How does Fertilisation occur in Drosophila?
As for other insects, fertilization in Drosophila is internal and occurs upon descent of the ovulated oocytes in the uterus. Thus, the earliest events of fertilization, such as sperm activation and paternal chromatin remodelling, are difficult to observe in Drosophila as they take place before egg deposition.
What are the three stages of Drosophila development?
Drosophila display a holometabolous method of development, meaning that they have three distinct stages of their post-embryonic life cycle, each with a radically different body plan: larva, pupa and finally, adult.
How does an oocyte develop?
Oocytes develop to maturity from within a follicle. These follicles are found in the outside layer of the ovaries. During each reproductive cycle, several follicles begin to develop. Typically, only one oocyte each cycle will become a mature egg and be ovulated from its follicle.
What is the main features of Drosophila embryo development?
During Drosophila early embryogenesis, the embryo undergoes 13 rounds of rapid, synchronized nuclear division cycles in a common cytoplasm, leading to the formation of a syncytial blastoderm that contains ∼6000 nuclei prior to cellular blastoderm formation.
What type of egg is Drosophila?
Each Drosophila egg arises from a multicellular structure within the ovary called an egg chamber (or follicle). The egg chamber itself consists of an internal cluster of germ cells comprised of 15 nurse cells and one posteriorly localized oocyte, surrounded by an epithelial monolayer of somatic follicle cells (Fig.
How does pattern formation in early development of Drosophila work?
It is during the early stages of fly embryonic development that the body plan of a fly is arranged into what will become the adult fly. Pattern formation is the development of a body according to a specific and planned spatial arrangement.
What stage is oocyte at fertilization?
After ovulation the oocyte is arrested in metaphase of meiosis II until fertilization. At fertilization, the secondary oocyte completes meiosis II to form a mature oocyte (23,1N) and a second polar body.
How many oocytes will develop up to ovulation?
Over a woman’s reproductive lifespan, only around 300–400 oocytes will reach the ovulatory state; the rest undergo atresia. The eggs remain dormant until nearer ovulation time when the rise in the levels of LH triggers continuation of the first meiotic division of the egg (oocyte).
What is the unique aspect of early development in Drosophila that allows this to occur without intervening steps?
A key aspect of Drosophila development that allows for a transcription factor to act as morphogen is the fact that the early embryo is a syncytium of nuclei within a common cytoplasm, allowing Bcd, as well as other factors, to freely diffuse throughout the embryo.
How many chromosomes are present in Drosophila?
four chromosomes
The Genome. THE basic karyotype of Drosophila melanogaster, which can be seen in mitotically active neuroblasts of the larval brain, is comprised by four chromosomes, the X and Y sex chromosomes, two larger autosomal elements, chromosomes 2 and 3, and the small dot fourth chromosome (Figure 1) (Metz 1914; Deng et al.
Where does fertilization of a Drosophila egg occur?
Fertilization of Drosophila can only occur in the region of the oocyte that will become anterior of the embryo. Moreover, the sperm tail appears to stay in this region. 2. Cleavage Most insect eggs undergo superficial cleavage, wherein a large mass of centrally located yolk confines cleavage to the cytoplasmic rim of the egg.
How are mutants related to fertilization in Drosophila?
Drosophila mutants affecting fertilization or zygote formation. Mutants are either considered for their paternal (blue) or maternal (green) contribution. Table 1. Drosophila mutants affecting fertilization or zygote formation. Mutants are either considered for their paternal (blue) or maternal (green) contribution. 2.
How does gonomery affect fertilization in Drosophila?
Gonomery presents a natural advantage for identifying fertilization mutants in Drosophila. Indeed, the separation of parental chromosomes implies that any defect specifically affecting one pronucleus does not necessarily prevent the unalduterated one to perform the first zygotic division within its own hemispindle.
How are human development and Drosophila development similar?
The various types of bristles and hairs found on the body are characters that we will use to identify different phenotypes of flies. Drosophila and human development are homologous processes. They utilize closely related genes working in highly conserved regulatory networks. Unlike humans, Drosophila is subject to easy genetic manipulation.