Blastoderm Formation and Cellularisation in Drosophila melanogaster


Immediately following fertilisation in Drosophila and many other arthropods, the embryo undergoes a series of rapid syncytial nuclear divisions. These divisions are driven by maternally supplied components and occur in the absence of zygotic transcription. Unlike typical cell divisions, these divisions alternate between S and M phases, resulting in cell cycles that last only from 10 to 25 min. After four rounds of division, the nuclei undergo axial expansion, a process that relies on microfilaments. Subsequently migration of the nuclei to the cortex relies on microtubules. Once at the cortex, the nuclear divisions occur on a single plane and rely on partial cleavage furrows to maintain an even distribution. The cortical nuclear divisions continue until the mid‐blastula transition (MBT), at which time cellularisation results in the formation of a multicellular embryo.

Key Concepts:

  • Fertilisation triggers a series of events that induces the first mitotic cycle, a gonomeric division between the male and female pronucleus.

  • After fertilisation, the embryo undergoes 13 synchronous divisions within a syncytium.

  • Divisions 10–13 occur at the cortex of the embryo and require reorganisation of actin and membrane into metaphase furrows.

  • At cycle 14, the cell cycle pauses and cellularisation occurs forming individual somatic cells.

  • Cellularisation, a key feature of the mid‐blastula transition, marks the time at which zygotic transcription occurs and maternal products are degraded.

Keywords: Drosophila; embryo; syncytial; blastoderm; cellularisation; mid‐blastula transition; fertilisation; furrow

Figure 1.

Fertilisation and pronuclear fusion. Sperm fertilises the meiosis I arrested egg. The egg then undergoes two meiotic divisions to generate three polar bodies and one pronucleus (blue). During this process, the male nucleus sheds its protamines (red) and deposits histones (purple) to become replication competent. Following this, chromosomes condense, the nuclear envelope breaks down and fusion with the female pronucleus occurs. (This figure was modelled after Figure in Landmann et al. .)

Figure 2.

Early nuclear divisions and migration during Drosophila embryogenesis. Cycle 1 is initiated after fusion of the male and female pronuclei. During divisions 1–3, nuclei divide in a sphere at the anterior of the embryo. During divisions 4–6, nuclei divide and spread out along the anterior–posterior axis (axial expansion). Nuclei migrate to the cortex of the embryo during divisions 8–10 (cortical migration). Pole cells form at the posterior end of the embryo (cycle 9), whereas yolk nuclei remain in the interior. After four rounds of cortical syncytial divisions, during interphase of nuclear cycle 14, invagination of the plasma membrane around each nucleus produces a cellularised embryo.

Figure 3.

Metaphase furrow formation. (a) During interphase, the actin (green) concentrates into apical caps centred above each cortical nucleus (blue) and its apically positioned centrosomes (yellow). (b) As the nuclei progress into prophase, the centrosomes migrate towards opposite poles and the actin caps undergo a dramatic redistribution to outline each nucleus and its associated separated centrosome pair. (c) At metaphase, the furrows invaginate to a depth of approximately 10 μm to surround each spindle both apically and laterally, but not basally. Vesicles (black circles) transport actin puncta (green) that fuse with the growing furrow. (d) and (e) During late anaphase and telophase, the metaphase furrows rapidly regress.

Figure 4.

Live imaging of metaphase furrow formation. Surface confocal sections highlight the reorganisation of interphase actin caps above each nucleus into metaphase furrows. Actin caps are distinct from one another during interphase, where gaps (*) can be observed. By metaphase, actin caps have expanded laterally to fill these gaps and invagination into metaphase furrows has reached maximum length (∼10 μm). Metaphase furrows retract by telophase, reforming apical caps. Actin (green) and microtubules (red). Scale bar=10 μm.

Figure 5.

Formation of the cellularisation furrows. (a) Cellularisation begins with actin (green) concentrated at the cortex above each nucleus and apical centrosome pair (yellow). Astral microtubules extend basally and form a cage within which nuclear elongation occurs. (b) The plasma membrane initiates invagination and actin is concentrated at the cortex and the leading edge of the furrow. (c) The slow phase of furrow invagination is initiated. Golgi‐ and recycling endosome‐derived vesicles drive furrow elongation. (d) Furrows invaginate rapidly once they have passed the fully elongated nuclei. (e) Once furrows have reached a depth of 35 μm, the leading edge relies on actin–myosin‐based contraction (red) to pinch off basally. Adherens junctions (brown) connect neighbouring cellular membranes.



Baker J, Theurkauf WE and Schubiger G (1993) Dynamic changes in microtubule configuration correlate with nuclear migration in the preblastoderm Drosophila embryo. Journal of Cell Biology 122: 113–121.

