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Biomedical subjects

R W Steger

Publications and source records attributed to R W Steger.

140 records · Page 8Linked to original sources
PubMed1977

Sequential changes associated with the degeneration of preovulatory rat follicles.

In 26-day-old rats, follicles capable of ovulation were present 48 h after PMSG injection and they degenerated if not exposed to an ovulating dose of HCG. In such follicles 125I-labelled LH bound to the thecal and granulosa cells. By 60 h after PMSG, LH binding to the granulosa cells was reduced by 46% although these follicles retained their ability to ovulate. LH binding to the granulosa cells was lost in most follicles by 72 h and ovulation could not be induced. The thecal cells still possessed LH binding sites at 72 h after PMSG. HCG stimulation of these follicles resulted in disruption of the granulosa and the invasion of blood cells into the antrum.

Acid Phosphatase↗
PubMed1977

Scanning electron microscopy of human female reproductive tract and amniotic fluid cells.

Scanning electron microscopy was used to examine surface ultrastructural characteristics of cells of the epithelium of female reproductive tract, cervical mucus, and amniotic fluid cells. The female epithelium undergoes hormone-dependent cyclical morphological alterations in cell shape, apical microvilli, ciliation, and secretory patterns. The frequency distribution of ciliated cells varies in different parts of the female reproductive tract and different segments of the same organ. In the endocervix, a few ciliated cells are randomly distributed. The density of ciliated cells is variable in several areas of the endometrium. The sparse distribution of ciliated cells in the central portion of the uterine wall may indicate a possible implantation site. According to surface ultrastructure of cells, three segments are noted in the uterotubal junction: cornual endometrium, interstitial tubal epithelium, and transitional area. The vaginal epithelium is made of flat polygonal cells with interdigitating borders and a fine interlacing network of microridges. After the menopause, the microridge pattern and distinct cell borders are lost or severely modified. Two types of fibrous structures can be found in cervical mucus: a) microfibrils that vary in diameter from 500 to 1,500 A and from bundles or networks, and b) long, thick fibers that vary in diameter from 0.5 to 5 micrometer run parallel to each other, and appear to be made up of microfibrils. Amniotic fluid cells, derived from amniotic epithelium and fetal ectoderm, consist of non-nucleated and nucleated cells with extensive microplicae.

Amniotic Fluid↗
PubMed1976

Effect of photoperiod on gonadotropin releasing hormone-induced LH release in the immature rat.

Female rats raised from birth under a light/dark (LD) or constant light (LL) regimen were given injections at either 24, 29, 33 or 35 days of age of either 5 IU PMSG or 0.1 ml saline. Two days following PMSG or saline injection, the rats were given injections of either 1,000 ng synthetic gonadotropin releasing hormone (GnRH) or 0.1 ml saline. Blood samples were taken before and 20 min after injection for LH determinations. PMSG caused a rise in basal LH levels, which was greater in LL than in LD animals. GnRH administration resulted in an LH surge in both LD and LL rats at all ages tested. The LL animals released greater amounts of LH in response to GnRH than did LD animals. In PMSG-primed animals there were no differences in the GnRH-induced LH surge due to either age or photoperiod. It is concluded that PMSG and LL enhance the pituitary's response to GnRH.

Age Factors↗
PubMed1976

Ultrastructure of testes and excurrent ducts in the bonnet monkey (Macaca radiata).

The testes and excurrent ducts of four bonnet macaques (Macaca radiata) were examined using scanning and transmission electron microscopy. The three layers of contractile and connective tissue composing the tunica albuginea, and the multilayered tunica propria of the seminiferous tubules were similar to that of man. Spermatids project from the epithelium or are found free in the lumen. The stages of the cycle of the germinal epithelium in the bonnet macaque were similar to that in other macaques. The epithelium of the rete testis consisted of thin brush-bordered cells, whereas the epithelium of the efferent ducts consisted of tall, prismatic or cylindrical cells lined by kinocillia or short stereocilia and basal cells. The height of the epididymal epithelium and lumen diameter was maximal in the caput region and minimal at the cauda. Spermatozoa were found among clusters of stereocilia. The epithelium of the vas deferens showed gradual transition from the stereocilia covering typical of the epididymis to that of a shorter, apical microvilli covering.

