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Biomedical subjects

L D Russell

Publications and source records attributed to L D Russell.

At least 145 records · Page 8Linked to original sources
PubMed1977

Degeneration of germ cells in normal, hypophysectomized and hormone treated hypophysectomized rats.

In normal adult rats some germ cells degenerate at several vulnerable steps of spermatogenesis. These are the type A spermatogonia, midpachytene spermatocytes, primary and secondary spermatocytes which degenerate during their respective maturation divisions and step 7 and 19 spermatitids. In the present study, these degenerating cells were examined under the electron microscope, and their frequency was determined in toluidine blue stained semithin sections of testes from normal, hypophysectomized (at 5.5 days after operation) and hypophysectomized rats injected with FSH and LH separately or in combination. With the exception of the step 19 spermatids, the degenerating germ cells underwent necrosis in vacuolated spaces delimited by Sertoli cells. In the case of the affected step 19 spermatids, an apical cytoplasmic process of the Sertoli cell initially ensheathed a long segment of their flagellum, and then each degeneration cell was drawn deep in the seminiferous epithelium where it was phagocytozed by the Sertoli cell. Soon after hypophysectomy the incidence of degenerating mid-pachytene spermatocytes, step 7 and 19 spermatids which are present in stages VII or VIII of the cycle of the seminiferous epithelium, increased significantly. In contrast the number of degenerating primary or secondary spermatocytes during the meiotic divisions seen in stage XIV of the cycle or of any other germinal cell was not significantly modified. While the injection of FSH alone had no influence on the number of degenerating cells in hypophysectomized rats, injections of LH at the two doses administered (0.7 microng or 20 microng) reduced significantly the number of degenerating cells seen in stages VII-VIII of the cycle; combined injections of FSH and LH (20 microng) reduced the number of these degenerating cells to the normal low values. Thus it appeared that the mid-pachytene spermatocytes and the step 7 and 19 spermatids, all present in the adluminal compartment of the seminiferous epithelium in stages VII or VIII of the cycle, were more sensitive to the presence of absence of gonadotropic hormones than the other germ cells present in the seminiferous epithelium.

Animals↗
PubMedDate not supplied

Characterization of boar sperm plasma membranes by two-dimensional PAGE and isolation of specific groups of polypeptides by anion exchange chromatography and lectin affinity chromatography.

High resolution, two-dimensional PAGE was used to characterize purified plasma membranes (PM) from boar spermatozoa. In addition to the abundance of polypeptides resolved, unusual features of PM discerned in gel patterns include a large number of basic polypeptides and the presence of at least three polypeptides with molecular weights in excess of 200 K daltons. In order to reduce these large numbers of polypeptides into smaller fractions, an important step in developing a surface map of these membranes, detergent-solubilized membranes were fractionated by the techniques of ion exchange chromatography and lectin affinity chromatography. PM polypeptides, solubilized in the nonionic detergents, were fractionated on DEAE Sephadex using phosphate ion gradients containing EDTA. Most of the major acidic polypeptides were eluted as a group at high phosphate ion concentrations. Membrane polypeptides can be separated into smaller populations by affinity chromatography on wheat germ agglutinin-agarose (WGA) or by Concanavalin A-agarose. Concanavalin A-agarose binds most PM glycoproteins, but partial purification of an important group of very basic proteins was obtained by repeated chromatography of polypeptides that failed to bind to this lectin. Since biologic activity (including immunologic potency) is often retained in the detergents used, the ability to fractionate the major polypeptide of the boar sperm PM into different and much smaller populations in large quantity and to characterize these proteins by electrophoresis provides a starting point for determining the functional significance and location of the major surface proteins of the boar sperm PM.

Animals↗
PubMedDate not supplied

Effect of (+)-gossypol on fertility in male hamsters.