Benoit B, He CH, Zhang F et al. (2009) An essential role for the RNA‐binding protein Smaug during the Drosophila maternal‐to‐zygotic transition. Development 136: 923–932.

Callaini G and Riparbelli MG (1996) Fertilization in Drosophila melanogaster: centrosome inheritance and organization of the first mitotic spindle. Developmental Biology 176: 199–208.

Cao J, Crest J, Fasulo B and Sullivan W (2010) Cortical actin dynamics facilitate early stage centrosome separation. Current Biology 20: 770–776.

Crest J, Oxnard N, Ji JY and Schubiger G (2007) Onset of the DNA replication checkpoint in the early Drosophila embryo. Genetics 175: 567–584.

von Dassow G and Schubiger G (1994) How an actin network might cause fountain streaming and nuclear migration in the syncytial Drosophila embryo. Journal of Cell Biology 127: 1637–1653.

Dawson IA, Roth S, Akam M and Artavanis‐Tsakonas S (1993) Mutations of the fizzy locus cause metaphase arrest in Drosophila melanogaster embryos. Development 117: 359–376.

Edgar BA, Sprenger F, Duronio RJ, Leopold P and O'Farrell PH (1994) Distinct molecular mechanism regulate cell cycle timing at successive stages of Drosophila embryogenesis. Genes & Development 8: 440–452.

Ephrussi A and Lehmann R (1992) Induction of germ cell formation by oskar. Nature 358: 387–392.

Foe VE and Alberts BM (1983) Studies of nuclear and cytoplasmic behaviour during the five mitotic cycles that precede gastrulation in Drosophila embryogenesis. Journal of Cell Science 61: 31–70.

Fogarty P, Campbell SD, Abu‐Shumays R et al. (1997) The Drosophila grapes gene is related to checkpoint gene chk1/rad27 and is required for late syncytial division fidelity. Current Biology 7: 418–426.

Horner VL and Wolfner MF (2008) Mechanical stimulation by osmotic and hydrostatic pressure activates Drosophila oocytes in vitro in a calcium‐dependent manner. Developmental Biology 316: 100–109.

Illmensee K and Mahowald AP (1974) Transplantation of posterior polar plasm in Drosophila. Induction of germ cells at the anterior pole of the egg. Proceedings of the National Academy of Sciences of the USA 71: 1016–1020.

Jayaramaiah RS and Renkawitz‐Pohl R (2005) Replacement by Drosophila melanogaster protamines and Mst77F of histones during chromatin condensation in late spermatids and role of sesame in the removal of these proteins from the male pronucleus. Molecular Cell Biology 25: 6165–6177.

Jin Z and Xie T (2006) Germline specification: small things have a big role. Current Biology 16: R966–R967.

Kao LR and Megraw TL (2009) Centrocortin cooperates with centrosomin to organize Drosophila embryonic cleavage furrows. Current Biology 19: 937–942.

Landmann F, Orsi GA, Loppin B and Sullivan W (2009) Wolbachia‐mediated cytoplasmic incompatibility is associated with impaired histone deposition in the male pronucleus. PLoS Pathogens 5: e1000343.

Lecuit T and Wieschaus E (2000) Polarized insertion of new membrane from a cytoplasmic reservoir during cleavage of the Drosophila embryo. Journal of Cell Biology 150: 849–860.

Longo FJ (ed.) (1985) Pronuclear Events during Fertilization. New York: Academic Press.

Lu X, Li JM, Elemento O, Tavazoie S and Wieschaus EF (2009) Coupling of zygotic transcription to mitotic control at the Drosophila mid‐blastula transition. Development 136: 2101–2110.

Markussen FH, Michon AM, Breitwieser W and Ephrussi A (1995) Translational control of oskar generates short OSK, the isoform that induces pole plasma assembly. Development 121: 3723–3732.

Megosh HB, Cox DN, Campbell C and Lin H (2006) The role of PIWI and the miRNA machinery in Drosophila germline determination. Current Biology 16: 1884–1894.

Miller KG and Kiehart DP (1995) Fly division. Journal of Cell Biology 131: 1–5.

Okada M, Kleinman IA and Schneiderman HA (1974) Restoration of fertility in sterilized Drosophila eggs by transplantation of polar cytoplasm. Developmental Biology 37: 43–54.

Peel N, Stevens NR, Basto R and Raff JW (2007) Overexpressing centriole‐replication proteins in vivo induces centriole overduplication and de novo formation. Current Biology 17: 834–843.

