calcitriol were systematically supplemented. For the test group, no oral calcium or calcitriol was supplemented to the patients. Levels of serum calcium and parathyroid hormone of patients on the first and 30th postoperative day were compared between the two groups.Results: Among all 68 selected patients, 56 patients had at least one well-perfused parathyroid gland evaluated by intra-operative ICG angiography. The 56 patients were randomized to the control group or test group. There were no statistically significant differences in the levels of serum calcium and parathyroid hormone between test group and control group on the first or 30th postoperative day.Conclusion: The postoperative measurements of serum calcium and parathyroid hormone and oral supplementation of calcium and calcitriol were evaluated as redundant, if patients had at least one well-perfused parathyroid gland evaluated by intra-operative ICG angiography.Abbreviations: ICG = indocyanine green; NIR = near infrared; POD = postoperative day; PTH = parathyroid hormone; SBR = signal background ratio     

Compensatory-restorative processes of the thyroid gland in 1- and 3-month-old rats in health and in desympathization

In 172 white male rats 1- and 3-month-old, using electron microscopical, autoradiographical, morphometrical and radioimmunological methods, analysis of structural-functional changes of the thyroid gland has been carried out both under normal conditions and at guanethidine desympathization (15 mg/kg for 14 days after birth). Resection of 2/3 of the organ has been performed on the 3d, 5th, 7th and 15th days before sacrifice. In the 1-month-old desympathized rats hypofunctional state of the gland is observed. By the 3d month at the expense of an increased production of thyrotropin and calcitonin the thyroid status becomes normal. The dynamics of the restorative processes in the thyroid gland after resection of 1/3 of the organ in the control and test rats occurs with a similar intensity. Proliferative potency of the desympathized thyroid tissue is much higher.     

Effects of pinealectomy on the ultrastructure of the golden hamster parathyroid gland

Ultrastructural changes of the parathyroid glands of pinealectomized golden hamsters were investigated. The main changes in the parathyroid glands 1 hour and 1 day after pinealectomy compared with the control and sham-operated groups were an increase of the Golgi complexes, cisternae of the granular endoplasmic reticulum and large vacuolar bodies. In addition, many chief cells contained numerous prosecretory granules in the Golgi areas and many secretory granules in the peripheral cytoplasm. The morphology of the parathyroid glands 7 and 30 days after pinealectomy resembled that of the control parathyroid glands. These results suggest that pinealectomy affects the secretory activity of the parathyroid gland.     

Effects of acute and chronic administration of secretin and caerulein on rat duodenal and gastric growth

We studied the effects of acute and chronic administration of secretin and caerulein, alone and in combination, on RNA and protein synthesis in the duodenum and oxyntic gland area as well as content of DNA, RNA and protein in rats. Secretin, 100 micrograms . kg-1, three times a day for 5 days, was associated with duodenal hypertrophy after the first 24 h of treatment and hyperplasia at the end of days 2 and 4; hypertrophy of the oxyntic gland area was observed only at 4 h after the first injection. Caerulein, 1 microgram . kg-1, also promoted duodenal hyperplasia after 2 and 4 days of treatment. The oxyntic gland area showed hypertrophy only at 4 h after the second injection of caerulein. These data indicate that both hormones can induce duodenal hyperplasia, probably by an amplification of the normal renewal cycle of the epithelial cells. They also demonstrated that growth of the oxyntic gland area is not promoted by these two peptides at the doses studied.     

Effects of isoproterenol on the fine structure of the hamster parathyroid gland

Ultrastructural changes of the parathyroid glands of isoproterenol-treated golden hamsters were investigated. Many chief cells in the parathyroid glands after 5 and 10 minutes of administration of isoproterenol contain well-developed Golgi complexes and granular endoplasmic reticulum, numerous prosecretory granules, and many secretory granules in the peripheral cytoplasm as compared with the control animals. Many chief cells in the parathyroid glands after 1, 3, 6 and 12 hours of administration have poorly-developed Golgi complexes, granular endoplasmic reticulum, many secretory granules and numerous lipid droplets as compared with the control animals. The morphology of the parathyroid gland after 30 minutes and 24 hours of administration resembles that of the control animals. It is considered that isoproterenol affects the secretory activity of the parathyroid gland.     

