発達研究のため培養

Explant culture is a technique where tissues or organs are removed from embryos and cultured outside the body, or ex vivo. This approach allows researchers to directly observe organogenesis—the growth and structural changes of developing organs—while manipulating tissues with experimental molecules. It provides a unique window into developmental processes that cannot be easily studied in living organisms.

Embryos are removed from euthanized pregnant rodents and surrounding membranes are carefully removed. The tissues or organs of interest are isolated from the extracted embryo and transferred to culture plates. Media containing antibiotics are added, and plates are incubated at 37°C. Once established, explant cultures are ready for experimental manipulation and observation.

Explanted tissues can be genetically manipulated using techniques like electroporation, where an electrical field drives injected DNA into cells to test gene roles in development. This approach, combined with molecular developmental biology and growth factors, allows researchers to determine how specific genes influence organogenesis and tissue differentiation in real time.

Signaling molecules like growth factors can be added directly to culture media for simple treatment, or small beads soaked in experimental compounds can be implanted into tissue for more controlled delivery. A major advantage is that effects of these chemical manipulations can be easily visualized in real time using light or fluorescent microscopy.

Light microscopy allows direct observation of tissue development on glass-bottom dishes. Transgenic tissues expressing fluorescent markers provide detailed views of developmental processes like tubule budding. Immunostaining enables researchers to monitor specific cell types during development, such as insulin-producing cells, offering multiple visualization approaches for studying organogenesis.

Explants from specific embryonic regions can be cultured separately and stained to characterize gene expression patterns. By comparing expression in different tissue types—such as dorsal versus ventral regions—researchers determine whether gene expression programs are encoded within embryonic cells or directed by later cell-cell interactions during development.

Explant cultures help decipher roles of specific molecules in organogenesis, such as how growth factors inhibit or promote airway formation in fetal lung tissue. They also reveal mechanisms controlling gene expression during early embryogenesis and allow direct visualization of morphogenesis—structural changes in developing tissues—making them powerful tools for understanding molecular mechanisms underlying animal development.