Biomedical subjects

M H Kaufman

Publications and source records attributed to M H Kaufman.

At least 109 records · Page 6Linked to original sources

PubMed1989

Prenatal development and innervation of the circumvallate papilla in the mouse.

The embryonic development of the circumvallate papilla in the mouse is described. Serial sections of Day 11 to Day 18 mouse embryos were stained by Linder's silver method and examined to determine the temporal events in relation to circumvallate papilla formation. This was complemented by scanning electron micrographs. On Day 13, the earliest sign of a single median circumvallate papilla formation was visible as an epithelial invagination which had bilateral nerve innervation. Scanning electron micrographs of this stage showed a median flattened area demarcated at its periphery by cells invaginating from the surface. On Day 14, the epithelial invagination appeared like an inverted cup with a dense nerve plexus within its core. By the afternoon of Day 14 a furrow had formed by a split in the epithelium. During that period the surface morphology changed from a flattened area to a central dome-shaped structure. As development progressed the furrow became accentuated by the elevation of its lateral walls. Nerve fibres penetrated the epithelium, but taste bud differentiation was not easily observable. The dense innervation of the circumvallate papilla was established from the start of its formation. The role of these nerves as an inductive factor or as providing a trophic effect on the formation of the circumvallate papilla remains to be investigated.

Animals↗

PubMed1988

Influence of postovulatory aging on chromosome segregation during the second meiotic division in mouse oocytes: a parthenogenetic analysis.

A high incidence of parthenogenetic activation was observed when postovulatory aged mouse oocytes were exposed briefly to hyaluronidase in culture medium at 18-26 h after the human chorionic gonadotropin injection for inducing superovulation. The majority of the activated oocytes extruded a second polar body and developed a single haploid pronucleus. Cytogenetic analysis of this class of parthenogenone at metaphase of the first-cleavage mitosis has clearly demonstrated that the completion of the second meiotic division in activated aged oocytes is not associated with a significant increase in the incidence of chromosome segregation errors. The increasing postovulatory age of oocytes prior to activation was observed to significantly decrease the capacity of activated oocytes to extrude the second polar body.

Animals↗

PubMed1988

Effect of exogenous hormones on the ovulation of primary and secondary oocytes in LT/Sv strain mice.

LT/Sv strain mice ovulate both primary and secondary oocytes. These are fertilizable and give rise to digynic triploid and normal diploid conceptuses, respectively. A previous study [Kaufman and Speirs, 1987] had indicated that just over 20% of embryos recovered on the 10th day of gestation from spontaneously ovulating females had a triploid chromosome constitution. This value was considerably lower than might have been expected by extrapolation from earlier studies in which LT/Sv mice had been given exogenous gonadotrophins. In the present study, therefore, cytogenetic analysis of fertilized eggs was performed at the first cleavage mitosis in (1) spontaneously ovulating females mated to F1 hybrid males, and (2) superovulated females mated to similar males. Additional females from group (1) were autopsied on the 10th day of gestation, and the ploidy of embryos isolated at this stage of gestation was determined. Exposure to exogenous gonadotrophins significantly increased the proportion of eggs that were ovulated as primary oocytes (34.4%), compared to the situation observed following spontaneous ovulation (24.4%). All the triploids encountered in both series were of the digynic type and characteristically (for LT/Sv mice) had an oocyte-derived set with 40 chromosomes present, and a sperm-derived set containing 20 chromosomes. Similar numbers of eggs were recovered from spontaneously ovulating females on the 1st and 10th days of gestation, and the incidence of triploidy observed on the 10th day was 22.1%. The influence of exogenous hormones in increasing the "spontaneous" level of triploidy in LT/Sv and in other strains of mice is briefly reviewed.

Animals↗

PubMed1988

Cytogenetic study of silver-staining NOR in 8-cell-stage mouse blastomeres fused to 1-cell-stage embryos.

