Pregnancy diagnosis in owl monkeys (Aotus trivirgatus): evaluation of the hemagglutination inhibition test for urinary chorionic gonadotropin.

The Subhuman Primate Pregnancy Test was evaluated as a means of detecting urinary chorionic gonadotropin to aid in pregnancy diagnosis in owl monkeys. Using radioimmunoassay, the excretion pattern of chorionic gonadotropin from pregnant owl monekys was delineated, the hormone being detected from 16 weeks prepartum until birth. By comparison, the pregnancy test kit detected chorionic gonadotropin between the fourteenth week prepartum and the last week of gestation with 94% accuracy. In a 2-year study using a simplified urine collection technique, the Subhuman Primate Pregnancy Test was shown to be a valuable procedure for diagnosing pregnancy and detecting spontaneous abortions in owl monkeys.     

Levels of metallothionein messenger RNA in foetal, neonatal and maternal rat liver

We have used translation in vitro of hepatic polyadenylated RNA to characterize the levels of metallothionein mRNA in foetal, neonatal, pregnant and nulliparous rats. The translation products of foetal hepatic metallothionein mRNA increased relative to other mRNA translation products from day 18 of gestation to birth and attained a maximum, maintained throughout suckling, which is tenfold above 17-day foetal hepatic levels and fourfold above adult levels. Maternal liver metallothionein mRNA decreased fivefold between 17 days and 20 days of gestation, rose sharply immediately before birth, and was low throughout lactation.     

Adenine nucleotides in foetal rat liver cells. Compartmentation and variation with age.

The digitonin method for the separation of cytosolic and mitochondrial fractions was applied to liver cells isolated from foetal rats. The cytosolic [ATP]/[ADP] ratio approximately doubles during the last 4 days of gestation, whereas the mitochondrial ratio remains constant. In the presence of oligomycin and added glucose, the cytosolic [ATP]/[ADP] ratio does not increase with age, but is still considerably higher than the mitochondrial ratio. Without added glucose, and when the glycogen content of foetal liver is still very low (more than 3 days before birth), the cytosolic [ATP]/[ADP] ratio in the presence of oligomycin becomes very low and equal to the mitochondrial ratio. It is concluded that the increasein the cytosolic [ATP]/[ADP] ratio during the last 4 days of gestation is solely due to enhanced mitochondrial activity in this period. Atractyloside and bongkrekic acid do not influence the O2 consumption, nor the [ATP]/[ADP] ratios in either compartment of foetal liver cells. Respiration of isolated foetal mitochondria, however, is strongly inhibited by both compounds. The implications of these findings are discussed.     

Detection of parturition in cow and mare by a useful warning system

An automatic device that uses the prolonged elevated position of the tail as an index of parturition in the cow and the mare has been tested, and the tail movements which accompany eliminative behavior and other events have been recorded in pre-partum vs mid-gestation animals.During the last week of pregnancy in the cow and the last 48 h in the mare, the mean elevated positions of the tail, corresponding to urination and defecation, increased from 19.5 to 27.6 from 16.4 to 17.4 per day in the mare.The presence of tail movements lasting more than 2 min in duration occurred at the time of parturition in the cow and the mare, but were also detected occasionally from 2 to 5 days before parturition.The use of a warning system which screens out all tail movements lasting less than 150 sec was found suitable for monitoring the time of parturition, especially in the mare. In this species, the number of false alarms occurred only one or two times during the 48 h preceeding parturition, while in the cow such movements lasting less than 240 sec will eliminate the alarms related to fetal kinesis or uterine contractions rather than parturition.     