Riggs B, Rothwell W, Mische S et al. (2003) Actin cytoskeleton remodeling during early Drosophila furrow formation requires recycling endosomal components nuclear‐fallout and Rab11. Journal of Cell Biology 163: 143–154.

Riparbelli MG and Callaini G (1996) Meiotic spindle organization in fertilized Drosophila oocyte: presence of centrosomal components in the meiotic apparatus. Journal of Cell Science 109(Part 5): 911–918.

Rodrigues‐Martins A, Riparbelli M, Callaini G, Glover DM and Bettencourt‐Dias M (2007) Revisiting the role of the mother centriole in centriole biogenesis. Science 316: 1046–1050.

Rothwell WF and Sullivan W (2000) The centrosome in early Drosophila embryogenesis. Current Topics in Developmental Biology 49: 409–447.

Royou A, Field C, Sisson JC, Sullivan W and Karess R (2004) Reassessing the role and dynamics of nonmuscle myosin II during furrow formation in early Drosophila embryos. Molecular Biology of the Cell 15: 838–850.

Royou A, McCusker D, Kellogg DR and Sullivan W (2008) Grapes(Chk1) prevents nuclear CDK1 activation by delaying cyclin B nuclear accumulation. Journal of Cell Biology 183: 63–75.

Sibon OC, Stevenson VA and Theurkauf WE (1997) DNA‐replication checkpoint control at the Drosophila midblastula transition. Nature 388: 93–97.

Sisson JC, Field C, Ventura R, Royou A and Sullivan W (2000) Lava lamp, a novel peripheral golgi protein, is required for Drosophila melanogaster cellularization. Journal of Cell Biology 151: 905–918.

Stevenson V, Hudson A, Cooley L and Theurkauf WE (2002) Arp2/3‐dependent pseudocleavage [correction of psuedocleavage] furrow assembly in syncytial Drosophila embryos. Current Biology 12: 705–711.

Sullivan M and Morgan DO (2007) Finishing mitosis, one step at a time. Nature Reviews Molecular Cell Biology 8: 894–903.

Sullivan W, Fogarty P and Theurkauf W (1993) Mutations affecting the cytoskeletal organization of syncytial Drosophila embryos. Development 118: 1245–1254.

Tadros W and Lipshitz HD (2009) The maternal‐to‐zygotic transition: a play in two acts. Development 136: 3033–3042.

Takada S, Kelkar A and Theurkauf WE (2003) Drosophila checkpoint kinase 2 couples centrosome function and spindle assembly to genomic integrity. Cell 113: 87–99.

Thomson T and Lasko P (2004) Drosophila tudor is essential for polar granule assembly and pole cell specification, but not for posterior patterning. Genesis 40: 164–170.

Walker JJ, Lee KK, Desai RN and Erickson JW (2000) The Drosophila melanogaster sex determination gene sisA is required in yolk nuclei for midgut formation. Genetics 155: 191–202.

Wilson PG, Zheng Y, Oakley CE et al. (1997) Differential expression of two gamma‐tubulin isoforms during gametogenesis and development in Drosophila. Developmental Biology 184: 207–221.

Zalokar M and Erk I (1976) Division and migration of nuclei during early embryogenesis of Drosophila melanogaster. Journal of Microbial Cell 25: 97–106.

Further Reading

Foe VE, Odell GM and Edgar BA (1993) Mitosis and morphogenesis in the Drosophila embryo. In: Bate M and Arias AM (eds) The Development of Drosophila melanogaster. Plainview, NY: Cold Spring Harbor Laboratory Press.

Karr TL and Alberts BM (1986) Organization of the cytoskeleton in early Drosophila embryos. Journal of Cell Biology 4: 494–509.

Mazumdar A and Mazumdar M (2002) How one becomes many: blastoderm cellularization in Drosophila melanogaster. BioEssays 11: 1012–1022.

Müller HA (2001) Of mice, frogs and flies: generation of membrane asymmetries in early development. Development, Growth & Differentiation 4: 327–342.

Shejter ED and Weishaus E (1993) Functional elements of the cytoskeleton in the early Drosophila embryo. Annual Review in Cell Biology 9: 67–99.

Tadros W and Lipshitz HD (2005) Setting the stage for development: mRNA translation and stability during oocyte maturation and egg activation in Drosophila. Developmental Dynamics 3: 593–608.

Tadros W and Lipshitz HD (2009) The maternal‐to‐zygotic transition: a play in two acts. Development 18: 3033–3042.

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Kotadia, Shaila, Crest, Justin, Tram, Uyen, Riggs, Blake, and Sullivan, William(Sep 2010) Blastoderm Formation and Cellularisation in Drosophila melanogaster. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0001071.pub2]