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.

Regulation of oviduct function in pigs by local transfer of ovarian steroids and prostaglandins: a mechanism to influence sperm transport

Blood was collected from a prominent ear vein and from the arterioles supplying the caudal portion of each oviduct in 5 estrous animals. Sampling was arranged at 4 preovulatory intervals, and just after ovulation in the fifth animal. Steroid hormones and prostaglandins were determined by radioimmunoassay of plasma. Whereas the concentration of cortisol did not differ between peripheral and oviduct blood samples, the overall values for progesterone, androstenedione and estradiol were significantly higher in oviduct samples (P less than 0.001) - frequently by 5- to 10-fold or more. The concentration of these three hormones in oviduct blood corresponded, in most instances, with the number of preovulatory follicles or recent ovulations in the adjacent ovary but suitable statistical correlations could not be performed. Prostaglandin F2 alpha was also present in higher concentrations in oviduct compared with peripheral plasma (P less than 0.005), although pulmonary clearance of prostaglandins would have influenced the peripheral values. Differences in the concentration of prostaglandin E2 were not significant. A local transfer of follicular hormones from the ovarian vein to the ovarian and utero-tubal arteries is proposed as a means of regulating oviduct function. Elevated concentrations of steroids and prostaglandins transferred in this way would permit incisive changes in the patency and contractile activity of the isthmus, thereby facilitating the periovulatory phase of sperm transport from the caudal portion of the oviduct to the site of fertilization.

Use of serum theophylline determinations during acute asthma therapy in children

Analyses of 90 admissions to the Cincinnati Children's Hospital Center, Cincinnati, Ohio, were used to assess the effects of the routine availability of serum theophylline determinations (STD) in treating acute in-hospital asthma over three one-year review periods coinciding with the relative availability of STD. Significant differences were found between the first and third periods for the mean outpatient theophylline dose used on admission, the mean initial in-hospital intravenous dose, the mean initial oral dose during admission and the mean oral discharge dose. No statistical differences were noted in the length of hospital stay, duration of intravenous therapy or report of theophylline toxicity (despite the use of larger theophylline doses). Utilization of STD must be guided by cost-effective pharmacokinetic principles.

Uterine secretion of prostaglandin F2 alpha in anaesthetized pigs during the oestrous cycle and early pregnancy

Uterine blood was sampled by venepuncture or an indwelling catheter in a total of 33 cyclic gilts and 26 mated animals subsequently confirmed to contain embryos; jugular blood was obtained simultaneously from catheterised animals. Prostaglandin F2 alpha and progesterone were determined by radioimmunoassay of the plasma. The concentration of PGF2 alpha in uterine venous blood of cyclic animals remained below 1.0 ng/ml until the corpora lutea were 12 days old. Highest PGF2 alpha values were associated with 15-17 day corpora lutea, with a mean of 5.9 ng/ml for six samples on Day 17. Likewise, the PGF2 alpha concentration in the uterine blood of mated animals did not exceed 1.0 ng/ml until the corpora lutea were older than 12 days, and a mean value of 6.0 ng/ml was found by acute sampling with 15-day corpora lutea. The highest mean concentrations of PGF2 alpha in uterine blood from a series of 14 catheterised pregnant animals were 2.8 and 2.3 ng/ml, respectively, with 15- and 16-day corpora lutea. Values for PGF2 alpha on the 17th, 18th and 19th days of pregnancy showed a downward trend. There was considerable day to day variation in the mean uterine and peripheral concentrations of progesterone in mated animals, but there was no sustained depression in response to elevated PGF2 alpha concentrations. The results suggest that exocrine secretion of PGF2 alpha into the uterine lumen of pigs under the influence of trophoblastic oestrogens does not provide a sufficient explanation for the establishment of the corpora lutea of pregnancy. Further attention should be devoted to the luteotrophic--as distinct from anti-luteolytic--rôle of pig conceptuses at the time of maternal recognition of pregnancy. Circumstantial evidence for luteal sensitivity to chorionic gonadotrophins is included.

Morphology, histology and steroid hormones of the gonads in intersex pigs

Studies of 3 genetically female, intersex pigs revealed that only one showed oestrous cycles and lordosis, the other 2 exhibited various components of male sexual behaviour. Each uterus was a patent bicornuate structure, but 5 of the oviducts were incompletely formed. Two of the animals had bilateral ovotestes, whilst the third had a functional ovary on the right and an ovotestis on the left. The small ovarian portion of each ovotestis contained Graafian follicles which did not respond to a systemic injection of PMSG. The major portion of each ovotestis consisted of extensive interstitial tissue and seminiferous tubules devoid of germ cells. A structure closely resembling an epididymis adjoined the ovotestes. Concentrations of oestradiol and progesterone in plasma corresponded with those expected in the follicular phase of an oestrous cycle, but concentrations of testosterone represented approximately one-tenth of the values found in mature boars.

