Studies on the mode of action of progesterone on chicken oviduct epithelium. I. Morphological changes associated with early differentiation of the tissue

Chick oviduct progesterone receptor: structure, immunology, function

Analysis of the purified chick oviduct progesterone receptor using biochemical and immunological approaches indicates that while the 'activated' receptor ('4S') is a mixture of two progestin-binding polypeptides, 'A' (Mr approximately 79 kDa) and 'B' (Mr approximately 110 kDa), the non-activated receptor ('8S') is a population of complexes containing a hormone-binding polypeptide (A or B, but probably not both) bound to a non-hormone-binding protein (Mr approximately 90 kDa). Two molecules of the 90 kDa protein appear to be present in each '8S' receptor molecule. The 90 kDa protein is also associated with the non-activated forms of receptors of other steroid hormones in the chick. Molybdate stabilizes the non-activated receptors, probably by forming weak coordination bonds with radicals provided by the subunits of the '8S' structure. Activation implies separation of the subunits, without a change in their primary structure, and does not require intervention of any protein other than those present in the '8S' receptor form. The presence of ligand at the binding site accelerates the activation process but, in vitro, is not necessary for it to occur. Unlike the non-activated form, activated receptors bind to the cell nuclei. However, histological studies with anti-progesterone receptor antibodies indicate that in the non-hormone-exposed tissue the (non-activated) receptors could be localized in the nuclei.

Augmentation of progesterone receptor concentration by progesterone and estrogen treatments in the chick oviduct

Cytosol receptors for progesterone in the chick oviduct were measured by charcoal-adsorption assay by using ORG 2058 as a ligand after long-term administration of progesterone and diethylstilbestrol (DES). Steroid administration was carried out by using daily injections or silastic capsules. DES treatment increased the progesterone receptor concentration (from 11500 to 21500 sites per cell, day 14). Progesterone also augmented the concentration of its own receptors (from 11500 to 29000 sites per cell, day 14). In the experiments with capsule administration the same trend was seen. This indicates that both diethylstilbestrol and progesterone are able to increase the concentration of progesterone specific cytosol receptors in the non-differentiated chick oviduct.

Endogenous avidin found in the magnum gland of the hen oviduct. Comparative cytochemical studies utilizing both biotinyl-peroxidase and immunoperoxidase methods

The location of endogenous avidin was studied cytochemically in the magnum tissue of the oviduct of laying hens. Two methods, based on an interaction of avidin-biotin with biotin hydrazide-peroxidase (B-HRP) as an affinity reagent, and on an immunoperoxidase technique, were tested by morphological analysis. The data obtained by both methods showed that in the magnum B-HRP is a strictly substitutive reagent for endogenous avidin. Avidin was clearly demonstrated in large amounts in the secretory granules of some epithelial cells and tubular gland cells, but was absent from mucous cells, the goblet cells, which had been believed to be the location of avidin production, and from ciliated cells. These granules had previously been demonstrated by both electron-microscopic cytochemical techniques. Especially in acinar cells, they were nonhomogeneous with a speckled core and a dense peripheral part. They ranged in size from 500 to 2200 nm in diameter in the gland and 180 to 720 nm in the epithelium. Columnar epithelial cells containing avidin granules had a strong resemblance to those of the protodifferentiated tubular gland cells in the magnum of chicks pretreated with daily estrogen or estrogen plus progesterone, and might have migrated towards the acinus as substitutional secretory cells. Therefore, the acinar cells of the magnum, considered to be composed of several secretory protein-producing systems, are dependent on estrogen and/or progesterone in the oviduct of the laying hen.

Effect of progesterone on the magnum proteins during primary stimulation of chick oviduct

The effect of progesterone on the secretion of protein by the magnum of 5-d-old, female chicks was determined. 2. The supernatant prepared by centrifuging an homogenate of the magnum at 105 000g was found, by immunodiffusion, to contain an antigenic component which precipitated the antisera for conalbumin 1, conalbumin 2 and ovalbumin after 5 d treatment with progesterone: there was no reaction to ovomucoid, lysozyme and avidin antisera. 3. Disc-electrophoresis of the homogenate revealed two bands at the site of ovalbumin. 4. Incorporation of 3H-lysine into the magnum proteins of progesterone-treated chicks did not differ from that of controls. 5. The secretion available in the magnum may be only a transudate from the serum and not a true secretory product. Progesterone behaved qualitatively as oestrogen in this study although the action is much less pronounced and was delayed.

