Morphological changes in the isolated rat liver perfused in a non-recirculating system: scanning and transmission electron microscopy

Isolated perfused rat livers have been used for various studies, but detailed investigation into the structural integrity of hepatocytes of this system is lacking. In this study, isolated rat livers were perfused in vitro with oxygenated Krebs-Ringer bicarbonate buffer solution, for 2 minutes and 1, 2, 3, and 4 hour(s) at 37 degrees C, using a non-recirculating perfusion system. The perfused livers were processed for semithin section light microscopy, transmission electron microscopy, and scanning electron microscopy. Sectional areas of cell deaths were measured by a camera-tracing assembly from 1.5 microns thick Araldite sections stained with toluidine blue. Progressive nuclear and cytoplasmic changes, leading to cell death, occurred in the hepatocytes of the centrilobular zone, during the 2nd, 3rd, and 4th hour of the perfusion at a rate of 9.03% +/- 1.5%, 38.7% +/- 2.7%, and 55.1% +/- 5.9% (mean +/- standard deviation) of the total sectional areas respectively. Midzonal hepatocytes showed normal basophilic staining but exhibited loss of glycogen granules, loss of microvilli, development of aqueous vacuoles and formation of blebs. The fine structures of cell organelles, glycogen granules, microvilli and plasma membrane of the cells in the periportal zone were well preserved throughout the experimental period. For further quantitative, metabolic and functional studies using isolated rat liver perfused with Krebs-Ringer solution, it is evident from the present investigation that the periportal zone represents the functional region of the hepatic lobule. Whilst progressive changes, leading to cell death, occurred in the centrilobular zone.     

小鼠生精细胞增殖与凋亡的年龄变化

为研究雄性小鼠睾丸在发生,发育过程生精细胞增殖与凋亡的年龄变化,本研究采用了免疫细胞化学,凋亡细胞原位检测,电镜及体视学图象分析等方法,对胚胎15天到生后10月后发育阶段生精细胞的超微结构,PCNA表达,凋亡情况进行了较深入地研究,结果：（1）精原细胞PCNA反应在胚胎15天为阳性,从胚胎18天到生后5天,降为弱阳性,而阳性的精原细胞在生后7天重新出现,一直到生后6月,仍可见部分精原细胞呈阳性反应;（2）生后3天,可见凋亡的精原细胞染色质浓缩,核膜出现明显的核周隙,核碎裂,凋亡细胞数从生后1天到生后第3周有增加的趋势,于生后第3周出现峰值,之后降低,之后降低,结论：（1）PCNA阳性细胞而密度到生后第2周出现峰值,而凋亡细胞数于生后3周出现峰值,生精细胞凋亡的高峰要滞后其增殖峰1周左右,而且与其所处生精周期的特定阶段有关;（2）精原细胞在胚胎发育过程中向曲细精管周边迁移,其排列由无序到有序;（3）在生后各发育 ,精原细胞始终保持DNA复制的能力。     

The influence of estradiol and progesterone on the concentrations of uterine oxytocin receptors and plasma PGFM in response to oxytocin in ovariectomized gilts

Peripubertal gilts (n = 25) were treated with corn oil (CO) or ovarian steroids, one month following an ovariectomy. The first day of treatment was assigned as the first day of the experiment. The gilts received: Group (Gr) I (n = 4)--CO (2 mL x day(-1) from 1st to 12th day), Gr II (n = 4) and Gr III (n = 4)--progesterone (P4; 10 to 100 mg x day(-1) from 1st to 12th day), Gr IV (n = 5)--estradiol benzoate (EB; 400 microg x day(-1) from 1st to 3rd day), Gr V (n = 4) and Gr VI (n = 4)--EB + P4 (EB 400 microg x day(-1) from 1st to 3rd day, 20 microg x day(-1) at 6th and 9th day, 50 microg at 12th day plus P4 10 to 100 mg from 4th to 15th day). All gilts were injected with oxytocin (OT; 20 IU; i.v.) on the following days of the experiment: 13th (Gr I and Gr II), 15th (Gr III and Gr IV), 16th (Gr V) and 18th (Gr VI). Concentrations of the PGF2alpha metabolite--PGFM were determined in blood samples, collected from 30 min before to 120 min after OT injection. Baseline PGFM concentrations (30 min before OT) differed among treatment groups and were the highest in Gr V and Gr VI (P < 0.01 vs. other groups). The magnitude of the PGFM response to OT increased only in four of the five gilts of Gr IV and in three of the four gilts of Gr VI, and it was higher (P = 0.009) in Gr VI than in Gr IV. In the remaining groups, PGFM concentrations did not increase above the baseline in response to OT. The day after OT injection, oxytocin receptors (OTR) were found in the uterine tissues of all animals studied. The lowest OTR concentrations were in Gr I--75.5 +/- 11.2 fmol x mg protein(-1) and the highest in Gr IV--712.9 +/- 86.7 fmol x mg protein(-1); (P < 0.05 vs. other groups). The values of K of OTR differed among groups (P < 0.001) and ranged from 1.62 +/- 0.44 nM in Gr I to 12. 08 +/- 1.9 nM in Gr VI. A positive correlation (r = 0.54; P < 0.01) between plasma E2 and uterine OTR concentrations was observed. In conclusion, E2 and P4 are involved in both PGF2 synthesis/secretion and OTR formation, however, full PGF response to OT does not develop before puberty. Estrogens are evident stimulators of uterine OTR synthesis ingilts.     

