Cat Uterus Research Articles

840 Quality assurance in conformal prostate radiation therapy: technology questionnaire for EORTC trial 22991

Hypoxia-inducible factors (HIFs) and vascular endothelial growth factor (VEGF) have critical roles during the development of the fetomaternal unit. The HIFs regulate placentation and vascularization by stimulation of VEGF gene expression. This study aimed to investigate the expression profiles of HIF gene family and VEGF in the cat uterus during pregnancy. Tissue samples of the whole uterine wall were collected after ovariohysterectomy and allocated to the following groups: embryo positive (group 1 [G1], n = 7, 7 days after mating), early pregnancy (group 2 [G2], n = 7, 20 days after mating), mid-pregnancy (group 3 [G3], n = 7, 24 days after mating), late pregnancy (group 4 [G4], n = 7, 30–45 days after mating), and oocyte positive groups (group 5 [G5], n = 7, 7 days after induction of ovulation with GnRH analog). Relative mRNA levels were determined by real-time polymerase chain reaction. As housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase was used. The relative gene expression of HIF1A in G5 was found to be significantly higher than that of other groups (G1, G2, G3, and G4) (P < 0.05). In addition, the expression of HIF2A in G5 was higher than that of G1 and HIF2A gene expression at placentation sites of G4 was higher than in G1, G2, and G3 (P < 0.05). Immunohistochemistry indicated that HIF1A, HIF2A, and VEGF expressions were observed in different cell types of uterine and placental tissues in late pregnancy and oocyte groups. The expression of HIF3A did not change significantly in any group investigated. These observations suggest that HIFs and VEGF may play a role in the establishment and development of pregnancy.

Sympathetic postganglionic cholinergic fibres. 1959.

When the postganglionic fibres to the nictitating membrane are stimulated in a cat treated with reserpine, the membrane contracts. The contraction is increased after the injection of eserine and is abolished with atropine. Thus the fibres stimulated appear to be cholinergic. When the splenic nerve is stimulated in a cat treated with reserpine there is similar evidence of the presence of cholinergic fibres; the spleen dilates, the dilatation is greater in the presence of eserine and is abolished by atropine. The hypogastric nerves when stimulated cause inhibition of the uterus of the virgin cat. When the cat is treated with reserpine, stimulation then causes contraction which is increased in the presence of eserine and abolished by atropine. There is also evidence of cholinergic fibres in the postganglionic supply to the vessels of the rabbit's ear. From this and other evidence it is suggested that a form of adrenergic mechanism may exist such that cholinergic fibres in the postganglionic sympathetic supply liberate acetylcholine; this in turn liberates noradrenaline from a store around the sympathetic nerve ending.

Detection of insulin-like growth factor binding protein-1 in cat implantation sites.

This study was undertaken to determine whether insulin-like growth factor binding protein-1 (IGFBP-1) was synthesized by the cat uterus and placenta during implantation and pregnancy. Endometrial and placental tissue explants from pregnant, pseudopregnant, and ovariectomized steroid-treated cats were cultured in the presence of 35S-methionine. Culture media proteins were separated by one-dimensional (1-D) and two-dimensional (2-D) SDS-PAGE, transferred to nitrocellulose, and immunostained using a rabbit polyclonal antibody against baboon IGFBP-1 and a murine monoclonal antibody to human IGFBP-1. The antibody cross-reacted with a protein with an M(r) = 30,000 and a pI = 5.1-5.4. Immunoreactive product was found in implantation site media from 16 days postcoitum (PC) through the end of pregnancy, and was confined to the superficial placental/junctional zone. Immunoreactivity was not detected in non-implantation site media until 7 wk PC and was never detected in serum or in media from liver, pseudopregnant endometrium, or endometrium from steroid-treated cats. Autoradiography and immunostaining of 2-D Western blots of culture media proteins demonstrated that implantation site and not non-implantation site tissue synthesized and released immunoreactive IGFBP-1 into the culture medium. 125Insulin-like growth factor-1 (IGF-1) specifically bound to this protein on 1-D Western ligand blots. Avidin-biotin immunocytochemistry utilizing the monoclonal antibody was used to localize IGFBP-1 in paraffin sections. Specific immunostaining was observed in the surface and glandular epithelium of the non-site endometrium throughout pregnancy, with stromal cell staining being detected later.(ABSTRACT TRUNCATED AT 250 WORDS)

