ABSTRACT
Junctions of myocardial cell, specially the intraeellular junctions of transverse tubule system with sarcoplasmie reticulum membranes were observed and described in the present paper. The tubular invaginations of the sarcolemma constitutes the transverse tubule (T tubule) which surround the myofibril in rabbit. The transverse tubular system of cardiac muscle are well developed. The tubule has an elliptical shape in cross section and 15 nm in diameter and is constantly located at the level of Z line. The sarcoplasmic retieulum consists of a simple plexiform arrangement of tubular elements forming a loose network around the myofibrillae. Small terminal expansions of the reticulum are closely applied to the membrane of the T tubules to form Diad. The membranes of the small flattened expansions of the reticulum and T tubules are in contact with each other, but the lumina of the two elements do not communicate. There is a gap of about I0 nm between them and foot processes from the membrane of sarcoplasmic reticulum are regularly extended toward the Ttubules. In addition, intracellular membranous junctions are observed between T tubules and sarcoplasmic reticulum of Diad. Each junction with membrane area of about 375 nm long becomes thicker and divides into two layers. Between them there is a gap of 31 nm wide, in which it is filled up with electron, dense material, forming some discontinuous spots which consisted of dense and light areas arranged at regular intervals.
ABSTRACT
This paper presents ultrastructural observations on the adrenal cortex of rats following gossypol administration of a daily dose of 10 and 25 mg/kg respectively for various time periods. Stereological analysis was olso carried out on the cellular components of zona glomerulosa.No detectable ultrastructural changes were observed in the glomerulosa cell organelles in the treated rats of 10 mg/kg dosage groups. However, changes, such as increase of the number of mitochondria, derangement and decrease in the number of their cristae, distension of endoplasmic reticulum and Golgi apparatus, and increase in lipid droplets were evident in the zona glomerulosa cells of experimental animals treated daily with 25 mg/kg of gossypol. Sstereological analysis of the zona glomerulosa cells also indicated that mitochondria and Golgi apparatus had a tendency to increase in number and size, although There was no significant difference statistically from that Seen in control animals. "Anomalous cells" that had never been seen in the control animals were observed in the zona fasciculata of almost all experimental animals treated daily with 25 mg/kg of gossypol. These cells were characterized by thier condensed cytoplasm and smaller size, shrinkage of nuclear membrane, decrease in amount of smooth endoplasmic reticulum as well as denature or decrease in mitochondrial matrix. Other compensatory changes such as the appearance of whorled membranous bodies and cholesterol crystals in the zona fasciculata cells were also discernible.No obvious changes in zona reticularis of rat adrenal cortex following gossypol treatment could be observed. The nature and the significance of the ultrastructural changes in the adrenal cortex following gossypol treatment are a nalysed and discussed.
ABSTRACT
The present study was designed to investigate the effects of cytochalasin E(CE) on the integrity of Sertoli cell barrier. The results indicate that: (1) In the CE-treated testis(1000-2000 ?mol/L CE/testis, 6-14 hr), actin filaments of the ectoplasmic specialization (ES) in area of Sertoli cell barrier were disrupted, the accumulation of amorphous material and fragmented small vesicles of SER were observed in cytoplasm of Sertoli cell. The above changes appeared to be dosage and duration dependent; (2)In the seminiferous tubules of animals receiving CE (1000-2000 ?mol/L testis, 6-14 hr) plus fixation with 10% hypertonic dextrose solutions, usually the germ cells shrinkage and exaggeration of intercellular spaces withint he basal as well asthe adluminal compartments were observed. The tight junction between Sertoli cells were also appeared to be separated by hypertonic action of dextros; (3) The results of tracing experiments showed that lanthanums as tracer could be seen to pass through the Sertoli-Sertoli cell junction of the barrier and enter into the adluminal compartment, the tracer that surrounding the spermatocytes and round spermatids were discernible readily. The above results suggest that cytochalsin E disturbed actin filaments of Sertoli ectoplasmic specialization thus altered the functional integrity of the Sertoli cell barrier. The relationship between the actin filaments and Sertoli cell barrier was discussed.
ABSTRACT
Observations of the ultrastructural changes on the gonadotrophic cells of adenohypophysis and the interstitial cells of testis were carried out in rats following gossypol treatment.It was found that four types of gonadotrophs in the rat adenohypophysis could be classified under the electron microscopic observation. The contral groups mainly consisted of the types Ⅰ and Ⅱ gonadotrophic cells and the latter appear to be the most numerous cell type, which constitute about 65% of the total gonadotrophs. Following gossypal administration, the number of type Ⅱ cells decreased obviously while that of the type Ⅲ cells increased steady and became the principal type of gonadotrophic cells in gossypol-treated animals. The proportion of the type Ⅲ cells were calculated as 56%, 44% and 58% of the total gonadotrophs after Ⅰ, 2 and 12 months of gossypol treatment, respectively. The type Ⅳ cells were characterized by the appearance of dilated vesicles derived from rough endoplasmic reticulum which occupied almost the entire cytoplasm. Morphologically, these cells were similar to "castration cells" which appeared in the rat adenohypophysis after gonadectomy. They were observed in the experimental animal groups following two months of gossypol treatment, and their proportion was about 13% of the gonadotrophs.No significant ultrastructural changes in the interstitial cells of the treated rat testis could be observed.The significance of the above mentioned changes and the possible mechanism of gossypol effect on the gonadotrophs were discussed.