(+)-Gossypol was isolated from the bark of Thespesia populnea and tested for its ability to inhibit the fertility of male hamsters. Male hamsters of proven fertility were treated orally for 54 days with 40 mg/kg of (+)-gossypol, 40 mg/kg of racemic gossypol, or 5% gum acacia (vehicle control) and were mated with estrous female hamsters during the fourth and seventh weeks of treatment. Both the control and the (+)-gossypol-treated animals exhibited normal fertility throughout the experiment. The racemic gossypol-treated animals were infertile when evaluated during both the fourth and seventh weeks of treatment. Morphologic examination of the testicular tissue could not explain the loss of fertility. These data demonstrate the inability of (+)gossypol to decrease male fertility and suggest that the activity of racemic gossypol may be due primarily to the presence of the (-) optical isomer.

Animals↗
PubMedDate not supplied

Improvement in the quality and fertilization potential of a human sperm population using the rise technique.

Semen from 63 individuals participating in an in vitro fertilization program was processed using a modified rise technique. Overall normal morphology was significantly improved in the rise (79.2%) as compared with the unprocessed sample (57.8%), and six of seven specific morphologic abnormalities were significantly reduced. Motility was significantly enhanced from 51.8% in the unprocessed samples to 89.1% in the rise samples. Spermatozoa recovered in the rise portion of the sample represented 5.9% of the total sample. Ultrastructural morphometry revealed that the rise was relatively free of abnormal sperm forms, acellular debris and non-sperm cellular elements as compared with the non-rise portion of the sample or a typical unprocessed sample. Volume density measurements demonstrated that only 18.1% of the volume of the non-rise sample was composed of normal spermatozoa compared with 83.4% of the volume of the rise. In a separate set of experiments utilizing 21 samples, the penetration of hamster eggs was significantly enhanced from 37.9% to 67.2% using spermatozoa from the initial washed sample and those from the rise, respectively. These data demonstrate the qualitative and quantitative improvements, as well as the increase in fertilizing potential, of the rise portion of the semen sample.

Evaluation Studies as Topic↗
PubMedDate not supplied

Effects of cocaine hydrochloride on reproductive function and sexual behavior of male rats and on the behavior of their offspring.

Cocaine hydrochloride (30, 15, or 0 mg/kg) was administered daily subcutaneously to male rats for a minimum of 72 days. Animals receiving the 15-mg/kg and 0-mg/kg doses were pair-fed with animals receiving the higher dose. A fourth group served as a nontreated ad libitum-fed control to assess the role of cocaine-associated decreases in food and water intake. Administration of cocaine resulted in dose-related decreases in body weights, increases in locomotor activity, and decreases in estradiol levels. The high dose of cocaine was also associated with an increase in the percentage of spermatozoa with heads separated from tails. Cocaine did not affect sexual behavior, relative weights of the testis or accessory organs, histology of the testis, number of implantations, resorptions, fetal or newborn weight of offspring, or offspring weight at 21 days of age but did result in hyperactivity and increased perseverance in a T maze.

Animals↗
PubMedDate not supplied

Cytochalasin D inhibits penetration of hamster eggs by guinea pig and human spermatozoa.

Fertilization experiments using zona-free hamster eggs and spermatozoa from both guinea pig and human were conducted in the presence of cytochalasin D to evaluate the possible role of actin filaments in fertilization processes. When the actin filament inhibitor, cytochalasin D, was added to fertilization media at concentrations of 10 to 30 microM, penetration of eggs was significantly inhibited. Preincubation of the eggs with cytochalasin D and washing prior to addition of spermatozoa had no effect on penetration as quantitated by the number of swollen heads in the egg cytoplasm. However, spermatozoa preincubated with cytochalasin D and subsequently washed prior to egg addition showed reduced penetration of the same magnitude as when spermatozoa and eggs were coincubated with cytochalasin D. Both the percentage of zona-free eggs showing decondensed sperm heads and the penetration indices (total decondensed spermatozoa/total eggs) were significantly affected when spermatozoa were exposed to cytochalasin D. The DMSO vehicle used to dissolve cytochalasin D had little effect on the number of decondensed heads. When the concentration of cytochalasin D was increased (DMSO remaining constant) in human sperm experiments, percent penetration decreased and progressively fewer decondensed spermatozoa were recorded, indicating dose-responsiveness to cytochalasin D. Motility parameters of human spermatozoa were not altered at any of the concentrations of cytochalasin D tested. Neither guinea pig sperm motility nor acrosome reaction was altered significantly by cytochalasin D or the DMSO vehicle. These experiments suggest that cytochalasin D may be an inhibitor of some fertilization processes such as sperm penetration or sperm head decondensation.