Response properties of hypogastric afferent fibers supplying the uterus in the cat

The present study was undertaken to examine the sensory function of uterine afferent fibers in cats at unknown stages of the estrous cycle. Single unit activity was recorded from strands of the hypogastric nerve of the anesthetized cat. Once a unit was found, the conduction velocity was determined and the mechanical receptive field localized on the uterus. The response properties of the unit to mechanical stimuli applied to the receptive field and to chemical stimuli applied by intra-arterial injection of algesic chemicals (bradykinin, KCl and capsaicin) into the uterine artery were studied. Single unit activity from a total of 52 units was examined in this study. Based on the conduction velocities, about 2/3 of these fibers were found to be unmyelinated C fibers and the remaining 1/3 were thinly myelinated Aδ fibers. The receptive fields of most of these fibers were located at different parts of the uterine horn and body while a few were at the uterine cervix. Mechanical thresholds, as determined by von Frey filaments applied to the external surface of the uterus, varied more than 150-fold among mechanically sensitive units, ranging from extremely low to high thresholds. In addition, most of these afferents were activated by intra-arterially injected algesic chemicals, often by more than one chemical. The data in the present study suggest that a large portion of the cat uterus is innervated by the hypogastric nerve and that these afferents originate from sensory receptors that have potentially a wide range of functions. Their potential functions as low threshold mechanoreceptors and nociceptors are discussed.

Immunocytochemical localization and messenger ribonucleic acid levels of a progesterone-dependent endometrial secretory protein (cathepsin L) in the pregnant cat uterus.

The purpose of this study was to localize immunocytochemically a progesterone-dependent protein (PDP) and to determine PDP mRNA levels during the initial stage of the implantation period. Uterine tissue was collected from Day 0-18 postcoital animals. The tissue was processed for immunocytochemical localization of PDP, and the endometrial RNA was isolated and analyzed for PDP gene expression by slot-blot hybridization. PDP was detected immunocytochemically as early as Day 5 postcoitus in the epithelial cells of the deep uterine glands, and the intensity of immunostaining appeared to peak by Day 12 postcoitus. PDP was absent in the endometrium obtained from implantation sites after Day 16 postcoitus, but the synthesis of PDP was maintained in the endometrium obtained from nonimplantation sites. Immunogold electron microscopy demonstrated that PDP was present in electron-dense granules of the glandular epithelial cells. PDP mRNA was detectable in the endometrium at Day 5 postcoitus and peaked around Day 10 postcoitus. PDP mRNA was absent in the endometrium from implantation sites after Day 16 postcoitus, but was maintained in the endometrium from nonimplantation sites. In summary, the results of this study illustrate that PDP is synthesized within the epithelial cells of the deep uterine glands, packaged within membrane-bound secretory granules, and released into the uterine lumen. Also, the process of implantation alters the gene expression in a very localized way since PDP mRNA and PDP-positive granules were absent in the endometrial glands obtained from the implantation site within 1-2 days of the onset of implantation, whereas both PDP mRNA and PDP-positive granules were maintained in the endometrial glands from nonimplantation-site regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Histopathologic features, environmental factors, and serum estrogen, progesterone, and prolactin values associated with ovarian phase and inflammatory uterine disease in cats

