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Showing papers on "Incubation published in 1976"


Journal ArticleDOI
TL;DR: The bird must achieve a nest ventilation which is a function of the water loss of the egg and brood patch and the difference between the water-vapor content of the ambient air and that in the microclimate of the nest.
Abstract: Water loss during incubation in the eggs of seven species of terns are reported. The nesting sites ranged from a relatively cold region, southern Alaska, to a tropical climate in the equatorial Pacific Ocean. In addition, measurements of various physical parameters of the eggs and eggshells were made, including the water-vapor conductance of the fresh egg, which allows one to calculate the total effective pore area of the shell. The rate of water loss during incubation was proportional to egg weight (9-39 g) but inversely proportional to incubation period (21-36 days); the eggs of all species lost about the same fractional amount of water, namely, 14% of their initial weight. The rate of water loss is determined by a species-specific water-vapor conductance or pore geometry of the shell, provided that a water-vapor pressure difference of about 27 torr is maintained between the egg and the microenvironment of the nest. Since water-vapor pressure in the incubating egg is determined by egg temperature and is...

110 citations


Journal ArticleDOI
TL;DR: The specific reversion of S. typhimurium TA1530 to histidine prototrophy provides experimental evidence that all the N-nitrosamines studied were converted by liver microsomal enzymes into monofunctional alkylating agents.
Abstract: The rat liver microsome-mediated mutagenicities of a series of N-nitrosodialkylamines and heterocyclic N-nitrosamines were determined in a liquid incubation system using Salmonella typhimurium TA1530. The influence on mutation frequency of the concentration of co-factors for mixed-function oxidase and composition and molarity of the buffer was investigated, using N-nitrosomorpholine as substrate. The mutagenicity of the N-nitroso compounds in the liquid incubation system under optimal reaction conditions at equimolar concentration was compared quantitatively with that obtained in a soft-agar incorporation assay. N-Nitrosodi-n-pentylamine and N-nitrosodi-n-butylamine showed no enzyme-mediated mutagenicity in the liquid incubation system, and metabolically activated N-nitroso-dimethylamine and N-nitroso-diethylamine showed negligible mutagenic activity in the soft-agar assays. In contrast with these results with the N-nitrosodialkylamines, the mutagenic effects of heterocyclic N-nitrosamines were similar in the liquid incubation system and in soft-agar incorporation assays. The heterocyclic N-nitrosamines showed rat-liver microsome-mediated mutagenicity in the following descending order: N-nitrosomorpholine greater than N-nitrosopyrrolidine greater than N-nitrosopiperidine greater than N-nitroso-N'-methylpiperazine. Seven human liver specimens converted all heterocyclic N-nitrosamines into mutagens; this activity was similar to that of rat liver, except that for N-nitroso-N'-methylpiperazine, fractions from three human liver biopsies were three to 30 times more active than those from untreated rats. The specific reversion of S. typhimurium TA1530 to histidine prototrophy provides experimental evidence that all the N-nitrosamines studied were converted by liver microsomal enzymes into monofunctional alkylating agents.

94 citations


Journal ArticleDOI
TL;DR: Ca2+ may be involved in steroidogenesis at a stage beyond the luteinizing hormone receptor-adenylate cyclase-protein kinase system and Activation of cyclic AMP-dependent protein kinase by luteInizing hormone was not decreased by omission of Ca2+ from the incubation medium, suggesting that Ca2+.
Abstract: Leydig-cell suspensions, prepared from rat testes, were incubated with different amounts of Ca2+ with and without added luteinizing hormone. The basal testosterone production in the absence of luteinizing hormone was unaffected by the Ca2+ concentration in the incubation medium. The luteinizing hormone-stimulated testosterone production, however, was progressively decreased in the absence of Ca2+ to one-third of that with 2.50 mM-Ca2+. This decrease in luteinizing hormone-stimulated testosterone production was independent of the different concentrations of luteinizing hormone (0-10mug/ml) used and could be restored by the addition of Ca2+ to the incubation medium. The restoration of the stimulation was achieved within 30 min after the addition of Ca2+ to the medium. Activation of cyclic AMP-dependent protein kinase by luteinizing hormone was not decreased by omission of Ca2+ from the incubation medium, suggesting that Ca2+ may be involved in steroidogenesis at a stage beyond the luteinizing hormone receptor-adenylate cyclase-protein kinase system.

