ISSN 1022-7954, Russian Journal of Genetics, 2007, Vol. 43, No. 10, pp. 1120–1134. © Pleiades Publishing, Inc., 2007.
Original Russian Text © A.A. Ogienko, S.A. Fedorova, E.M. Baricheva, 2007, published in Genetika, 2007, Vol. 43, No. 10, pp. 1341–1357.
Production of functional gametes is important for all
multicellular organisms with sexual reproduction.
oogenesis is a sophisticated
process that is based on coordinate development of ger-
mline and somatic cells and results in the mature egg.
The formation and development of the egg involves
many genes, controlling various oogenetic steps.
FORMATION OF THE FEMALE REPRODUCTIVE
SYSTEM DURING EMBRYO DEVELOPMENT
The female reproductive system originates in early
embryo development in
gradually move to the periphery during the ﬁrst syncy-
tial cleavages. By cleavage 9, corresponding to the third
embryonic instar, 8–10 nuclei reach the germ (polar)
plasm at the posterior pole of the embryo. Germ plasm
contains polar granules, speciﬁc organelles that are
detectable as electron-dense bodies and consist of RNA
and proteins. Polar granules are unique to germ plasm
and germline cells and are essential for the storage and
translational regulation of mRNAs of genes determin-
ing the fate of germline cells . By cleavage 10, sev-
eral nuclei are differentiated in the polar plasm region
(Fig. 1a), acquire the cell envelope, and become pri-
mordial germ cells (PGCs). Transcription in PGCs stops
until the eighth or ninth embryonic instar. PGCs cease
to divide synchronously with both syncytial nuclei and
each other. While syncytial nuclei synchronously
undergo 11–13 cleavage cycles, PGCs experience 0–
2 asynchronous divisions to produce approximately 40
large cells at the posterior pole of the embryo .
As the genital ridge grows and the hindgut anlage
invaginates during gastrulation, PGCs move inside the
embryo (Figs. 1b, 1c). Then, PGCs acquire amoeboid
features and actively migrate through the hindgut epi-
thelium in the posterodorsal direction (Figs. 1e, 1f).
During further movement, PGCs are divided into two
groups and adhere to mesodermal somatic cells (Figs.
1f, 1g). Mesodermal cells give origin to the tunic and
follicular cells of pupae and adults. PGC migration
through the hindgut epithelium and adherence to meso-
dermal cells depend on the activities of the
endoderm-1, Hmgcr, fpps, quemao
slow as molas-
genes . Incorrectly migrating PGCs undergo apo-
ptosis . By the 13th embryonic instar, primordial
gonads, each consisting of approximately 200 somatic
cells and 10–15 PGCs, are formed on both sides of the
ventral furrow. PGCs are surrounded by somatic cells
to complete the formation of the primordial gonads at
this stage (Fig. 1h).
Thus, the two rounded primordial gonads consisting
of somatic and germline cells are formed in the ﬁfth
abdominal segment of females by the end of embryo
DEVELOPMENT OF THE FEMALE
REPRODUCTIVE SYSTEM IN LARVAE
The larval female gonads contain small somatic
cells, which are at the anterior and posterior poles ,
and large germline cells, which are in the central region
of the gonad . In third-instar larvae, somatic cells of
the anterior pole are divided into 16–20 groups, each
consisting of eight or nine disclike cells. Later, these
cells give origin to terminal ﬁlaments, which are at the
end of each ovariole [7, 8]. The oviducts, accessory
glands, uterus, vagina, and external genitals of the adult
female originate from cells of the genital imaginal disc
and are not combined with the other ovarian cells until
the third day of pupal development .
Basic Aspects of Ovarian Development
A. A. Ogienko, S. A. Fedorova, and E. M. Baricheva
Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, 630090 Russia;
fax: (383) 333-12-78; e-mail: email@example.com
Received March 7, 2007
—Modern views of the development and structural organization of the female reproductive system in
are reviewed. Special emphasis is placed on the generation and development of fol-
licles in the germarium and the interactions of germline and somatic cells in the egg chamber. Detailed consid-
eration is given to the main events that ensure and regulate the transport of mRNA, proteins, and organelles from
nurse cells to the oocyte in the germarium and at later stages of egg chamber development.