Changes In Follicular Cells Research Articles

Flow cytometric evaluation of canine follicular cell apoptosis during the oestrous cycle.

Apoptosis is the cellular mechanism of ovarian follicular atresia in mammals; the aim of this study was to examine the apoptosis-related cyclic changes in follicular cells of different-sized antral follicles throughout the oestrous cycle in canines. Ovaries were collected from 26 adult female dogs (1-4years) following routine ovariohysterectomy. Antral follicles were classified as small, medium or large antral or preovulatory. The percentage of apoptotic cells was determined flow cytometrically using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) DNA nick end labelling (TUNEL) assay. Apoptosis rate was quantified as the percentage of TUNEL-positive cells on a logarithmic scale. Percentages of TUNEL-positive cells obtained in the flow cytometric assay were compared among oestrous phases and follicular sizes using analysis of variance. Apoptotic follicles were observed in all types of canine follicles in different cycle phases and stages of development, possibly corresponding to the physiological process of the oestrous cycle. Both the oestrous phase and follicular size significantly influenced the apoptosis rate (p<.05). Apoptosis rate increased significantly (p<.05) as follicular development progressed. Apoptosis rate was the highest in large follicles during the oestrous phase (9.2%; p<.05) and the lowest in small follicles during the anestrus period (1.8%; p<.05). In conclusion, our results demonstrate significant differences in the apoptosis rate during the oestrous cycle related to follicle development in the canine ovary. Furthermore, flow cytometry using the TUNEL assay was found to be an effective method for detecting apoptosis in canine follicles.

Apoptosis within bovine follicular cells and its effect on oocyte development during in vitro maturation

Developmental competence of oocytes is compromised if they originate from atretic follicles. Apoptosis is the underlying process of atresia. Apoptotic changes in follicular cells are thought to influence the outcome of IVF. The aim of this study was to investigate apoptosis in different compartments of single bovine follicles (follicular wall, granulosa and cumulus cells (CC)) in relation to COC morphology, and to determine whether the addition, in vitro, of exogenous follicular cells from atretic follicles to maturing cumulus oocyte complexes (COCs) influenced the development of oocytes. Antral follicles were dissected from bovine ovaries and opened to obtain COCs and free floating granulosa cells (GC). The COCs were classified according to morphology. Apoptosis was determined in cumulus and granulosa cells and in homogenates of the remaining follicular wall. For every morphological class of COCs, a large variability of apoptotic expression was found in all follicle compartments. Follicular wall apoptosis was not correlated to COC morphology or to the percentage of apoptotic granulosa or cumulus cells. In grade 1 (best morphology) COCs, the degree of apoptosis in granulosa cells was comparable to cumulus cell apoptosis ( P<0.01). The overall expression of apoptosis in granulosa cells of follicles containing grade 3 COCs (median±median absolute deviation: 37.8±13.8%) was significantly higher ( P<0.05) than in follicles with grade 1 (22.7±10.4%) or grade 2 COCs (20.0±17.0%). About 48.3% of grade 3 COCs possessed strongly apoptotic cumulus cells compared to 27.8 and 28.2% of grade 1 or grade 2 COCs, respectively. Nonapoptotic cumulus complexes were observed in grades 1 and 2 COCs only. Adding exogenous follicular cells from atretic follicles to bovine COCs (grades 1 and 2) during in vitro maturation (IVM) had no impact on fertilization, blastocyst formation or hatching after IVF. This is of particular practical relevance to embryo production after ovum pick up (OPU), as during this process, good quality COCs are cultured together with simultaneously collected slightly atretic COCs.

Histomorphometry and quantification of nucleolar organizer regions in bovine thyroid containing methylthiouracil residues.

