Plasma cortisol measurements in precocious male and nonprecocious male juvenile steelhead trout (Salmo gairdneri)

Summary The mean biweekly plasma cortisol levels of juvenile nonmigratory precocious male steelhead trout,Salmo gairdneri, maintained from June through November in our laboratory under natural photoperiodic conditions ranged from 2.4–27.2 g/dl. Greatest mean cortisol occurred during the month of greatest gonadal mass, suggesting a direct interrenal-testicular relationship in this population of trout. The monthly mean plasma cortisol level of nonprecocious juvenile steelhead males captured prior to their downstream migration to the ocean from an Idaho hatchery and maintained in the laboratory simultaneously with the precocious males was low. For some months plasma cortisol was less than 0.1 g/dl. In June, however, plasma cortisol in nonprecocious males was 11.0 g/dl.     

The spermatozoon of Oikopleura dioica Fol (Larvacea,Tunicata)

Summary The spermatozoon of Oikopleura dioica is about 30 m long, with a spherical head, about 1 m wide, a 3 m long and 1 m wide midpiece, and a 25 m long tail with a tapered end piece. The head contains a nucleus with the chromatin volume limited to about 0.1 m³. A small acrosome is found in an anterior inpocketing, and a flagellar basal body in a posterior inpocketing of the nucleus. The midpiece contains a single mitochondrion with the flagellar axoneme embedded in a groove along its medial surface. The flagellar axoneme has the typical 9 + 2 substructure, and the basal body the typical 9+0 substructure. A second centriole and special anchoring fibres are absent.     

Ultrastructural analysis ofSpinacia oleracea sperm cells isolated from mature pollen grains

Summary In isolated condition, the sperm cells ofSpinacia oleracea are no longer arranged in pairs as in the pollen grain. The vegetative membrane, which surrounds a sperm cell pair in a mature pollen grain, is lost during the isolation procedure. The sperm cells become spherical in shape.The isolated sperm cell is surrounded by an intact plasma membrane. The heterochromatic or euchromatic sperm cell nucleus is located in the cell center. Mitochondria are round to oval and have distinct cristae. Often they are clustered in groups of 5 to 10 mitochondria. Dictyosomes are present in the cytoplasm and consist of 4 to 5 cisterns. Endoplasmatic reticulum is mostly situated at the sperm cell periphery, as single cisterns very near the plasma membrane.From diameters of sectioned sperm cells in electron micrographs, it is possible to calculate the average diameter of the whole sperm cell. This average diameter is 3.66 m with a variation of 3.0 m to 4.2 m, resulting in an average volume of 25.6 m³. The nuclear volume is 12.8 m³ (50.0% of the whole cell) and the mitochondrial volume is 0.7 m³ (2.5% of the whole cell). The frequency distribution of the isolated sperm cells diameters shows only one peak with a normal distribution, indicating that there is no dimorphism in volume.     

Choline Administration Reverses Hypotension In Spinal Cord Transected Rats: The Involvement of Vasopressin

Intracerebroventricular (i.c.v.) choline (50–150 g) increased blood pressure and decreased heart rate in spinal cord transected, hypotensive rats. Choline administered intraperitoneally (60 mg/kg), also, increased blood pressure, but to a lesser extent. The pressor response to i.c.v. choline was associated with an increase in plasma vasopressin. Mecamylamine pretreatment (50 g; i.c.v.) blocked the pressor, bradycardic and vasopressin responses to choline (150 g). Atropine pretreatment (10 g; i.c.v.) abolished the bradycardia but failed to alter pressor and vasopressin responses. Hemicholinium-3 [HC-3 (20 g; i.c.v.)] pretreatment attenuated both bradycardia and pressor responses to choline. The vasopressin V1 receptor antagonist, (-mercapto-, -cyclopenta-methylenepropionyl¹, O-Me-Tyr², Arg⁸)-vasopressin (10 g/kg) administered intravenously 5 min after choline abolished the pressor response and attenuated the bradycardia-induced by choline. These data show that choline restores hypotension effectively by activating central nicotinic receptors via presynaptic mechanisms, in spinal shock. Choline-induced bradycardia is mediated by central nicotinic and muscarinic receptors. Increase in plasma vasopressin is involved in cardiovascular effects of choline.     

