Ovarian steroidogenesis during follicular maturation in the domestic fowl (Gallus domesticus)

The steroidogenic potential of various physiological compartments within the ovary of the hen were examined using in vitro systems. Three-hour incubations of individual whole small follicles (less than 1 mm-1 cm) or 100,000 collagenase-dispersed theca cells of the five largest ovarian follicles (F1-F5) were conducted in 1 ml of Medium 199 at 37 degrees C in the presence and absence of luteinizing hormone (LH) (0.39, 0.78, 1.56, 3.13 and 6.25 ng), progesterone (5 ng), and dehydroepiandrosterone (DHEA, 5 ng). Steroid output was measured by radioimmunoassay of incubation media. Progesterone was not produced by small follicles although they are a major source of DHEA and estradiol and a significant source of androstenedione. Output of DHEA, androstenedione and estradiol was highly stimulated by LH. The substrate for androstenedione and estradiol in small follicles is probably DHEA. Output of DHEA and androstenedione in theca cells of F2-F5 was stimulated by LH in a dose-related manner. A dose-response relationship between estradiol output and the concentration of LH in media was not apparent in theca cells from F2-F5. Steroidogenesis in theca tissue of large follicles occurs predominantly via the delta 4 pathway. The ability of these theca cells to metabolize progesterone to androstenedione is lost between 36 and 12 h before ovulation. Their ability to metabolize DHEA to androstenedione is still present 12 h before ovulation. Aromatase activity is significantly reduced between 36 and 12 h before ovulation. These data indicate that both large and small follicles can be stimulated by LH. The small follicles are the major source of estrogen. As the large yolky follicles mature, steroidogenesis shifts from the delta 5 to the delta 4 pathway. By 12 h before ovulation, the F1 follicle has lost the ability to convert progesterone to androstenedione. The inability of the largest ovarian follicle to convert progesterone to androstenedione contributes at least in part to the preovulatory increase in the plasma concentration of progesterone that generates the preovulatory LH surge by positive feedback.     

The excretion of urate and cationic electrolytes by the kidney of the male domestic fowl (Gallus domesticus)

Summary Four groups of roosters were obtained from combinations of high and low protein diets (33% or 11%), and two drinking solutions (tap water or 1% NaCl solution). Ureteral urine was analyzed for urate, Na⁺ and K⁺, in both the liquid and precipitated fractions of the urine.Birds fed a high protein diet-salt water combination excreted unusually large amounts of urate. In all groups, most of the excreted urate was in the form of a precipitate. This precipitate also contained large amounts of Na⁺ and K⁺ (Table 2).The presence of abundant urinary urate, due to high protein diet and large NaCl intake, aids in the excretion of Na⁺ and K⁺, by reducing their contribution to the osmotic pressure of the urine. However, some of these cations, although present in the urine precipitates, do not appear to be in the form of monobasic urate salts. The significance of urate in the excretion of electrolytes is discussed.We wish to thank Dr. Paul B. Siegel, Department of Poultry Science, V.P.I. and S.U., who generously supplied the roosters used in this study. We also wish to thank Mr. Douglas Bartley for his determination of urine pH values, and Dr. Alan G. Heath for the use of his microelectrode pH apparatus. This work was supported by USPHS-NIH grant, number AM 14991.     

Fertilizing competency of multiple ovulated eggs in the domestic fowl (Gallus domesticus)