89 citations


Journal ArticleDOI
TL;DR: Hatchability of fertile eggs was 19.5% lower in eggs stored for 14 d and proportionately more embryos died between 4 d and 18 d incubation than in the non‐stored eggs, and rate of weight loss during incubation was similar in both non-stored and stored eggs.
Abstract: 1. A time‐lapse photographic technique has been developed which enables routine recording of the hatching times of up to 192 chicken embryos. 2. Storage of eggs for 14 d caused a delay of 134 h in the mean total incubation period. 3. Female embryos hatched about 3 h earlier than males in the non‐stored eggs but there was no difference between the sexes in eggs stored for 14 d. 4. Rate of weight loss during incubation was similar in both non‐stored and stored eggs: there was no relationship between weight loss at 19 d incubation and total incubation period. 5. Hatchability of fertile eggs was 19.5% lower in eggs stored for 14 d and proportionately more embryos died between 4 d and 18 d incubation than in the non‐stored eggs.

84 citations


Journal ArticleDOI
TL;DR: In this article, different intervening activities represented various mechanisms that might produce incubation (e.g., set breaking, facilitation by analogy, review of the problem's elements) and none of them showed evidence of incubation, despite previously reported incubation with the same problem.
Abstract: Subjects worked on a problem, engaged in an intervening activity, and then resumed work on the problem. Different intervening activities represented various mechanisms that might produce incubation (e.g., set breaking, facilitation by analogy, review of the problem's elements). These various treatment groups were compared to a control group that worked on the problem continuously. None of them showed evidence of incubation, despite previously reported incubation with the same problem. Since these systematically negative findings are consistent with those of several recent studies, the status of incubation as an objectively demonstrated phenomenon is questioned and directions for further research are suggested.

69 citations


Journal ArticleDOI
01 Jun 1976-Steroids
TL;DR: The inhibition of testosterone 5alpha-reductase activity by 3-oxo-4-androstene-17beta-carboxylic acid in the male reproductive organs of the rat was demonstrated in vitro and the highest concentration of testosterone was recorded in medium for incubation of decapsulated testis.

54 citations


Journal ArticleDOI
TL;DR: The effect of inositol pentaphosphate on increasing P50 of the whole blood is more gradual and appears to become of major influence in the chick after 4–5 days post-hatching, and correlates best with the amount of ATP in the cells.

48 citations


Journal ArticleDOI
TL;DR: Addition of cow serum to diluted bull spermatozoa induced marked head-to-head agglutination which declined during incubation for 9 hr at 37 degrees C, which resulted in marked acrosomal deterioration in single cells in the same treatment groups.
Abstract: Addition of cow serum to diluted bull spermatozoa induced marked head-to-head agglutination which declined during incubation for 9 hr at 37 degrees C. Maintenance of the acrosomal cap during incubation was not adversely affected by serum. Agglutinating cells were those with intact acrosomal and cell membranes, as determined by differential interference-contrast and electron microscopy. Single cells in the same treatment groups experienced more rapid acrosomal deterioration than did untreated spermatozoa. Ultrastructurally, agglutinated cells were associated by a close apposition of the cell membranes in the acrosomal region. Structural integrity of the cell membrane and acrosome of agglutinated cells was the same after 9 hr of incubation as at the onset of the incubation period.

45 citations


Journal Article
TL;DR: The capacity of periphal blood lymphocytes from patients with untreated Hodgkin's disease to form E rosettes with sheep erythrocytes and to respond in vitro to PHA stimulation were found to be profoundly impaired.
Abstract: The capacity of peripheral blood lymphocytes from patients with untreated Hodgkin9s disease to form E rosettes with sheep erythrocytes and to respond in vitro to PHA stimulation were found to be profoundly impaired. In 49% of the patients, the percentage of E rosette-forming cells (E-RFC) was more than two standard deviations below the mean for normal donors. Overnight incubation of the peripheral blood lymphocytes from these patients in culture media containing 20% fetal calf serum was followed by restoration of the percentage of E-RFC up to normal levels. Similar results have been observed after incubation in fetal human serum, but not in adult human AB serum or adult bovine serum. Incubation of peripheral blood lymphocytes from untreated patients in 20% fetal calf serum also resulted in a remarkable restoration of their capacity to respond normally to PHA. Possible mechanisms involved in these reversible cell surface and in vitro lymphocyte function abnormalities in Hodgkin9s disease are discussed.