A catalase microbiosensor for detecting hydrogen peroxide

A microbiosensor for hydrogen peroxide (H₂O₂) was constructed by immobilizing catalase in a polyacrylamide gel on the tip of a Clark-type oxygen microelectrode. The outer tip diameter was 15–40 m. The sensors had response times of 0.7–1.2 s, and could detect as little as 2–4 M H₂O₂. They could measure with a spatial resolution of about 100m and remained operational for up to three weeks.     

Genetic variation of physiological response to aflatoxin in Gallus domesticus

Summary A pedigreed, commercial broiler population of 31 sire families was administered dietary aflatoxin at levels of either 0.0 or 5.0 g of aflatoxin per g of diet from 7 to 21 days of age and their response assessed by various physiological parameters.Body weight, gain, packed red blood cell volume (PCV). plasma albumin, plasma protein and cholesterol responses were significantly reduced from control values by the 5.0 g/g aflatoxin diet. Males had greater body weights and gains in both dietary regimes than females. Females had significantly higher PCV, protein, albumin and cholesterol values in the 5.0 g/g aflatoxin group than their male counterparts. These differences resulted in significant sex × aflatoxin level interactions for these parameters. Coefficients of variation were increased for all parameters measured in the 5.0 g/g aflatoxin treatment compared to values for the control group. This increase was greatest for plasma protein, albumin, and cholesterol responses. Heritabilities were calculated for all responses within both treatment groups and were found to be increased in all cases by the 5.0 g/g aflatoxin diet. Highly significant phenotypic correlations were determined between body weight and gain and between plasma albumin and total plasma protein in both treatment groups. High phenotypic correlations among PCV, plasma cholesterol, plasma protein, and plasma albumin were noted in the 5.0 g/g aflatoxin group. Significant genetic correlations were determined between body weight and gain and between plasma albumin and plasma protein in the control group. Body weight and gain and plasma protein, albumin, cholesterol and PCV were genetically correlated in the 5.0 g/g aflatoxin group. Genetic correlations calculated across environments for the same traits were high for PCV, body weight and gain and much lower for plasma albumin, plasma protein, and plasma cholesterol.The results of this study demonstrate that genetic variability for resistance to aflatoxin exists in commercial broiler populations. Strong genetic and phenotypic relationships, and high heritabilities associated with plasma albumin and protein suggest their applicability as selection criteria for aflatoxin resistance. Genetic correlation for these traits across dietary environments indicate that responses for aflatoxin resistance should be measured during aflatoxin challenge and suggest that selection for growth and selection for aflatoxin resistance are not antagonistic.     

Endogenous phosphorylation of rat brain synaptosomal plasma membranes in vitro: Some methodological aspects

The time course of endogenous phosphorylation in vitro of total or separted synaptic plasma membrane proteins (SPM) has been correlated with that of hydrolysis of the phosphate donor (ATP) in the incubation medium. The ATP/SPM ratio in the medium was varied. In a low-ratio medium (7.5 M ATP; 2.2 g SPM/l) a complete hydrolysis of ATP occurred almost instantaneously as was measured by the release of free phosphate in and the disappearance of ATP from the medium. As a consequence, only a very short peak of phosphorylation, followed by dephosphorylation was observed. However, when higher ATP/SPM ratios were used (200 M ATP; 0.4 g SPM/l and 500 M ATP; 0.4 g SPM/l), the incorporation of phosphate into SPM proteins was linear for 20 sec, and the maximum level of phosphate incorporation was increased. Similar results were obtained after separation of³²P-labeled phosphoproteins by slab gel electrophoresis. However, analysis of the autoradiographs obtained fromone SPM preparation under different ATP/SPM ratios revealed dependence of phosphorylation of individual protein bands on the conditions used.     

Image processing technique for measuring specific growth rates of Gibberella fujikuroi

Summary Two methods were compared for estimating of Gibberella fujikuroi grown with different proportions of glucose and starch. They were, =Ln2 (V_r/Le) on Petri dish (V_r= rate of tip extension and L_e= mean hyphal length) and, ₂=d (LnX)/dt in stirred fermenter. Values of ₁ and ₂ were in close agreement with each other.     