The adsorptive and transport capacity of tanycytes during the perinatal period of the rat

Summary Transport of ferritin and horseradish peroxidase from the 3rd ventricle to the median eminence was examined in rats during the perinatal life, the time when functional interrelations between hypothalamus and hypophysis are established. Protein tracers injected into the lateral ventricle are adsorbed on the apical surface of the tanycyte, mainly on its protrusions or in indentations. On the 18th day of prenatal life a few small bleblike protrusions are observed. After birth microvilli appear. In time their concentration increases to result in an increase of adsorbed substances. They are taken up by smooth and coated pinocytotic vesicles and transported to the basal portion of the cell or to the intercellular space bypassing junctional complexes. In addition to pinocytotic vesicles protein tracers fill channels of smooth ER or Golgi complex and multivesicular bodies illustrating a process probably involved in metabolic or secretory processes.     

Isolation of rat hepatocyte plasma membranes. I. Presence of the three major domains

A rat liver plasma membrane preparation was isolated and characterized both biochemically and morphologically. The isolation procedure was rapid, simple and effective in producing a membrane fraction with the following biochemical characteristics: approximately 40-fold enrichment in three plasma membrane markers, 5'-nucleotidase, alkaline phosphodiesterase I (both putative bile canalicular membrane enzymes), and the asialo-glycoprotein (ASGP) receptor (a membrane glycoprotein present along the sinusoidal front of hepatocytes); a yield of each of these plasma membrane markers that averaged approximately 16%; and minimal contamination by lysosomes, nuclei, and mitochondria, but persistent contamination by elements of the endoplasmic reticulum. Morphological analysis of the preparation revealed that all three major domains of the hepatocyte plasma membrane (sinusoidal, lateral, and bile canalicular) were present in substantial amounts. The identification of sinusoidal membrane was further confirmed when ASGP binding sites were localized predominantly to this membrane in the isolated PM using electron microscope autoradiography. By morphometry, the sinusoidal front membrane accounted for 47% of the total membrane in the preparation, whereas the lateral surface and bile canalicular membrane accounted for 6.8% and 23% respectively. This is the first report of such a large fraction of sinusoidal membrane in a liver plasma membrane preparation.     

Analysis of hepatocyte plasma membrane domains during rat development using monoclonal antibodies

The plasma membrane of adult rat hepatocyte consists of three domains, which have been identified by the monoclonal antibodies A39 and A59 as markers of the sinusoidal domain, B1 of the lateral, and B10 of the canalicular domains (Eur J Cell Biol 39:122, 1985). These monoclonal antibodies were used to study, by indirect immunocytochemistry, formation of the hepatocyte plasma membrane domains during development, from day 15 of gestation to day 35 post partum. The antigens defined by A39, B1, and B10 were detected, from day 15, over the major part of the hepatocyte plasma membrane except for the membranes of newly formed bile canaliculi, which were not labeled by B1 and only poorly labeled, if at all, by A39 and B10. As soon as fetuses were 16 days old, B1 labeled predominantly the lateral domain, as in the adult. Labeling with B10 progressively intensified on the membranes of bile canaliculi, but localization was not exclusively canalicular until day 21 post partum. A39 intensely labeled the canalicular membranes at 19-21 days of gestation, while at 35 days post partum it exhibited the predominantly sinusoidal labeling observed in adult hepatocytes. The antigen defined by A59 was not detected before birth and was found exclusively on the sinusoidal domain, as in the adult. These results show that the patterns of antigen distribution on different plasma membrane domains establish themselves at different rates. The marked differences observed between fetal or neonatal and adult hepatocytes might be responsible for immaturity of liver functions in the neonate.     