45 citations


Journal ArticleDOI
TL;DR: Unidirectional K+ fluxes were estimated in isolated rat thymocytes by 42K exchange kinetics by estimating the cellular uptake of isotope during incubation for one hour at 38°C.
Abstract: Unidirectional K+ fluxes were estimated in isolated rat thymocytes by 42K exchange kinetics. The cells were either preloaded with isotope and the release of it measured during incubation for one hour at 38°C, or the cellular uptake of isotope during a similar incubation was measured. The influx rate of untreated thymocytes was: 2.3·10−12 moles cm −2. S−1 and efflux rate: 1.8·10−12 moles cm −2· S−1· When con A was added to the cells, influx was raised 74% and efflux 65%. Maximal effect was obtained when the concentration of con A was 15 μg/ml, but concentrations as low as 0.75 μg/ml were effective. Hydrocortisone resistant thymocytes responded at least as well as untreated cells to con A, which also raised RNA synthesis rate in the former cells 2.5 times. Using an extracellular marker, 51CrEDTA, intracellular concentrations of some ions was estimated in the thymocytes after one hour incubation: Na+: 30 mmoles/kg water, K+: 177 mmoles/kg water and Cl−: 43 mmoles/kg water. Cellular water content: 69%. These values were not found significantly altered when con A was present. Since con A raised influx and efflux to the same extent and no net flux of K+ could be detected, it is proposed that both active and passive transport of K+ was increased by con A. The increased fluxes induced by con A, can apparently not be reversed by removal of con A from the incubation medium or by addition of the inhibiting hapten, α-methyl-D-mannoside.

38 citations


Journal ArticleDOI
TL;DR: Results from the zona-free eggs indicated that penetration, i.e., sperm fusion with the vitellus, had not been achieved in all eggs during the shorter incubations, thus indicating that under similar environmental conditions sperm genotype can significantly affect the rate of penetration.
Abstract: (C57BL/10 X CBA)F1 mouse eggs were incubated in vitro with either F1 or outbred TO sperm for 15 minutes-6 hours. Upon removal from the sperm suspensions some eggs were treated with pronase to remove zonae and then cultured, while the remainder were simply cultured to allow a comparison of the fertilization rates in the two groups. Although a brief incubation was sufficient for a high rate of fertilization when the zonae remained intact, results from the zona-free eggs indicated that penetration, i.e., sperm fusion with the vitellus, had not been achieved in all eggs during the shorter incubations. Results from the latter groups of eggs indicated that a 1 hour incubation with TO sperm and a 2 hour incubation with F1 sperm were needed to obtain a mean fertilization rate of 50%. Fertilization was complete within 1.5 hours using TO sperm and 2.5 hours using F1 sperm, thus indicating that under similar environmental conditions sperm genotype can significantly affect the rate of penetration.

Journal ArticleDOI
TL;DR: The synaptosomal pool of dopamine which is radioactively labelled after pulse labelling with dl‐[2‐14C]DOPA appears to be prone to oxidation to DOPAC and homovanillic acid which are preferentially released from thesynaptosomes.
Abstract: — Synaptosomes prepared from sheep corpus striatum showed a linear rate of respiration over a 90 min period of incubation in Krebs-bicarbonate medium containing glucose (10 mm) and the rate of respiration was stimulated by electrical pulses. Dopamine was released from synaptosome beds to the medium by either electrical pulses or 56mm-K+ (10min), increasing 108% and 76% respectively above control levels of release. The presence of d- or 1-amphetamine (0.12mm) in the incubation medium (40 min) increased the accumulation of dopamine in the medium by 310 and 275% respectively and 56mm-K+ also caused a significant increase in the release of glutamate, GABA and aspartate. Radioactively labelled dopamine was synthesized by the synaptosomes from l-[14C]tyrosine, l-DOPA or dl-DOPA, and electrical pulses caused a 35% increase in the rate of dopamine production from [U-14C] tyrosine. No increased release of [14C]dopamine in response to depolarizing stimuli was found to occur when synaptosome beds were transferred from medium containing radioactive precursors to fresh medium for further incubation (20 min). In the presence of 1- and d-amphetamine, accumulation of 14C-labelled doparnine in the incubation media was increased 129% and 380% respectively, the latter was partially depressed by absence of calcium from the medium. Three radioactively labelled metabolites formed by synaptosomes during incubation in dl-[2-14C]DOPA were detected; the major ones were dihydroxyphenylacetic acid and homovanillic acid and the third was unidentified. When the synaptosome beds were transferred to medium containing no radioactive precursors, it was found that labelled dihydroxyphenylacetic acid was 7 times more abundant than labelled dopamine in the incubation medium (20 min) and one-third as abundant in the synaptosomes. The dihydroxyphenylacetic acid n Ci/dopamine n Ci ratio was greatly affected by K+ stimulation, decreasing 52% and 34% in the incubation medium and synaptosomes respectively. A pathway of dihydroxyphenylacetic acid degradation was shown to occur through decarboxylation. These results are discussed in terms of the compartmentation of dopamine and its metabolism. It is proposed that one pool of dopamine is released by depolarizing agents and during the period of incubation it is replaced by synthesis from the endogenous tyrosine (19.5 nmol/100 mg protein) and not by the labelled dopamine in the synaptosome. The synaptosomal pool of dopamine which is radioactively labelled after pulse labelling with dl-[2-14C]DOPA appears to be prone to oxidation to DOPAC and homovanillic acid which are preferentially released from the synaptosomes.