Impact of maternal undernutrition during the periconceptional period, fetal number, and fetal sex on the development of the hypothalamo-pituitary adrenal axis in sheep during late gestation

Evidence from epidemiologic, clinical, and experimental studies has shown that a suboptimal intrauterine environment during early pregnancy can alter fetal growth and gestation length and is associated with an increased prevalence of adult hypertension and cardiovascular disease. It has been postulated that maternal nutrient restriction may act to reprogram the development of the pituitary-adrenal axis, resulting in excess glucocorticoid exposure and adverse health outcomes in later life. It is unknown, however, whether maternal nutrient restriction during the periconceptional period alters the development of the fetal pituitary-adrenal axis or whether the effects of periconceptional undernutrition can be reversed by the provision of an adequate level of maternal nutrition throughout the remainder of pregnancy. We have investigated the effect of restricted periconceptional nutrition (70% of control feed allowance) from 60 days before until 7 days after mating and the effect of restricted gestational nutrition from Day 8 to 147 of gestation on the development of the fetal hypothalamo-pituitary adrenal (HPA) axis in the sheep. In these studies, we have also investigated the effects of fetal number and sex on the pituitary-adrenal responses to periconceptional and gestational undernutrition. In ewes maintained on a control diet throughout the periconceptional and gestational periods, fetal plasma ACTH concentrations were higher and the prepartum surge in cortisol occurred earlier in singletons compared with twins. Plasma ACTH concentrations were also significantly higher in male compared with female singletons, and in twin fetuses, the prepartum surge in cortisol concentrations occurred earlier in males than in females. Periconceptional undernutrition resulted in higher fetal plasma concentrations of ACTH between 110 and 145 days of gestation and a significantly greater cortisol response to a bolus dose of corticotropin-releasing hormone in twin, but not singleton, fetuses in late gestation. We have therefore demonstrated that fetal number and sex each has an impact on the timing of the prepartum activation of the HPA axis in the sheep. Restriction of the level of maternal nutrition before and in the first week of a twin pregnancy results in stimulation of the fetal pituitary-adrenal axis in late gestation, and this effect is not reversed by the provision of a maintenance control diet from the second week of pregnancy.     

Critical periods for foetal mortality in gilts identified by analysing the length distribution of mummified foetuses and frequency of non-fresh stillborn piglets

The objective of this study was to investigate the timing of foetal mortality in gilts of a segregating F2 cross of Large White and Meishan pigs on the basis of the length distribution of mummified foetuses and the frequency of non-fresh stillborn piglets in order to establish whether critical periods for foetal mortality exist. All expelled conceptuses and placentae of 192 farrowing gilts with a normal health status were meticulously investigated to recover all mummified foetuses. The length of each mummified foetus was measured. The predicted number of foetuses present per gilt at the early foetal stage of gestation was calculated as the sum of numbers of mummified foetuses and non-fresh stillborn, fresh stillborn and liveborn piglets. Foetal loss was calculated as the sum of mummified foetuses and non-fresh stillborn piglets. The average foetal mortality rate per gilt was 8.7%. In total 162 mummified foetuses were found (average 0.84 per litter), ranging in length from 0.4 to 33.0 cm. This indicates a range in foetal age at death of approximately 35-100 days. Although mummified foetuses of all lengths within the above mentioned range were found, relatively many had a length of less than 4 cm or of 10-21 cm. The total number of non-fresh stillborn piglets (i.e. late foetal deaths) was 58 (average 0.30 per litter). It can be concluded that foetal mortality occurred in these gilts throughout the period from day 35 to term, with relatively high incidences at the early foetal stage (days 35-40), shortly after mid-pregnancy (days 55-75) and after approximately day 100 of gestation. These three periods coincide with reported periods of change in porcine placental growth.     