Lack of carcinogenicity of agaritine by subcutaneous administration in mice

Agaritine (A), an ingredient of the cultivated mushroom of commerce Agaricus bisporus, was administered by subcutaneous injection to two groups of randomly bred Swiss mice. In the first group the animals of both sexes were treated at a 100 g/g body weight basis five times at weekly intervals, while in the second group the mice received a single A treatment of 100 g/g body weight for females and 50 g/g body weight for males. The administration of the compound resulted in no detectable carcinogenic effect in the animals. Since some of the breakdown products of A were shown to be carcinogenic in mice and the mushroom itself was found to be mutagenic, the field is discussed in the light of the obtained results.     

Effects of lead and cadmium on chemical composition and total water content of the pupal parasitoid, Pimpla turionellae

The parasitoid Pimpla turionellae L. (Hymenoptera, Ichneumonidae) was fed on Cd, Pb and Cd+Pb-contaminated food (33g Cd, 82g Pb and 33g Cd+82g Pb per gram food fresh weight, respectively). Significant decrease in the total lipid and protein content was found along with an increase in the water content particularly in Cd-contaminated parasitoids.     

Effect of aldosterone on incorporation of amino acids into renal medullary proteins

Summary Studies on the effects of pretreatment with aldosterone on the incorporation of³H leucine or³H methionine into proteins in renal slices were carried out in Joklik-modified minimal essential medium. Administration of aldosterone (2 g/100 g body wt) to adrenalectomized rats increased³H leucine incorporation into trichloroacetic acid insoluble fractions of crude homogenates of cortical slices by 15.5±0.4% and of medullary slices by 53.5±1.3%. No increase in isotope incorporation was observed in slices of renal papilla or spleen prepared from the same rats. Aldosterone had no effect on the³H-leucine content of the trichloroacetic acid-soluble fractions of all three renal zones and the spleen. The dose of aldosterone that elicited a half-maximal increase in³H-methionine incorporation into proteins of renal medullary slices (0.45 g of aldosterone/100 g body wt) was indistinguishable from that needed to elicit a halfmaximal increase in the urinary K⁺/Na⁺ ratio (0.35 g of aldosterone/100 g body wt). Dexamethasone, a potent glucocorticoid, at a dose of 0.8 g/100 g body wt did not augment³H-leucine incorporation into renal medullary proteins but was effective at 8 g/100 g body wt. Spirolactone (SC-26304), a potent anti-mineralocorticoid, abolished the effect of aldosterone on amino acid incorporation into medullary proteins when administered at a 100-fold higher dosage [i.e., 80 gvs. 0.8 g (per 100 g body wt)]. These results imply that the action of aldosterone on amino acid incorporation is mediated by the mineralocorticoid rather than the glucocorticoid pathway, presumably the mineralocorticoid receptors. Moreover, pretreatment of the rats with actinomycin D (70–80 g/100 g body wt) erased the effect of aldosterone (0.8 g/100 g body wt) on amino acid incorporation into medullary proteins.In paired experiments with³H and³⁵S methionine, aldosterone (0.8 g/100 g body wt) increased methionine incorporation into trichloroacetic acid precipitable proteins of subcellular fractions of the renal medulla. The effect of aldosterone on incorporation of methionine into medullary cytosol proteins was analyzed further by polyacrylamide gel electrophoresis at pH 8.3 in tris-glycine buffer. The gel profiles indicate that aldosterone significantly increased methionine incorporation into at least one protein (independent of the isotope) with a molecular weight of 31,000. This increase was inhibited by either pretreatment of the rat with actinomycin D (70–80 g/100 g body wt or SC-26304 (80 g/100 g body wt). Dexamethasone (0.8 g/100 g body wt) did not increase incorporation of methionine into the medullary cytosol proteins resolved by polyacrylamide gel electrophoresis.     

Effect of Halothane in Cortical Cell Cultures Exposed to N-Methyl-D-Aspartate

In vivo studies have shown potent protection by volatile anesthetic agents against cerebral ischemic insults. Volatile agents have also been shown to antagonize glutamatergic neurotransmission at the N-methyl-D-aspartate (NMDA) receptor. This study examined the potential for halothane to reduce neuronal excitotoxic lesions caused by NMDA. Fetal rat cortical cell cultures were allowed to mature 13–16 d. Culture wells (n = 13–16) were treated with 0 mM – 3.96 mM halothane in the presence/absence of 30 M NMDA. Additional cultures were exposed to 30 M NMDA in the presence/absence of 10 M MK-801 or 10 ACEA 1021. Cellular lethality was assessed by measurement of lactate dehydrogenase (LDH) 24 hrs later. A maximal effect of halothane was observed at 0.70 mM (2.1 vol%) wherein a 36% reduction in NMDA-stimulated LDH release occurred relative to untreated controls. Both MK-801 and ACEA 1021 caused complete inhibition of NMDA-stimulated LDH release. These data confirm that halothane has modulatory effects at the NMDA receptor but potency of this drug is less than that of specific antagonists of either glutamate or glycine. These findings suggest that halothane protection in vivo can be partially explained by anti-excitotoxic properties although other mechanisms of action are probably also important.     

