Patched (Ptc, green) is expressed in most cells of the Drosophila wild-type germarium including follicle stem cells. Hedgehog (Hh, red) accumulates on the surface of the apical cells. Germ cells are i...

Boi (green) and Hedgehog (Hh, red) are expressed in apical cells of the Drosophila wild-type germarium. In the absence of boi (boi[e] mutant), Hh is redistributed from apical cells to the extracellula...

Smoothened (Smo; green), a downstream effector of Hedgehog (Hh), is expressed in most cells of the wild-type Drosophila germarium including follicle stem cells, but is excluded from Boi- and Hh-expres...

The Hedgehog (Hh) pathway is activated in follicle stem cells of animals lacking boi (CIL# 13757), relative to wild-type Drosophila (this image), based on activated cubitus interruptus (ci) staining (...

boi controls follicle stem cell proliferation. Germaria from boi[e] mutant in which germ cells (blue, anti-Vasa) and differentiating follicle cells (red, anti-Fas3) are labeled. Stalks between the ger...

Boi (green) and Hedgehog (Hh, red) are expressed in apical cells of the Drosophila wild-type germarium (CIL# 13744). In the absence of boi (boi[e] mutant), Hh is redistributed from apical cells to the...

Hamster sperm fertilizing a hamster oocyte. This scanning electron micrograph shows hamster sperm fertilizing a hamster oocyte. Fertilization was performed in vivo. Sperm are shown binding to the out...

Scanning electron micrograph showing in vitro fertilization of a hamster oocyte. The sperm head, near the center of the field of view, is engulfed by the microvilli on the surface of the oocyte membr...

Scanning electron micrograph showing a lateral view of sperm penetration of a hamster oocyte during vitro fertilization. As the membrane of the sperm head fuses with that of the oocyte, the microvill...

In situ hybridizations showing the localization of bicoid (top), oskar (middle) and gurken (bottom) mRNAs in the stage 10 Drosophila egg chambers. These localizations define the anterior- posterior a...