Influence of level of nutrition during late pregnancy on reproductive productivity of red deer I. Adult and primiparous hinds gestating red deer calves

The present study aimed to relate feed intake of red deer hinds during late pregnancy to dam body condition, foetal development and calf growth. Across 3 years, multiparous (n=33) or primiparous (n=18) hinds with known conception dates were housed in individual pens from days 150-220 of pregnancy, during which time they were each offered one of three daily allowances of pelletised rations (11 MJME/kg DM; 16% CP): high (H; ad libitum), medium (M; approximately 30% less; multiparous hinds only) and low (L; approximately 50% less). Restricted intake levels were retrospectively calculated from the mean intake of H hinds in the previous week. Hinds were returned to pasture at day 220 and calving was closely monitored. Liveweights, body condition score (BCS), and lactation score (LS) of hinds were recorded weekly from day 130 of pregnancy until calves were weaned at 12 weeks of age. Calves were tagged and weighed at birth, and subsequently weighed at 7 and 12 weeks of age. Additionally, hinds in the first year of study underwent CT scans on days 150 and 215 of pregnancy to assess compositional changes of the dam and conceptus. Mean daily ad libitum intakes of H hinds increased from 1.8 to 2.0 kg DM (0.6-0.7 MJME/kg0.75) at around day 150 to 2.8-3.2 kg DM (0.8-0.9 MJME/kg0.75) by day 220. Those of M and L hinds peaked at 1.8 and 1.6 kg DM, respectively, by day 220. This was reflected in significant treatment effects on liveweight gain and change in BCS and LS by the time of calving. CT scans indicated a significant treatment effect by day 215 on the mass of hind tissues (fat and lean) and a non-significant trend on conceptus/foetal weights. Despite apparent differences in foetal growth trajectories, there were no discernable treatment effects on sex-adjusted birth weights. However, there was an unexpectedly wide spread in calving dates that reflected considerable variation in gestation length. Furthermore, gestation length was negatively correlated with change in hind liveweight (but not BCS) between days 150 and 220 of pregnancy for all groups of hinds (P<0.05). Of three neonatal calf mortalities, none were related to overweight (dystocia) or underweight (non-viability) calves. Subsequent growth rates (g/day) of surviving calves did not reflect prior treatment of their dams, although variation in birth date influenced weights on specific dates. It is concluded from this study that while variation in nutrition to hinds during the last trimester may strongly influence foetal development, under conditions of modest feed imbalance, variation in gestation length compensates to ensure optimisation of birth weight.     

Variation in the amounts of hepatic copper, zinc and metallothionein mRNA during development in the rat.

Amounts of hepatic metallothionein mRNA were assessed in RNA from foetal and neonatal rat livers by using dot-blot hybridization. Metallothionein mRNA began to increase about day 15 of gestation and reached a foetal maximum of 5-fold higher than adult values between 18 and 21 days of gestation. The amounts fell significantly for the first 3 days after parturition, and rose again to 6-fold above adult values 6 days after birth. By 15 days after birth the metallothionein mRNA had declined to adult amounts. In comparison, amounts of ornithine transcarbamoylase mRNA did not vary greatly during development. Hepatic zinc concentrations increased from day 14 of gestation to a maximum just before birth, and remained above adult values until 30 days after birth. From 14 days of gestation to 8 days after birth, hepatic copper concentrations were about 4-fold higher than in the adult, but a substantial increase (to about 9-fold higher than in the adult) occurs between 10 and 15 days after birth. CdCl2 administered to pregnant rats on day 18 of gestation was shown to block placental transfer of zinc, and we found decreased foetal hepatic zinc concentration after the CdCl2 treatment, but this failed to cause a significant decrease in metallothionein mRNA, suggesting that zinc may not be the primary inducer of hepatic metallothionein mRNA during foetal life.     

Impairment of rat fetal beta-cell development by maternal exposure to dexamethasone during different time-windows

Aim

Glucocorticoids (GCs) take part in the direct control of cell lineage during the late phase of pancreas development when endocrine and exocrine cell differentiation occurs. However, other tissues such as the vasculature exert a critical role before that phase. This study aims to investigate the consequences of overexposure to exogenous glucocorticoids during different time-windows of gestation for the development of the fetal endocrine pancreas.

Methods

Pregnant Wistar rats received dexamethasone acetate in their drinking water (1 µg/ml) during the last week or throughout gestation. Fetuses and their pancreases were analyzed at day 15 and 21 of gestation. Morphometrical analysis was performed on pancreatic sections after immunohistochemistry techniques and insulin secretion was evaluated on fetal islets collected in vitro.

