Differentiation of decidual cells in cultures of rat endometrium.

Endometrial scrapings were collected from rat uteri at various times (0-4 days) after induction of a decidual reaction by i.p. injection of pyrathiazine hydrochloride (20 mg/animal) on the 5th day after a sterile mating.

Organization of intramembrane particles in freeze-cleaved gap junctions of rat graafian rollicles: optical-diffraction analysis.

Gap junctions were identified in the membrana granulosa and cumulus oophorus, and between cells of the internal theca, of the preovulatory rat follicle. In replicas of freeze fractured follicles, the A face presented clusters of closely packed intramembrane particles, 7--9 nm in diameter, forming a mosaic pattern, while the B face showed a similar pattern of small pits. Optical diffraction analysis of these electron micrographs revealed that both the intramembrane particles and the corresponding pits were organized in hexagonal lattices with centre-to-centre spacing of 9-10 nm.

Appearance and disappearance of acetycholine receptor during differentiation of chick skeletal muscle in vitro.

During differentiation of embryonic chick skeletal muscle in culture, elaboration of acetylcholine receptor (AChR) and acetylcholinesterase occurs shortly after myoblast fusion. During further development, AChR was found to decrease markedly on the myotube surface, while acetylcholinesterase continued to increase. Surface distribution of AChR, as followed by autoradiography using 125I-alpha-bungarotoxin, was homogeneous in newly fused myotubes.

Distribution of binding sites for human chorionic gonadotropin in the preovulatory follicle of the rat.

The distribution of binding sites for human chorionic gonadotropin (hCG) in the preovulatory follicle was studied by autoradiography. An ovulatory dose (10 IU/rat) of [125I]hCG (1.4 muCi/IU) was administered intravenously, and large Graafian follicles were isolated 3 h later by microdissection.

Studies on dispersed pancreatic exocrine cells. II. Functional characteristics of separated cells.

The functional characteristics of separated guinea pig pancreatic exocrine cells have been examined following dissociation of the gland by a procedure described in the previous paper (J. Cell Biol. 1974.

Studies on dispersed pancreatic exocrine cells. I. Dissociation technique and morphologic characteristics of separated cells.

A procedure for dissociation of the guinea pig pancreas into individual cells is described which employs enzymatic digestion with pure collagenase, chymotrypsin, and hyaluronidase, utilizes an interposed chelation of divalent cations by EDTA, and is terminated by gentle shearing. Yields of cells are 50-60%, based on DNA recovered. The population comprises approximately 95% exocrine cells, the remainder consisting of endocrine, duct, and vascular endothelial cells.

Structural and functional characterization of isolated pancreatic exocrine cells.

Viable isolated exocrine cells have been obtained from guinea-pig pancreas by a tissue dissociation procedure using crude collagenase (EC 3.4.4.

Concomitant synthesis of membrane protein and exportable protein of the secretory granule in rat parotid gland.

After enzyme secretion the membrane of the secretory granule, which had been fused to the cell membrane, was resorbed into the cell. Experiments were therefore carried out to test whether formation of new secretory granules involves reutilization of the resorbed membrane or synthesis of a new membrane, de novo, from amino acids. Incorporation of amino acids-(14)C into proteins of various cell fractions was measured in vivo, 30, 120, and.

Epinephrine-induced vacuole formation in parotid gland cells and its independence of the secretory process.

Catecholamines cause rapid release of K(+) and formation of vacuoles in acinar gland cells. A high K(+) concentration in the medium bathing parotid gland slices prevents vacuole formation by epinephrine and facilitates the secretion of most of the exportable amylase. N(6)-monobutyryl 3':5'-cyclic AMP does not cause K(+) release and vacuole formation although it efficiently induces amylase secretion.

Dynamic changes in the ultrastructure of the acinar cell of the rat parotid gland during the secretory cycle.

Synchronization of the secretory cycle in vivo was obtained by injecting isoprenaline as an inducer of secretion. A quantitative correlation between enzyme release, its subsequent reaccumulation, and the sequence of ultrastructural changes was found. At the ultrastructural level secretion was paralleled by depletion of zymogen granules through fusion of the granule membrane with the lumen membrane and discharge of the content.

Rapid release of the zymogen granule protein by osmium tetroxide and its retention during fixation by glutaraldehyde.

Fixation by osmium tetroxide and glutaraldehyde of zymogen granules isolated from rat parotid and pancreas was investigated. Protein determinations showed that osmium tetroxide caused rapid release of most of the soluble protein of the granule during fixation in buffered isotonic sucrose. Such granules when examined in the electron microscope after shadow casting appeared quite flat, indicating that most of the contents had indeed been removed.