Preservation of hepatocyte plasma membrane domains during cell division in situ in regenerating rat liver

We have utilized antibodies against five domain-specific integral proteins of the rat hepatocyte plasma membrane to examine the fates of the plasma membrane domains during hepatocyte division in the regenerating rat liver. The proteins were quantified on immunoblots of liver homogenates prepared during the peak of hepatocyte mitotic activity, 28-30 hr after two-thirds hepatectomy. Two sinusoidal/lateral proteins, CE 9 and the asialoglycoprotein receptor, and one bile canalicular protein, dipeptidylpeptidase IV, were not changed significantly in amount; whereas one sinusoidal/lateral protein, the epidermal growth factor receptor, and one bile canalicular protein, HA 4, were reduced to less than or equal to 50% of control levels. Light microscopic examination of plastic sections of regenerating liver tissue revealed that the mitotic hepatocytes generally appeared to retain normal contacts with neighboring interphase hepatocytes. Immunofluorescence was used to localize the domain-specific proteins on mitotic hepatocytes identified in 0.5-micron frozen sections of 28- to 30-hr regenerating liver tissue. Independent of mitotic stage, the hepatocytes retained mutually exclusive bile canalicular and sinusoidal/lateral domains, as defined at the molecular level by the distributions of specific proteins, such as HA 4 and CE 9, respectively.     

Growth of the eye and pigment epithelium of the retina during postnatal development of rats]

By the weight changes, the rat's eye grows during the whole life, whereas its scleral sector with the area equal to that of pigment epithelium of the retina grows most intensively between the 2nd and 5th days after birth. During this period, its weight attains half of the value characteristic of the scleral sector for one year old rats. This period of growth of the scleral sector coincides with the previously established peak of proliferative activity and appearance of first binuclear cells in the pigment epithelium. From the 5th day till the 12th month after birth, the weight of scleral sector increases twice and its area 6 times. This suggests that the mechanical tension of the scleral sector walls is one of the factors of growth of this eye part. On the basis of comparison of the scleral sector growth, changes in proliferative activity and number of polyploid cells in the pigment epithelium of the central zone of fundus oculi, the following periodization of the life cycle of cell population of the pigment epithelium is proposed: (1) from birth till the 15th day--period of principal determination (the number of binuclear tetraploid cells attains 80%), (2) from the 15th day till, at least, the 5th month--period of stabilization, (3) after 5 months--period of senescence characterized by the accumulation of highly ploid tri- and tetranuclear cells; its lower limit is not clearly defined.     

大鼠发育过程中肝、肺r-GT酶活性和定位

用生物化学和组织化学方法研究正常发育中大鼠肝、肺r-GT活性和定位。结果表明:肝r-GT活性自胚龄17天开始升高,21天达高峰,出生第一天明显降低,第六天降至接近成年低水平。在胚胎期肝r-GT主要位于肝细胞内,出生后则主要位于胆小管。该结果提示胚胎期肝r-GT主要参与肝细胞膜上氨基酸的转运。出生后可能主要参与解毒功能,大鼠肺r-GT活性随发育逐步升高,主要分布于肺支气管上皮细胞。提示肺r-GT可能参与解毒功能。     

圈养大熊猫乳汁营养成分分析

本文收集了一只14岁大熊猫产后17d内的乳汁样品10个,包括产后第2,3,5,6,7,8,9,11,12和17天,并测定了这些样品的营养成分的含量。即粗蛋白(CP)、粗脂肪(EE)、乳糖(Lac)、17种氨基酸(AA)含量的总和、5种常量元素(Ca,P,K,Na,Mg)和6种微量元素(Fe,Cu,Mn,Zn,Co,Se)。结果如下：(1)每个样品的粗蛋白和17种氨基酸含量的总和十分接近,分别在5．20％～7．50％和5．17％～7．62％的范围内波动;乳糖含量的变化范围为0．87％～1．51％;粗脂肪为0．6％～3．2％;(2)粗蛋白和总氨基酸含量第3天明显低于第2天,从第3天到第6天逐步升高,第7天有些下降,从第7到17天逐渐上升;乳糖含量变化不大,在1％左右,第2,3和5天接近,第6天明显升高。之后逐渐降低直至第17天;粗脂肪含量波动较大,没有明显变化趋势;绝大多数矿物元素含量随产后时间的延长都有不同程度的升高趋势;(3)产后6～7天的乳汁样品营养物质含量与一周后有明显差别。作者建议在幼大熊猫人工乳的配制方面,应依据大熊猫乳汁的营养物质含量,充分保证蛋白质水平。降低乳糖含量,同时供给充足的矿物质元素;必须根据幼大熊猫的日龄及其生长发育情况,调整人工乳的营养水平。     

