The eggshell of Drosophila melanogaster. II. New staging characteristics and fine structural analysis of choriogenesis

Abstract

The characteristics of the stages of choriogenesis have been identified using light and electron microscopy. Nine stages have been discerned (11A, 11B, 12A, 12B, 12C, 13A, 13B, 14A, 14B), replacing the four stages used so far (11, 12, 13, 14). Characteristics used to determine the stage of the choriogenesis include (a) the size of oocyte as compared with the whole follicle, (b) the length of the chorionic appendages, and (c) the fine structure of the chorionic layers at the main shell and at the specialized regions. Factors a and b were detected by dark-field light microscopy on living follicles, whereas factor c was studied with electron microscopy. At stage 11A the vitelline membrane has just been completed. At stage 11B the follicle cells secrete the wax layer and the respiratory appendages start to form. Stage 12A follicles secrete endochorion at the anterior pole and the appendages elongate, whereas at stage 12B the main shell follicle cells start to secrete endochorion complex. Stage 12C shows initiation of pillar formation at the main shell and 150 μm long appendages. Stage 13A is characterized by 200 μm long appendages and formation of endochorionic cavities at the main shell, through the participation of a "flocculent" material. At stage 13B the endochorionic "roof is formed, which is completed at stage 14A by the simultaneous formation of the "roof network." The last stage, 14B, exhibits 300 μm long appendages and the secretion of exochorion over the entire follicle. The above stages are accompanied by region-specific formation of specialized structures which include the respiratory appendages, the operculum, the posterior pole, the micropyle, and the collar.

Stage-specific regulation of programmed cell death during oogenesis of the medfly Ceratitis capitata (Diptera, Tephritidae)

“…Dissections were carried out in cold Ringer's solution and ovaries were separated into single ovarioles. Staging of the developing egg chambers during oogenesis was accomplished according to Margaritis (1986), Mouzaki and Margaritis (1991) and Nezis et al (2001;.…”

“…The nurse cells support the development of the oocyte providing organelles, proteins and maternal RNAs to the oocyte through the ring canals (Mahajan-Miklos and Cooley, 1994;Trougakos and Margaritis, 2002). The development of the egg chamber has been divided into several discrete stages (fourteen according to King, 1970; twenty according to Margaritis, 1985;1986). Programmed cell death is an evolutionary conserved and genetically regulated process, where superfluous cells undergo self-destruction by activation of a cell suicide program (Danial and Korsmeyer, 2004).…”

Genetic analysis of chorion formation in Drosophila melanogaster: I. The effects of one somatic‐specific and seven germ‐line‐specific mutations

“…Less complete information is available for a number of fs mutants that have been shown to produce abnormal eggshells: the third chromosome mutants 108-1 7, 350-7, 293-19, and 272-9 [Snyder et al, 19861 as well as the X-chromosome mutants cor-36 [Digan et al, 19791, oc [Underwood and Mahowald, 19801, K79 [Komitopoulou, 19821, the 384 or decl allelic series [Bauer and Waring, 19871, K451, K1214, K575Ts [Komitopoulou et al, 19881, and several others [Margaritis, 1980;Komitopoulou, 19821. The 473Ts and K1563 mutations, which show major ultrastructural defects in the chorion, are somatic line specific [Perrimon and Gans, 19831.…”

Morphological irregularities and features of resistance to apoptosis in thedcp-1/pita double mutated egg chambers duringDrosophila oogenesis

“…Staging of the developing wild type and mutated egg chambers was accomplished according to Margaritis [1986] and Spradling [1993]. Because of the abnormal development of the mutated egg chambers, the staging was based on the beginning of choriogenesis [Margaritis, 1986].…”

“…Thus, each ovariole contains a linear array of 6 -7 developmentally ordered egg chambers. According to various morphogenetic criteria, their development has been divided into 14 stages [King, 1970;Margaritis, 1985Margaritis, , 1986Spradling, 1993]. Each egg chamber consists of 16 germline cells (15 nurse cells and one oocyte) surrounded by a monolayer of somatic epithelial cells, called follicle cells [Margaritis, 1985].…”