SUMMARY Forty-four female American Shorthair cats with inflammatory uterine disease or infertility were evaluated. Data collected included age, month of diagnosis, housing, reproductive history, results of bacteriologic culture of uterine specimens, serum concentrations of estrogen, progesterone, and prolactin and histopathologic features of the ovaries and uterus. Histologically, the ovaries of 19 cats were dominated by active or cystic follicles, whereas 25 cats had luteal-phase ovaries. Of the 25 cats with active corpora lutea, 20 had either recently weaned litters (n = 11) without subsequent exposure to a male cat, or had been housed individually for lengthy periods (n = 9). The finding of active corpora lutea under these circumstances indicates that in queens, ovulation may occur by mechanisms not involving coitus. Prominent, active corpora lutea on the ovaries were associated with adenomatotic proliferative changes in the superficial and glandular epithelium of the uterus and with myometrial hyperplasia, compared with the uterus of cats with follicular ovaries (P &lt; 0.01). Serum progesterone concentration ≥ 1.87 ng/ml was consistently associated with luteal-phase ovaries. Serum progesterone values ≤ 0.15 ng/ml were consistently associated with follicular-phase ovaries. Escherichia coli was the organism most commonly isolated from uterine contents.

Progesterone-Dependent Cathepsin L Proteolytic Activity in Cat Uterine Flushings1

Sequence analysis of a cDNA clone for the progesterone-dependent protein (PDP) of the cat uterus revealed that PDP may be cathepsin L. This study was undertaken to directly measure the cathepsin L activity in uterine flushings from pregnant and ovariectomized steroid-treated animals in order to confirm that PDP is cathepsin L. Optimum activity toward the substrate Z-Phe-Arg-NMec was observed at a pH of 5-6. Z-Phe-Phe-CHN2, a specific inhibitor of cathepsin L, significantly inhibited the proteolytic activity present in uterine flushings. Immunoabsorption of PDP from uterine flushings obtained from progesterone (P)-treated cats reduced cathepsin L proteolytic activity to levels observed in ovariectomized and estradiol (E2)-treated animals. In E2-primed and E2 + P-treated animals, proteolytic activity in uterine flushings was detectable after 7 days and peaked after 11-13 days of E2 + P treatment. This proteolytic activity was also dramatically increased before implantation (10-12 days after coitus) in pregnant cats. Thus, our data indicate that changes in cathepsin L activity in uterine flushings are correlated with changes in PDP, the uterine protein synthesized and released from the epithelial cells of the deep uterine glands. PDP, via its cathepsin L proteolytic activity, may play a role in the implantation process.

Changes in Endometrial and Placental Protein Synthesis and Morphology during Pregnancy and Pseudopregnancy in the Cat1

This study was undertaken to determine the effect of the implanting cat blastocyst on endometrial morphology and protein synthesis. Placental and endometrial tissues were obtained from pregnant and pseudopregnant cats and then cultured with L-[35S]methionine and analyzed for protein synthesis by 2-dimensional polyacrylamide gel electrophoresis followed by fluorography, and also processed for light microscopy. The progesterone-dependent protein (PDP), described previously by Boomsma and Verhage (Biol Reprod 1987; 37:117-126) and Verhage et al. (Biol Reprod 1989; 41:347-354), was identified by immunocytochemical and immunoblot analysis. Attachment began after 12 days, and the deep glands contained large deposits of PDP. By 20 days the placenta was well developed, and the deep endometrial glands under the placenta had regressed and lacked deposits of PDP. The placenta continued to develop and thicken as pregnancy progressed. The surface epithelium in the non-implantation site regions developed extreme convolutions, while the well-developed deep glands with large deposits of PDP began to regress by 4 weeks, becoming similar to those in the implantation site. The endometrial glands in the pseudopregnant animals maintained deposits of PDP even though apoptotic bodies were observed between 20 and 35 days. PDP synthesis was not detected in the implantation site after 16 days, but it continued in the nonimplantation site through 5 weeks. The synthesis of nine other proteins was significantly altered by the end of implantation such that the pattern in the non-site endometrium was different from the implantation site but similar to the pattern found in the pseudopregnant endometrium. As pregnancy progressed, protein synthesis was altered in the placental/junctional zone and the non-site endometrium, but in the deep endometrial portion of the implantation site it was largely unchanged and similar to the deep portion of the non-site. Thus, the implanting cat blastocyst has a significant effect on the morphology of the implantation site and non-site endometrium, and alters the protein synthetic activity of the implantation site endometrium but apparently not the non-site region. The morphology and protein synthetic patterns of the pregnant cat uterus show regional differentiation and continue to change as pregnancy progresses.