Isolated blastomeres from 8- to 16-cell-stage embryos were fused by standard micromanipulatory means with either unfertilized eggs or fertilized or haploid parthenogenetically activated pronuclear-stage embryos. The hybrid eggs/embryos were incubated overnight in the presence of Colcemid until they had entered the first cleavage division. Air-dried chromosome preparations were then stained with silver nitrate in order to detect active nucleolar organizing regions (NOR). While control unfertilized eggs and 1-cell-stage fertilized and parthenogenetically activated embryos showed no evidence of silver-staining NOR-positive regions, the metaphase plates from 8- to 16-cell embryos showed characteristic NOR-positive regions, while their interphase nuclei also showed a characteristic reticular staining appearance. When hybrids between blastomere nuclei and unfertilized eggs were examined, none of the blastomere nuclei entered mitosis. However, when hybrids between blastomere nuclei and fertilized embryos were examined, in two thirds of the embryos, a single blastomere-derived diploid metaphase plate was present in association with two pronuclear-derived haploid metaphase plates. In most instances, the blastomere-derived chromosomes did not display silver-nitrate-staining NOR. Similar findings were observed when the blastomere-derived chromosomes in hybrids between blastomere nuclei and haploid parthenogenetic embryos were analysed. In the majority of cases, when blastomere nuclei remained in interphase, the characteristic silver-nitrate-staining fine reticular material either was not seen, or the nuclear contents were dispersed into clumps of chromatin-like material. Occasionally, the diploid chromosomes in the hybrids displayed morphological abnormalities. Our findings suggest that the cytoplasm of activated (but not nonactivated) 1-cell embryos is capable of influencing the nucleolar activity of the introduced 8- to 16-cell nuclei, effectively erasing from their chromosomes the memory of at least three previous rounds of rRNA synthesis.

Animals↗

PubMed1988

Observations on the development of the aortico-pulmonary spiral septum in the mouse.

The differentiation of the bulbar region and arterial outflow tract of the developing mouse heart was investigated by analysing serial transverse sections through the heart region of mouse embryos isolated between the eleventh and fifteenth day of gestation. Over this period of time, we observed the configurational and cellular changes occurring within the wall of this region of the heart, being particularly interested in the histological appearance of the cellular constituents of the spiral ridges and their eventual apposition and fusion to form the spiral septum. We observed that the mesenchyme cells of which the ridges are largely composed are initially orientated in the direction of the outflow tract, but subsequently realign themselves when the individual ridges become oblique and spiral in their configuration. The tissue that gives rise to the spiral septum, namely the 'bulbar cushions' proximally, and the 'truncal cushions' in the rest of the outflow tract appear at all stages to be continuous structures. We saw no evidence that they initially develop as separate entities, and subsequently fuse. Furthermore, no evidence of cell death was observed in either the mesenchyme tissue or in the wall of the outflow tract. We have therefore suggested that, contrary to the findings of Pexieder (1978), pre-programmed cell death probably plays no significant part in the development of the spiral septum in the mouse, though we cannot exclude the possibility that there may be species differences between the events associated with spiral septum formation in avian and mammalian embryos. We conclude from our histological observations that the changes that occur in the arterial outflow tract in the mouse are probably brought about by the haemodynamic effect of the forces of blood flow impinging on its walls and that this initiates a series of events that are controlled to a considerable degree by pre-programmed genetic instruction.

Animals↗

PubMed1987

Ovulation and fertilization of primary and secondary oocytes in LT/Sv strain mice.