The effect of 6-hydroxydopamine on the autogenic motor activity of newborn rat pups

At the 1st, 2nd and 3rd days after birth, subcutaneous injections of 6-oxydopamine in physiological solution containing 0.1% of ascorbic acid have been made to rat puppies in a dose 100 mg/kg per one injection. Within first three weeks, electromyographic studies were made on outbursts of autogenic periodic motor activity which is typical of animals at this age. It was shown that at the 3rd day of postnatal life, after 6-oxydopamine administration, total duration of motor excitation is significantly lower, whereas mean duration of the outbursts of continuous activity is lower even at the 7th day. Beginning from the 10th day, these parameters undergo opposite changes at the background of the increase in the number of outbursts and the decrease of intervals between the latter. The data obtained are discussed in relation to the role of catecholaminergic systems in regulation and realization of age dynamics of autogenic motor activity.     

Effect of vitamin E on serum aminotransferase and thioredoxin levels in patients with viral hepatitis C

OBJECTIVES: Oxidative stress induces cellular responses such as cell death, gene activation and cell proliferation, in the liver. Vitamin E (Vit. E) has been found to protect the liver against oxidative stress in animal experiments. Thioredoxin (TRX) is a stress inducible, multifunctional protein, secreted during oxidative stress. This study evaluated effects of Vit. E on serum TRX and aminotransferase levels in hepatitis C virus (HCV) patients, partly non-responsive to initial interferon (IFN), with higher than average level of serum alanine aminotransferase (ALT) after receiving anti-inflammatory drug treatment. METHODS: Seventeen HCV patients (male = 3; female = 14) of age 62 +/- 7.65 years receiving anti-inflammatory drug therapy, at least 6 months prior to Vit. E administration, were given d-alpha-tocopherol 500 mg/day, orally, for a period of 3 months. ALT, aspartate aminotransferase (AST), TRX and Vit. E were measured at 0, 1, 2 and 3 months and 1 month after end of treatment. As controls, the same patients biochemical data, 3 months from the start of therapy were used. Patients were divided into three categories: total patients "T", low ALT group "L" (ALT < 70 IU/l) and high ALT group "H" (ALT > 70 IU/l), respectively. RESULTS: The ALT level was lowered, significantly in group H, in the 1st, 2nd, 3rd and 1-month post therapy, compared to the initial value. But group L showed little or no change in ALT. Post Vit. E therapy, in groups T and H, the TRX level was elevated but remained below initial levels, whereas in group L, TRX level remained significantly lower than the pretreatment value. Groups T and L, showed significant reduction (p < 0.05) in serum TRX levels in the 2nd and 3rd month. Group H showed a tendency towards TRX reduction, but not significantly. Serum Vit. E levels increased significantly (p < 0.0001) from the 1st to 3rd month in all three T, H and L groups. CONCLUSION: Oxidative stress induced liver damage is reduced by Vit. E in patients with viral hepatitis C, particularly those with initial ALT levels > 70 IU/l. Vit. E treatment causes reduction of oxidative stress markers as TRX and ALT in sera. Therefore, Vit. E can act as a supportive therapy to combat liver damage caused by oxidative stress, in such patients with continuously high levels of ALT even after anti-viral and anti-inflammatory drug therapy.     

Clonogenic hemopoietic cells (CFU-S) in mouse pre- and postnatal ontogeny

Content of three classes of clonogenic haemopoietic cells (CFU-S-7, CFU-S-11 and CFU-S-ep) was determined in haemopoietic organs of mouse during embryogenesis (10, 14 and 18 day) and postnatal ontogenesis (2, 3 and 7 day, 1, 2, 3 and 18 month). CFU-S-7 and CFU-S-11 that from big splenic colonies on 7th and 11th days of transplantation are present in liver, spleen and bone marrow at all developmental stages. However their concentration and CFU-S-7 CFU-S-11 ratio change in haemopoietic organs. CFU-S-ep that form small colonies on 11th day are observed before birth in liver and spleen and 1 week after birth there and also in bone marrow but are practically absent from haemopoietic organs of older animals. Thus, CFU-S compartment structure is characterized by definite ratio of its subpopulations. It seems to reflect functional state of haemopoietic system during development.     