Journal ArticleDOI
TL;DR: Throughout embryonic development, iodine was bound more and more to TG molecules, which were resistant to dissociation with SDS, and the low efficiency of the TG of the chick embryo as a thyroidal hormone-forming protein was compensated for by its high degree of iodination.
Abstract: Stable iodine was measured in the thyroid gland of the chick embryo from day 9 to day 20 of incubation in order to evaluate quantitatively the functional development of the gland. Total iodine content increased progressively during incubation. From day 9 to day 17 of incubation, this increase resulted from the increases of pellet-bound iodine and of soluble iodine. Afterwards, it essentially paralleled the increase of the soluble thyroglobulinbound iodine which reflected the increase in both thyroglobulin content and the degree of iodination of the thyroglobulin. The total iodine, thyroglobulinbound iodine and thyroglobulin (TG) content, increased as power functions of time during incubation, with critical times on days 11 and 15. Their concentrations also increased during the whole incubation period, while the iodide concentration remained roughly constant (25 ng/mg) from day 13 to day 19. Only one iodoprotein, 19.5 S TG, was found, and its heterogeneity of iodination was demonstrated during the whole pe...

Journal ArticleDOI
TL;DR: The alkaline protease activity in the gut of Spodoptera litura was found to increase with the development of larvae and decreased with the onset of pupation, and the preparation was not completely homogeneous and showed three clearly separable protein bands by polyacrylamide gel electrophoresis.

Journal ArticleDOI
TL;DR: The data support the view that one mode of regulation of hepatic HMG-CoA reductase is dependent on the relative rates of movement of cholesterol into and out of cells.

Journal ArticleDOI
TL;DR: Gel chromatography indicated that incubation of brain CPK in human plasma did not markedly change the molecular size of the enzyme and the presence of the reducing agent mercaptoethanol tended to reduce the rate of change of electrophoretic mobility of BB-CPK.

Journal ArticleDOI
TL;DR: It was concluded that the thyroxine release by isolated cells represents a real secretion and suggests that the normal mechanisms of proteolysis of thyroglobulin and deiodination of iodotyrosines inside the cells are preserved.

Book ChapterDOI
TL;DR: It is suggested that an incubating bird may be affected by the growing embryos inside its eggs even before the pre-hatching stages, as well as progressive thermogenesis, changes in weight, and gravitational properties.
Abstract: Publisher Summary Mutual stimulation during incubation may have immediate as well as long-term effects on the onset of chick care in the parent and on hatching and early postnatal responses in chicks. This chapter describes the aspects of incubation behavior and embryonic development, effects of embryonic stimuli on behavior of the incubating bird and the onset of chick care, and effects of parental stimuli during incubation on survival and behavior of the embryo and newly hatched chick. The chapter suggests that an incubating bird may be affected by the growing embryos inside its eggs even before the pre-hatching stages. The effects may result from embryonic movements as well as progressive thermogenesis, changes in weight, and gravitational properties. Under normal conditions of incubation, the behavior of the incubating birds undergoes significant changes, starting in some cases about 2 days before the hatching of their young. However, more detailed observations are desirable on the degree of attentiveness in correlation with incubation temperature, as well as on the frequency of rising, egg shifting, and parental vocalization, both in birds sitting on developing and non-developing eggs.