Actins↗
PubMedDate not supplied

Germ cell transplantation and the study of testicular function.

Spermatogonial stem cell transplantation is a novel technique in which donor testicular cells are transferred into recipient testes. A population of germ cells from a transgenic or mutant donor is introduced into the seminiferous tubules of recipient testes by microinjection. Following injections, spermatogonial stem cells can colonize the recipient testis, initiate spermatogenesis and produce sperm capable of fertilization. This technique will allow scientists to: (1) investigate fundamental aspects of spermatogenesis; (2) provide a method to regenerate spermatogenesis in infertile individuals; and (3) genetically manipulate spermatogonial stem cells to develop transgenic animals.

Animals↗
PubMedDate not supplied

Developing culture-specific interventions for Latinas to reduce HIV high-risk behaviors.

Latina women are among the fastest-growing segments of the U.S. population to become infected with HIV. Health care providers must use culture-specific HIV prevention strategies and must address cultural roles and values of the Latin community to empower Latinas to reduce high-risk behaviors. Some Latinas adhere to their cultural traditions that place the female subservient to the male in the sexual relationship. A review of the literature reveals that skills-building, a group participatory tool that engages the individual to examine high-risk behaviors and provides methods to make behavior changes, and nurse counseling, which focuses on an individual's specific risk behaviors, are more effective modes of reducing high-risk behaviors in women than an information-only intervention.

Cultural Diversity↗
PubMedDate not supplied

Increased proliferation of Leydig cells induced by neonatal hypothyroidism in the rat.

Treatment of male rat pups with the reversible goitrogen 6-n-propyl-2-thiouracil (PTU), administered by adding 0.1% PTU to the mother's drinking water from birth through weaning, increases adult testis size, number of Sertoli cells, and daily sperm production. Adult Leydig cell numbers are also increased by 70%, despite permanent suppression of serum luteinizing hormone (LH). The present study was designed to test whether this effect results from an increase in proliferation of Leydig cells or the mesenchymal precursors. The labeling indices (LI) of six interstitial cell types were measured by tritiated thymidine autoradiography. With the exception of Leydig cells, LI declined after birth for all interstitial cell types in both control and PTU-treated rats, but mesenchymal cell proliferation was not significantly different in control and treated rats. In contrast, the LI of Leydig cells from PTU-treated rats rose by day 10, remained elevated through day 45 (highest on day 35 at 3.6-fold higher than control, P < 0.05), and declined to control values by day 50. The LI of Leydig cells in control rats was unchanged during the experiment. Proliferating Leydig cells were immature, as shown by their cytoplasmic lipid droplets. Adult Leydig cells, which lack lipid droplets, did not proliferate. Mesenchymal and immature Leydig cells contained thyroid hormone receptor mRNA; levels in adult Leydig cells were reduced but detectable. In conclusion, proliferation of Leydig cells, rather than increased proliferation of their mesenchymal precursors, is the principal mechanism responsible for the increase in Leydig cell number after neonatal hypothyroidism. Increased Leydig cell proliferation could result from direct effects of hypothyroidism on these cells. Alternatively, the increased Sertoli cell population that results from PTU treatment could also stimulate increased Leydig cell proliferation, or both of these mechanisms could contribute to the Leydig cell increase.

Animals↗
PubMedDate not supplied

Ultrastructural observations of spermatogenesis in mice resulting from transplantation of mouse spermatogonia.