Clonal propagation of Callistemon by tissue culture techniques

Callus development in Callistemon viminalis was readily achieved when axillary buds derived from nodal tissue were placed in a medium containing macro- and micro-nutrients, sucrose (0.06 M), inositol (300 M), nicotinic acid (20 M), pyridoxine hydrochloride (3 M), thiamine hydrochloride (2 M), riboflavin (10 M), cytokinins (5 M) and auxins (0.1 M). The presence of benzylaminopurine (5 M) and p-chlorophenoxyacetic acid (0.1 M) promoted the most vigorous callus development and sprout formation. Rooting of nodal material was rare but occurred readily following the transference of sprouts developed on callus to a basal medium containing sucrose and salts. Root initiation was stimulated, however, by the presence of auxins. Chlorophenoxyacetic acid while stimulating root initiation repressed root growth. Indole butyric acid stimulated both root initiation and shoot growth at concentrations of 0.005 to 0.1 M. The treatment of choice for rooting and shoot growth was the addition of indole butyric acid at a concentration of 0.01 M.     

Effect of washing on the plasma membrane and on stress reactions of cultured rose cells

The effects of plant growth regulators, light intensity, and end-of-day (EOD) light quality treatments on node and microtuber induction (% of cultures with microtubers) and development (fresh weight of microtubers) in yam (Dioscorea alata L. cv. Oriental) cultures were investigated. Nodal segments were excised from plantlets cultured on tuberization medium containing growth regulators and exposed to various light treatments. Absciscic acid (1 M) stimulated and cytokinins (2.5 M) inhibited microtuber development from yam nodal segments cultured on Mantell's and Hugo's full-strength tuberization medium under 8-h photoperiods. EOD far-red (FR) light inhibited microtuber induction and development and enhanced node formation. EOD FR light effects were nullified by immediately following the FR treatment with red light. This suggested the involvement of phytochrome in these processes. The lowest light intensity evaluated (12 mol m^–2 s^–1) inhibited microtuber, root and shoot production as compared to light intensities of 42, 72 and 102 mol m^–2 s^–1. Kinetin (2.5 m) in half-strength tuberization medium inhibited microtuber induction and development but did not affect node production in the light intensity evaluation.Abbreviations ABA abscisic acid - BA 6-benzylaminopurine - 2iP 6-(c,c-dimethylallylamino)-purine - NAA napthaleneacetic acid - R light red light - FR light far-red light - EOD light end-of-day light     

Enzymatic properties of overexpressed human hexokinase fragments

Full-length hexokinase (HK; ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1), a truncate form of the enzyme lacking the first 11 amino acids (HK-11aa) and the 50 kDa C-terminal half (mini-HK) containing the catalytic domain, were overexpressed and purified to homogeneity to investigate the influence of the N-terminal region of human hexokinase type I (HK) on its regulatory properties. All forms of the enzyme are catalytically active with the HK-11aa being the most active. All the forms of HK showed the same affinity for glucose and MgATP and were also inhibited by glucose 6-phosphate (Glc 6-P) competitively vs. MgATP with similar Kis (28.5-37 M). Glucose 1,6-bisphosphate (Glc 1,6-P2) was also a strong inhibitor of all HKs without significant differences among the different truncate forms of the enzyme (Kis 49.5-59 M). At low concentrations (0-3 mM), Pi was able to reverse the sugar phosphate inhibition of the full-length HK and HK-11aa but not of the mini-HK. In contrast, at high concentrations Pi was an inhibitor of all the hexokinases investigated. These findings confirm that Pi has a low affinity binding site on the C-terminal of HK while counteracts glucose 6-phosphate inhibition by binding to or requiring the N-terminal half of the enzyme. The first 11 N-terminal amino acids influence the specific activity of HK but are unable to affect the kinetic properties investigated.     