Bacterial flora of the vagina and uterus of healthy cats

Summary Bacterial culturing was conducted on samples from the reproductive tracts of 53 clinically healthy female cats. Aerobic bacteria were isolated from 52 of 53 vaginal swab samples and from 2 of 29 uterine swab samples. Anaerobic bacteria were detected in 4 of 30 vaginal and 1 of 29 uterine cultures. The aerobic bacteria included species of Acinetobacter, Actinomyces, Corynebacterium, Escherichia, Haemophilus, Klebsiella, Lactobacillus, Staphylococcus, and Streptococcus. Coagulase-negative Staphylococcus, Streptococcus canis, and E coli were the most common organisms and were isolated from 56%, 52%, and 44% of the vaginal samples, respectively. Anaerobes isolated from vaginal samples included 3 species of Bacteroides and 2 isolates of Peptococcus. The single uterine anaerobe isolate was a Lactobacillus sp. The number of bacterial species isolated from each vaginal culture ranged from I to 8 (mean, 3). The number of colony forming units tended to vary inversely with the number of bacterial species detected in each sample.

Immunological characterization and immunocytochemical localization of a progesterone-dependent cat endometrial secretory protein.

The major objective of this study was to make a polyclonal antibody to a previously described group of progesterone (P)-dependent low molecular weight secretory proteins of the cat uterus. Proteins present in uterine flushings obtained from a P-treated cat were partially purified using Sephadex G-75, separated on two-dimensional polyacrylamide gels, and transferred to nitrocellulose membranes. The region containing the polypeptides were cut out, solubilized in dimethyl sulfoxide, mixed with Freund's adjuvant, and injected at 2-wk intervals into a male rabbit. The antiserum used in this study was obtained 8 wk after the initial injection and crossreacted with antigens on Western blots of uterine flushings and uterine culture medium obtained from ovariectomized estradiol (E2)-primed cats treated with P, and from pregnant preimplantation animals. Polypeptides in three molecular weight regions crossreacted with the antisera (Mr approximately equal to 28,000, pI 5.5 6.0; Mr approximately equal to 36,000, pI 6.0 6.5; Mr approximately equal to 41,000, pI 5.5 6.0), and each region consisted of several isoelectric variants. The Mr approximately equal to 28,000 proteins were the dominant form observed in culture media, and the Mr approximately equal to 36,000 proteins were the major form present in uterine flushings. The antigens were not detected in uterine flushings or culture medium obtained from ovariectomized, E2-treated, and estrous animals. The antigens were also absent in serum and other reproductive and nonreproductive tract tissues. Immunocytochemical analysis demonstrated that antigen staining was limited to the epithelial cells of the deeper uterine glands of the P-dominated animal. Immunoperoxidase staining was diffuse throughout the cytoplasm of these epithelial cells. Thus, the epithelial cells of the uterine glands in the P-dominated cat synthesize and secrete a complex group of P-dependent, uterine-specific proteins that may have potential functional significance during early blastocyst development and implantation.

Histochemical demonstration of a concomitant reduction in neural vasoactive intestinal polypeptide, acetylcholinesterase, and noradrenaline of cat uterus during pregnancy

Noradrenaline, acetylcholinesterase, and vasoactive intestinal polypeptide (VIP) were visualized in uterine nerves of cats by histochemical techniques. Alterations were followed in different regions of the organs at various stages of pregnancy and compared with the situation in non-pregnant controls. Positively stained nerve fibres, the adrenergic type being particularly well developed, were found along the muscle bundles and around blood vessels in the smooth muscle layers, as well as in the mucosa, of both uterine horns and cervix. The nerve supply was especially prominent in the upper part of the cervix. The distribution of VIP-immunoreactive and acetylcholinesterase-positive nerve fibres resembled each other, but they were less numerous than the adrenergic fibres. In the course of pregnancy there was a marked reduction in the number of all positively reacting nerves, so that almost no fibres were visible in the uterine horns near term. A small number of positive nerve fibres was found to remain, however, in the wall of the sterile (empty) horn during unilateral pregnancy. The reduction was less prominent in the cervix, particularly its lower part. Distinct changes were encountered already during early and mid pregnancy in those parts of the uterine wall distended by the growing conceptus, where almost no fibres were seen. The nerve supply was more intact in the non-distended portions located between the fetuses, and especially in the empty horn of unilateral pregnancy. No overt reduction in the number of positively stained nerve fibres was found in the cervix at these pregnancy stages. The results show that marked alterations take place in the uterine autonomie innervation during such an entirely physiological event as pregnancy. There is reason to assume that the histochemical observations reflect both structural and functional alterations in the innervation related both to the type of nerves involved and to the localization of the conceptus.