Fertilizing competency of multiple ovulated eggs in the domestic fowl was examined by fertilization in vitro and early development in culture. Normal laying hens (White Leghorn) were treated with 75 IU of PMSG for 7 days followed by injection of anterior pituitary extracts from chickens (CAPE). Ovulation began to occur 7.5 h after injection of CAPE. These hens ovulated 1-7 ova but some premature ovulation of GV stage ova were observed. In vitro fertilization of the multiple ovulated ova was examined by inseminating 10(6)-10(7) sperm onto the germinal disks in m-Ringer's solution. The gamete or zygote nuclei were detected by DNA specific fluorescence using DAPI (4',6'-diamidino-2-phenylindole) in the histological section prepared from the germinal disk. Process of fertilization was examined in the eggs incubated for 4 h after insemination in DMEM + liquid albumen at 41 degrees C under the atmosphere of 5% CO2 in air. Fertilization rate of the total multiple ovulated eggs was 55% (11/20), in which 90% (9/10) and 10% (1/10) in the eggs recovered 7.5-8.5 h and 9.0-9.5 h after CAPE injection were obtained, respectively. Normal pronuclei were formed in five eggs of those recovered 7.5-8.5 h after CAPE injection. Early development after fertilization in vitro was also examined by incubation for 12 h in DMEM + liquid albumen at 41 degrees C under the atmosphere of 5% CO2 in air. Although development in vitro was delayed compared to that in utero condition, normal development was observed in naturally and multiple ovulated eggs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cell membrane amino acid transport processes in the domestic fowl (Gallus domesticus)

Intestinal absorption of amino acids in the chicken occurs by way of processes which are concentrative, Na+-dependent and dependent upon metabolic energy in the form of ATP. Intestinal transport is carrier-mediated, subject to exchange transport (trans-membrane effects) and is inhibitable by sugars, reagents which inactivate sulfhydryl groups, potassium ion, and by deoxpyridoxine, an anti-vitamin B6 agent. It is stimulated by phlorizin, a potent inhibitor of sugar transport, and in Na+-leached tissue by modifiers of tissue cyclic AMP levels, e.g. theophylline, histamine, carbachol and secretin. Separate transport sites with broad, overlapping specificities function in the intestinal absorption of the various classes of common amino acids. A simple model for these sites includes one for leucine and other neutral amino acids, one for proline, beta-alanine and related imino and amino acids, one for basic amino acids, and one for acidic amino acids. Absorption of amino acids appears to be widespread in occurrence in the digestive tract of the domestic fowl; transport has been reported to be present in the crop, gizzard, proventriculus, small intestine and in the colon. By the end of the first week of life post-hatch, the caecum loses its ability to transport. Similarly, the yolk sac loses its ability by the second day post-hatch. Intestinal transport was noted before hatch and was found to be maximal immediately post-hatch. A requirement for Ca2+ appears to be lost after the first week of life post-hatch. The cationic amino acids appear to be reabsorbed by a common mechanism in the kidney. Transport rates of leucine measured in the intestine or in the erythrocyte were found to cluster about discrete values when many individual chickens were surveyed; such patterns may be an expression of gene differences between individuals. Two lines of chickens have been developed, one high and the other low uptake, through selective breeding based on the ability of individual birds to absorb leucine in erythrocytes. High leucine absorbing chickens were found to be more effective in absorbing lysine and glycine, were more effectively stimulated by Na+, had greater erythrocyte Na+, K+-ATPase activity, and their erythrocytes contained about 20% less Na+ than low line erythrocytes. The underlying genetic difference between these lines may reside at the level of the Na+, K+-ATPase and (or) with a regulatory gene determining carrier copies. Amino acid transport in erythrocytes was noted to be highest in pre-hatch chicks and to diminish during post-hatch development.(ABSTRACT TRUNCATED AT 400 WORDS)     

Early nuclear events of in vitro fertilization in the domestic fowl (Gallus domesticus)

In vitro fertilization in the domestic fowl (Gallus domesticus) was investigated by observation of the early nuclear events. Ova retrieved from the fimbria following ovulation were inseminated in vitro with 10(6)-10(7) spermatozoa in Dulbecco's modified Eagle's medium (DMEM) for 10 min and then further incubated in DMEM + albumen for 1, 2, 3, or 4 hr. These eggs were histologically examined by epifluorescent microscopy after staining with 4',6'-diamidino-2-phenylindole (DAPI). Nuclei of spermatozoa at various stages of transformation were observed in the ova incubated for 1-3 hr. Close pairing of two pronuclei, presumed to be male and female juxtaposition, was detected in ova incubated for 4 hr. These data provide direct evidence for the in vitro fertilization of fowl eggs and suggested that the early process of in vitro fertilization is comparable to that of in vivo fertilization.     

