Modification of cell evagination and cell differentiation in quail oviduct hyperstimulated by progesterone

Quail oviduct development is controlled by sex steroid hormones. Estrogen (E) induce cell proliferation, formation of tubular glands by epithelial cell evagination and cell differentiation. Progesterone (P) strongly increases the secretory process in E-treated quails, but inhibits cell proliferation, cell evagination and differentiation of ciliated cells. The balance between E and P is critical for harmonious development of the oviduct. After 6 daily injections of two doses of estradiol benzoate (10 or 20 micrograms/d) and high doses of P (4 mg/d), tubular gland formation by epithelial cell evagination was inhibited, while epithelial cell proliferation occurred, as shown by the height of the villi and the increase in DNA. Secretory processes were strongly stimulated. Ovalbumin, a tubular gland cell marker and avidin, a mucous cell marker, were localized by immunofluorescence and immunogold labeling. Ovalbumin was localized only in the rudimentary tubular glands, whereas avidin was dispersed throughout the secretory cells. High doses of progesterone inhibited tubular gland cell proliferation, disturbed the distribution of avidin and inhibited differentiation of ciliated cells. Ovalbumin synthesis occurred only in epithelial cells which were evaginated despite the hyperstimulation. Ovalbumin gene expression appeared highly dependent upon the cell position.     

A novel oncogene related to c-mil is transduced in chicken neuroretina cells induced to proliferate by infection with an avian lymphomatosis virus.

Non-dividing neuroretina cells from chicken embryos are induced to proliferate after a long latency, following infection with Rous associated virus type 1, an avian retrovirus which does not carry a transforming gene. We have isolated from these proliferating cells an acutely mitogenic retrovirus, designated IC10, which contains a novel oncogene. Nucleotide sequencing showed that the IC10 virus has transduced 1101 nucleotides of cellular origin inserted between the gag and env genes of RAV-1. This oncogene, designated v-Rmil, is 70.1% homologous to v-mil. v-Rmil encodes a protein of 40,976 daltons sharing 83.8% homology with the catalytic domain of the v-mil protein. Divergence with the v-mil gene product is observed at the NH2- and COOH-terminal portions of the v-Rmil protein. Restriction analysis of normal chicken DNA indicated that v-Rmil is derived from a cellular gene distinct from c-mil. The c-Rmil gene is transcribed through a major mRNA, greater than 10 kb in length, that is detected at much higher levels in neuroretinas, as compared to other embryonic tissues.     

Magnum morphogenesis during the natural development of the quail oviduct: analysis of egg white proteins and progesterone receptor concentration

The histological development of the quail oviduct and the changes in concentrations of progesterone receptor, ovalbumin, conalbumin, ovomucoid and ovoglycocomponents are analyzed during the period spanning 7-35 days of age. The initiation of luminal epithelial cell proliferation is the first event of magnum growth. The epithelial cells begin to evaginate into subepithelial stroma and form tubular glands. Meanwhile, luminal epithelium starts cellular pleomorphism through ciliogenesis. No egg white proteins are detectable in the developing glands; at the same time, the concentration of the progesterone receptor increases from about 5500 sites/cell to 30,300 sites/cell. Tubular gland cells then begin to synthetize and accumulate egg white proteins, mucous cells differentiate in the luminal epithelium, and the cell proliferation decreases and finally stops. Compared with earlier studies dealing with the blood levels of estrogen and progesterone in developing quails during the same period, and the cellular changes induced in the oviducts of ovariectomized and ovariectomized-hypophysectomized quail by exogenous steroids, these results distinguish between the cellular responses that are physiologically controlled by estradiol and other responses that have multihormonal regulation.     

Immunocytolocalization of human gastric lipase in chief cells of the fundic mucosa

Summary The presence in human gastric juice of a lipase secreted by the gastric mucosae has been reported previously, but its exact cellular origin has not yet been established. Polyclonal antibodies specific to human gastric lipase (HGL) were prepared, and used by an immunofluorescence technique to label cells producing HGL. This immunocytolocalization was correlated with that of pepsin (chief cells) and parietal cells using specific polyclonal or monoclonal antibodies.Our results clearly establish that HGL is exclusively located in the chief cells of fundic mucosa; furthermore, it was found to be always co-located with pepsin. No HGL was observed in the parietal or mucus cells. HGL was always detected intracellularly, either in secretory granules of the apical region of the chief cells, or revealed by more diffuse cytoplasmic labelling.Abbreviations HGL Human gastric lipase - SDS PAGE Sodium dodecyl sulfate-polyAcrylamid gel electrophoresis - PBS Phosphate buffer saline     

Alternative male reproductive strategies in the peacock blenny

A 4-year study (1989–1992) of a population of Lipophrys pavo living in a brackish lagoon (Maugio, France) revealed three types of male during the spawning season (April to September): (i) nest-breeder males which are territorial, and have well-developed secondary sexual characteristics; (ii) non-functional males which were abundant only in 1991 when population density was very high and (iii) 1-year-old kleptogamic males with small body size which possess neither secondary sexual organs nor a testicular gland, although their testes are functional and hyperdeveloped (up to 10.5% of carcass weight). The percentage of kleptogamic males was fairly stable in the population (from 7.9 to 10.0%) and highly variable in their age class (from 8.5 to 51.3%). It is suggested that kleptogamy is a conditional strategy adopted by smaller males.     

Ionic currents across pancreatic acinar cell membranes and their role in fluid secretion

Fluid and enzyme secretion from a number of mammalian exocrine glands is controlled by the action of neurotransmitters and hormones on acinar cell membranes. Sustained stimulation evoking sustained fluid and enzyme secretion also evokes sustained membrane depolarization and increase in conductance. Mouse and rat pancreatic fluid and enzyme secretion, as well as membrane depolarization and conductance increase evoked by sustained stimulation with acetylcholine or cholecystokinin-gastrin peptides, are acutely dependent on extracellular calcium. However, the initial stimulant-evoked conductance increase and secretion appear to be triggered by calcium released from inside the cells. Direct measurement of membrane current during sustained stimulation in voltage-clamp experiments with resolution of the total current into its Na, Cl and K components has allowed calculations of stimulant-evoked Na and Cl uptake into the acinar cells. The NaCl uptake is quantitatively sufficient to account for the stimulant-evoked fluid secretion. The role of the stimulant-evoked transmembrane ionic current appears to be the supply of salt for the fluid secretion. Calcium derived from intracellular sources in the initial phase of secretion, and from the extracellular fluid in the sustained phase, couples fluid and enzyme secretion to hormone-receptor interaction.