bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for the involvement of a sperm trypsinlike enzyme in the membrane events of the hamster sperm acrosome reaction
Authors: Dravland J. Eric , Llanos Miguel N. , Munn Robert J. , Meizel Stanley 
Published: June 2005

AbstractPrevious studies from this laboratory have suggested a role for sperm trypsinlike activity in the membrane events of the hamster sperm acrosome reaction, but these conclusions have been disputed by studies done with guinea pig, mouse, and ram sperm. This study was designed to further investigate the role of such activity in the hamster sperm acrosome reaction. Washed hamster epididymal sperm were examined by electron microscopy after incubation in a defined medium. Fewer sperm incubated in the presence of the trypsin inhibitor benzamidine underwent the membrane events of the acrosome reaction compared to controls. Benzamidine did not interfere with the loss of the acrosomal contents in the sperm which did undergo acrosome reactions. The trypsin inhibitor NPGB (previously shown to inhibit the hamster acrosome reaction under other conditions) did not inhibit the membrane events or the loss of acrosomal contents when the acrosome reaction was induced by the fusogen lysophosphatidyl choline (a method of induction which may have bypassed the need for a trypsinlike enzyme). In a bioassay designed to measure acrosome reactions, fewer sperm preincubated with benzamidine subsequently penetrated zona‐pellucida‐free hamster eggs.The present results together with those of an earlier study by this laboratory strongly suggest that a sperm trypsinlike enzyme has a direct or indirect role in the membrane events of hamster sperm acrosome reaction. The relationship of these results to studies with other species is discussed.
Reproductive development of female Schistosoma mansoni (Digenea: Schistosomatidae) following bisexual pairing of worms and worm segments
Authors: Popiel Irene , Basch Paul F. 
Published: June 2005

AbstractMaturation and maintenance of normal reproductive function in female Schistosoma mansoni require a permanent association with the male, but the nature of this relationship is not well understood. The regional localization of a stimulatory factor in the male and its target in the female were investigated. Unisexual female and mature male worms were transected into segments of various lengths. Various combinations of transected male and female segments and intact worms were transferred to the mesenteric veins of recipient hamsters and were also maintained in vitro. In hamsters and in vitro, pairing took place between intact worms of each sex and segments of the other, and between segments of both sexes. The majority of female worms and segments so paired showed some reproductive development, as assessed by vitelline gland differentiation. In intact unisexual females paired with small male segments, vitelline gland development was limited to that portion of the worm that had been held by the male. Worm segments continued to display normal body contractions throughout 24 days of in vitro maintenance and morphological integrity was retained. It is concluded that 1) in the absence of a functioning gut, worm segments can survive for prolonged periods on nutrients absorbed through the tegument; 2) worm pairing, male stimulation, and the female developmental response are independent of central nervous control by the cerebral ganglia; 3) males have no centralized localization for the female‐stimulating factor; 4) vitelline gland differentiation in the female requires local stimulation through male contact, and this is not propagated throughout the worm.
Antagonistic effects of estradiol dipropionate and progesterone on the histology of the vagina and uterus of the mouse
Authors: Tripathi Ghanashyam 
Published: June 2005

AbstractAdministration of estradiol dipropionate (20 μg/day; 7 days) to ovariectomized mice caused heavy epithelial proliferation and intense cornification in the vagina and cellular as well as glandular proliferation in uterine tissues. Endometrial hypertrophy with cystlike appearance of uterine glands was seen in response to a long‐term (14 days) administration of estradiol dipropionate. Daily injection of progesterone (2 mg; 7 days) to ovariectomized mice resulted in desquamating mucosa, without any trace of vaginal cornification, and the presence of dense uterine connective tissue in the stromal region with typical uterine glands. However, treatment of estradiol depropionate in combination with progesterone at 1:100 dose ratio for 7 days produced vaginal histology similar to that in proestrus and uterine histology equivalent to the ovariectomized condition. The results revealed that progesterone antagonized the estrogenic effects and also that estradiol dipropionate antagonized the effects of progesterone. The effects of the two female sex steroids (estradiol dipropionate and progesterone) in vivo appeared to be more potent in the uterus than in the vagina.
On the role of fibronectin during the compaction stage of somitogenesis in the chick embryo
Authors: Lash James W. , Seitz Anna W. , Cheney Clarissa M. , Ostrovsky David 
Published: June 2005