The effects of estrogen and progesterone on glycogen and the enzymes involved in its metabolism in the cat uterus.

In the endometrium of the spay cat, estradiol treatment causes a drastic reduction in glycogen content. The initiation of simultaneous progesterone treatment causes a replenishment of glycogen with the levels surpassing those observed in the spayed animal. The effect of the hormones on glycogen synthetase I follows the same pattern as the changes in glycogen content, while the effect on phosphorylase a is the mirror image. The total content of glycogen synthetase and phosphorylase do not show appreciable changes with the same hormone treatment. The possible reproductive role of these changes in glycogen content are discussed.

Subcellular compartmentalization of the progesterone receptor in cat uteri following the acute administration of progesterone.

Cytosol and nuclear progesterone receptors in the cat uterus were measured by Scatchard analysis to determine the relationships between dose of progesterone administered and the time following administration with the content of receptor in these two cellular compartments. Cats were ovariectomized, treated for 7 days with estradiol and then injected via the saphenous vein with progesterone. One uterine horn was removed prior to, and the other uterine horn after the injection of progesterone. The amount of cytosol receptor translocated was found to be dose-dependent over the range of 0-200 micrograms of progesterone. A maximum of 40% of the cytosol receptor was depleted even when the amount of progesterone injected was increased. In non-estradiol-primed animals it was also found that approximately 40% of the cytosol receptor was depleted following a progesterone injection. Within 3 h of the injection of 300 micrograms of progesterone, the cytosol and nuclear receptor levels had returned to preinjection values. A second administration of progesterone at 1 or 3 h after the first injection of progesterone caused a partial depletion of the cytosol receptor and an increase in nuclear progesterone receptor concentration. These data suggest that the translocation of cytosol receptor and the appearance of nuclear receptor is dose-dependent until approximately 40% of the cytosol receptor is depleted following a single injection of progesterone, that the retention of nuclear receptor after an acute injection of progesterone is of short duration (less than 1 h), and that the replenishment of cytosol receptor is complete within 3 h.

The uterine progestational response in cats: ultrastructural changes during chronic administration of progesterone to estradiol-primed and nonprimed animals.

AbstractThe development of a progestational response in the glandular epithelium of the cat uterus was studied using electron microscopy and special glycogen staining techniques. In ovariectomized and adrenalectomized animals, the epithelial cells were low cuboidal and lacked an active secretory apparatus. Estradiol treatment induced hypertrophy and the formation of secretory cells which contained numerous profiles of RER, an enlarged Golgi apparatus and apical electron‐opaque secretory granules. The chronic administration of progesterone to estradiol‐primed animals resulted in antagonism of estradiol‐induced cytodifferentiation and the development of a progestational response in the glandular epithelium. After 1 day of estradiol plus progesterone treatment fewer secretory granules were observed, the RER was constricted, and the Golgi apparatus appeared less active; after 2 days, very few secretory granules were observed. Coincident with this antiestrogenic action, progesterone induced additional hypertrophy and the differentiation of cytoplasmic organelles associated with glycogen synthesis. Glycogen deposition occurred between days 2 and 4 of estradiol‐plus‐progesterone treatment. Numerous polyribosomes and circular profiles of membrane appeared to be associated with glycogen deposition. These membranes frequently had glycogen around their perimeter, and sometimes they were found embedded in large glycogen deposits. With continued progesterone treatment, glycogen processing occurred. The RER became extremely dilated, and a few halo granules were observed. Both the dilated RER and the halo granules appeared to be surrounding glycogen, and glycogen was frequently found bound by membrane as well as within the electron‐lucent portion of the halo granule. As glycogen processing continued, the glycogen deposits began to disappear, and some cells appeared to die. The remainder differentiated into shorter residual cells which, after 10–14 days, contained numerous halo granules and constricted RER. The chronic administration of progesterone to nonprimed ovariectomized and adrenalectomized animals resulted in a cytodifferentiation sequence similar to that in the estradiol‐primed animals, except that the response was delayed and was not as uniform between cells from the same animal. Thus, within each epithelial cell of the endometrial glands of the cat, the principal responses induced by progesterone in both estradiol‐primed and nonprimed animals were the synthesis, deposition, and eventual disappearance of glycogen.