Results

Dexamethasone given the last week or throughout gestation reduced the beta-cell mass in 21-day-old fetuses by respectively 18% or 62%. This was accompanied by a defect in insulin secretion. The alpha-cell mass was reduced similarly. Neither islet vascularization nor beta-cell proliferation was affected when dexamethasone was administered during the last week, which was however the case when given throughout gestation. When given from the beginning of gestation, dexamethasone reduced the number of cells expressing the early marker of endocrine lineage neurogenin-3 when analyzed at 15 days of fetal age.

Conclusions

GCs reduce the beta- and alpha-cell mass by different mechanisms according to the stage of development during which the treatment was applied. In fetuses exposed to glucocorticoids the last week of gestation only, beta-cell mass is reduced due to impairment of beta-cell commitment, whereas in fetuses exposed throughout gestation, islet vascularization and lower beta-cell proliferation are involved as well, amplifying the reduction of the endocrine mass.     

Circadian and Ultradian Time Patterns in Human Behaviour: Part 1: Activity Monitoring of Families from Prepartum to Postpartum

Time patterns of activity-rest rhythms during and after pregnancy are increasingly recognised as important factors for the well-being and health of young families. This longitudinal study examined activity-rest patterns of couples during late pregnancy and subsequently the alterations in the periodic structure of parental and neonatal time patterns during the first four months after birth. Part I concentrates on the effects of late pregnancy and birth to the mother's rest-activity patterns and those of the father and, after birth, what time pattern the infant developed. Part II attempts to clarify how activity patterns of the entire family agree or disagree with each other and investigates how the infant synchronises with the environment that includes the process of parent-infant interaction. Activity data of, so far, seven families (father, mother and child) were continuously recorded using non-invasive Actiwatch units. Recordings of parental activity started at the beginning of the 37th week of gestation, and were continued in parallel with the infants' recordings in three series of three weeks each until four months after birth: 1st to 3rd week, 7th to 9th week and 13th to 15th week of life. In a standardised diary, record was kept of household routines, parental activities, type of feeding, initiation of sleep or waking up. Activity data of seven non-pregnant women were collected and used as a control. Irregular nocturnal activity epochs occurred frequently in pregnant women and were absent in non-pregnant women. Period lengthenings and shortenings of the circadian rhythms appeared in both parents from prepartum to postpartum. Activity at night increased from prepartum to postpartum in mothers and fathers. Three infants showed a marked circadian rhythm between day 3 and 14 after birth. All seven infants showed a predominant circadian rhythm between day 8 and 19 after birth. The onset of daytime activity of mothers and their infants corresponded well to each other. Postpartum frequency spectra of parents and child always had some ultradian components in common. Time patterns of activity-rest rhythms of couples and parents are shown to be altered during and after pregnancy and we suggest that the infants' adaptation to the environment begins during the first week that includes the process of mother-infant interaction.     

Effects of ethanol infusion on foetal EEG and breathing movements

Ethanol (0.3 g/kg and 0.5 g/kg administered over 2 hours) was infused intravenously into 15 chronically instrumented pregnant ewes between 128 to 135 days of gestation (0.85 to 0.92 gestation time, term 147 days). Brainstem dissection above the pons was made in 7 foetuses. Foetal breathing movements were suppressed for 7 hours following a 30 ml ethanol infusion. Low voltage foetal electrocortical activity was suppressed or replaced by an intermediate voltage electrocortical activity for 5 and 3 hours following the 60 ml and 30 ml ethanol infusions, respectively. In brainstem dissected foetuses the effects of ethanol infusion on the foetal EEG were similar. Foetal blood gases and pH were not altered. These data suggest that ethanol moves across the foetal blood-brain barrier and suppresses foetal breathing movements by a direct central mechanism.     

The development of gluconeogenic enzymes in the liver and kidney of fetal and newborn foals.