β2-Adrenoceptor activation by zinterol causes protein phosphorylation,contractile effects and relaxant effects through a cAMP pathway in human atrium

Evidence from ventricular preparations of cat, sheep, rat and dog suggests that both ₁-adrenoceptors (₁AR) and ₂-adrenoceptors (₂AR) mediate positive inotropic effects but that only ₁AR do it through activation of a cAMP pathway. On the other hand, our evidence has shown that both ₁ AR and ₂ AR hasten relaxation of isolated human myocardium consistent with a common cAMP pathway. We have now investigated in the isolated human right atrial appendage, a tissue whose -AR comprise around 2/3 of ₁AR and 1/3 of ₂AR, whether or not ₂AR-mediated effects occur via activation of a cAMP pathway. We carried out experiments on atria obtained from patients without advanced heart failure undergoing open heart surgery. To activate ₂AR, we used the ₂AR-selective ligand zinterol. Experiments were carried out on paced atrial strips (1 Hz) and tissue homogenates and membrane particles. Zinterol caused positive inotropic and lusitropic (i.e. reduction of t_1:2 of relaxation) effects with EC₅₀ values of 3 and 2 nM, respectively. The zinterol-evoked effects were unaffected by the AR-selective antagonist CGP 20712A (300 nM) but blocked surmountably by the ₂AR-selective antagonist ICI 118551 (50 nM) which reduced both EC₅₀ values to 1 M. Zinterol stimulated adenylyl cyclase activity with an EC₅₀ of 30 nM and intrinsic activity of 0.75 with respect to (–)-isoprenaline (600 M); the effects were resistant to blockade by CGP 20712A (300 nM) but antagonised surmountably by ICI 118551 (50 nM). Zinterol bound to membrane PAR labelled with (–)-[¹²⁵I] cyanopindolol with higher affinity for ₂AR than for - 1 AR; the binding to ₂AR but not to - BAR was reduced by GTPyS (10 M). In the presence of CGP 20712A (300 nM) (–)-isoprenaline (400 M); (to activate both ₁AR and ₂AR maximally) and zinterol (10 M); increased contractile force 3.4-fold and 2.5-fold respectively and reduced relaxation tut by 32% and 18% respectively. These effects of (–)-isoprenaline and zinterol were associated (5 min incubation) with phosphorylation (pmol P/mg supernatant protein) of troponin I and C-protein to values of 8.4 ± 2.0 vs 12.4 ± 2.3 and 10.1 ± 2.5 vs 8.6 ± 1.6 respectively. (–)-Isoprenaline and zinterol also caused phosphorylation of phospholamban (1.8 ± 0.3 vs 0.4 ± 0.1 pmol P/mg respectively) specifically at serine residues. We conclude that in human atrial myocardium activation of both ₁AR and ₂AR leads to cAMP-dependent phosphorylation of proteins involved in augmenting both contractility and relaxation.     

Chemical induction of interleukin-8, a proinflammatory chemokine,in human epidermal keratinocyte cultures and its relation to cytogenetic toxicity

Tumor promoters, proinflammatory cytokines, endotoxins, and protein synthesis inhibitors can modulate cell cycle kinetics of various cell types, stimulate production of reactive oxygen species, and induce keratinocytes to produce interleukin-8 (IL-8), a potent chemotactant for polymorphonuclear neutrophils and T lymphocytes. The aim of this study was to determine whether perturbations of cytogenetic responses correlated with the induction of IL-8 expression. Cultures of primary human keratinocytes were grown in serum-free medium with 5 mol/L bromodeoxyuridine to label DNA and exposed either to phorbol-13-myristate-12-acetate (PMA) (0.0001–100 ng/ml), cycloheximice (CHX) (0.01–50 g), lipopolysaccharide (0.1–100 g/ml), tumor necrosis factor- (TNF) (3.13–50 ng/ml), or interleukin-1 (IL-1) (1–182 pg/ml). Metaphase chromosome preparations were stained by a fluorescence-plus-Giemsa technique to differentiate sister chromatids. For IL-8 production, keratinocytes were grown to 70% confluency and then exposed to chemicals for 24 h. Immunoreactive IL-8 was quantitated from the supernatants by ELISA. With the exception of benzo(a)pyrene used as a positive control, none of the agents induced sister chromatid exchanges. However, PMA and TNF induced IL-8 production that coincided with significant cell cycle inhibition. IL-1 had no effect on cytogenetic endpoints, yet stimulated a 6.3-fold increase in IL-8. CHX inhibited cell cycle progression and mitotic activity at concentrations that were 200 times lower than required for IL-8 induction; however, puromycin (0.31–10 g/ml), another protein synthesis inhibitor, did not induce IL-8. At all concentrations tested, TNF reduced the mitotic index by 45%, slowed cell cycle progression by 3.5 h, and induced a flat, albeit large, IL-8 response at concentrations 12.5 ng/ml. These agent-specific response patterns suggest that induction of IL-8 production is not always the inevitable result of cell cycle perturbations or genetic damage.Abbreviations B(a)P benzo(a)pyrene - BrdU 5-bromo-2-deoxyuridine - CHX cycloheximide - ICAM intercellular adhesion molecules - IL-1 interleukin-1 - IL-8 interleukin-8 - KGM keratinocyte growth medium - LPS lipopolysaccharide - PKC protein kinase C - PMA phorbol-13-myristate-12-acetate - PMN polymorphonuclear neutrophil - ROS reactive oxygen species - SCE sister chromatid exchange - TNF tumor necrosis factor      

