Architecture of the myosalpinx of the isthmus in the guinea pig by means of scanning electron microscopy.

The three-dimensional architecture of the isthmic myosalpinx in the guinea pig was investigated by means of a technique that involves stretching the myosalpinx under a dissecting microscope, followed by selective digestion of the interstitial connective tissue with KOH and, finally, observation under a scanning electron microscope. The images obtained in this way prove that the myosalpinx is arranged in single bundles of smooth muscle cells which essentially do not show any specific geometrical course. Furthermore, smooth muscle cell bundles following an oblique course, not referred in the literature prior to this report, were demonstrated. These new three-dimensional microanatomical results call for a reevaluation of the functional role of oviduct motility.     

Oviducal Contribution to Alteration of the Vitelline Coat in the Frog, Rana japonica. An Electron Microscopic Study

The vitelline coat (VC) surrounding coelomic eggs of the frog, Rana japonica , comprises bundles of filaments running both parallel and perpendicular to the egg surface. The coat gives little or no staining reaction with PA-CrA-Silver methenamine. In contrast, in the VC of uterine eggs the filament bundles are less conspicuous. and the interstices between the filament bundles stain strongly for carbohydrate. This alteration occurs during passage of the eggs down the first 1/20 th of the oviduct, the pars recta. The epithelium of the p. recta contains secretory cells, which contain electron-dense granules distinct from those in the jelly-secreting cells in more caudal portions of the oviduct. Treatment of coelomic eggs with an extract of p. recta followed by exposure to a sperm suspension resulted in marked swelling and softening of the VC. These results indicate that the contents of the granules secreted from the epithelial cells in the p. recta are deposited in the VC to increase its susceptibility to a fertilizing sperm.     

Distribution of NADPH-diaphorase and nitric oxide synthase (NOS) in different regions of porcine oviduct during the estrous cycle.

Nitric oxide synthase (NOS) is responsible for the biological production of nitric oxide (NO) in several organs, including those of the reproductive tract. We investigated potential changes in NADPH-diaphorase (NADPH-d) activity (marker for NOS activity) and the presence and distribution of NOS in the porcine oviduct. Tissues were obtained from gilts (n=16) on different days of the estrous cycle. One fallopian tube was used for histo- and immunohistochemistry and the other for Western blotting analysis. NADPH-d activity was much higher in the epithelium of the mucosa than in the myosalpinx. The highest activity of NADPH-d was always found in the epithelium of the isthmus. The intensity of the reaction (arbitrary units +/- SEM) in isthmus epithelium increased from the postovulatory period until early proestrus (96.2 +/- 11.2) and then gradually decreased. The lowest intensity of NADPH-d reaction in the epithelium of the isthmus was seen at estrus (58.4 +/- 7.7). The most intense NADPH-d activity in myosalpinx of all parts of the oviduct was observed at the postovulatory stage of the estrous cycle (isthmus 38.3 +/- 2.5; ampulla 35.6 +/- 4.2; infundibulum 24.7 +/- 0.8) and then decreased during the remaining stages of the estrous cycle (p< 0.001). The presence of endothelial NOS (eNOS) was detected in epithelial cells of mucosa and in endothelium of vascular tissues and myosalpinx during all studied days of the estrous cycle. The positive reaction for inducible NOS (iNOS) was restricted only to the endothelium of lymph vessels and some blood vessels. Because our Western blotting analysis revealed that porcine oviduct contains eNOS but not iNOS, we suggest that eNOS is the main isoform of NOS expressed in the porcine oviduct. We concluded that the different activity of NADPH-d in the various regions of the oviduct, accompanied by changes in its activity during the course of the estrous cycle, could indicate an important role of NO in regulation of tubal function.     

C-type natriuretic peptide system in rabbit oviduct.

C-type natriuretic peptide (CNP), a third member of the natriuretic peptide family, is known to be distributed mainly in brain and vascular endothelium and is considered to act as a local regulator in many tissues. The purpose of this study was to determine the presence of CNP system and its biological function in rabbit oviduct. The serial dilution curve of tissue extracts was parallel to the standard curve of CNP((1-22)) and a major peak of molecular profile of tissue extracts by HPLC was CNP((1-53)). mRNA of CNP which was the same size as positive control was also detected by Southern blot analysis. CNP increased the production of 3',5'-cyclic guanosine monophosphate (cGMP) in the purified membrane of oviduct, which was more in membranes derived from the isthmic portion than in the ampullar portion. The presence of mRNAs of natriuretic peptide receptor-A (NPR-A) and NPR-B was demonstrated by RT-PCR. Synthetic CNP((1-22)) inhibited both frequency and amplitude of basal motility of oviduct in a dose-dependent manner. The inhibitory effect of CNP on the basal motility was more potent in the isthmic portion than in the ampullar portion. These results demonstrate the presence of CNP system in the oviduct and regional differences in motility inhibition by CNP between isthmic and ampullar portions. Therefore, these findings suggest the possible existence of a CNP system that may exert a local regulator of basal motility, either alone or in concert with other hormones.     