Scanning electron microscopy of normal rat liver: the surface structure of its cells and tissue components.

Scanning electron microscopy (SEM) allows the surface ultrastructure of intrahepatic cells and other tissue components of liver to be delineated. Excellent depth of focus of the SEM makes it possible to visualize surfaces of intact cells in their native configurations. This report details the surface characteristics and inter-relationships of hepatocytes and hepatic plates, sinusoidal endothelial cells and sinusoids, presumed Kupffer cells, vessels, bile ducts, connective tissue, and the capsule of rat liver. Hepatocytes present three structurally distinctive faces--the intercellular face containing flat surfaces and bile canaliculus, the sinusoidal face, and the connective tissue face which abuts portal tracts and hepatic veins. Sinusoidal endothelium is penetrated by large (1 to 3 mum) and small (0.1 mum) fenestrae, the latter occurring in clusters of up to 50. The width of bile canaliculi and distribution of large fenestrae vary proximodistally along hepatic plate or sinusoid. The cells of portal bile ductules contain microvilli located in linear rows and sparse cilia. Endothelium of hepatic artery and of portal vein is sparsely fenestrated.     

Enzyme activity of the bile and liver after disruption of its innervation and bile loss]

Continuous loss of bile in rats with a bile reservoir applied to the common bile duct caused an increase in specific activity of malic dehydrogenase, lactic dehydrogenase, glutamic dehydrogenase, glucose-6-phosphoric dehydrogenase, alkaline and acid phosphatase, urokinase and histidinase in the liver homogenates by the 7th day; the specific activity decreased by the 10th day. Disruption of innervation of the liver caused a sharp decrease of the ATP content and the abovementioned specifc activity in this organ. In continuous loss of bile there were revealed oscillations in the activity of the above-mentioned enzymes and sorbitol dehydrogenase in bile from the 1st to the 10th day of the experiment. Marked changes in the oscillations in the dysinnervated liver were in favour of the fact that those oscillations coursed under the control of the nervous system.     

Haematological studies in relation to environmental temperature and different periods of breeding cycle in an air breathing fish, Heteropneustes fossilis.

Investigations were made on different haematological parameters in H. fossilis at two environmental temperature (18 degrees C and 32.5 degrees C) and different periods of breeding cycles. The RBC counts 302.0-10(4)/mm3), WBC counts (10.6-10(4)/mm3), Hb concentration (19.0g%), haematocrit (36.0%), M.C.H.C. (57.7%), total blood volumes (0.966 ml) and per cent blood volumes (1.542%) gave significantly high values but M.C.V. (119.2 micrometer3) and erythrocyte surfaces (52.96 micrometer2) gave low values at higher temperature (32.5 +/- 1 degrees C) and during breeding period (G.S.I. = 10.4 +/- 0.52 g). The higher values obtained for different haematological parameters during breeding period at high temperature may be probably related to greater physical activity and higher metabolic activity at the time of reproduction.     

The effect of dimethyl sulfoxide on cholesterol and bile acid metabolism in rats

The effect of DMSO on cholesterol and bile acid metabolism was studied in rats. Male Sprague-Dawley rats were randomly assigned to one of two groups and given either tap water or 2% DMSO (v/v) in tap water to drink for 9 days. Both food (stock rat diet) and water were available ad libitum. Animals in both groups gained weight equally throughout the study. They also had similar liver weights (g/100 g body wt) at the end of the study (control: 5.0 +/- 0.1 (N = 6) vs DMSO: 4.9 +/- 0.1 (N = 6]. The activity of hepatic cholesterol 7 alpha-hydroxylase (pmole/mg/min), the rate-limiting enzyme of bile acid biosynthesis, was significantly (P less than 0.005) reduced in the treated animals (control: 9.7 +/- 1.0 (N = 6) vs DMSO: 4.3 +/- 0.7 (N = 6)). Plasma cholesterol (mg/dl) was significantly (P less than 0.005) elevated in the treated animals (control: 90 +/- 3 (N = 6) vs DMSO: 107 +/- 4 (N = 6)), a finding consistent with the reduced CH-7 alpha hydroxylase activity in this group. DMSO treatment did not affect either microsomal cholesterol content or hepatic glutathione content. Thus, this study has shown that DMSO treatment per se can affect cholesterol and bile acid metabolism. However, the precise mechanisms whereby DMSO exerts the observed effects are not known.     