THE INFLUENCE OF SERIAL REMOVAL OF FELINE FOETUSES ON RETINAL DEVELOPMENT

The cat, albeit an expensive animal to breed and maintain, affords a relatively large eye ideal for studies on the embryonic retina. This study reports on the efficacy of serial removal of feline foetuses for studies on the histogenesis of the retina. Single feline foetuses were serially removed from the uterus of pregnant cats to determine if there were histologic changes in the foetal retina of the remaining foetuses during subsequent development. The retinas of neonates from mothers that had undergone hysterotomies were compared by light and transmission electron microscopy to those from animals whose mother's had not had hysterotomies. No histologic differences in the retinas were detected between the 2 groups. The duration of gestation was unaffected. This study indicates that it is possible to obtain embryonic retinal tissue at more than one stage of development from the same pregnant female without inducing histologically observable anomalies.

Cytosol and nuclear progesterone receptor in cat uterus and oviduct

Binding of progesterone (P) to a specific cytosol receptor and the in vivo translocation of the cytosol receptor complex to the nucleus was studied in the cat uterus and oviduct. Cytosol and nuclear fractions were prepared from the reproductive tracts of ovariectomized animals treated for 14 days with estradiol (E 2) and from those which were subsequently infused with a P solution for 15 min. In vitro cytosol incubation with [ 3H]-P included cortisol to eliminate binding to CBG. The specific binding of [ 3H]-P reached equilibrium within 90 min at 0°C and was stable for at least 4 h in both tissues. Competitive binding studies revealed the following binding affinities for the cytosol receptor; R5020 (17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione) = P ⪢ corticosterone = E 2 = testosterone. Scatchard analysis of [ 3H] P binding in cytosols from E 2-treated animals yielded a K D of 3.2 × 10 −8 M in the uterus and 2.5 × 10 −8 M in the oviduct. The P binding protein had a sedimentation coefficient of 6.8 S. The content of nuclear receptor was assessed by an exchange assay using R5020. Equilibrium was reached within 4 h at 22°C and remained unchanged for another 2h. The relative binding affinities for the nuclear receptor were; R5020 > P > corticosterone > testosterone > E 2. The K D was 8.2 × 10 −9 M in uterine nuclei and 6.0 × 10 −9M in oviduct nuclei from E 2 + P treated animals. Following P-infusion the decrease in the quantity of specifically bound [ 3H]-P in the cytosol, and the increase in the quantity of specifically bound [ 3H]-R5020 in the nuclei, were significant in both tissues.

Changes in nuclear estradiol receptor and cell structure during estrous cycles and pregnancy in the oviduct and uterus of cats.

Oviducts and uteri were removed from cats at various intervals during the estrous cycle and pregnancy. Systemic blood was drawn on the day the tissues were removed and plasma estradiol (E2) and progesterone (P) were measured by radioimmunoassay. The amounts of nuclear E2 receptor in the oviducts and uteri were determined with an exchange assay; portions of these same organs were fixed and embedded in Araldite for morphological study. In both the oviduct and uterus, the content of nuclear E2 receptor is low in anestrus, rises significantly during proestrus and estrus (E2 -dominated) and then declines significantly during pregnancy (P-dominated). During the estrous phases of the cycle, the oviducts become hypertrophied, fully ciliated and secretory; during pregnancy these organs atrophy, deciliate and stop secreting. The epithehium of the endometrial glands also hypertrophies during the estrous phases of the cycle; during pregnancy, hyperplasia, further hypertrophy, glycogen deposition and formation of unique basophilic granules characterize the progestational response in this species. Thus, although both uterus and oviduct are depleted of nuclear E2 receptor during pregnancy, the endometrial glands hypertrophy and show altered and heightened secretion while the oviduct atrophies and dedifferentiates.