Animals↗
PubMed1976

Development of gonadotrophin-binding sites in the immature rat ovary.

There was a temporal relationship between ovarian development and the sites to which 125I-labelled gonadotrophins became bound. Labelled human LH and FSH bound uniformly to 5- and 15-day-old ovaries. At 21 days, heavy FSH and light LH binding was observed over the granulosa cells increased at Day 33 and again at Day 38. Quantitative determination by gamma-ray spectrophotometry of binding to ovarian sections showed that LH binding gradually increased with advancing age, but FSH binding remained relatively constant between Days 5 and 33 with a significant increase between Days 33 and 38.

Age Factors↗
PubMed1976

Gonadotropin binding sites in human postmenopausal ovaries.

Glucose-6-phosphate dehydrogenase (G6PD) activity and gonadotropin binding sites were localized within seven postmenopausal ovaries. G6PD was localized in the cells of cortical stroma and hilus using a histochemical technique for the reduction of the tetrazolium salt, Nitro-Blue tetrazolium. Gonadotropin binding sites were localized by autoradiography following incubation of ovarian sections with (125I-hLH) and 125I-labeled follicle-stimulating hormone (125I-hFSH) were identified in the cortical stroma and hilus cells. Since these cells contain G6PD and other enzymes necessary for steroidogenesis and also have the capacity to bind both hLH and hFSH, steroidogenesis in postmenopausal ovaries appears to be controlled by circulating gonadotropins. Blood vessels within postmenopausal ovaries also bound both gonadotropins, but 125I-hFSH binding was often more intense than 125I-hLH binding.

Aged↗
PubMedDate not supplied

Pituitary and testicular function in spontaneously hypertensive rats.

Levels of plasma gonadotropins, prolactin (PRL), and testosterone, and the testicular concentration, total content, and affinity of hCG binding sites were measured in male spontaneously hypertensive rats (SHR) and in genetically matched normotensive (WKY) rats. Hypertensive rats had higher plasma PRL and FSH levels and lower plasma testosterone levels. The affinity of testicular hCG binding sites was similar in SHR and WKY rats, but SHR had considerably lower concentration and total content of hCG-binding sites than did WKY animals. The comparison of these findings with those obtained previously with pituitary-grafted rats and with tumor-bearing rats indicates that the endocrine effects of hyperprolactinemia may vary depending on the rate and magnitude of the increase in peripheral PRL levels. Species differences in the response to hyperprolactinemia and differences between SHR and other rat strains suggest that hormonal responses to PRL elevation depend also on the genetic characteristics of the animal.

Animals↗
PubMedDate not supplied

Testicular LH receptors during aging in Fisher 344 rats.

Levels of serum LH, prolactin, testosterone, progesterone and 17-OH progesterone and the testicular concentration and total content of LH receptors were measured in 4-, 11-, 18-, and 27-month-old Fisher 344 rats. All 27-month-old rats had Leydig cell tumors. At first, testicular LH receptor levels decreased with age, but with the appearance of the testicular tumors, these levels increased dramatically. Serum prolactin levels fluctuated with age, but were significantly decreased in 27-month-old rats, as were serum LH levels. Serum testosterone levels decreased steadily with age, while the testosterone-LH receptor ratio remained constant until the appearance of the testicular tumors, after which the ratio decreased precipitously. Serum progesterone levels remained constant throughout the life of Fisher 344 rats until the appearance of testicular tumors, when they increased dramatically. Serum 17-OH progesterone levels were increased significantly at 11 and 27 months as compared to four months of age, but levels at 18 months were similar to those seen in the 4-month-old animals. Therefore, in aged Fisher 344 rats with spontaneous Leydig cell tumors, there is an alteration in the testicular testosterone synthesizing pathway at a step after progesterone.

17-alpha-Hydroxyprogesterone↗
PubMedDate not supplied

Effects of age on hormone levels and in vitro steroidogenesis by rat ovary and adrenal.