In this study, the chromosome constitution of both unfertilized oocytes and fertilized eggs isolated from the oviducts of LT/Sv strain mice were analyzed. Air-dried chromosome preparations from unfertilized oocytes revealed that about one-third of those examined were ovulated as primary oocytes. These were arrested at metaphase of the first meiotic division and exhibited the characteristic "tetrad" chromosome configuration. The remaining two-thirds of the unfertilized oocytes were ovulated at metaphase of the second meiotic division. The fertilized eggs were isolated from the oviducts of LT/Sv females previously mated to (C57BL x CBA) F1 hybrid males. Analysis of the fertilized eggs at metaphase of their first cleavage mitosis revealed that about one-third of the eggs examined were digynic triploids, whereas the remaining two-thirds had the normal diploid chromosome constitution. In the triploids, the 40 female chromosomes present (mouse, n = 20) were derived from a single diploid pronucleus formed after the extrusion of a first polar body, and following the monospermic fertilization of primary oocytes. The female pronuclear-derived chromosomes invariably exhibited "homologous pairing," and these were associated at their centromeres. The ovulation, penetration, and subsequent fertilization of primary oocytes is an extremely unusual phenomenon in mammals and only appears to occur on a regular basis in LT/Sv mice. The premature "cytoplasmic maturation" of these oocytes is of interest, as they clearly have the same developmental capacity as secondary oocytes. The significance of these observations in relation to folliculogenesis and litter size in LT/Sv mice is discussed.

Animals↗

PubMed1987

Cytogenetic analysis of first cleavage fertilized mouse eggs following in vivo exposure to ethanol shortly before and at the time of conception.

In this study, the chromosome constitution of mouse eggs exposed in vivo to a dilute solution of ethanol during specific stages of the first and second meiotic divisions was determined at the first cleavage mitosis. Exposure to ethanol prior to the completion of the second meiotic division induced an incidence (7-10%) of aneuploidy involving only one chromosome in 98% of malsegregation events. This investigation provides indirect evidence that ethanol may induce aneuploidy by disrupting the functioning of the meiotic spindle. Karyological analyses of chromosome spreads prepared at the first cleavage metaphase suggest that only a small proportion of the total chromosome complement may be induced to undergo malsegregation.

Aneuploidy↗

PubMed1987

The postimplantation development of spontaneous digynic triploid embryos in LT/Sv strain mice.

When spontaneously ovulating LT/Sv female mice are mated with fertile males, between one third and one half of the zygotes analyzed at the first cleavage mitosis are found to be triploid. This is due to the fact that LT/Sv females ovulate both primary and secondary oocytes, all of which are capable of being fertilized. Fertilization of the former group results in the production of digynic triploid conceptuses, while their diploid littermates result from the fertilization of normal secondary oocytes. The present study was therefore carried out in order to investigate the 'spontaneous' level of triploidy in these mice, and to provide insight into the developmental fate of the LT/Sv triploid embryos, as previous studies had indicated that in this species triploids invariably fail to develop beyond the early postimplantation period. This study revealed that when autopsies were carried out on the 7th and 8th days of gestation, it was generally difficult to distinguish between the karyologically normal diploids and the digynic triploid conceptuses when only morphological criteria were used. However, by the 10th day of gestation, the triploid conceptuses could usually be readily distinguished from their diploid littermates by their smaller size and (occasionally) by their disorganized or abnormal morphological appearance.

Animals↗

PubMed1987

The sphenoidal canal.

The sphenoidal canal is described in perinatal material, and was found in 57 out of 58 disarticulated human skeletal remains collected in Egypt between 1918 and 1928. The canal showed considerable variations in extent and morphology, but ran essentially from the region of the developing rostrum of the sphenoid in an anterosuperior direction to end in the tuberculum sellae, immediately behind the optic groove. The canal represents the impression left by the remnants of the sphenoidal synchondrosis between the presphenoid and postsphenoid. The arrangement suggests that as a growth area this synchondrosis is of limited importance once the perinatal period is reached. The spatial relationship between craniopharyngeal and sphenoidal canals is described.

Egypt↗

PubMed1986

The histochemical identification of primordial germ cells in diploid parthenogenetic mouse embryos.