AbstractDuring the early stages of somitogenesis in the chick embryo the presomitic cells in the segmental plate undergo compaction. The aggregation of segmental plate cells is stimulated by fibronectin. The stimulation of segmental plate cells to aggregate and undergo compaction can be effected in isolated segmental plate cells, in isolated segmental plates, and in intact embryos removed from the yolk. The fact that the segmental plate cells react with greater vigor to cellular fibronectin than to plasma fibronectin suggests a specific molecular mechanism in the initiation of somitogenesis.
β‐Endorphins (β‐EP) in amphibians: Higher β‐EP levels during regenerating stages of anuran life cycle and immunocytochemical localization of β‐EP in regeneration blastemata
Authors: Vethamany‐Globus Swani , Globus Morton , Milton Guy 
Published: June 2005

AbstractPlasma β‐endorphin (β‐EP) levels were measured at different stages of metamorphosis in anuran species, namely Rana catesbeiana, R. pipiens, and Xenopus laevis. The mean levels of β‐EP in tadpoles and postmetamorphic juveniles were significantly higher than adult levels in all three species examined. The pattern of high tadpole levels and low adult levels corresponds with the limb regeneration ability of the tadpole and restriction in the adult. We have also reported plasma β‐EP levels in two urodele species, Ambystoma tigrinum and A. jeffersonianum. Localization of β‐EP by immuno‐cytochemistry shows bright fluorescence to β‐EP antiserum in the wound epithelium of the regeneration blastema. The mesoderm and nuclei of all blastema cells remain nonreactive. It is suggested that receptors to β‐EP reside in the epidermis.
Regulation of the follicular hierarchy and ovulation
Authors: Bahr J. M. , Johnson A. L. 
Published: June 2005

AbstractStudies are discussed which investigate the regulation of follicular maturation and the ovulation sequence of the domestic hen. The number of FSH receptors of ovarian granulosa cells decreases as the follicle matures, and this decrease in receptor number is paralleled by a gradual loss of FSH‐stimulable adenylyl cyclase (AC) activity. By contrast, LH‐stimulable AC activity increases as the follicle progresses through the hierarchy. In addition, FSH stimulates progesterone secretion by granulosa cells of the smaller preovulatory follicles, whereas these cells are only minimally responsive to LH. These data suggest that the maturation of less mature (smaller) follicles is primarily controlled by FSH, while LH may serve primarily as the ovulation‐inducing hormone. The ability of LH to stimulate progesterone release and induce premature ovulation is dependent upon the stage of the sequence. Injection of ovine LH 12 hr prior to ovulation of the first (C1) egg of the sequence induces fully potentiated prevulatory plasma progesterone surges and 100% premature ovulation, whereas injection prior to the second (C2) ovulation of the sequence fails to stimulate prolonged progesterone release and induces premature ovulation in less than 50% of injected hens. These results are consistent with data obtained in vitro which suggest that granulosa cells obtained 12 hr prior to a C1 ovulation secrete more progesterone in response to chicken LH compared to those obtained 12 hr prior to the C2 ovulation. These data are discussed in terms of the ovary's ability to act as a regulator of the ovulatory cycle.
Interrelationships between the hypothalamus, pituitary gland, ovary, adrenal gland, and the open period for LH release in the hen (Gallus domesticus)
Authors: Etches R. J. , Petitte J. N. , Anderson‐Langmuir C. E. 
Published: June 2005