Microspectrophotometric study of the lipid content in regenerating connective tissue

An experimental quantitative histological investigation was performed to study lipids in cellular elements of the regenerated connective tissue. Flap wounds were cut on the back of white mice and granulation tissue dissected 1, 3, 7, 14 30 and 60 days after the operation was investigated. Lipids and cellular elements were revealed with Sudan III-IV black B and Nile blue. Lipid quantity was estimated by means of a modified scanning integrating microphotometer. The greatest amount of lipids in the cellular elements of the granulation tissue was revealed on the 3d day of the experiment, total optic density (TOD) of lipids in leucocytes was 0.83, TOD in histiocytes--0.6. On the 7th day the amount of lipids decreased, their TOD in leucocytes was 0.6, in histiocytes--0.4. By the 14th day only phospholipids were revealed, in histiocytes their TOD was 0.3. In subsequent days phospholipid contents continued decreasing and by the 30th day their TOD was 0.2. By the 60th day, when a scar was formed in the wound, in fact, there were no lipids in the cellular elements. The microphotometric investigation performed demonstrated qualitative and quantitative characteristics of lipids in the cellular elements of the granulation tissue in dynamics and their close dependence on the time of wound healing. It was also revealed that the regenerative process was accompanied by decreasing lipid amount in the cellular elements, and this phenomenon could be used as a peculiar test to prognosticate the process of wound healing.     

Effects of cigarette smoke exposure on the ultrastructure of the golden hamster parathyroid gland

Cigarette smoking has been identified as one of the risk factors to induce osteoporosis. However, we find no study on the morphology of the parathyroid gland under smoking exposure. We studied the ultrastructure of the parathyroid gland, lung and femur of the golden hamster exposed to cigarette smoke. Four-week-old male hamsters were housed in a plastic case (48x31x30 cm) and were exposed to cigarette smoke for 12 weeks, 5 minutes exposure, 4 times a day, 4 days a week. There were no differences in serum calcium level and the whole bone mineral density between the control and the smoke-exposed groups. In the parathyroid gland of the smoke-exposed animals, the Golgi complexes associated with many prosecretory granules were well developed and many secretory granules were located near the plasma membrane. Large lipid-like inclusion bodies were observed in the alveolar macrophages of the smoke-exposed animals. The femur morphology showed a wider area of resorbing surface in the smoke-exposed group than in the control group. From these findings, it is conceivable that the secretory activity of the parathyroid gland was stimulated with cigarette smoke exposure.     

An assessment of the relative contribution of the processes of cellular proliferation, polyploidization and hypertrophy to the increase in liver mass at various stages in the postnatal development of rats

Changes in isolated hepatocyte dry mass, its ploidy and liver mass at different stages of the rat postnatal ontogeny were investigated. The determination of these processes and special calculation made it possible to estimate quantitatively a relative contribution of cell proliferation, polyploidization and hypertrophy, not associated with DNA synthesis to the increase in the liver mass at different stages of the rat development. During the first week after the rat's birth, its liver growth is provided by 61 and 39% with hepatocyte proliferation and hypertrophy, respectively. Between the 14th and the 21st days of development, when considerable functional changes occur in the rat liver, the contributions of proliferative and polyploidization processes, and of cell hypertrophy into the liver mass increasing are roughly identical. Later on, the contribution of cell hypertrophy into the liver growth is noticeably reducing to reach within 1-2 months only 1%. On this developmental stage the liver mass increment by 2/3 is provided due to cell proliferation and by 1/3--to its polyploidization. As a whole, the accelerated growth of the rat liver from the birth to sex puberty is described as follows: the contribution of processes of proliferation and polyploidization, and of cell hypertrophy correspond to 28, 30 and 42%, respectively; afterwards, the liver growth being retarded. Within the period from 2 to 6 months, the liver mass increase is provided mainly (up to 76%) by cell proliferation, the shares of polyploidization and cell hypertrophy being 8 and 16%, respectively.