An attempt has been made to improve the early post-implantation development potential of diploid parthenogenetic mouse embryos by transferring parthenogenetic blastocysts to one uterine horn of a pseudopregnant recipient and a similar number of fertilized embryos to the contralateral horn. In control studies, diploid parthenogenetic embryos were transferred to both uterine horns of appropriate recipients. Unfortunately no obvious advantage appeared to be gained by carrying out the former manoeuvre. A significant improvement in the development potential of the parthenogenones could have indicated that their poor post-implantation survival might have been associated with a deficiency, possibly of hormonal origin, in the functioning of their decidual reaction. However, sufficient somite-containing parthenogenetic embryos were obtained in this study to allow a comparison to be made between them and fertilized embryos that were morphologically at a comparable stage of development. The parthenogenones were found to have a markedly smaller crown-rump length than their fertilized counterparts. A high proportion of both the parthenogenetic and fertilized embryos were subsequently fixed and appropriately stained in order to localize alkaline phosphatase activity. The analysis of this material clearly demonstrated that parthenogenetic mouse embryos are in fact capable of producing primordial germ cells. The latter were recognized by their morphology, histochemical staining appearance, and characteristic location, being found in the early 'turned' embryos within the dorsal mesentery in close proximity to the developing gut tube, and in the more advanced limb-bud stage embryos within the gonadal ridges.

Animals↗

PubMed1986

The secretions of the cumulus-oocyte complex in relation to fertilization and early mouse embryonic development: a histochemical study.

A study has been made of the histochemical composition of the murine cumulus-oocyte complex and zona pellucida following treatment of immature females with exogenous gonadotrophins. Selected developmental stages were studied in detail, namely the ovulated and unfertilized egg, the fertilized oocyte and the preimplantation embryo. In addition, the histochemical features observed in normal fertilized embryos have been compared with those of haploid and diploid parthenogenetic embryos at comparable stages following activation. Shortly after fertilization, glycosaminoglycans, which form a major component of the extracellular matrix surrounding the cumulus cells, become incorporated into the zona pellucida of the fertilized egg. In oocytes with few or no attendant cumulus cells, there appeared to be a diminished uptake of glycosaminoglycans and a reduced intensity of the zona staining reaction to Alcian Blue. In these oocytes, uptake of glycosaminoglycans appeared to be from the secretions lining the oviduct. There was little incorporation of the glycosaminoglycans from the extra-cellular matrix of the surrounding cumulus cells into the zona pellucida in unfertilized or parthenogenetic eggs despite the activation stimulus. After fertilization or activation, the zona pellucida became increasingly PAS-positive. Enzymic studies clearly indicate that the composition of the zona pellucida of the early embryo is histochemically different from the zona that surrounds the oocyte in the preovulatory follicle. These findings are discussed in relation to the decreased viability of embryos from oocytes which have been ovulated.

Alcian Blue↗

PubMed1986

Chromosome analysis of single-pronuclear haploid parthenogenetic blastocysts and their inner cell mass derivatives.

Single-pronuclear haploid parthenogenetically activated mouse embryos were transferred to the oviducts of suitable recipients. One group of embryos was isolated at the morula stage and subsequently allowed to develop to the expanded blastocyst stage in vitro. Intact embryos were either analysed by the air-drying technique at that stage to determine their total cell number and ploidy, or treated by immunosurgery to isolate their inner cell mass. These were either analysed to establish their total cell number and ploidy, or retained in culture for an additional 24h or 72h. The inner cell mass derivatives were then analysed to establish the total cell number and ploidy. A second group of recipients was ovariectomized on the 4th day of pseudopregnancy, treated with Depo-Provera and blastocysts recovered 5 or 6 days later. The 'delayed' blastocysts recovered were treated by immunosurgery, and the inner cell masses isolated and either analysed at this time or transferred to culture for 72h, 96h or 144h. As in the previous groups, the inner cell mass derivatives were analysed to establish the total cell population present and their ploidy. The analysis of this material was found to be technically particularly difficult, though in general the non-'delayed' embryos and their inner cell mass derivatives yielded higher success rates than the 'delayed' inner cell mass derivatives. The 'delayed' inner cell masses initially contained on average about twice the number of cells compared to the number present in those isolated from the non-'delayed' expanded blastocysts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Differentiation of the myocardial rudiment of mouse embryos: an ultrastructural study including freeze-fracture replication.