Unexpected flagellar movement patterns and epithelial binding behavior of mouse sperm in the oviduct

In order to better understand how sperm movement is regulated in the oviduct, we mated wild-type female mice with Acr-EGFP males that produce sperm with fluorescent acrosomes. The fluorescence improved our ability to detect sperm within the oviduct. Oviducts were removed shortly before or after ovulation and placed in chambers on a warm microscope stage for video recording. Hyperactivated sperm in the isthmic reservoir detached frequently from the epithelium and then reattached. Unexpectedly, most sperm found in the ampulla remained bound to epithelium throughout the observation period of several minutes. In both regions, most sperm produced deep flagellar bends in the direction opposite the hook of the sperm head. This was unexpected, because mouse sperm incubated under capacitating conditions in vitro primarily hyperactivate by producing deep flagellar bends in the same direction as the hook of the head. In vitro, sperm that are treated with thimerosal to release Ca(2+) from internal stores produce deep anti-hook bends; however, physical factors such as viscous oviduct fluid could also have influenced bending in oviductal sperm. Some sperm detached from epithelium in both the ampulla and isthmus during strong contractions of the oviduct. Blockage of oviduct contractions with nicardipine, however, did not stop sperm from forming a storage reservoir in the isthmus or prevent sperm from reaching the ampulla. These observations indicate that sperm continue to bind to oviductal epithelium after they leave the isthmic reservoir and that sperm motility is crucial in the transport of sperm to the fertilization site.     

Attachment and release of spermatozoa from the caudal isthmus of the hamster oviduct

Female hamsters were mated shortly after the onset of oestrus. At 3 or 6 h after mating, the right oviduct was flushed in situ with 30, 90 or 180 microliters medium to remove spermatozoa from the lumen, leaving only those firmly attached to the isthmic mucosa of the oviduct. When eggs were recovered from oviducts at 20 h after flushing the majority were fertilized, indicating that the spermatozoa that were firmly attached to the mucosa were capable of detaching and ascending to the ampulla to fertilize eggs. Neither the time of flushing nor the volume of flushing medium had a significant effect on the percentage of spermatozoa that remained in the isthmus after flushing. These results suggest that there is no change in the surface of the oviduct mucosa that causes the release of spermatozoa from the caudal isthmus near the time of ovulation. When incapacitated spermatozoa were introduced into the oviduct, many of them attached to oviductal mucosa, while capacitated spermatozoa did not. This indicates that it is a change in the sperm surface, rather than the mucosal surface, that causes the release of spermatozoa, i.e. spermatozoa remain attached to the isthmic mucosa until they become capacitated and then detach and migrate to the ampulla to fertilize the eggs.     

Effect of steroid hormones on sulfated oviductal glycoprotein secretion by oviductal explants in vitro

Explants of rabbit ampullary and isthmic tissue were cultured 4 days with and without exogenous steroids, and the sulfated oviductal glycoprotein (SOG) concentration in the explant culture supernatants was determined. Tissues cultured with progesterone plus estrogen secreted significantly more SOG than control tissues, whereas tissues cultured with estrogen alone did not. Ampullary tissues cultured with progesterone plus estrogen secreted significantly more SOG than control tissues on Days 2 and 3, whereas SOG secretion by isthmic tissues was significantly above control secretion on Day 4. Ampullary and isthmic tissues differed significantly in their secretory capacity. Maximum ampullary SOG secretion was approximately 650 ng SOG/mg tissue/day. Maximum isthmic SOG secretion was approximately 30 ng SOG/mg tissue/day. These findings suggest that the oviduct is composed of discrete functional regions that provide support to gametes and developing embryos through the unique secretory characteristics of each region.     

Segmental distribution and gestational changes of GABA-transaminase activity in the rat oviduct

The occurrence and the localization of 4-aminobutyrate:2-oxoglutarate transaminase (GABA-transaminase) in the non-pregnant and pregnant rat oviduct were examined using biochemical and enzyme histochemical techniques. Specific GABA-transaminase activity was detected in the ampullary and isthmic portions of the oviduct as well as in the utero-tubal junction. The enzymic activity was lower in the ampullary than in the isthmic or intramural segments of the oviduct. Pregnancy induced a significant increase of GABA-transaminase activity in each portion of the oviduct. Enzyme histochemistry showed the highest GABA-transaminase reactivity at the level of the epithelial cells of the oviduct irrespective of the portion of the tube examined. A faint specific activity was demonstrated in the smooth muscle of the oviduct while the serosa did not show specific staining. Our findings indicate that: the observed increase of GABA-transaminase activity in the oviduct of the pregnant rat may be responsible for the reduced GABA levels in the oviduct during gestation; and the extraneuronal localization of GABA-transaminase activity does not seem to support the suggestion of a possible GABAergic innervation of the oviduct.     