AbstractThe asynchronous ovulatory cycle of the hen is believed to be the consequence of two interacting systems, one of which is circadian and regulates the timing of the preovulatory LH surge. In suport of this proposition, the open period for LH release was shown to oscillate with the same periodicity as the photoschedule when the hens were exposed to 14 L:7 D, 14 L:10 D, and 14 L:14 D. In addition, it was demonstrated that follicular maturation is not affected by or synchronized with the photoperiod. The physiological system that transduces the light/dark cycle into an open period for LH release has not been identified although circumstantial evidence supports the idea that the adrenal gland plays a role in this function. This evidence includes the anatomical juxtaposition of the left ovary and adrenal gland, innervation of steroid‐producing cells within the follicle by nerve tracts passing through the adrenal glands, the ability of injections of metyrapone to alter the timing of preovulatory LH release, the ability of injections of corticosterone to induce ovulation when a mature follicle is present in the ovary, and the ability of dexamethasone or infusions of corticosterone to block ovulation. Recently we have also shown that infusions of corticosterone will block the gonadotropic effect of PMSG, will inhibit the photoperiodic response, and do not affect the release of LH in response to injections of GnRH. The addition of corticosterone to incubations of dispersed granulosa cells does not affect their response to LH. These data suggest that corticosterone may modulate the responsiveness of the hypothalamus to tropic stimuli and demonstrate that exposure to corticosterone can alter the responsiveness of some ovarian tissues to gonadotropins.
Prior light alters the circadian clock in the chick pineal gland
Authors: Binkley Sue , Mosher Karen 
Published: June 2005

AbstractN‐Acetyltransferase activity (NAT) exhibits a circadian rhythm in the pineal gland and retinas of chickens and is responsible for melatonin circadian rhythms. Chick pineal gland NAT was measured in vivo and/or in vitro after light‐dark cycles and after pretreatments with short photoperiod, long photoperiod, and constant light. Prior lighting changed the shape (phase, amplitude, and duration) of the rhythm in vivo. Some of the alterations are “programmed” into the pineal gland because they were observed in vitro in pineal glands from chicks similarly exposed to lighting pretreatments.
Circadian organization in Japanese quali
Authors: Underwood Herbert , Siopes Thomas 
Published: June 2005

AbstractOur recent studies have implicated both the eyes and pinealas major components of the circadian system of Japanese quail. We assessed the role of these organs by examining the effect fo their removal on the circadian activity rhythm of quail exposed to either 24 hr light‐dark (LD) cycles or to continuous darkness (DD). Removal of only the pineal had no effect on the activity rhythm of quail in either LD or DD. Blinding (by orbital enucleation) had a major effect under both LD and DD. One third of the blinded birds showed entrainment under LD although entrainment patterns were very variable, whereas two thirds of blinded birds were arrhythimic. All blinded plus pinealectomized brids were arrhythmic in LD as were all blinded and blinded plus pinealectomized birds in DD. Accordingly, effects of pinealectomy can be seem only when pinealectomy is combined with blinding. The fact that blinding disrupts circadian organization in both LD and DD indicates that the eyes must act as major components of the quail's circadian system. In view of the postulated role for melatonin, an indoleamine, in circadian systems, the eyes, pineal, and blood of quail were assayed for this compound. Robust daily rhythms in melatonin content were observed in all three tissues. The blood rhythm is due to secretion of melatonin into the vascular system by both the pineal and eyes. The ocular melatonin rhythm continued after sectioning of the optic nerve, was reentrainable to a shift in the phase of the LD cycle, and persisted for at least 2 days in DD. These data suggest that the eyes play a major role within the circadian system and support the hypothesis that circadian pacemakers may reside within the eyes of quail. The results are discussed in view of the findings of others in both quail and other avian species. A general model for circadian organization in birds in presented in which the eyes, the pineal, and the suprachiasmatic nuclei of the hypothalamus comprise major elements of a multioscillator circadian system.
Photorefractoriness in European starlings: Associated hypothalamic changes and the involvement of thyroid hormones and prolactin
Authors: Nicholls T. J. , Goldsmith A. R. , Dawson A. 
Published: June 2005

AbstractResponsivity to photostimulation in previously photorefractory European starlings is caused by subjection to short daylengths and is characterized by a marked activation of the hypothalamus in terms of synthesis of gonadotropin releasing hormone. This active hypothalamic state is amplified for a time by a subsequent exposure to long days but is soon completely reversed as the birds become photorefractory again. This latter effect of long photoperiods and the concurrent secretion of prolactin are dependent on the presence of thyroid hormones. Conceivably, prolactin causes photorefractoriness by inhibition at a hypothalamic level.
Photorefractoriness in Japanese quail: Possible involvement of the thyroid gland
Authors: Follett B. K. , Nicholls T. J. 
Published: June 2005