The differentiation of the myocardial rudiment was examined in mouse embryos, isolated between the afternoons of the eighth and ninth days of gestation, by means of transmission electron microscopy of ultrathin sections and of freeze-fracture replicas; some of the material used for sectioning was labelled with ruthenium red. Formation of the presumptive pericardial cavity commences during the late presomite stage (afternoon of the eighth day) and the myocardial rudiment originates in situ as a thickening of the splanchnic pericardial lining. Initially, the myocardium comprises an epithelium or plate directly exposed to the pericardial lumen and overlying a separate layer of endocardial elements. As the heart tube bulges into the pericardial coelom, it becomes surrounded by a sleeve of myocardium which thickens and stratifies during the ninth day and subsequently (on the tenth day) acquires an epicardial covering of flattened cells. The myocardium commences pulsations at or about the 3-4 somite stage (morning of the ninth day) by which time the myoblasts already contain striated myofibrillae and specialised cell junctions. From its earliest appearance, the myocardial plate contains tight junctions and desmosomes between the lateral borders of the apical parts of the myoblasts. Gap junctions soon appear in the same regions and they increase in number and extent, as the myoblasts elongate and divide, thus establishing contact in various planes; they are supplemented by the formation of fasciae adherentes and of more desmosomes. On the other hand, tight junctions decline in extent and are eventually confined to the epicardium. Other features such as caveolae and T-tubules are not established by the end of the ninth day and coupling arrangements of the sarcoplasmic reticulum are only in the rudimentary stages of formation.

Animals↗

PubMed1985

Pregnant and pseudopregnant mice produce a low cytotoxic alloantibody response when challenged by fetal but not adult F1 alloantigens.

The tertiary cytotoxic alloantibody response of syngeneically pregnant, pseudopregnant and non-pregnant BALB/c mice immunised with semi-allogeneic lymphocytes from fetal and adult (CBA X BALB/c)F1 donors was investigated by the microcytotoxicity method. The pregnant and pseudopregnant animals showed a significantly lower response to fetal alloantigens compared to that towards adult alloantigens (P less than 0.001). In contrast, control non-pregnant recipients showed no diminution of response to fetal alloantigens. These observations suggest that the hormonal status of pregnancy, even in the absence of a conceptus, permits a low cytotoxicity antibody response when challenged specifically by fetal, but not when challenged by adult, F1 alloantigens.

Animals↗

PubMed1985

An hypothesis regarding the origin of aneuploidy in man: indirect evidence from an experimental model.

Recent studies have clearly demonstrated that aneuploidy may be induced in about 10 to 20% of oocytes and recently ovulated eggs when female mice are given an intragastric injection of a dilute solution of ethanol. Similar rates of aneuploidy have also been observed when recently ovulated eggs are briefly exposed in vitro to a dilute solution of ethanol in tissue culture medium. These findings are briefly reviewed, and observations made on the possible underlying mechanism of induction of chromosome malsegregation in the ethanol exposed groups. Attention is drawn to evidence from a wide range of studies on the effect of ethanol, acetaldehyde (its primary metabolite), and anaesthetics on cell division and chromosome segregation in an attempt to substantiate an hypothesis regarding the mode of action of these agents. In the light of this information, it is hypothesised that exposure to ethanol probably interferes with the normal functioning of the cytoskeletal elements of the spindle apparatus, or its precursor elements, during the first or second meiotic divisions. An attempt is also made to account for the very high incidence of aneuploid conceptuses in man, a high proportion of which are spontaneously aborted. It is hypothesised that exposure to ethanol and other spindle active agents during appropriate stages of oogenesis (in particular during the first meiotic division), and possibly also during spermatogenesis, may be important aetiological factors in a proportion of those cases of spontaneous abortion with a numerical chromosome anomaly for which no other obvious cause is recognised. If it is valid to extrapolate from these experimental findings to the clinical situation in man, it is suggested that attention should also be drawn to the potentially greater hazard to the conceptus which could result from maternal alcohol consumption at and shortly before conception.