In order to study the morphology and morphometry and to characterize and quantify the nucleolar organizer regions (NORs) of bovine thyroids containing methylthiouracil (MTU) residues, five animals were orally treated with a suspension of MTU (5 g/animal/day) for 20 days (group A). This treatment protocol was interrupted 5 days before the the animals were slaughtered. Six animals receiving placebos composed group B. A third group (group C) was composed of normal thyroids obtained from a slaughterhouse. All glands were previously assessed for detection of antithyroid residues by chromatography, and only those glands from MTU-treated animals were positive. Follicles of glands from group A showed wide variation in size and shape. There was a predominance of small follicles covered by multiple layers of columnar cells, sometimes forming papillary projections into the lumen, characterizing severe interfollicular and intrafollicular adenomatosis. Many follicles had vacuolated cells with nuclei showing karyolysis or pyknosis and reduced amounts of a low-density and very excavated colloid. They also showed higher follicular epithelia and larger proportions of their structural components when compared with glands of groups B and C. In the thyroids from group A, the argyrophilic nucleolar organizer region-associated proteins (AgNORs) were greater in number, with small ones scattered all over the nucleus. Although the size of AgNORs in thyroids from groups B and C was variable, these AgNORs were fewer and larger than were those in glands from group A. In conclusion, the MTU induces proliferation and regressive changes in follicular cells, and the AgNOR technique is efficient to distinguish different degrees of thyroid hyperplasia.

Ultrastructural changes in follicular cells induced by granulosa and theca cell interactions

Bovine granulosa and theca cells were cultured on the opposite sides of a collagen membrane, and the morphological and structural effects of the interaction between theca and granulosa cells were studied. The apical surface of both granulosa and theca cells in the cocultured group appeared convex, while control cells were thin and flat. Numerous filopodia spread over the cellular surface connecting the cells. Constituents of rough endoplasmic reticulum in the cocultured cells were extended and swollen when compared with those observed in the cells cultured alone. Cocultured granulosa cells formed multilayered sheets, while granulosa cells cultured alone formed monolayered sheets. Theca cells in the cocultured group were more densely packed than cells cultured alone. These results indicate that the levels of cellular activity and intercellular communication among each type of cell are increased by the granulosa and theca cell interactions.

Ultrastructural alterations of the thyroid follicular cells in domestic fowls following neonatal olfactory bulbectomy.

1. In order to investigate if ultrastructural alterations of thyroid follicular cells are induced by removal of the olfactory bulb at hatching, chicks were olfactory bulbectomised within 24 h after hatching and the thyroid follicular cells were examined at 5 months of age by electron microscopy. 2. Olfactory bulbectomised chickens showed a well-developed Golgi area, a highly-developed rough endoplasmic reticulum, many mitochondria and a paucity of secretory granules and lysosomes in thyroid follicular cells. 3. These hypertrophic ultrastructural changes in follicular cells of operated birds indicated that the thyroids glands were stimulated by neonatal olfactory bulbectomy. 4. This finding may suggest an establishment of the olfactory bulbothyroid glandular system during the early days of life in the chicken.

FUNCTIONAL AND MORPHOLOGICAL ASPECTS OF DRUG-INDUCED ENDOCRINE LESIONS

Initially, morphological and endocrinological features of the thyroid gland are reviewed in view of the recent progress in thyroidology. The second part of this article deals with morphology and hormone measurement in the rat following drug-induced alteration in thyroid function. Single and short-term injection of hypothalamic thyrotropin-releasing hormone (TRH) resulted in an increase in serum TSH concentration but not in thyroid hormone concentration. Electron microscopic observation revealed that augmented TSH stimulation after administration of TRH, induced follicular exocytosis, followed by endocytosis. The increase in colloid droplet counts after TRH-treatment differed between follicles as well as between follicular cells in the same thyroid. Treatment with the antithyroid drug, propylthiouracil (PTU) caused a progressive decrease in serum thyroid hormone levels and an elevation of serum TSH. The earliest morphological changes in follicular cells after short-term administration of PTU were the appearance of subapical vesicles and colloid droplet formation in response to the elevated level of serum TSH. Conversely, prolongation of goitrogen-treatment led to the disappearance of exocytotic and endocytotic vesicles. Substained decrease of serum TSH after thyroxine (T4) treatment led to colloid and thyroglobulin (Tg) accumulation in the follicular lumen and to the disappearance of exocytotic and endocytotic vesicles. In the T4-treated rats hypothalamic stimulation (TRH injection) resulted in a rise in the serum level of TSH, accompanied by apparent colloid droplet formation in the follicular cells.