Electron microscopy of adrenergic, cholinergic, and “p-type” nerves in the myometrium and a special kind of synaptic contacts with the smooth muscle cells

In the cat uterus, three types of axons have been identified by electron microscopy on the basis of the appearance of the synaptic vesicles in the axon varicosities following treatment with 5-hydroxydopamine: (1) most axons were adrenergic, with numerous small osmiophilic vesicles of a diameter of approximately 50 nm. together with large (100 to 150 nm. in diameter) granules, (2) some axons contained only empty small granules together with the large granules; these are probably cholinergic, and (3) a small number of the axon varicosities had only large-sized vesicles with a moderately electron-densecontent. They are interpreted as a polypeptide type of nerves (“p-terminals”). Close appositions at a distance of 25 nm. were sometimes found between the varicosities. A specialized neuromuscular connection was found: the muscle cells at “the end” of muscle bundles extended small stout processes, containing numerous myofilaments, onto a small nerve bundle, the distance being 20 to 25 nm.

An insoluble, dityrosine-containing protein from uterus

Attempts to isolate elastin from rat and cat uterus by extraction with hot NaOII yielded a fluorescent (405 nm emission) protein rich in polar amino acids, and containing dityrosine and trace amounts of hydroxyproline. The alkali-insoluble protein is similar in composition to extractable acidic protein fractions isolated from various tissues by us and others. This insoluble fraction may represent a more highly polymerized form of the soluble protein, or may result from covalent bonding of the soluble protein to the elastin matrix. The dityrosine content was higher in the alkali-insoluble protein than in the alkali-extractable protein and increased in both during pregnancy.

Membrane potential and ion content in cat and guinea-pig myometrium and the response to adrenaline and noradrenaline.

1. Cats, virgin and 17 days pregnant, and guinea-pigs, virgin and 14-60 days pregnant, or treated for 1-8 days with oestradiol+progesterone, were used. The response of the uterus to adrenaline and noradrenaline was observed and, in pieces from the same tissues, the resting and active membrane potentials were recorded and the ionic content was determined.2. Adrenaline and noradrenaline relaxed the virgin cat uterus, adrenaline being 20-100 times more potent in vivo and about 10 times or less in vitro.3. Adrenaline and noradrenaline caused contraction of the early pregnant cat uterus, the ratio of potency being about 1.4. Adrenaline and noradrenaline had a biphasic effect on the guinea-pig uterus in all conditions. The ratio of potency was about 1.5. The mean membrane potential was 48 mV in virgin cat uterus and 64 mV on the seventeenth day of pregnancy.6. In guinea-pigs the average membrane potential increased from 38 mV in the virgin uterus to 58 mV on the thirtieth day of pregnancy. A similar increase was produced by eight daily injections of 5 mug oestradiol and, on the last 4 days, additional 1.5 mg progesterone.7. In the cat, no significant change in K and Na content was observed during pregnancy. The intracellular chloride content, however, rose from 51.5 m-moles/1. fibre water in the virgin uterus to 89 m-moles in the early pregnant uterus. As a result, the calculated chloride equilibrium potential changed from - 25 mV in virgin uterus to - 11 mV in pregnant uterus.8. In the guinea-pig no significant change in ion content was observed and the calculated potassium and chloride equilibrium potentials remained both unaltered during pregnancy.9. In contrast to guinea-pig uterus in all conditions, and to virgin cat uterus, early pregnant cat uterus was not spontaneously active and excess calcium caused no hyperpolarization.10. The reversal of the uterine response to adrenaline as a result of pregnancy is discussed in relation to the increase of the intracellular chloride content which was only observed in the cat.