The objective of the present study was to provide a morphological characterization of spermatogenesis following germ cell transplantation into the seminiferous tubular lumen of another mouse. The recipient mice (W-locus) were sterile because of a defect in spermatogenesis resulting from the failure of virtually all germ cell precursors to migrate to the genital ridge during embryonic development. Recipient mice containing intratubular injections of testis cell suspensions from C57 mice were allowed to develop for over 1 year, whereupon animals were sacrificed and testis tissue examined by light and electron microscopy. Donor mouse cells formed normal cell associations (stages) as viewed in cross-sectioned tubules. Spermatogonia were found exclusively in the basal compartment, indicating that they were translocated from the tubule lumen through the Sertoli cell junctions, eventually to reside on the basal lamina. Some tubules looked entirely normal from both a quantitative and qualitative standpoint. Others showed qualitative and quantitative impairment. In some tubules a generation of cells was missing from a cell association. A variety of degenerating cells and structural abnormalities were responsible for this impairment, however, the most common abnormalities were seen during the elongation phase of spermatogenesis. Elongation abnormalities and the subsequent degeneration of these cells led to the presence of fewer-than-expected elongate spermatids. There were regions of the testis where no spermatogenesis was noted and only Sertoli cells were present. These regions were generally typical of the testis histology seen in animals not exposed to injected germ cells. However, Sertoli cells in these regions phagocytosed sperm produced in spermatogenically active regions of the tubules. Because transplantation of germ cells, either from fresh or from frozen cells, had wide-ranging implications in biology and medicine, characterization of spermatogonial transplants is an important step in improving this procedure.

Animals↗
PubMedDate not supplied

Ultrastructural observations of spermatogenesis following transplantation of rat testis cells into mouse seminiferous tubules.

The testes of busulfan-treated immunodeficient mice receiving seminiferous tubule injections of testis cells from rats were examined by light and electron microscopy. The presence of active rat spermatogenesis was verified by criteria that are known to characterize spermatogenic cells of this species. In addition, spermatogenesis from the mouse was identified as taking place in some seminiferous tubules as the result of reinitiation of spermatogenesis after busulfan treatment. Rat spermatogenesis in mouse seminiferous tubules showed the generally recognized associations of cells known to characterize stages of spermatogenesis of the rat. The Sertoli cells associated with rat spermatogenesis were identified ultrastructurally as being of mouse origin. Thus, rat spermatogenesis, which has a cycle length that is 50% longer than mouse spermatogenesis, can proceed among mouse Sertoli cells, which supposedly exert much shorter cyclic influences in concert with mouse germ cell development. Studies are needed to determine if the timing of rat spermatogenesis is controlled by the germ cells or the Sertoli cells. These observations are considered preliminary since a thorough study of somatic-germ cell relationships was not undertaken. It is concluded that a mouse Sertoli cell in the environment provided by the mouse testis can produce both mouse and rat gametes.

Acrosome↗
PubMedDate not supplied

Hormonal regulation of spermatogenesis in the hypophysectomized rat: FSH maintenance of cellular viability during pubertal spermatogenesis.

The potential for follicle-stimulating hormone (FSH) to promote germ-cell survival and the cellular sites of FSH action were studied using a gonadally maturing (pubertal), hypophysectomized (Hx) rat model in which residual testosterone (T) activity was blocked by injections of an androgen-receptor antagonist, flutamide. Recombinant human FSH was given to androgen-deprived and androgen-blocked male rats at 27 days of age to determine maintenance of individual germ-cell types at 35 days of age. Follicle-stimulating hormone significantly increased testis weights and tubular diameters as compared with Hx and Hx-flutamide controls, although testis weights in FSH-treated animals were significantly lower than in pituitary-intact animals. Morphometric assays to determine ratios of germ cells to Sertoli cells and to determine the number of germ cells present per hour of development showed that the population of type A spermatogonia in the early stages of the cycle was not responsive to FSH. Follicle-stimulating hormone had a marked ability to maintain cell viability in the rapid, successive divisions that begin in the latter part of the cycle and that continue through the next cycle (i.e., from type A1 to A4 and from intermediate spermatogonia to type B spermatogonia to preleptotene spermatocytes to leptotene/zygotene spermatocytes to young pachytene spermatocytes). The data also suggest T responsiveness of these cell types since the Hx-FSH-flutamide group showed lower cell viability at the aforementioned steps when compared with the Hx-FSH group. Too few cell types were present at subsequent phases of spermatogenesis to allow a sensitive determination of FSH activity in the maintenance of cell viability. The data show the potential of FSH in the absence or relative absence of T activity to maintain cell viability. These data support the concept of overlapping and synergistic (or additive) effects of T and FSH in the immature rat and identify the cellular sites of FSH action.

Androgen Antagonists↗