Journal ArticleDOI
TL;DR: The uptaken of alpha-aminoisobutyric acid by slices of kidney cortex from newborn rats is enhanced by a preliminary incubation of the tissue in buffer at 37 degrees C, and the phenomenon indicates that the enhanced uptake is due to an increased entry rate into the cells without a change in effux.

Journal ArticleDOI
TL;DR: Incubation of tritiated 2,5,-2′,5′-tetrachlorobiphenyl with normal monkey liver microsomes in a NADPH-generating system results in the formation of active metabolite(s) of the [3H]2,5,2′-5′, 5′-TetrACHlorob Piphenyl capable of covalently binding to RNA and protein isolated from the incubation mixture.
Abstract: SummaryIncubation of tritiated 2,5,-2′,5′-tetrachlorobiphenyl with normal monkey liver microsomes in a NADPH-generating system results in the formation of active metabolite(s) of the [3H]2,5,2′,5′-tetrachlorobiphenyl capable of covalently binding to RNA and protein isolated from the incubation mixture. The metabolite is not formed when the control microsomes are held at 100° for 10 min prior to incubation. The addition of microsomal supernate to the solution causes an increase in the binding of the active metabolite to macromolecules while the addition of glutathione to the incubation medium significantly inhibits this increase.This investigation was supported in part by U.S. Public Health Service Grants ES-00472, ES-00958, and RR-00167 from the National Institutes of Health. This is Primate Center Publication No. 15-019.

Journal ArticleDOI
TL;DR: The mean incubation period for eggs of the hawksbill turtle, Eretmochelys imbricata (L.) under laboratory conditions was 63 days as mentioned in this paper, which is the highest reported for marine turtles.

Journal ArticleDOI
TL;DR: It is suggested that predator-induced desertion in natural populations may increase embryonic mortality and chick age heterogeneity, which in turn may reduce chick survival.
Abstract: Field observations have shown that nocturnal predation may cause nest desertion by adult larids. Such desertion was simulated by exposing laboratory-incubated ring-billed gull eggs to 10 °C at either early, intermediate, or late periods of incubation. Hatchability was not significantly reduced by exposure. However, when eggs classed as 'non-viable at collection time' were eliminated, an increase in embryonic mortality was found to occur in late samples. The mean incubation time of all experimental eggs was slightly increased and the variance of incubation time was significantly greater for groups of eggs that suffered longer exposures at middle and late points in incubation. It is suggested that predator-induced desertion in natural populations may increase embryonic mortality and chick age heterogeneity, which in turn may reduce chick survival.

Journal ArticleDOI
TL;DR: Respiration of potato tuber discs increases during incubation for 1 day at 25 °C to a value which is roughly twice as high as the respiration immediately after slicing, mainly in the period from harvest to january.

01 Jan 1976
TL;DR: Examination of reaction products by means of gas chronatography-mass spectrometry gave evidence for the formation of a dihydroxydiethylstilbestrol, a diHydroxydienestrol, and a monomethoxydiethelstil bestrol.
Abstract: Aerobic incubation of a misture of E[1,1,1-D3]-3,4;bis(p-hydroxyphenyl)-hex-3-ene admixed with an approximately equimolar amount of unlabeled diethylstilbestrol and [ 2-(14)C ] diethylstilbestrol with rat liver homogenates in the presence of NADPH yielded water-soluble metabolites as well as products more and less polar than the starting material Addition of 5-adenosyl-L-methionine increased the quantity of nonpolar metabolites Incubation with rat liver microsomes yielded similar results When polar metabolites from incubation with rat liver microsomes were incubated with catechol O-methyltransferase and S-adenosyl[methyl-3 H]-L-methionine there was conversion to 3H-labeled nonpolar products Examination of reaction products by means of gas chronatography-mass spectrometry gave evidence for the formation of a dihydroxydiethylstilbestrol, a dihydroxydienestrol, and a monomethoxydiethylstilbestrol

Journal ArticleDOI
01 May 1976-Steroids
TL;DR: The results exclude a mechanism for the biosynthesis of (20R, 22R)-20,22-dihydroxycholesterol from the monohydroxylated cholesterol derivatives by way of dehydration followed by epoxidation and hydration.

