1,721,168 research outputs found
Microanatomy of the epididymis and vas deferens
No full textIn this review, the structural and functional characteristics of the human epididymis, including vas efferens and ductus deferens, are revisited under the morphological and ultrastructural point of view New surface sperm antigens, enabling the fertilizing power during the epididymal transit, various epididymal microenvironments and their activities on the spermatozoa are reported. This revision is important because the recent procedures of assisted reproduction, aimed at overcoming the cases of obstructive azoospermia, use the spermatozoa aspirated from the proximal segments of the epididymis and suggest a flexibility of the epididymal function with regard to the fertilizing sperm capacity. In my opinion these proce dures must be based on an accurate investigation on the function of the different epididymal districts. Moreover, in patients affected by congenital absence of the vas deferens (CAV), the ultrastructural examination of the spermatozoa aspirated from the proximal segments of the epididymis revealed that most of them are defective: in fact the absence of the vas deferens seems to affect the development and the functional properties of the epididymal spermatozoa
The role of mitochondria in energy production for human sperm motility
No full textMitochondria of spermatozoa are different from the corresponding organelles of somatic cells, in both their morphology and biochemistry. The biochemical differences are essentially related to the existence of specific enzyme isoforms, which are characterized by peculiar kinetic and regulatory properties. As mitochondrial energy metabolism is a key factor supporting several sperm functions, these organelles host critical metabolic pathways during germ cell development and fertilization. Furthermore, spermatozoa can use different substrates, and therefore activate different metabolic pathways, depending on the available substrates and the physico-chemical conditions in which they operate. This versatility is critical to ensure fertilization success. However, the most valuable aspect of mitochondria function in all types of cells is the production of chemical energy in the form of ATP which can be used, in the case of spermatozoa, for sustaining sperm motility. The latter, on the other hand, represents one of the major determinants of male fertility. Accordingly, the presence of structural and functional alterations in mitochondria from asthenozoospermic subjects confirms the important role played by these organelles in energy maintenance of sperm motility. The present study gives an overview of the current knowledge on the energy-producing metabolic pathways operating inside human sperm mitochondria and critically analyse the differences with respect to somatic mitochondria. Such a comparison has also been carried out between the functional characteristics of human sperm mitochondria and those of other mammalian species. A deeper understanding of mitochondrial energy metabolism could open up new avenues of investigation in bioenergetics of human sperm mitochondria, both in physiological and pathological conditions
Embryo development pregnancy and twin delivery after microinjection of 'stump' spermatozoa
No full textIntracytoplasmic sperm injection was performed with immotile spermatozoa affected by tail 'stump' defect, and resulted in normal fertilization, embryo transfer and pregnancy in a 35-year-old female. The husband had a consanguineous ancestry. Two healthy babies, a male and a female, were born and this confirms that male infertility due to certain genetic sperm defects can be overcome by the intracytoplasmic sperm injection-assisted reproduction technique. The likely genetic origin of this sperm defect and the probability of the male offspring inheriting this sperm defect should be considered. The fertilization ability of stump spermatozoa, microinjected into the oocyte, is explained on the basis of experience from our previous research
Oxygen uptake by mitochondria in demembranated human spermatozoa: A reliable tool for the evaluation of sperm respiratory efficiency
No full textIn this work we report a relatively simple and fast method for analysing oxygen consumption and therefore mitochondrial functionality, in individual human ejaculates. This oxygraphic method requires a low number of cells, is highly reproducible and linearly correlates with sperm concentration. Our results have shown that oxygen uptake by mitochondria of demembranated sperm cells from normozoospermic subjects is significantly stimulated by a large set of respiratory substrates and ADP. The respiratory control ratio (RCR) values indicate a good coupling between respiration and phosphorylation by sperm mitochondria and thus a well preserved integrity of the mitochondria themselves. Interestingly, whereas the rates of oxygen uptake, as expected, changed with different sperm concentrations, the RCR values remained constant, thus demonstrating a linear response of the assay. In asthenozoospermic subjects, however, a significant decrease in the sperm respiratory efficiency was found. In our opinion, the implications of this study are the following. On the one hand, a careful and detailed investigation of the mitochondrial bioenergetics of sperm will provide more insight into the basic biology of the spermatozoon with the aim of obtaining more information on the role of sperm mitochondria in motility and on the overall quality of the gametes. On the other hand, we are confident that this relatively simple and fast assay, requiring a limited amount of sperm cells, can be used as a routine semen analysis in clinical investigation
Mathematical analysis of submicroscopical sperm alterations as a tool for the evaluation of defective spermatogenesis
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