Distribution, morphology and epithelial interactions of bovine spermatozoa in the oviduct before and after ovulation: a scanning electron microscope study

In cows undergoing spontaneous oestrous cycles and mated during the first 6 hours of oestrus, the distribution of spermatozoa in the oviduct isthmus and changes in their surface membranes and neighbouring epithelium have been examined shortly before and after ovulation. In agreement with previous histological studies, relatively few spermatozoa were detected in the oviduct lumen: most were located in the caudal isthmus before ovulation, frequently among folds and in the presence of a viscous secretion. A majority of spermatozoa in this region showed strands and droplets of secretory material distributed over the anterior portion of an intact head before ovulation, whereas distribution of material over the post-nuclear cap of spermatozoa close to vesiculation or already acrosome-reacted was characteristic of the post-ovulatory situation. These changes in sperm head membranes were viewed as an expression of the completion of capacitation, and seemingly permit microvillous engagement with the rostral tip of the head. In conjunction with a narrow lumen and viscous secretions in the caudal isthmus, microvilli may thus serve to regulate periovulatory sperm progression towards the site of fertilisation, and be the basis of intermittent phases of adhesion to the oviduct epithelium as seen by phase-contrast microscopy. Although cilia do not similarly engage the heads of bull spermatozoa (cf. boar spermatozoa), they may act to regulate progression of capacitated spermatozoa by contacting the principal piece of the flagellum. In the light of these observations, changes in the molecular composition of sperm surface domains during the process of capacitation in vivo now require specific definition.

Characterization of ovarian follicular fluids of sheep, pigs and cows using proton nuclear magnetic resonance spectroscopy

Proton NMR spectra were produced for Graafian follicular fluids obtained by aspiration from sheep, pig and cow ovaries. The following low molecular mass, non-protein-bound metabolites were detected at concentrations exceeding 0.1 mM: acetate, alanine, creatinine/creatine, glycine, D-3-hydroxybutyrate, lactate, valine. Glucose was difficult to quantify and N-acetyl sugars gave a broad resonance at 2.06 ppm, presumably representing side-chains of glycoproteins. Ethanol was detected at up to millimolar concentrations in some specimens, though the physiological significance of this finding was not clear. The concentrations of all metabolites were comparable to those of plasma. These results have therefore shown that NMR spectroscopy is useful for gaining a broad and semiquantitative impression of the more abundant metabolites in the fluids of preovulatory Graafian follicles.

Luteinizing hormone response to an oestradiol challenge in 5 intersex pigs possessing ovotestes

After challenge with oestradiol benzoate, the mean maximum LH concentration in 5 XX intersex pigs possessing ovarian and testicular tissue, or only testicular tissue, was 2.10 (+/- 0.41) ng/ml compared with 8.9 ng/ml in mature domestic gilts. These results indicate that exposure of the pig brain to testosterone before Day 30 of gestation is important, or that early testicular secretions other than testosterone are involved in the determination of brain gender. The observation that some intersex pigs show normal oestrous cycles implies that the response to these prenatal factors is primarily quantitative rather than qualitative.

Influence of cell cycle stage at nuclear transplantation on the development in vitro of mouse embryos

Nuclei were transplanted from embryos of mice at different stages of the 1st and 2nd cell cycle to oocytes enucleated at various times after fertilization. After transfer of pronuclei, a greater proportion of embryos developed to blastocysts if donor and recipient embryos were at the same stage of the cell cycle (synchronous transfer = 94%, asynchronous transfer = 76%). By contrast, when 2-cell blastomere nuclei were fused to the cytoplasm of enucleated zygotes, there was a significant effect of both cytoplast and karyoplast cell cycle stage on the development of the reconstituted embryos. Karyoplasts and cytoplasts derived from embryos at later stages of the cell cycle had greater potential to support development to blastocysts in vitro. It is suggested that the secretion of stage-specific messengers and the timing of nuclear membrane breakdown are the main factors causing the karyoplast and cytoplast effects, respectively.