AbstractQuail have a form of refractoriness to long daylengths that is relative and not absolute. The properties of “relative refractoriness” are compared with the more typical “absolute” form seen in starlings and the question is posed as to whether the two types represent the extremes of a single underlying process or are quite separate phenomena. A model is offered that assumes that a single process is involved, and some tests of the hypothesis, notably the involvement of the thyroid gland, are described.
Influence of weather on reproduction
Authors: Wingfield John C. 
Published: June 2005

AbstractLaboratory investigations suggest that the effects of weather on avian reproduction could be manifest via a “stress” response resulting in an elevation of circulating levels of corticosterone and a depression of reproductive hormone secretion. However, field investigations indicate that additional endocrine responses also occur. Inclement weather early in the breeding season, i.e., before the nesting phase has begun, is generally not stressful in terms of plasma levels of corticosterone but does result in a delay of gonadal maturation and decreases in circulating levels of LH and sex steroid hormones. Conversely, storms that strike after the nesting phase has begun and when adults are feeding young do appear to be stressful, resulting in an increase in corticosterone and loss of body weight, but do not affect plasma levels of LH and sex steroid hormones. This latter fact is thought to be highly adaptive because the reproductive apparatus is maintained in a functional state so that renesting can begin immediately when environmental conditions improve. These data indicate that two endocrine mechanisms may be important for regulating responses to inclement weather under natural conditions.
Effects of polyamines upon capacitation and fertilization in the guinea pig
Authors: Fleming Alan D. , Armstrong David T. 
Published: June 2005

AbstractThe effects of polyamines upon the ability of guinea pig spermatozoa to undergo the acrosome reaction and upon sperm‐egg fusion were investigated. All of the polyamines (polyarginines and compound 48/80) stimulated the occurrence of the acrosome reaction, although differences in the duration of the preincubation period required were noted. The stimulatory effect of the polyarginines could not be reversed by washing, while that of 48/80 was abolished by its removal prior to induction of the acrosome reaction. Polyarginine‐treated spermatozoa were fully capable of fertilizing intact guinea pig eggs. In contrast, 48/80 completely blocked sperm‐egg fusion at only 5–10 μg/ml. This inhibition was reversible by washing either treated gamete. The ability of polyamines which may also be present at the time and site of fertilization, in vivo, to inhibit or stimulate gamete functions or interactions is discussed.
Role of soluble factors (gamones) and calcium ions in conjugation of the ciliate Euplotes patella syngen 2
Authors: Akada Rinji 
Published: June 2005

AbstractConjugation between cells of mating type IV and V in Euplotes patella syngen 2 was studied with respect to mating inducing factors (gamones) and their effects on pair formation. Type IV cells excreted into the medium gamone(s) of type IV which induced selfing pairs in and enhanced the gamone's excretion by cells of type V. The same effects on type IV cells were induced by cells and gamone(s) of type V. The number of homotypic pairs (IV‐IV, V‐V) increased with an increase in the level of Ca2+ in the medium. However, heterotypic pairs (IV‐V) were constantly formed even in the absence of Ca2+, and their formation was not influenced by the level of Ca2+. When cells of two types were mixed, heterotypic pairs were predominantly produced, although cells were capable of forming pairs between homotypic types. These results revealed that pair formation between heterotypic cells was different from that between homotypic cells in the requirement of Ca2+, and that the specificity of pair formation between heterotypic cells was more predominant than that of homotypic ones.
Peroxidase activity in the epithelium of the digestive tract of the bullfrog, Rana catesbeiana
Authors: Sugimoto Keiji , Ichikawa Yasuaki , Nakamura Itsuo 
Published: June 2005