动情周期中大鼠输卵管与植物凝集素BS-1结合的糖蛋白的表达

目的初步鉴定大鼠输卵管中存在与植物凝集素BS-1结合的糖蛋白,并研究其在输卵管中的定位和不同动情周期中糖蛋白的表达变化.方法根据阴道涂片检查将大鼠分为:间情期(DE)组、动情前期(PE)组、动情期(E)组和动情后期(ME)组.用冰冻切片法、荧光组化技术和共聚焦显微镜技术观察大鼠输卵管中与BS-1结合糖蛋白的分布及表达变化.结果大鼠输卵管中存在与BS-1结合的糖蛋白,并呈节段性分布,即峡部＞壶腹部.动情周期中大鼠输卵管糖蛋白的表达:动情期＞动情前期＞动情后期＞间情期.结论大鼠输卵管与植物凝集素BS-1结合的糖蛋白在动情期(E)峡部上皮表达最明显,具有雌激素依赖性.     

A model of ovum transport

A theoretical fluid dynamical model of ovum transport in the oviduct incorporating transport mechanisms due to ciliary activity, muscular activity and an applied pressure drop across the oviduct is developed. Theory suggests that the cilia provide the steady component of ovum transport whereas muscular activity results in highly oscillatory motion. If muscular activity is to provide transport in a pro-uterine direction, a coordinated sequence of muscular activity with a strong pro-uterine bias is needed. Changes in pressure are highest in the narrowest sections. The highly convoluted rugae may allow "leakback" around the ovum so relieving the pressure drop across the ovum in narrower sections of the oviduct.     

Scanning electron microscopy of the equine oviduct and observations on ciliary currents in vitro at day 2 after ovulation

There are considerable differences between mammalian species in the distribution and activity of ciliated cells within the oviduct, and limited information is available concerning either the distribution or activity of cilia within the equine oviduct. Patterns of ciliary activity were characterized in the ampulla and isthmus of oviducts recovered at 2 d after ovulation from 10 mares, and scanning electron microscopy was used to examine regional differences in the distribution of cilia in oviducts from 3 of these mares. Based upon the motility of 15 microm latex microspheres, ciliary activity was significantly (P < 0.001) greater in the ampullar oviduct compared with that of the isthmic oviduct. The direction of ciliary beat was consistently toward the uterus in all regions of the oviduct. Scanning electron microscopy revealed ciliated and secretory cells in both regions of the oviduct at 2 d after ovulation, with no apparent differences in the proportion of ciliated versus secretory cells.     

兔输卵管峡部平滑肌阵发性活动与卵巢激素的关系

本文记录了不同卵巢激素状态下兔离体输卵管峡部平滑肌收缩活动及肌电变化。成年动情兔和排卵兔输卵管峡部活动强,呈现阵发性收缩或放电;幼兔及切除卵巢成年兔峡部活动弱,无典型的阵发收缩,若给这种兔补充雌激素阵发性收缩又可出现。结果表明峡部平滑肌阵发性活动与卵巢激素有密切关系,雌激素在维持阵发性活动中起着相当重要的作用。     

Effects of intraluminal administration of adrenoceptor agonists on transisthmic flow in the rabbit oviduct

By perfusing the isthmic segment of the rabbit oviduct in vivo at low hydrostatic pressures with Ringer's solution (+38 degrees C), the resistance of the isthmic segment could be measured quantitatively using a drop-recording system. Transisthmic flow, from mid-tube to the uterine end, was thus studied in 45 animals, 48 h after human chorionic gonadotropin (hCG) injection. Stimulation of alpha-adrenoceptors by administration of norepinephrine or phenylephrine to the perfusate resulted in an immediate reduction or cessation of the basal flow. The duration of this effect varied dose-dependently. The administration of beta-adrenoceptor agonists (isoprenaline, prenalterol or terbutaline) markedly increased transisthmic flow. The beta 2-adrenoceptor agonist terbutaline was considerably more potent than the other beta-agonists. Thus, it seems that the isthmic contraction caused by adrenergic luminal stimulation is mediated via alpha-adrenoceptors, while the isthmic dilation is mediated via beta-adrenoceptors, mainly of the beta 2-type.     

Carbohydrate components of hare oviduct studied by histochemical and biochemical techniques

Biochemical and histochemical analyses were carried out on the carbohydrate components of hare (Lepus europaeus) oviduct in anoestrous condition. Biochemical tests demonstrated that all the glycosidic components typical of glycoproteins and glycosaminoglycans are present in the ampulla and in the isthmus regions of oviduct, and that statistically significant differences exist in the sugar content between these two regions. In addition, lectin histochemistry combined with glycosidase digestion and selective histochemical stainings provided a series of rather detailed information on the localization of different neutral sugars and aminosugars. Hypotheses are advanced on the probable meaning of the different composition of ampullary and isthmic glycoconjugates in relation to the physiologically differentiated roles of the two oviduct tracts.     