In order to evaluate age-related changes in ovarian and adrenal steroid production, in vitro steroid production by adrenal glands and ovaries from young (3-4 mo) and middle-aged (10-11 mo) cycling rats was compared to serum steroid and gonadotropin levels on each morning of the estrous cycle. Basal LH levels were not different between young and mid-aged cycling rats except on estrus, when elevated estrogen (E) levels were correlated with depressed LH in the mid-aged rats. Basal FSH levels were generally elevated in mid-aged cycling and mid-aged constant estrus (CE) rats, but the FSH rise on estrus morning was not seen in the mid-aged rats. Serum progesterone levels were not changed with age or reproductive state, although in vitro ovarian progesterone secretion was decreased in mid-aged CE rats. Adrenal progesterone secretion increased significantly with age. Serum total testosterone was similar in young and mid-aged cycling and mid-aged CE rats, despite a highly significant increase in in vitro testosterone secretion by the CE ovary. Serum estradiol (E2) levels were significantly elevated on proestrus and estrus in the mid-aged rats. Although estrone (E1) levels appeared higher in the mid-aged than in the young cycling rats, the differences were not significant. Mid-aged CE rats had significantly elevated serum levels of both E1 and E2. In vitro ovarian estrone production was depressed in mid-aged cycling rats. Adrenal total estrogen production was similar in young and mid-aged animals. These results demonstrate that serum gonadotropin and steroid levels are altered in aging female rats prior to the loss of reproductive cycles. Changes in serum steroid levels are probably due to changes in circulating LH and FSH levels or the ovarian response to these gonadotropins, but changes in vitro basal steroid production suggest that intrinsic ovarian function may also change with advancing age. As rats enter a CE state, alterations in basal ovarian and adrenal steroid production are seen and may be partially responsible for maintenance of the acyclic state.

Adrenal Glands↗
PubMedDate not supplied

Testicular function after local injection of 6-hydroxydopamine or norepinephrine in the golden hamster (Mesocricetus auratus).

Although there is evidence for the sympathetic innervation of the mammalian testis, the function of noradrenergic fibers is not understood. This in vivo and in vitro study in the adult golden hamster examines testicular function after unilateral intratesticular application of a single dose of 6-hydroxydopamine (6-OHDA), a neurotoxic drug known to produce depletion of noradrenergic stores in nerve endings. The contralateral testis in each animal was injected with vehicle alone and served as the control. After 24 h, the content of norepinephrine (NE) in testicular parenchyma was reduced in most testes injected with 6-OHDA. At this time, concentration of luteinizing hormone receptors (LH-R) was significantly decreased in the 6-OHDA treated testis, compared with the vehicle-injected testes. This decrease was followed by a significant increase at 72 h. The concentration of LH-R was not significantly altered 10, 48, 144, or 168 h after 6-OHDA administration. Changes in testicular testosterone (T) concentrations paralleled the changes in LH-R at most time points. In the incubations of control vehicle injected testes, addition of NE did not affect T production but stimulatory action of hCG was significantly augmented by concomitant exposure to NE at most time points after injection of vehicle. In incubations of 6-OHDA-injected testes, a comparable pattern of T responses to NE and hCG was found only 48 h after injection. At 24 h post injection NE alone significantly stimulated T production; at 10 and 24 h the ability of NE to potentiate the action of hCG was significantly reduced, while at 72 and 144 h basal T production and the stimulatory hCG effect were significantly increased. Moreover, at 72, 144, and 168 h, the effect of NE & hCG on T production was significantly greater in 6-OHDA-injected testes than in the vehicle injected testes of the same animals. In incubations of untreated hamster testes, addition of 6-OHDA at doses similar to those used for injections did not affect T production. Weights of 6-OHDA injected testes were slightly but significantly reduced after 144 and 168 h. These changes were most likely due to degenerative changes of the germinal epithelium, which were clearly detectable 168 h post injection. Because 6-OHDA can release NE from nerve terminals, the observed effects of 6-OHDA might have been initiated by supernormal testicular NE concentrations. To examine this possibility, the authors have tested the effects of intratesticular NE injections. This treatment caused decrease of LH-R at 24 h followed by an increase at 72 h.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