Biomedical subjects

A I Cisneros

Publications and source records attributed to A I Cisneros.

5 recordsLinked to original sources

PubMed2002

Morphometric study of testis of Wistar rat after open-ended vasectomy.

The effects on the testis of open-ended vasectomy in the Wistar rat have been assessed morphometrically and evaluated statistically at 1, 4, 12, and 24 weeks after operation, and compared to those in sham-operated controls. The open-ended technique, ie, without ligation of the epididymal end of the cut ductus deferens, allowed drainage of sperm into the spermatic cord. During the period of our study, it did not affect the structure of the testis; although the germinal epithelium, basement membrane, and the stroma and cells of the interstitial space all showed variations when compared to the control group, these were not statistically significant.

Animals↗

PubMed2002

Fetal development of the human tympanic ossicular chain articulations.

OBJECTIVES: To obtain further knowledge on the morphogenesis of the articulations in the tympanic ossicular chain in humans. MATERIAL AND METHODS: In 25 temporal bones of human fetuses the structural development of incudomallear, incudostapedial and stapediovestibular articulations was studied. The chronological ages were between the 7th week (21 mm) and the 29th week (270 mm). RESULTS AND DISCUSSION: Incudomallear articulation showed diarthrosis and sellar joint characteristics. It showed a homogenous interzone in the 7th week of development, a three-layered interzone in the 8th week, the first cavitation signs in the 9th week and the presence of an articular cavity in the 10th week. The presence of a hyaline cartilage covering articular surfaces was observed starting in the 20th week of development. Incudostapedial articulation showed typical characteristics of a diarthrosis and spheroidal joint with a homogenous interzone at the 7th week, showing similar characteristics for 12 weeks, and completed its cavitation at the 16th week. We observed hyaline cartilage on articular surfaces from 29 weeks. Stapediovestibular articulation showed typical characteristics of syndesmosis. The annular ligament primordium derived from cartilage differentiation, both from stapedial footplate and from the surrounding otic capsule, into mesenchyme and its subsequent transformation into fibrous tissue, reaching definitive characteristics from the 12th week.

Body Patterning↗

PubMed2001

Contributions to the study of the foetal development of physiological intimal thickening in the human uterine artery.

The morphological study of the development of "intimal thickenings" of the human uterine artery in physiological condition was performed on 72 uterine arteries obtained from foetuses from the 12th week of gestation up to birth. Our results indicate that intimal thickening is formed by the migration and displacement of mesenchymal cells around the site of origin of collateral vessel from uterine mesothelium. These cells firstly differentiate into the myoblasts and then into the myocites. During the development the internal limitans membrane separates the intimal thickening from the tunica media and the elastic fibres appearing inside possessing a muscle-elastic nature. The function of intimal thickenings is the regulation of local blood flow by means of the control of myocitic contractile capacity; these cells play a fundamental role in endothelium-intimal smooth muscle cell contact.

Arteries↗

PubMedDate not supplied

The vasectomized testis.

We have performed a qualitative study on effects of vasectomy on the testicular structure. Vasectomy performed with the traditional technique changes testicular structure. At first, the injuries are slight and restricted, but gradually, and in a time-dependent manner, become more severe and extensive. Ultrastructure studies indicate that the spermatogonia and Sertoli's cells are the most resistant to vasectomy, and are even observed in some regenerating testes lacking a complete germinal epithelium. Morphometric studies revealed a decrease in epithelial depth, an increase in the thickness of the basement membrane and in surface of the interstitial space, all significant (P < 0.01) with respect to the control. However, the percentage of the interstitial tissue occupied by cells, did not show any significant difference. We propose that the increase of intraluminal pressure is the essential factor that provokes testicular atrophy.

Animals↗

PubMedDate not supplied

[Structural peculiarities of the human cerebral communicating arteries and their repercussion in encephalic vascular pathology].

INTRODUCTION: The cerebrovascular accidents are one of the most frequent causes of morbimortality. Most of them are caused for the break of aneurysms in communicating arteries. The weak structure of these vessels explain the reason of these accidents. OBJECTIVE: The reason of this paper is study the organization of communicating arteries as cause of this fragility. Material and methods. The material of this study is composed of 61 human cerebral communicating arteries, grouped in decades. The study has been carried out by histological routine. RESULTS: In general the structure of cerebral communicating arteries is characterized for the thinness and irregularity of the wall. In the childhood the internal elastic membrane and tunica media show thicker, while in young and adult people appear elastic fibers and reticulin as well as smooth muscle cells in tunica media. In adulthood (50 60 years) collagen in adventicia occupies tunica media, and adventicia is weaked. There are frequent media defects in these communicating arteries, that are usually repaired for conjunctive tissue stopper with abundance of collagen fibers. Starting from 4th decade the internal elastic membrane shows a great number of fenestrae through muscle and fiber tissue of media occupying subintimal space. Doubtless media defects mean the most severe threat of vascular outbreak. CONCLUSION: The structural evolution with the age of communicating arteries, with predominance of collagen over elastin and reticulin, could be their reason of fragility.

Adult↗