Effects of Human Chorionic Gonadotropin and Progesterone on Follicular Development in the Immature Rat*

To determine if small sustained increases in serum LH (hCG) activity can stimulate the maturation of small antral follicles in intact prepubertal rats, 24- or 29-day-old animals were injected twice daily for 2 days with 0.15 IU hCG. Functional changes in follicular cells were determined by measuring granulosa and thecal cell LH/hCG receptor content, follicular arornatase activity, endogenous estradiol production, and hormonally responsive progesterone accumulation, prostaglandin production, and adenylate cyclase activity in vitro. Each of these follicular components or activities increased progressively after the administration of 0.15 IU hCG in vivo. A bolus injection of 5 IU hCG induced ovulation in these low dose hCGtreated animals, with an average of 11 ovulations/rat, indicating that preovulatory follicles had developed. To determine if physiological concentrations of serum progesterone have an effect on the responsiveness of small antral follicles to hCG, progesterone implants (delivering 50–70 ng/m...

A correlation between the function and the aspiration cytology in chronic thyroiditis (author's transl)

The correlation between the function and the aspiration cytology in chronic thyroiditis was studied. In 184 cases of chronic thyroiditis (hyperthyroid state: 19 cases, euthyroid state: 113 cases, hypothyroid state: 52 cases) and 36 cases of hyperthyroidism, aspiration biopsy was performed by a fine needle of 22 gauge. The smears were stained with May-Grünwald-Giemsa and Papanicolaou's stain. In all specimens, the cytological investigations were done as for follicular epithelial cells, oxyphilic changes of follicular epithelial cells and non-epithelial cells, oxyphilic changes of follicular epithelial cells and non-epithelial cells per se. The relationships between the thyroid function and cytological pictures in chronic thyroiditis were studied. The following conclusions were obtained by this study: 1. Compared to hyperthyroidism, chronic thyroiditis has the following characteristic cytological picture: i) Hyperplasia of small follicular cells with many lymphoid cells ii) Oxyphilic changes in follicular cells, lymphoid cells, plasma cells and reticulum cells 2. As for the correlation between the cytological findings and the thyroid function or thyroid antibodies, the following conclusions were obtained: i) There is a negative correlation between the grade of the number of oxyphilic cells or lymphocytes and the titer of the microsome test (MCHA). (p less than 0.005)

Fine Structural Alterations in Thyroid Follicular Cells (FC) and Changes in Serum Thyroxine Produced by Feeding Polychlorinated Biphenyl (PCB) to Rats

The widespread contamination of the environment with PCB, a compound used extensively by industry in hydraulic and heat transfer fluids as well as plasticizers and solvents in adhesives and sealants, has resulted in detectable tissue levels in a large portion of the human population, domestic animals, and wildlife. Intoxication with PCB produces severe hepatic necrosis, degeneration of lymphoid tissues and kidney, skin lesions, decreased reproductive performance, reduced feed efficiency, and decreased weight gain. PCB also has been reported to reduce the binding of thyroid hormone to serum proteins and enhance the peripheral metabolism of thyroxine with increased excretion of thyroxine-glucuronide in the bile (Bastomsky, Endocrinology 95: 1150-1155, 1974).The objectives of this investigation were (1) to investigate the histopathologic, histochemical, and ultrastructural changes in thyroid FC produced by the acute (4 week) and chronic (12 week) administration of low (50 ppm) and high (500 ppm) doses of PCB to rats, (2) to correlate these alterations to changes in serum immunoreactive thyroxine concentration, and (3) to investigate the persistence of the effects of PCB on the thyroid gland.