Ciliary activity in the oviduct of cycling, pregnant, and muscarinic receptor knockout mice

The transport of the oocyte and the embryo in the oviduct is managed by ciliary beating and muscular contractions. Because nonneuronally produced acetylcholine influences ciliary beating in the trachea via the muscarinic receptors M2 and M3, we supposed that components of the cholinergic system may also modulate ciliary activity in the oviduct. To address this issue, we analyzed the expression profile of muscarinic receptors (CHRMs) in the murine oviduct by RT-PCR and assessed ciliary beat frequency (CBF) and cilia-driven particle transport speed (PTS) on the mucosal surface of opened oviductal segments in correlation with histomorphological investigations. RT-PCR of laser-assisted microdissected epithelium revealed expression of Chrm subtypes Chrm1 and Chrm3. In opened isthmic segments, particle transport was barely seen, correlating with a significantly lower number of ciliated cells compared to the ampulla. In the ampulla, basal PTS and CBF were high (71 μm/sec and 21 Hz, respectively) both in cycling and pregnant wild-type mice and in mice with targeted deletion of the Chrm genes Chrm1, Chrm3, Chrm4, and Chrm5. In contrast to the trachea, where basal ciliary activity was low and largely enhanced by muscarinic stimulation, muscarinic agonists and antagonists did not affect the high ampullar PTS. Our results imply that this high oviductal autonomous ciliary activity is independent from the intrinsic cholinergic system and serves to maintain optimal clearance of the tube throughout all stages of the estrous cycle and early pregnancy.     

Motility characteristics of sperm from the uterus and oviducts of female mice after mating to congenic males differing in sperm transport and fertility

Motile sperm were videotaped after removal from the uterus and isthmus of the oviducts of female mice 1 h after mating with congenic males carrying none, one, or two t complexes. Males carrying one t complex (tw32/+) are fertile, and sperm carrying the t complex have an advantage in fertilization; males carrying two complexes (tw32/t0) are sterile. For each sperm, 2 sec of movement of the head-midpiece junction were traced from the videotape. For each tracing, five motility parameters were used: curvilinear velocity (Vc), and index of the sperm's mean swimming speed; coefficient of variation of move length (CVML), an index of speed constancy; progressiveness ratio (PR), an index of all deviation of the sperm's movement from a straight line; linear index (LI), an index of the straightness of the sperm's trajectory; and curvilinear progressiveness ratio (PRc), an index of the degree of lateral oscillation about that trajectory. Uterine sperm from fertile males were progressive, with straight trajectories and little lateral oscillation. There were no consistent differences in any motility parameter between uterine sperm from tw32/+ and congenic +/+ males. Uterine sperm from sterile tw32/t0 males were extremely slow and showed very little progressive movement, which could explain their lack of transport to the oviduct. For all fertile males, isthmic oviductal sperm differed significantly from uterine sperm in every motility parameter except Vc: isthmic sperm were less consistent in swimming speed, and less progressive with less straight trajectories and more lateral movement. One or more of these motility characteristics may be related to hyperactivation. A large proportion of isthmic sperm from tw32/+ males had nonlinear trajectories (LI less than .50); these nonlinear sperm were faster than nonlinear isthmic sperm from congenic +/+ males. These motility characteristics of isthmic sperm from tw32/+ males may be related to hyperactivation, or to their previously observed abnormal transport within the oviduct.     

Synthesis and secretion of sulphated glycoproteins by rabbit oviduct explants in vitro

The ability of rabbit oviduct explants to incorporate radiolabelled precursors into specific secretory products was investigated. Ampullary and isthmic oviduct segments were cultured in the presence of [3H]glucosamine or [35S]sodium sulphate. Medium samples were analysed for the presence of secreted, labelled macromolecules. Explants incorporated the [3H]glucosamine and secreted labelled glycoproteins in vitro. SDS gel electrophoresis and subsequent fluorographic analysis of culture medium demonstrated a differential secretion of glycoproteins between the ampulla and the isthmus. Although ampullary tissue secreted a greater amount of labelled glycoproteins during the sampling period, the major secretory constituent of Mr approximately 66,000 was common to both oviduct segments. Tissue incubated with [35S]sodium sulphate also secreted a labelled glycoprotein or subunit of Mr approximately 66,000. The results indicate that rabbit oviduct explants are capable of synthesis and secretion of specific sulphated glycoproteins in vitro and that there is a difference in the type and amount of secretion produced between the two oviduct segments.