The effect of monoterpenes on astaxanthin production by a mutant ofPhaffia rhodozyma

Summary The total pigment and astaxanthin content ofPhaffia rhodozyma increased with increasing concentrations -pinene up to 500 l -pinene/l. Above this concentration the total pigment and astaxanthin content as well as the biomass production decreased. The addition of 500 l -pinene/l increased the total pigment content from 1652 g/g to 2201 g/g and the astaxanthin content from 1554 g/g to 1883 g/g. A sharp decrease in maximum specific growth rate occurred above 150 l -pinene/l.     

Saccharomyces cerevisiae 2-mum DNA. An analysis of the monomer and its multimers by electron microscopy.

Summary The non-tandem inverted duplication in the 2-m DNA of Saccharomyces cerevisiae has a length of 0.19 m and is located asymmetrically along the molecule. The majority of the dumb-bell structures that are formed upon denaturation and selfannealing of the 2-m monomer consists of the renatured inverted duplication sequences as double stranded stem and two single stranded loops of 0.67 m±0.06 m (S-loop) and 0.86 m±0.05 m (L-loop) length. Two additional size classes which comprised 5–10% of the measured molecules had contour lengths of around 1.7 m and 2.1 m. The smaller dumb-bells contained two S-loops and the larger dumb-bells contained two L-loops as was shown by heteroduplex mapping with an HindIII fragment from the L-loop. Two models which assume illegitimate or site specific recombination, are presented to explain the generation of double S-loop and double L-loop molecules. At least part of the 4-m and 6- circular molecules present in the yeast supercoiled DNA fraction are shown to be dimers and trimers of 2-m monomers, but often with inverted loop segments most probably due to intramolecular recombination between sequences of the inverted duplication.2-m DNA is used to indicate the supercoiled DNA fraction although in our measurements the average monomeric length is 1.9 mPart of this work has been presented at the Conference: The Genetics and Biogenesis of Chloroplasts and Mitochondria, Munich, August, 1976     

Immunocytochemical study of the hypothalamo-neurohypophysial system

Summary An antiserum cross-reactive against ovine neurophysins-I-II and -III has been used in conjunction with the immunoperoxidase histochemical procedure to localize the cells of the sheep paraventricular (PVN) and supraoptic nuclei (SON). In order to describe the topographical distribution of the SON and PVN a study was made on the serial sections cut (a) transversely from rostral to caudal positions and (b) sagittally from lateral to medial positions of the hypothalamus.The cells of the SON, when examined in the transverse aspect, extended approximately 1900 caudally and when examined in the sagittal plane were contained within a lateral-medial distance of 4830 . In each case the SON cells lay adjacent to the optic chiasm.As sections were cut transversely, the cells of the PVN first appeared in a rostral position defined as 0 and close to the ventral lining of the third ventricle. This general ventral and ventro-lateral distribution of cells maintained up to a caudal distance of approximately 840 . From positions 1260–2310 there was a dramatic dorsal shift of the PVN cells which by this time had also extended laterally. The total rostral-caudal distance occupied by the PVN cells was 3150 . That the lateral-medial distance occupied by the PVN was small (1050 ) was determined on examining the magnocellular nuclei in sagittal section.This work was financed by a grant awarded by the Medical Research Council of New Zealand