Effects of estrogen and progesterone on transcription, chromatin and ovalbumin gene expression in the chick oviduct

The effects of estrogen, progesterone and estrogen + progesterone combined on nuclear transcriptional processes in oviducts of immature chicks, previously withdrawn from estrogen, are reported. The responses to the steroids of the endogenous nuclear RNA polymerase activities, both nucleolar (I) and nucleoplasmic (II), the chromatin compositions and template capacities, and the appearance of ovalbumin messenger RNA (mRNA) are compared. When immature chicks (previously treated at 14 days with estrogen) are withdrawn from estrogen treatment, there is a gradual reduction in both polymerase activities. Diurnal variations in polymerase II activties in the oviduct of withdrawn chicks required that subsequent experiments include time-matched controls. The hormones alter RNA polymerase II and II activities in vivo as assayed in isolated nuclei. Progesterone represses the polymerase I and II activities, while estrogen alone and estrogen + progesterone enhance both polymerase activities immediately after injection. Diethylstillbestrol, a synthetic estrogen, causes changes similar to those of estrogen. The effects of these steroids on the polymerases are detected within 15 min of hormone injection. Changes in the capacities of chromatins to serve as template for RNA synthesis in general correlated with changes in polymerase II activities. Interestingly, in the case of estrogen treatment, the acidic chromatin protein (but not histone) levels fluctuate positively with the template capacities of the chromatin. An antagonism between estrogen and progesterone is observed in the responses of both RNA polymerases I and II activities as well as in the chromatin template capacity. Levels of messenger RNA coding for ovalbumin, as detected by hybridization with labeled complementary DNA, increase in oviducts of withdrawn chicks within 2--3 of the injection of estrogen, progesterone or estrogen + progesterone. This rapid accumulation of ovalbumin mRNA is not accompanied in each case by a similar increase in polymerase II activity or chromatin template capacity.

Immunofluorescence demonstration of avidin in the immature chick oviduct epithelium after progesterone

Immature chicks were used for the experiments 1-2 days after hatching. A group of chicks were injected with 5 mg of progesterone and sacrificed 1 or 24 hr later. An other group of chicks were injected daily for 9 days with 5 mg of diethylstilbestrol and thereafter with single injection of progesterone. Cryostat sections were incubated with rabbit anti-avidin serum and with fluorescein labelled antirabbit globulin for fluorescence histochemistry. In the control animals no epithelial cells of the oviduct were fluorescence positive independently whether or not the animals were pretreated with diethylstilbestrol. One hour after administration of progesterone epithelial cells showed occasionally a slight synthesis of avidin. 24 hours after the injection of progesterone most, however never all, of the epithelial cells showed avidin in the apical part of the cell. The fluorescence reaction was clearly more intense if the animals were estrogen-primed. Diethylstilbestrol caused a differentiation of oviductal glands which were, however, only occasionally avidin positive after progesterone. These results suggest that primitive oviductal cells can produce avidin without preceding differentiation whereas estrogen causes a differentiation of new line of cells which have regularly lost their capacity of avidin synthesis after progesterone administration.

Interaction of estrogen and progesterone in chick oviduct development. 3. Tubular gland cell cytodifferentiation

Administration of estrogen (E) to immature chicks triggers the cytodifferentiation of tubular gland cells in the magnum portion of the oviduct epithelium; these cells synthesize the major egg-white protein, ovalbumin. Electron microscopy and immunoprecipitation of ovalbumin from oviduct explants labeled with radioactive amino acids in tissue culture were used to follow and measure the degree of tubular gland cell cytodifferentiation. Ovalbumin is undetectable in the unstimulated chick oviduct and in oviducts of chicks treated with progesterone (P) for up to 5 days. Ovalbumin synthesis is first detected 24 hr after E administration, and by 5 days it accounts for 35% of the soluble protein being synthesized. Tubular gland cells begin to synthesize ovalbumin before gland formation which commences after 36 hr of E treatment. When E + P are administered together there is initially a synergistic effect on ovalbumin synthesis, however, after 2 days ovalbumin synthesis slows and by 5 days there is only 1/20th as much ovalbumin per magnum as in the E-treated controls. Whereas the magnum wet weight doubles about every 21 hr with E alone, growth stops after 3 days of E + P treatment. Histological and ultrastructural observations show that the partially differentiated tubular gland cells resulting from E + P treatment never invade the stroma and form definitive glands, as they would with E alone. Instead, these cells appear to transform into other cell types-some with cilia and some with unusual flocculent granules. We present a model of tubular gland cell cytodifferentiation and suggest that a distinct protodifferentiated stage exists. P appears to interfere with the normal transition from the protodifferentiated state to the mature tubular gland cell.