The activities of glucose-6-phosphatase (G6P), fructose diphosphatase, phosphoenolpyruvate carboxykinase (PEPCK), aspartate and alanine transferases were measured in liver and kidney of fetal foals between 100-318 days of gestation (term approximately 335 days) and during the immediate postnatal period (0-48 h after birth). All 5 enzymes could be detected in the fetal liver and kidney at the youngest gestational age studied. Mean fetal activities were lower than those observed in their mothers and showed no change with gestational age for the majority of enzymes studied. However, renal PEPCK and renal and hepatic G6P did increase towards term. At birth, hepatic and renal activities of these two enzymes were higher than those found in late gestation or in the adult animals. There was no apparent change in the activities of any of the other enzymes at birth. In late gestation (80-90% gestation), the activities of G6P and PEPCK in the foal were low compared to those in other species at the same stage of gestation. Similarly, the perinatal increase in enzyme activity occurred closer to term in the foal than in most other species. These observations indicate that maturation of glucogenic capacity occurs relatively late in the fetal foal and suggests that this process may be dependent on the prepartum rise in fetal cortisol as occurs in other species.     

Circadian and Ultradian Time Patterns in Human Behaviour: Part 1: Activity Monitoring of Families from Prepartum to Postpartum

Time patterns of activity-rest rhythms during and after pregnancy are increasingly recognised as important factors for the well-being and health of young families. This longitudinal study examined activity-rest patterns of couples during late pregnancy and subsequently the alterations in the periodic structure of parental and neonatal time patterns during the first four months after birth. Part I concentrates on the effects of late pregnancy and birth to the mother's rest-activity patterns and those of the father and, after birth, what time pattern the infant developed. Part II attempts to clarify how activity patterns of the entire family agree or disagree with each other and investigates how the infant synchronises with the environment that includes the process of parent-infant interaction. Activity data of, so far, seven families (father, mother and child) were continuously recorded using non-invasive Actiwatch units. Recordings of parental activity started at the beginning of the 37th week of gestation, and were continued in parallel with the infants' recordings in three series of three weeks each until four months after birth: 1st to 3rd week, 7th to 9th week and 13th to 15th week of life. In a standardised diary, record was kept of household routines, parental activities, type of feeding, initiation of sleep or waking up. Activity data of seven non-pregnant women were collected and used as a control. Irregular nocturnal activity epochs occurred frequently in pregnant women and were absent in non-pregnant women. Period lengthenings and shortenings of the circadian rhythms appeared in both parents from prepartum to postpartum. Activity at night increased from prepartum to postpartum in mothers and fathers. Three infants showed a marked circadian rhythm between day 3 and 14 after birth. All seven infants showed a predominant circadian rhythm between day 8 and 19 after birth. The onset of daytime activity of mothers and their infants corresponded well to each other. Postpartum frequency spectra of parents and child always had some ultradian components in common. Time patterns of activity-rest rhythms of couples and parents are shown to be altered during and after pregnancy and we suggest that the infants' adaptation to the environment begins during the first week that includes the process of mother-infant interaction.     

The effects of confinement on periparturient behaviour and circulating prolactin,prostaglandin F2α and oxytocin in gilts with access to a variety of nest materials