鸡垂体前叶提取物诱导鸡超数排卵

Chicken anterior pituitary extract(CAPE) and acetone dried chicken anterior pituitary (ACAPE) were injected intraperitoneally into normal laying hens (‘ovulation suppressed’ following pretreatment with daily subcutaneous injection of PMSG) to induce multiple ovulations. The dose of PMSG, the effect of CAPE and ACAPE and the time required for induction of ovulation following injection of ovulation inducing hormone were determined. The results revealed that (1) when 75 IU PMSG was administered daily, egg laying stopped in 33% of the treated hens within 6 days after the first injection. However, the percentage of hens showing the same effects changed significantly (over 95%) within 3 to 6 days when the amount of PMSG was increased to 100 IU; (2) the number of ovulated ova was 1 00±0 00, 2 33±0 26,2 20±0 20 respectively after receiving 100 mg, 200 mg and 300 mg; the number of ovulated ova was 2 00±0 00, 2 86±0 48, 3 00±1 50 respectively after receiving 10 mg, 15 mg and 20 mg ACAPE; (3) The time from injection to ovulation in almost all hens was about 7 5 h except one hen ovulated about 6 5 h after receiving ACAPE .     

Isolated adrenocortical cells of the domestic fowl (Gallus domesticus): steroidogenic and ultrastructural properties

Isolated adrenocortical cells from White Leghorn chickens (Gallus domesticus) were compared to those from rats (Rattus norvegicus). Cells were prepared from collagenase-dispersed adrenal glands of sexually mature male animals. Corticosterone was measured by radioimmunoassay after incubation for 2 h with steroidogenic agents. Of the four ACTH analogues used, three were 6-17 times more potent with rat cells than with fowl cells (potencies were indicated by half-maximal steroidogenic concentrations). However, 9-tryptophan (O-nitrophenylsulfenyl) ACTH was 8 times more potent with fowl cells than with rat cells, thus suggesting that ACTH receptor differences exist between the two cell types. In addition, cAMP analogues were 10 times more potent with rat cells than with fowl cells suggesting that fowl corticosteroidogenesis is less dependent on cAMP than is rat corticosteroidogenesis. At equal cell concentrations, rat cells secreted 20-40 times more corticosterone than did chicken cells when they were maximally stimulated. Although rat cells converted 8 times more pregnenolone to corticosterone than did fowl cells, the half-maximal steroidogenic concentration for pregnenolone-supported corticosterone synthesis was the same for both cell types (about 5 microM). This suggests that fowl cells have lower steroidogenic enzyme content rather than lower steroidogenic enzyme activity. An unusual feature seen in the isolated fowl adrenocortical cells was an abundance of intracellular filaments.     

Gluconeogenic and lipogenic properties of isolated kidney tubules from the domestic fowl (Gallus domesticus)

Isolated kidney tubules synthesize glucose actively from fructose, lactate, glycerol and pyruvate and, to a lesser extent, from a variety of amino acids. Ethanol stimulated gluconeogenesis from pyruvate and inhibited it from lactate. The aminotransferase inhibitor, aminooxyacetate, greatly reduced synthesis from lactate but not from pyruvate. Quinolinate inhibited gluconeogenesis from both precursors, indicating an active role for cytosolic phosphoenolpyruvate carboxykinase (PEPCK) in the gluconeogenic pathway. Incorporation of lactate or glucose into triglycerides was relatively low, and since no fatty acid synthase (FAS) activity could be detected, probably represented chain elongation or reesterification.     

Effect of hemorrhage on hepatic tissue blood flow in the domestic fowl (Gallus domesticus)

1. Thermal Pulse Decay (TPD) methodology was used to monitor hepatic tissue blood flow (hepatic perfusion) in anesthetized birds prior to and during hemorrhagic hypotension. 2. Hemorrhage was accomplished by periodic removal of blood through a carotid cannula. Reducing the estimated blood volume (BV) from 100 to less than 50% decreased hepatic perfusion from 4.36 +/- 0.7 to 1.88 +/- 0.7 ml/min/g. 3. Changes in hepatic perfusion during the experiment were related to mean arterial blood pressure (MABP) by the following linear regression equation: hepatic perfusion = -1.79 +/- 0.0807x (r2 = 0.57).     