AbstractPeroxidase activity was examined cytochemically in the mucosal epithelium along the length of the digestive tract from the esophagus through the large intestine during the development of the bullfrog, Rana catesbeiana. In the tadpole of this species, cells with peroxidase activity were found abundantly in the esophagus, stomach, and large intestine; and the types of such cells differed according to the region: ciliated cells and mucous cells in the esophagus; ciliated cells in the stomach; and brush cells, absorptive cells, and goblet cells in the large intestine, respectively. After metamorphosis, however, peroxidase activity was observed exclusively in absorptive cells and goblet cells in the large intestine. Peroxidase activity was commonly demonstrated in apical vesicles or granules, to some degree in rough endoplasmic reticulum, and in some elements of the Golgi apparatus. Furthermore, reaction product was also found in mucus covering the luminal surface of such epithelial cells. These findings indicate that peroxidase‐positive cells, which may have the ability to synthesize peroxidase as a secretory product, were distributed mainly in three regions of the digestive tract in tadpoles (esophagus, stomach, and large intestine), but were centered in one specific region, the large intestine, after metamorphosis. Concomitantly, the variety of types of peroxidase‐positive cells decreased during metamorphosis. Our results indicate that some of the peroxidase in the digestive tract may have a secretory origin and may play a role in the defense against microorganisms.
Steroidal enhancement of growth in parasitic larvae of Ascaris suum: Validation of a bioassay
Authors: Fleming Michael W. 
Published: June 2005

AbstractThird‐stage larvae of the swine parasitic roundworm, Ascaris suum, were grown in stationary multiwell cultures in the presence of synthetic steroid hormones or the HPLC fractions of a steroid extract of adult female reproductive tracts to determine the subsequent effect of these compounds on length of 4th‐stage larvae. Log doses of ecdysone, 20‐hydroxyecdysone, progesterone, and makisterone standards, from 50 pg/ml to 500 ng/ml, were incubated with larvae for 1 day in RPMI‐1640 supplemented with cholesterol. Length measurements were made on 4th‐stage larvae after an additional 6 days of incubation. All compounds and extracts had a dose‐dependent enhancement on length of these larvae; the partially purified extracts were more potent than their synthetic analogs. All standards and extracts except makisterone showed reduced or no response at higher dose levels. In contrast, makisterone continued to have maximal effect from 500 pg/ml to 500 ng/ml. Short exposure period to the steroid and low concentration were critical to demonstrate enhanced growth in this homologous bioassay.
Annual testicular cycle of the lizard Anolis carolinensis: Effects of pinealectomy and melatonin
Authors: Underwood Herbert 
Published: June 2005

AbstractThe effects of pinealectomy and exogenous melatonin treatment on the reproductive system of male anoles were examined at several different times of year. In September pinealectomy of anoles exposed to either a stimulatory LD 14:10 light cycle or a nonstimulatory LD 10:14 light cycle induced significant testicular growth and development over that observed in sham‐operated anoles. At a nonphotosensitive time of year (December) pinealectomy also had a significant progonadal effect but no effect of pinealectomy was seen in February‐March. Daily melatonin injections given either in the morning or afternoon (or both) failed to block gonadal growtheither (1) in sham‐operated or pinealectomized anoles exposed to LD 14:10 in the fall or (2) in pinealectomized lizards exposed to LD 10:14 in the fall. Continuous melatonin administration via subcutaneous silastic implants blocked the progonadal effects of pinealectomy in the winter (December).The results show that (1) pinealectomy can have significant progonadal effects; (2) these effects are seasonal but can encompass phases of the annual testicular cycle which are either photoperiod‐dependent or temperature‐dependent; and (3) melatonin may be a reproductively active factor involved.
Influence of the uterine environment on rat sperm motility and swimming speed
Authors: Goeden Helen M. , Zenick Harold 
Published: June 2005

AbstractThe present study compared several rat sperm parameters in semen samples recovered from a natural uterine environment (i.e., intact estrous female) to those recovered from an artificially induced uterine environment (i.e., ovariectomized hormonally primed female). The sperm parameters measured were percent motile, percent exhibiting forward progressive motility, actual swimming speed, and linear swimming speed. The comparisons were conducted at four postcopulatory time points (0.25, 1.5, 3, and 6 hours) in order to detect differences as a function of residence time within the uterus. No significant differences (P<0.05) in the parameters were seen between the two types of uterine environments. Residence time within the reproductive tract had no significant effect on the parameters with the exception of percent motile, which was significantly increased (P<0.01) at the 1.5‐hour postcopulatory time point.