Hepatocyte cell surface polarity as demonstrated by lectin binding

We performed an investigation at the ultrastructural level of the differential distribution of lectin-binding sites among sinusoidal, lateral, and bile canalicular domains of adult rat hepatocytes. Lectin binding to hepatocyte glycocalices was studied in situ or after cellular dissociation by enzymatic (collagenase), chemical (EDTA), and mechanical methods, as well as during cell culture. Using thirteen biotinylated lectins and an avidin-biotin-peroxidase complex (ABC), we have identified lectin-binding sites that are predominantly localized in the bile canalicular [Ricinus communis agglutinin (RCA)] or sinusoidal [Phaseolus vulgaris (PHA)] domains in situ and in mechanically dissociated cells. Lens culinaris (LCA) staining was prominent on sinusoidal surfaces, slight along lateral surfaces, and completely absent in the bile canalicular domain. Concanavalin A (ConA) was unique in binding equally to all domains. Triticum vulgaris [wheat germ agglutinin (WGA)] was also bound to all domains, but most intensely to the bile canalicular region. Cells dissociated via collagenase or EDTA treatment exhibited a spherical morphology characterized by many surface microvilli and absence of morphological domains. Lectin binding to dissociated cells was uniformly distributed over the entire cell surface, suggesting a redistribution of lectin receptors that was independent of the separation procedure. Hepatocytes in culture exhibited a partial restoration of morphological domains, but lectin binding polarity was not re-established.     

Longitudinal study of the dietary selenium intake of exclusively breast-fed infants during early lactation in Korea and Japan.

213 samples of human breast milk were collected from 51 healthy Korean women. Selenium content of the samples was determined by atomic absorption spectrometry with hydride generation. The selenium content of Korean milk decreased with increase of days after birth: The arithmetic mean of selenium content was higher in colostrum (< 4 days) 34 micrograms/kg (SD +/- 11, n = 44) than in transitional milk 21 micrograms/kg (SD +/- 8, n = 78) or in mature milk (> 10 days) 13 micrograms/kg (SD +/- 6, n = 91). The daily dietary selenium intake of 0-1 month aged Korean infants fed on breast milk is estimated to be around 10 micrograms per day (3 micrograms/kg body weight) regardless of days postpartum, resulting from the calculation of our selenium data and daily milk intake during early lactation. The same result on selenium intake for Japanese newborns, as well as Korean infants, is also estimated to be around 10 micrograms per day (3 micrograms/kg body weight) regardless of days postpartum.     

Ketonic bile acids in urine of infants during the neonatal period

Ketonic bile acids have been found to be quantitatively important in urine of healthy infants during the neonatal period. In order to determine their structures, the bile acids in urine from 11 healthy infants were analyzed by gas-liquid chromatography-mass spectrometry (GLC-MS) and three samples with particularly high levels of ketonic bile acids were selected for detailed studies by ion exchange chromatography, fast atom bombardment mass spectrometry, microchemical reactions, and GLC-MS. The major ketonic bile acid was identified as 7 alpha, 12 alpha-dihydroxy-3-oxo-5 beta-chol-1-enoic acid, not previously described as a naturally occurring bile acid. The positional isomer 7 alpha, 12 alpha-dihydroxy-3-oxo-4-cholenoic acid, recently described as a major urinary bile acid in infants with severe liver diseases, was also excreted by most infants. Three acids related to cholic acid were identified: 7 alpha, 12 alpha-dihydroxy-3-oxo-, 3 alpha, 12 alpha-dihydroxy-7-oxo-, and 3 alpha, 7 alpha-dihydroxy-12-oxo-5 beta-cholanoic acids. Five bile acids having one oxo and three hydroxy groups were also present. Based on mass spectra and biological considerations two of these were tentatively given the structures 1 beta, 7 alpha, 12 alpha-trihydroxy-3-oxo- and 1 beta, 3 alpha, 12 alpha-trihydroxy-7-oxo-5 beta-cholanoic acids. Some of the others had a hydroxy group at C-4 or C-2. The levels of ketonic bile acids were higher on the third than on the first day of life, and lower after 1 month. The formation and excretion especially of 3-oxo bile acids is proposed to result from changes of the redox state in the liver in connection with birth.