Episodic growth hormone secretion in the domestic fowl (Gallus domesticus): alpha adrenergic regulation

In animals the secretion of GH is characterized by a series of spontaneous peaks. The situation in avian species, however, is unknown. The present study examines this in the domestic fowl. Blood samples were obtained via a remote catheter at 5-min intervals from young male chickens. An episodic pattern of GH secretion was observed having an interpulse interval (frequency) of approximately 1 h. Episodic GH secretion was altered by peripheral administration of drugs which influence adrenergic function. Spontaneous GH peaks were not observed following the administration of (1) bis-(4-methyl-1-homopiperazinyl-thiocarbonyl) disulfide (FLA63) or diethyldithiocarbamate (DDC) (which blocks norepinephrine (NE) and epinephrine (E) synthesis by inhibiting dopamine-beta-hydroxylase), (2) phenoxybenzamine (an alpha 1-adrenergic antagonist) and (3) clonidine (an alpha 2-adrenergic agonist). Neither alpha-methyl-p-tyrosine, which blocks dopamine (DA), NE and E synthesis, nor yohimbine, a predominantly alpha 2-antagonist could completely suppress episodic GH secretion. These data support a role for NE/E, acting via alpha adrenergic receptors, in the control of epidosic GH secretion in the domestic fowl.     

Histochemical demonstration of the presence of serotonin in the hen (Gallus domesticus) reproductive tract

The purpose of the present study was to demonstrate visually and localize the presence of serotonin (5-HT) in the ovary and oviduct of the domestic hen using a histochemical Falck-Hillarp method. Experiments were carried out on White Leghorn laying hens with no egg in the shell gland. The specific yellow fluorescence, indicating the presence of 5-HT, was found both in the ovary and all examined oviductal parts. The strongest fluorescence was present in the ovarian stroma containing small follicles with a diameter under 4 mm. In the wall of the largest preovulatory follicle a very strong fluorescence was located mainly in the theca layer. In the oviductal parts, the intensity of 5-HT fluorescence in the infundibulum and magnum was fairly strong, whereas in the isthmus and shell gland it was weak. Fluorescence seen in the infundibulum, magnum, and isthmus was primarily localized along the luminal borders of the fold surface epithelium. In the shell gland 5-HT fluorescence was found within the uterine folds, especially in the tubular glands. Moreover, the presence of an egg in the definite oviductal segment (infundibulum or isthmus) increased the intensity of yellow fluorescence in this part.     

Distribution of CRF- and tyrosine hydroxylase-immunoreactive neurons in the brainstem of the domestic fowl (Gallus domesticus)

The distribution of CRF and tyrosine hydroxylase (TH)-immunoreactive neurons was examined in the brainstem of the chicken. Very dense populations of both CRF and TH-immunoreactive (-ir) perikarya are co-extensive in separate neuronal systems throughout a large field of the rostral brainstem, encompassing locus ceruleus, the mesencephalic reticular formation, parabrachial nucleus, and the dorsal and ventral tegmental areas. They are present also in nucleus tractus solitarius, and sparsely in the ventral and lateral areas of the medulla. This co-distribution suggests that the effects of CRF upon central autonomic activity may be mediated via brainstem catecholamine systems. CRF-ir neurons alone are present also in midline nuclei, including n. centralis superior, n.annularis, n.linearis caudalis, and the raphe.     

Ground-roosting in domestic fowl (Gallus gallus domesticus) in The Gambia: the anticipation of night

The ground-roosting behaviour of a semi-feral population of domestic hens with broods of chicks was measured in The Gambia, West Africa. Although neither day length nor time of sunset changed significantly over the duration of the study (January–March 1995), mean daily light intensity showed a significant increase. This resulted in an increasingly rapid decline in light intensity at dusk as the season progressed. Hens went to roost significantly later in the day, and at lower light levels, over the course of the season. The results support a model suggesting that the cue to start roosting is a certain light level, constant over the season, but the `settling period' required means that the hens finally roost at later times and at lower light levels as the season progresses.