Sperm transport and reservoirs in the pig oviduct in relation to the time of ovulation

The rate of establishment of a population of viable spermatozoa in the oviducts was studied using a technique of post-coital transection in conjunction with subsequent examination of the proportion of eggs fertilized. Gilts were mated early in oestrus (before ovulation) or on the 2nd day of oestrus (after ovulation), and 30, 45 or 60 min later the reproductive tract was sectioned just above or below the utero-tubal junction in a total of 48 animals; these were slaughtered 1 or 2 days after the operation. Some fertilized eggs were recovered from 40 animals, and 72.3% of the 679 eggs examined were fertilized. Mean percentage fertilization increased overall (a) with the time elapsing from mating to transection, (b) with transection below the utero-tubal junction compared with in the caudal isthmus, and (c) with a post-ovulatory versus pre-ovulatory mating. In a further 6 gilts, the results of transection in the lower third of the oviduct 3 h after mating at the onset of oestrus indicated that spermatozoa were initially sequestered in the caudal portion of the isthmus. It is concluded that a population of spermatozoa sufficient to give maximum fertilization is established in the oviducts within 1--2 h of mating, thereby affording protection from the uterine invasion of polymorphonuclear leucocytes.

Distribution of spermatozoa in the utero-tubal junction and isthmus of pigs, and their relationship with the luminal epithelium after mating: a scanning electron microscope study

The epithelial cell morphology and distribution in the utero-tubal junction and isthmus of pigs was documented by scanning electron microscopy around ovulation. In animals mated at different times before slaughter, our observations confirmed that the utero-tubal junction and posterior part of the isthmus regulate the transport of spermatozoa. The utero-tubal junction appears clearly as a form of mechanical valve strongly limiting the number of sperm cells penetrating the oviduct. The isthmus, and especially its posterior part poor in ciliated cells, is a storage place for spermatozoa which appear as though trapped in the epithelial folds. It remains to be demonstrated if they stay in such reservoirs due to the constriction of the lumen by the thick muscular wall of the duct, or to some chemotactic attraction by tubal secretions, or simply due to adhesion on the epithelium. Our study supports the hypothesis that transport of spermatozoa in the isthmus towards the site of fertilization depends in part on ciliary motion. The instant direction of propagation appears random for spermatozoa escaping from the reservoirs. Other factors such as tubal contractions probably ensure that the resultant movement is a progressive ascent.

Transport of spermatozoa in the ewe: timing of the establishment of a functional population in the oviduct

The technique of post-coital transection of the oviducts from the uterus at various intervals after mating has been used to establish how soon a population of spermatozoa competent to fertilize the egg(s) first appears in the oviduct of the ewe. Fertilised eggs were not found as a sequel to transection at 4 or 6 hrs after mating, whereas the incidence of fertilization in a small series of ewes was 30 p. 100 following transection at 8 hrs and 100 p. 100 at 10 hrs. The mean number of spermatozoa associated with the zona pellucida at these later times increased from 2 to 13.4. The results are interpreted as indicating only a gradual progression of viable spermatozoa from the cervix to the oviduct, although the possible contribution of a rapid phase of sperm transport to the events of fertilisation is discussed. Finally, the isthmus rather than the cervix is reasoned to act as the functional sperm reservoir at the time of ovulation, with some form of peri-ovulatory programming of sperm release from this region of the tract.

Comparison of five information services as sources for bioavailability data

The usefulness of five drug information services in obtaining bioavailability data from journal literature is compared. The deHAEN Drugs in Use system, the Iowa Drug Information Service (IDIS), Index Medicus, MEDLINE and International Pharmaceutical Abstracts (IPA), each for a 10-year period, were searched for citations on bioavailability studies on the oral dosage forms of acetaminophen, lithium carbonate, phenytoin, nitrofurantoin and theophylline. Both quantity of references indexed and quality of data were considered. No significant difference was found in the mean value scores for the five services. Index Medicus provided 79 citations but required 7.7 hours of search time. MEDLINE yielded 62 citations but required only 1.1 hours to search. IPA, IDIS and deHaen had lower numbers of citations and intermediate search times. IPA, deHaen and Index Medicus all cited unique articles, with 11%, 7% and 3%, respectively. Index Medicus had the lowest percent of articles duplicated by two or more services (49%). The most comprehensive serch with the fewest duplicate citations would be obtained from searching deHaen's Drugs in Use, IPA and Index Medicus.

Effect of obtrusive measures on antibiotic compliance

The influence of compliance measurement activities on patient behavior was studied. The project measured the relationship among physical capsule counts, patient interviews, and the amounts of excreted ampicillin. The capsule counts and patient interviews were conducted in a manner that disguised their intent. Sixty college-age patients were assigned to one of three experimental groups: a telephone interview, a personal interview and capsule count, or a control group. Stimulation (interviews) occurred on the 2nd day of the prescribed regimen, and urine was collected on random days thereafter. Results indicated that both stimulation types were associated with more positive compliance rates. The influence diminished rapidly. The reactive influence of experimentor intervention associated with personal and phone communication was demonstrated.