Capacitation potential of the fallopian tube: a study involving surgical insemination and the subsequent incidence of polyspermy

In an attempt to demonstrate limitations in the capacitating potential of the Fallopian tube, ejaculated boar spermatozoa were introduced directly into the isthmus at varying intervals before ovulation. The incidence and degree of polyspermy subsequently observed were taken as indicators of the population of capacitated spermatozoa confronting the newly ovulated eggs: the more extensive the condition of polyspermy, the greater the number of capacitated spermatozoa presumed to have been available at the site of fertilization. Results are based on 673 eggs from 53 animals. When suspensions containing 2.21-3.87 x 10(8) sperm per ml were introduced 36-40 hours and 26-30 hours before ovulation, 85% and 61% respectively of the eggs were polyspermic, such eggs exhibiting mainly dispermy and trispermy. By contrast, when comparable sperm suspensions from the same boar were instilled 17-18 hours before ovulation, 70% of the eggs were polyspermic but the degree of polyspermy had increased dramatically: most eggs contained 40 or more sperm heads in the vitellus, invariably forming swollen chromatin aggregates rather than male pronuclei. Surgical insemination at times closer to ovulation significantly reduced the incidence and degree of polyspermy, reaching a low of 2% with insemination 1-2 hours before ovulation. These results therefore support the concept of a limited capacitation potential of the Fallopian tube. In a separate series of observations, mating animals shortly before surgical insemination with sperm suspensions from the same boar markedly reduced the incidence of polyspermy. This latter observation may be of clinical significance in procedures of laparoscopic or transcervical insemination into the tubes to alleviate human infertility. The manner whereby myosalpingeal physiology could be modified in response to coital stimulation is discussed.

Electrophysiological properties of the follicle wall in the pig ovary

The transmural potential difference and short-circuit current of the porcine Graafian follicle have been measured in an attempt to test whether antral fluid accumulates as a result of active transport of salt. The values obtained by mounting explants of follicle wall in Ussing chambers were close to zero and the specific electrical resistance was only 59 delta.cm2. The elemental composition of the follicular fluid was similar to that of ovarian venous plasma with the exception of follicular Na+ which was slightly more abundant. Bicarbonate concentrations were slightly lower in follicular fluids. These findings were interpreted as evidence that the follicular wall is a leaky epithelium and, therefore, any charge resulting from net ion transport will be shunted along low resistance paracellular pathways.

Human fertilization in vivo, with special reference to progression, storage and release of competent spermatozoa

Whilst very large numbers of spermatozoa accumulate in the cervical mucus and crypts in the hours following coitus, evidence is offered from species with comparable gonadotrophin surge-to-ovulation intervals to suggest that the cervix is not the site of the functional sperm reservoir in women. On the contrary, human spermatozoa involved in the events of fertilization may spend the greater part of the pre-ovulatory interval in the distal portion of the Fallopian tube, that is in the intra-mural segment. This would enable spermatozoa to be arrested within reach of the site of fertilization in the ampullary region of the tube, and to be activated and released close to the time of ovulation by means of a local transfer of high concentrations of ovarian follicular hormones. The clinical importance of confirming this proposed role for the intra-mural segment of the tube is stressed, as is the possibility of specific micro-environments within the lumen of the duct.

Simple measures of progress and outcome in the evaluation of mental health services

There is a tautology regarding the use of progress and outcome measures. Such measures are easy to use in a reliable and valid fashion if the language of the measures is used as an integral part of (a) treatment planning and progress review, (b) clinical supervision, and (c) program management. The paper describes example guidelines and uses of measures in each of these functions. Also included are listings of scales with documented reliability and validity (by target population) and some sources for finding computer software for scoring some of the scales.