Acetaldehyde↗

PubMed1984

Influence of ethanol on chromosome segregation during the first and second meiotic divisions in the mouse egg.

This study was carried out to investigate the influence of ethanol on chromosome segregation during the first and second meiotic divisions. Female mice were given a single intragastric injection of a dilute solution of ethanol either just before or at various times after the HCG injection for inducing superovulation. The mice were mated, and the chromosome constitution of fertilized eggs was determined at the first cleavage mitosis. The technique employed allowed the male- and female-derived pronuclear sets to remain as two discrete groups. Exposure from 1.5 h before to 17 h after the HCG injection induced a high incidence of aneuploidy (15-25%) involving in over 90% of cases only one chromosome, so that either 19 or 21 instead of the normal complement of 20 chromosomes were present in one of the two sets (a previous study using a "marker" chromosome has demonstrated that the nondisjunction induced here invariably involves the female set). We suggest these findings draw attention to the susceptibility of chromosome segregation in female germ cells to interference by ethanol and that the mode of action is likely to be via interference with the normal functioning of the spindle apparatus. It is possible that interference with meiotic chromosome segregation by spindle-acting agents such as ethanol might account for a proportion of human spontaneous abortions with similar chromosomal defects where no other obvious cause is apparent.

Aneuploidy↗

PubMed1984

The development potential of ethanol-induced monosomic and trisomic conceptuses in the mouse.

The development potential of fertilized embryos isolated from female mice previously given a single dose of either a dilute solution of ethanol or distilled water (controls) by mouth was studied. Exposure to ethanol occurred at various times during the cycle leading to ovulation and shortly after fertilization. The chromosome constitution of all preimplantation embryos isolated from these females was determined either at the first cleavage mitosis or at the morula stage. The incidence of aneuploidy in the ethanol-exposed groups at these times was approximately 19% and 13.5%, respectively, with a similar number of monosomic and trisomic conceptuses observed at these times. In addition, about 2% of all conceptuses examined were triploid. Further females were autopsied on the 10th or 11th day of gestation, though the chromosome constitution of only the morphologically abnormal or developmentally retarded embryos was determined. Eight embryos out of a total of 16 studied in the ethanol-exposed group were either aneuploid or triploid, whereas in the control group only one out of 11 examined proved to be aneuploid. The triploids and ethanol-induced aneuploid conceptuses appeared to be capable of surviving to the morula stage but generally failed to survive to the 10th/11th day. No monosomics were in fact observed in the postimplantation series. The present findings are briefly discussed with reference to the possible pathogenesis of spontaneous abortions in man, which often possess similar types of chromosomal anomalies.

Abnormalities, Drug-Induced↗

PubMed1984

Influence of injected pluripotential (EK) cells on haploid and diploid parthenogenetic development.

A number of pluripotential embryo-derived EK cells were introduced into the blastocoele of haploid and diploid parthenogenetic embryos which were subsequently transferred to suitable recipients. At autopsy on day 10 or 11 of pseudopregnancy 22% of decidua in the diploid series contained somite-stage embryos while an additional 12% contained abnormal egg cylinder-like sacs. In the haploid series, 7% of the decidua contained somite-stage embryos and an additional 5% contained abnormal 'sacs'. In 'injected' diploid and haploid 'controls' in which the zonae were pierced with an empty injection pipette 3% and 0% respectively of decidua in these two series contained somite-stage embryos, while an additional 17% and 3% respectively of decidua in these two series contained abnormal sacs. GPI analysis revealed that the EK cells were incorporated into somite-stage conceptuses in only one third of the diploids and in none of the haploid embryos. Although the presence of EK cells considerably increases the chance of normal embryonic development taking place, a detectable contribution from the EK cells into the resulting somite-stage embryo is apparently not necessary. Possible mechanisms allowing successful early post-implantation development to occur in this study are discussed.

Animals↗