Not All Germ Cells Are Bad: Some Need to Grow for Us to Grow


Image of sperm and egg

Image via Wikimedia, used under Creative Commons

Do you remember sex education and how awkward it was? Almost everyone had some form of sex education at school. Usually, it focused on certain parts of the female and male anatomy that middle schoolers always giggle at. (It also conceived some memorable moments involving certain phallic objects and fruits, but we are not going to get into that…)

But what about the parts of sex education we don’t emphasize as much? Isn’t there more to it than that? Well, yes there is!

Reproductive Biology is an expansive field which revolves around understanding and studying the male and female reproductive system. It is more than those awkward moments. It is uncovering the science of how these systems develop and mature. Understanding these systems helps us to more fully understand fertility and how it can impact society.

For example, germ cell development research explores how germ cells mature over time. Most people know the germ cell by its more common name: as an “egg” (or the female-oriented term “oocyte”). For the purposes of this article, we will stick to “germ cell” as the term of choice. Development of a germ cell is highly dependent on several different signals and cues from its environment, some of which come from the surrounding cells, called somatic cells.

I like to look at germ cell development like a child growing up and maturing.

For cells and for people, growth comes in stages. Infants become toddlers, then children, teens, and eventually adults. And a germ cell also goes through multiple stages of development, changing and maturing along the way.

As with any child, there are adults and mentors who support the child’s growth and maturity. The adults typically do this by providing advice, rules, guidelines, and protection. Somatic cells play a similarly key role in developing the germ cell for competency and providing the inputs needed for progress.

As the child transitions to adulthood, the information and guidance they need changes with each step and level. For example, children need to be guided differently depending on their stage in life – in things such as taking initiative, building study habits, and taking accountability for doing wrong. As the germ cell matures, it also gets different signals from the somatic cells which impact its development.

Keep in mind that these signals are not a one-way street. A child reacts to the rules set by its mentors and adults. And the adults respond and adapt to the child too. Similarly, at different times in the development cycle, somatic cells adjust their inputs in response to changing signals from the germ cell. This type of feedback loop creates steady communication between the adult and child – and the germ and somatic cells – and both adapt as they progress and mature together. This feedback exchange is important in developing a germ cell to its fullest potential for reproductive use.

So how does this feedback exchange happen in cell development? Through the generation of a structure called the follicle. The follicle is comprised of the germ cell and its surrounding somatic cells. This structure, and the signals which effect its maturation and development, are vital to the success and evolution of the germ cell.

My study revolves around understanding these signaling processes which govern the formation and growth of the follicle. Truly understanding the timing and emphasis of signals at different points into follicle development – and the feedback between the somatic and germ cells – help us understand the progression and maturation of the germ cell. Of the multiple signals used in this process, the one we are most fascinated with in my lab is the Notch signaling pathway, a pathway that can be activated by the direct interaction between the two cells. We found that an activated Notch signaling pathway can regulate and send signals that help in follicle development. Without these temporal and spatial signals, follicle formation and growth are affected, which disrupts the environment necessary for the germ cell to mature.

Studies like this contribute to our overall understanding of reproduction and fertility. It is important to know how germ cells (and their maturation within follicles) fit into the larger picture, because they are vital to preserving our species! Understanding the signaling pathways critical to maturing these follicles – and the germ cells inside them – is a vital part of this process. By understanding what happens “under the hood”, we can then disseminate correct information, make more informed decisions, create more impactful education and resources, personalize medicine, and design effective and efficient treatments for reproductive diseases.



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