Pre- and peri-ovulatory distribution of viable spermatozoa in the pig oviduct: a scanning electron microscope study

Using sexually mature animals, the distribution of spermatozoa has been examined at the utero-tubal junction and in the distal and proximal portions of the oviduct isthmus. Mating occurred during early oestrus and, with one exception, specimens were prepared shortly before or after ovulation. Distinct reservoirs of spermatozoa were identified in furrows between the terminal folds of the isthmus, and particularly within the troughs and transverse ridges of this region. The density of spermatozoa diminished steeply from the utero-tubal junction towards the isthmus, especially in the pre-ovulatory specimens. The membranes of most spermatozoa in the isthmus were intact up to the time of ovulation, suggesting that the acrosome reaction is a peri- or post-ovulatory event. Whilst the flagella of spermatozoa in the reservoirs were usually straight or only slightly curved, those on the surface of the epithelial folds were undulating (S-shaped). Specific microenvironments may therefore exist in the distal portion of the isthmus to regulate sperm motility; droplets of secretion were a notable feature in this region. In specimens prepared 24 hr after ovulation, spermatozoa were almost absent from the utero-tubal junction and isthmus. However, denuded eggs were observed in the proximal portion of the isthmus in this animal, and they had spermatozoa associated with the zona pellucida. Arguments are presented for a peri-ovulatory endocrine regulation of sperm redistribution and capacitation.

A preovulatory temperature gradient between the isthmus and ampulla of pig oviducts during the phase of sperm storage

Fine thermistor probes positioned in each end of the same oviduct and connected to the same scale were used to measure temperature gradients in the lumen before and after spontaneous ovulation in normally-cyclic gilts. Readings were taken after full surgical closure of a mid-ventral incision and a subsequent period of stabilization, but whilst animals remained under general anaesthesia. A small but consistent difference in temperature was recorded between the proximal ampulla and distal isthmus of the same oviduct in each of 20 preovulatory gilts. In 10 of these animals that had not mated, the isthmus was a mean of 0.43 degree C cooler than the ampulla (range 0.2-0.7 degree C) whereas in 10 mated animals the isthmus was 0.69 degree C cooler (range 0.2-1.6 degree C); 3 animals in the latter group had within-oviduct differences of greater than or equal to 1 degrees C. By contrast, in 12 animals that had recently ovulated, the isthmus was a mean of only 0.1 degree C cooler than the ampulla; there was no measurable temperature gradient in 3 of the animals, whilst the isthmus was 0.1 degree C warmer in 2 animals. The preovulatory temperature differences are thought primarily to reflect the extent and activity of the vascular and lymphatic beds in the oviduct tissues and, together with specific chemical microenvironments, may facilitate the relatively prolonged period of sperm storage in the distal portion of the isthmus.

Cumulus oophorus mucification during resumption of meiosis in the pig. A scanning electron microscope study

The process of cumulus mucification in pig preovulatory follicles was examined by scanning electron microscopy. The localization of extracellular material and changes in the granulosa cell surface were observed at 0, 16, 20 and 40 h after hCG injection. At 0 h the pig oocyte cumulus complex was closely attached to the parietal layer of granulosa cells. Cumulus and parietal granulosa cells had microvilli and cytoplasmic projections connecting neighbouring cells. The network of extracellular amorphous material was observed for the first time at 16 h after hCG around the cells that formed a stalk between the parietal granulosa and the cumulus oophorus. At 20 h after hCG, the intercellular matrix was thicker and extended to almost all the cumulus oophorus surface; when visible, cells were often covered by blebs and ruffling membranes. All oocytes examined by light microscopy at 16 and 20 h after hCG were at the germinal vesicle stage with condensing bivalents. Therefore, it was concluded that oocyte nuclear maturation started at the same time that a mucified peduncle was forming between the cumulus oophorus and the parietal granulosa. Shortly before ovulation (40 h after hCG) the matrix material filled all intercellular spaces and mucification had extended to the corona cell layer and the zona pellucida surface.