In a 2×2 factorial experiment, the effects of gestation and farrowing housing on (1) periparturient behaviour and circulating prolactin, prostaglandin F_2α (PGF_2α) and oxytocin in gilts with access to peat, straw and branches, and (2) correlational relationships between the periparturient behaviour and hormones were studied. The treatments consisted of housing in stalls or pens from mating to day 110 of gestation followed by farrowing crates or pens until after parturition. Landrace×Yorkshire gilts were observed from video recordings (n=25) from 20 h prepartum and blood sampled via jugular catheters (n=16) from 24 h prepartum until 2 h after the birth of the first piglet.There was an interaction between gestation and farrowing housing affecting the start of nest-building (P=0.03). Gilts that experienced a change in type of housing accommodation commenced nest-building closer to parturition than gilts that were penned both during gestation and at farrowing (both P<0.05). There were no effects of the housing environment on the timing of termination of nest-building, behaviour during parturition, or the course of parturition. However, relative to base level, crated gilts sat more from 16 to 6 h prepartum, whereas this was the case for penned gilts only from 9 to 7 h prepartum. Crated gilts also tended to change posture more often (P=0.07) and lie more in sternal recumbency (P=0.095). This suggests that familiarity with the environment in combination with space to move about and/or availability of materials is important in the timing of nest-building. Confinement during farrowing did not appear to impair feed-back from the materials and the nest, although increased number of postural changes may reflect the motivation but inability to nest-build, or general discomfort in the crate.There was a development over time in postural and nest-building behaviours as well as in plasma concentrations of prolactin, PGF_2α (measured by the metabolite PGFM) and oxytocin, but there were only few effects of housing treatments on hormones or associations between behaviour and hormones. The results suggest that nest-building occurs independently of a prepartum rise in prolactin, but that oxytocin may be associated with the termination of nest-building as there was a negative correlational relationship with nosing (P<0.01) and arranging nest-building materials (P<0.001).Farrowing crate housing appeared to have fewer effects on periparturient behaviour and course of parturition than reported in previous studies where effects of confinement and provision of nest-building materials may have been confounded. Thus, provision of nest-building materials to crated sows may have beneficial effects on sow behaviour and welfare.     

Lipid synthesis in vivo by tissues of the maternal and foetal guinea pig.

The rate of lipid biosynthesis in vivo was determined in pregnant guinea pigs after maternal and foetal injections of 3H2O. Synthesis in the maternal tissues was low and in the foetal liver and adipose tissues relatively high. In the foetal liver it reached a peak at about two-thirds of gestation, whereas that in the foetal adipose tissue occurred later. These results were used to support the view that lipid synthesis in the foetal guinea-pig liver at two-thirds of gestation is largely from short-chain fatty acids, whereas in foetal adipose tissue glucose is probably the major substrate.     

Variables associated with peripartum traits in dairy cows. V. Hormonal profiles associated with retained fetal membranes

Profiles of certain hormones measured by radioimmunoassay in 41 Holstein cows and heifers with retained fetal membranes (RFM; >12 hr postpartum) were compared to 41 peers without RFM (NRFM). Peers were matched by parity, season of calving, gestation length, dystocia and parturient paresis within prepartum diet group. Linear covariates of natural photoperiod, mean daily temperature, calf birth weight, length of gestation, and age and body weight of cow were included in the leastsquares analyses of data. Plasma profiles of prolactin and estrone were nearly identical from day 8 prepartum to day 2.5 postpartum. Plasma estradiol-17α was approximately one-third higher each day in group RFM (P<.05 across days) but estradiol-17β (Eβ) tended to be lower until day 2 prepartum (not significant). Also, plasma progesterone (P) was higher in group RFM between days 8 to 3 prepartum (p<.05 across days).Relationships between plasma P and Eβ were indicative of subsequent RFM (>24 hr rather than >12 hr), but only on day 6 prepartum. Three of four cases of 12 to 24 hr RFM had P and Eß profiles similar to NRFM. Either a combination of low P (<3.0 ng/ml) and low Eß (<100 pg/ml) or only high P (>7.9 ng/ml) were associated with a ten-fold higher rate of RFM (>24 hr) than when P was intermediate (4 to 8 ng/ml) and Eß exceeded 99 pg/ml. These results are in agreement with prior data wherein RFM were induced at premature births either by ovariectomy during pregnancy or by glucocorticoids.     