Journal ArticleDOI
TL;DR: An in vitro method of culturing the excised rudimentary embryos of 11 llex species has been developed and the light inhibitory effect on in vitro embryo growth was universal in all 11 tested cultivars.
Abstract: A B S T R A C T The mature seeds of llex opaca Ait. contain rudimentary heart-shaped embryos. When excised embryos of cv. Farage were grown in vitro with a 16-hr photoperiod, only 20 % reached germination size after 13-day incubation, while 75 % of the embryos reached the same stage when incubated in darkness. This light inhibitory effect increased with the length of daily light exposure as the daily photoperiod reached 4 hr. Nearly 50%, growth reduction resulted as the cultures were preincubated in light continuously for 2 days before a 10-day dark incubation. After 4 days of light incubation the inhibitory effect could no longer be reversed by the subsequent dark incubation. Once the heart-shaped embryos started to grow in darkness they become progressively insensitive to subsequent light inhibition. After a 6-day initial dark incubation the embryos become immune from the inhibitory effect of light. This light inhibitory effect on in vitro embryo growth was universal in all 11 tested cultivars. THE SEEDS of llex opaca (American holly) contain rudimentary embryos which remain in the heart-shaped stage after the fruits have reached maturity (Ives, 1923). A minimum of 15 months under the proper germination conditions is required for the seeds of mature berries to complete their embryonic development and to begin germination (Barrett, 1962; Ives, 1923). Barrett (1962) referred to this period of embryonic development (from heart-shaped stage to mature embryo) as "late embryogeny." To bypass this period of embryo dormancy, an in vitro method of culturing the excised rudimentary embryos of 11 llex species has been developed (Hu, 1975a).


Journal ArticleDOI
TL;DR: It is tentatively concluded that a period of maximal sensitivity to the behavior effects exists prior to Day 7 and that the mechanisms of embryolethality is different from that producing the functional deficits.
Abstract: Methylmercury dicyandiamide (0.05 to 10 mg/kg egg) injected into the yolk sac of fertilized chicken eggs prior to incubation produced a dose related decrease in the percentage of chicks hatched (90-57% of control). With dosage fixed at 0.5 or 5.0 mg/kg egg and injections made on Days 0, 7 or 14 of incubation, hatches were 90, 68 and 75%, respectively, for the low dose and 63, 13 and 18% for the high dose. In contrast to results obtained from chicks hatched from eggs injected on Day 0 of incubation, chicks hatched from eggs injected with 0.5 or 5.0 mg MMD/kg on Day 7 or 14 were not different from controls in a detour learning situation. Administration of 14-C methylmercury revealed maximal brain radiolabel in embryos injected on Day 0 to be 10% that seen with eggs injected on Day 7 but twice that seen with eggs injected on Day 14. We tentatively conclude that a period of maximal sensitivity to the behavior effects exists prior to Day 7 and that the mechanisms of embryolethality is different from that producing the functional deficits.

Journal ArticleDOI
R.E. Isaacks1, Donald R. Harkness1, J.L. Adler1, C.Y. Kim1, P.H. Goldman1, S. Roth1 
TL;DR: The whole blood P50 during the last week of incubation and the first 8 days after hatching correlates best with the amount of ATP in the erythrocytes, and the effects of inositol pentaphosphate on P50 of the whole blood is much more gradual and appears to become of major influence after 2-3 weeks post-hatching.

Journal ArticleDOI
TL;DR: It was found that there was a remarkable time lag for the development between the pre- and the postsynaptic potentials, and the presynaptic potential appeared early and developed its maximum height within 10 to 20 min from the onset of incubation.
Abstract: Thin slices, 500μm in thickness, prepared from the guinea pig olfactory cortex and maintained in vitro, generate presynaptic and postsynaptic potentials following electrical stimulation of the lateral olfactory tract. These responses, however, cannot be elicited immediately after slice preparation;they start to develop gradually as the incubation continues. It was found that there was a remarkable time lag for the development between the pre- and the postsynaptic potentials. The presynaptic potential appeared early and developed its maximum height within 10 to 20 min from the onset of incubation. This time course was only slightly influenced by low temperature. Development of the postsynaptic potential in incubation was delayed and the time required to obtain the maximum height was about 30 min at 37°C and 70 min at 22°C. Upon step-like warming from 24°C to 37°C, there was a rapid increase in the amplitude of the response. In the glucose-deficient solution the presynaptic potential maintained its amplitude longer than the postsynaptic potential. Frequency potentiation of the postsynaptic potential was studied by applying a train of six stimuli. The maximum augmented ratio among six responses was the highest in early incubation and reached a steady at 50min. The ratio of the post-tetanic potentiation of olfactory neurons was the highest at 5 min incubation and reached a steady at 20 min.