Intersexuality in five pigs, with particular reference to oestrous cycles, the ovotestis, steroid hormone secretion and potential fertility

Reproductive tissues, steroid hormone secretion, and sexual behaviour have been examined in five gilts, in each of which the right gonad was an ovotestis. Although from different females, these animals were sired by the same boar and each possessed an XX sex chromosome constitution as determined by karyotype analysis of blood cells. Despite variable amounts of testicular tissue in the ovotestis and unilateral development of a prominent epididymis, four of the animals had oestrous cycles of normal duration (20-22 days) and extended periods of standing oestrus (3-6 days). The fifth animal did not have detectable oestrous cycles but was extremely aggressive in the presence of a mature boar. Two of the gilts were mated, and there were small numbers of embryos in each uterine horn 23 and 26 days later. Removal of the ovary did not prompt compensatory hypertrophy in the ovarian portion of the ovotestis, nor did injection of pregnant mare serum gonadotrophin stimulate detectable follicular growth in ovarian tissue adjoining testicular tissue. Concerning the aetiology of this intersex condition, the unilateral appearance of an ovotestis precludes any simple involvement of a translocated portion of the Y chromosome or systemic effects of unusual titres of the putative H-Y antigen. However, bearing in mind a predisposition to gonadal asymmetry in eutherian mammals, a case is advanced for apposition or incorporation of adrenocortical tissue in the right embryonic ovary. The resultant virilization of neighbouring reproductive tissues would stem from adrenocortical androgen synthesis.

Massive spontaneous superovulation in a sexually mature pig

Ovulation of 97 follicles was recorded in a gilt that had not received any hormonal treatment, and circumstantial evidence adduced for a rapidly proliferating tumour of the adenohypophysis. A lesser degree of superovulation had occurred in the previous oestrous cycle, whilst the rate of follicular development in the current cycle was exceptional. None of the 93 eggs recovered from the oviducts was a primary oocyte, but three were polyspermic pronucleate eggs. The most advanced stage of embryonic development was that of 4-cells. Such a degree of spontaneous superovulation has never been observed before during careful examination of more than 1200 pairs of ovaries from gilts in the same herd.

Ovarian follicular fluid concentrations of prostaglandins E2, F2 alpha and I2 during the pre-ovulatory period in pigs

The concentrations of prostaglandin (PG) E2, PGF2 alpha and PGI2 (measured as 6-oxo-PGF1 alpha) in follicular fluid collected from the ovaries of mature, cycling pigs during the immediate pre-ovulatory period have been estimated by radioimmunoassay. The concentrations of all three prostaglandins were low 24-32 hrs before the expected time of ovulation, with the ratio of the mean concentrations of PGE2, PGF2 alpha and 6-oxo-PGF1 alpha being 0.7:1.1:1.0. The concentration of PGE2 showed a small increase during the next 22 hrs but, in the 2 hr period before the expected time of ovulation, the mean concentrations of PGE2, PGF2 alpha and 6-oxo-PGF1 alpha increased 119-, 11- and 5-fold, respectively, which produced a ratio of these mean concentrations of 14.8:2.2:1.0. One sample of follicular fluid contained the highest concentration of 6-oxo-PGF1 alpha (54.4 ng/ml) yet reported for any tissue from any species, but this concentration was still lower than those of PGE2 (529 ng/ml) and PGF2 alpha (94.6 ng/ml). These results show that prostaglandin concentrations increase in the follicular fluid of mature, cycling pigs in the immediate preovulatory period, with PGE2 being the predominant prostaglandin produced. In "preovulatory" follicles which failed to ovulate, prostaglandin concentrations were at baseline values. The findings in this study are consistent with follicular prostaglandins being essential for ovulation in the pig.

Sperm transport into the oviducts of heifers mated early in oestrus

An estimate has been made of the time required for a population of spermatozoa capable of fertilizing the egg to be established in the oviducts of heifers mated early in oestrus. During a general or local anaesthetic, the caudal isthmus of the oviduct was ligated and sectioned 6, 8, 10 or 12 hr after mating. The proportion of eggs fertilized as judged 2-4 days later was very low if ligation was carried out after 6 hr (1 of 11) and only approached normal levels of 85% or more following ligation at 12 hr (7 of 10). These results suggest that the population of spermatozoa capable of fertilisation is established in the oviduct over a period of not less than 6 hours and probably more than 12 hr. These results contrast with reports of rapid transport of spermatozoa to the oviduct in a period of minutes.