Litter-size-dependent intrauterine growth restriction in sheep

Regulation of foetal development in sheep depends on interactions between the intrinsic capacity of the foetus for growth and the maternal environment. Lambs born in multi-foetus litters have relatively small placentae with fewer cotelydons, and lower birth weights. Litter-size-dependent intrauterine growth restriction (IUGR) is evident at mid gestation when metabolic needs of the conceptus are moderate, and overnutrition of ewes with multiple foetuses does not promote growth of their foetuses to the size of singletons. Those observations suggest that placental and conceptus growth in multi-foetus pregnancies is reprogrammed at mid gestation by an as yet undefined mechanism to attenuate foetal growth. This may protect the foetus from severe nutritional insult during late gestation, when its daily growth rate is at a maximum. In that way, lambs born in large litters with relatively lower birth weights may not experience the long-term physiological insults that can be observed in small lambs born to undernourished ewes.     

Maternal exposure to paternal antigens can modulate the foetus immune system and is associated with reduced atopy in the childhood

The influence of the maternal immune system on pregnancy and on the foetus immune system have given rise to a variety of observations and interesting hypotheses. For example, the higher prevalence of atopy in first-born children as compared to their brotherhood is known as the “birth order effect”. The “hygienic hypothesis” states that more hygienic live conditions, and consequently reduced exposure to pathogens in young age (included the period of foetal development), increases the risk of atopy. Here we review the ideas concerning maternal exposure to paternal antigens and immunomodulation. In particularly, we discuss the idea that this phenomenon may induce a regulatory environment in women that interfere with the developing foetal immune system. This regulatory environment could be responsible for protecting children to the development of atopy during adulthood. We propose that maternal exposure to paternal antigens through different situations, such as pregnancy, repeated exposure to sperm or Paternal Leukocyte Immunization (PLI) would combine the “birth order effect” and the “hygienic hypothesis” and thus lower the risk to atopy in children through the transference of a regulatory environment to the foetus.     

Changes of gamma-glutamyltranspeptidase activity in the rat during development and comparison of the fetal liver, placental and adult liver enzymes

Changes in the activity of gamma-glutamyltranspeptidase (GGT, EC 2.3.2.2) during development in rats were investigated. The activity of GGT in fetal liver increased rapidly immediately before birth, reached a maximum at birth and then decreased rapidly within a week after birth to nearly the level in adult rat liver. In contrast, placental GGT showed higher activity at an early stage (from day 13 to day 15) of the gestation period, but the activity decreased in the last part of fetal life. The activity in the amniotic fluid increased significantly just before birth, in parallel with the increase of activity in the fetal liver. No change of activity in the uterine wall was observed throughout gestation. The kinetic and immunological properties of partially purified GGTs from fetal liver and placenta were almost identical with those of adult liver GGT. However, the activity of soluble GGT in fetal liver was less effectively inhibited by antibody against adult kidney GGT. Thus, it is likely that at least one isozyme of GGT is present in the soluble fraction of fetal liver.     

Distribution of peptide-immunoreactive nerves in the foetal and newborn guinea-pig caecum

Summary The distribution of vasoactive intestinal polypeptide-, substance P-, [met]enkephalin- and somatostatin-like immunoreactive nerves was studied in the caecum from foetal guinea-pigs of 6–9 weeks gestation (i.e., approximately 1–4 weeks before birth) and 4–5-day-old guinea-pigs. Peptide-immunoreactive nerves were first detected in the myenteric and submucous plexuses and circular muscle layer at 6 weeks of gestation and in the mucosa at 7 weeks of gestation. The density of fibres in these layers increased during prenatal development until, by 9 weeks of gestation, their distribution resembled that seen in the postnatal animals. This distribution was similar to that described previously in adult animals. A different pattern of development was observed in the caecal taenia coli muscle. Peptide-immunoreactive fibres were not detected until 8 weeks of gestation in this tissue layer, and were then only sparsely distributed. A dramatic increase in the number of labelled fibres, however, occurred between 8 and 9 weeks of gestation. Further, vasoactive intestinal polypeptide- and substance P-immunoreactive fibres were more numerous in the taeniae coli of 9-week-old embryos than in those of postnatal animals. Thus, the guinea-pig enteric nervous system, which in many respects is well-developed at the time of birth, may still be undergoing developmental changes at this time.