Fernando Ureña

  • Citations Per Year
Learn More
DNA fingerprinting allows the verification of conventional methods used to implement beef traceability. At any point along the supply chain, the identity of an animal or piece of meat can be checked by comparison of its DNA profile with an initial sample. Practical application of DNA fingerprinting to trace beef requires a choice of DNA markers as well as(More)
The ultrastructure of adult hamster (Mesocricetus auratus) testis was studied by means of light and electron microscopes during fourteen months after bilateral vasectomy. In all the vasectomized animals there was marked degeneration of the semniiferous tubules as well as reduction of spermatogenesis. The thickening of the basal membrane was quite evident(More)
  • F Ureña
  • Revista de biología tropical
  • 1988
The ultrastructure of mitotic nuclei of the promastigote Leishmania mexicana ssp. was studied by serial thin sections and three-dimensional reconstructions of each divisional stage. At the beginning of nuclear division (equatorial stage), a set of six dense plaques located about the equatorial region of the nucleus and a microtubular spindle develops in the(More)
Electron microscopy studies on the epididymal epithelium and lumen contents of hamster between 3 and 14 months after vasectomy, showed ultrastructural changes in the clear cells and spermatozoids within the lumen. These changes on the clear cells were as follows: accumulation of electron dense bodies of irregular forms distributed between luminal and basal(More)
During meiosis and espermiogenesis the Golgi apparatus shows the greatest morphological and physiological changes. During the second meiotic division it appears as a very large organelle, formed by prominent dictyosomes and by two types of vesicles: one in the external part of the body with diameters that range from 40--100 nm, and the other in the central(More)
  • Raymundo Sánchez-Orozco, Beatriz Timoteo-Cruz, Teresa Torres-Blancas, Fernando Ureña
  • 2017
This study was conducted to explore the potential of superabsorbent polymers (SAPs) from used disposable diapers as soil moisture conditioner. Swelling behavior of the proposed hydrogel in response to external stimuli such as salt solutions, temperature and pH was studied. In addition, laboratory experiments were carried out to evaluate the effects of(More)
Ultrastructural studies of different types of spermatogonia by thin section techniques and transmission electron microscopy showed that Cuniculus paca has two types of Type A spermatogonia (A-O and A-1). Samples were taken at different stages of the cycle in the seminiferous tubule epithelium presented a similar pattern as those of other rodents. Type B(More)
Ultrastructures spermatozoa taken from the seminiferous tubules of rat testes (Rattus norvegicus) were observed under transmission electron microscopy, using the techniques of ultrathin sections, microspreading specimens and replicas. The heads of isolated spermatozoa were of homogeneously high electron density, and had a slightly curved end; in(More)
  • 1