Pre-ovulatory arrest and peri-ovulatory redistribution of competent spermatozoa in the isthmus of the pig oviduct

Using the surgical approach of post-coital ligation and transection of the distal oviduct at different times relative to ovulation, together with subsequent recovery of the eggs, gilts mated at the onset of oestrus were studied for progression of viable spermatozoa within the isthmus. Results are derived from 76 animals and examination of 1047 eggs. Transection of the isthmus 1.5-2.0 cm proximal to the utero-tubal junction at intervals from 3 to 36 h after mating prevented fertilization in 269 of 270 eggs, whereas 98% of 223 eggs were fertilized in the control oviducts. Transection at 38 h (pre-ovulatory), 40 h (peri-ovulatory) and 42-44 h (post-ovulatory) after mating yielded, respectively, 5%, 40% and 100% fertilization. The mean number of spermatozoa associated with the zona pellucida increased in a parallel manner. These results, and those obtained with ligatures placed closer to the site of fertilization just after ovulation, indicate a pre-ovulatory arrest of viable spermatozoa in the caudal region of the isthmus for 36 h or more followed by an active ad-ovarian redistribution.

Sperm transport in the cow : peri-ovulatory redistribution of viable cells within the oviduct

Using a surgical approach involving double ligatures and transection, together with subsequent recovery of the eggs, heifers mated at the onset of oestrus have been examined for progression of spermatozoa within the oviducts relative to the time of ovulation; the latter occurred 28-31 hours after the onset of oestrus. Evidence was obtained that spermatozoa competent to penetrate the egg(s) do not pass directly to the site of fertilisation at the isthmic-ampullary junction but instead are largely sequestered before ovulation in the caudal region of the isthmus, possibly for 18-20 hours or more. Thus, 3 of 14 eggs (21%) were fertilised when the oviduct was transected in pre-ovulatory animals 2.0 cm proximal to the utero-tubal junction 16 or more hours after mating compared with 7 of 8 eggs (88%) with a similar post-ovulatory transection 28-36 hours after mating (P less than 0.01). A redistribution of spermatozoa appears to be associated with imminent release of the egg. The distal portion of the oviduct is therefore seen as the functional sperm reservoir--that is the immediate source of viable spermatozoa at the time of ovulation. Parallels are drawn with storage of relatively quiescent sperm cells in the distal portion of the epididymal duct, and procedures of insemination are examined in the light of this storage rôle of the isthmus and the reported incidence of fertilisation in cattle.

Transport of spermatozoa in the sheep oviduct: preovulatory sequestering of cells in the caudal isthmus

Progression of ram spermatozoa within the sheep oviduct has been studied in relation to the time of ovulation. Ewes were mated at the onset of estrus and, at increasing intervals thereafter, the oviduct isthmus was transected 1.5-2.0 cm proximal to the utero-tubal junction. The incidence of fertilization and number of accessory spermatozoa were examined in eggs recovered 1 to 3 days after surgery. Ovulation occurred 24-26 hours after the onset of estrus. None of 52 eggs recovered from 48 oviducts transected up to 21 hours after mating was fertilized, nor were spermatozoa associated with the zona pellucida. Two of 33 eggs (6.1%) from 29 oviducts transected between 22 and 24 hours after mating were fertilized, while 3 of 14 eggs (21.4%) and 13 of 16 eggs (81.3%) were fertilized with transection at 25 and 26 hours, respectively. The mean numbers of accessory spermatozoa on eggs in the latter two groups were 0.7 (range 0-2) and 7.9 (range 0-26). Results from transection at 27-30 hours after mating indicated a progressive release and adovarian movement of spermatozoa. Viable spermatozoa are apparently sequestered in the caudal isthmus for as long as 17-18 hours, until shortly before ovulation, when a local transfer of ovarian follicular hormones is thought to facilitate their redistribution. The adrenergic stimulation of powerful adovarian waves of contraction in the isthmus at this time may also act to provoke the capacitation and hyperactivation of ram spermatozoa.