We've updated our Privacy Policy to make it clearer how we use your personal data.

We use cookies to provide you with a better experience. You can read our Cookie Policy here.

Cel­lu­lar Mech­an­isms of Early Mam­mary Gland De­vel­op­ment Un­raveled

Cel­lu­lar Mech­an­isms of Early Mam­mary Gland De­vel­op­ment Un­raveled

Cel­lu­lar Mech­an­isms of Early Mam­mary Gland De­vel­op­ment Un­raveled

Cel­lu­lar Mech­an­isms of Early Mam­mary Gland De­vel­op­ment Un­raveled

Optical section of a confocal microscopy image of the mammary bud (marked with dashed line) stained with an epithelial marker in green at the time when ring cells form (left) and analysis of cell roundness of segmented cells with ring cells in dark blue (right). Credit: Ewelina Trela
Read time:

Want a FREE PDF version of This News Story?

Complete the form below and we will email you a PDF version of "Cel­lu­lar Mech­an­isms of Early Mam­mary Gland De­vel­op­ment Un­raveled"

First Name*
Last Name*
Email Address*
Company Type*
Job Function*
Would you like to receive further email communication from Technology Networks?

Technology Networks Ltd. needs the contact information you provide to us to contact you about our products and services. You may unsubscribe from these communications at any time. For information on how to unsubscribe, as well as our privacy practices and commitment to protecting your privacy, check out our Privacy Policy

Despite long-standing interest, the cellular mechanisms driving the initiation of mammary gland development have remained elusive for decades, mostly due to technical limitations in studying dynamic cell behaviors in live tissues. Recent advances in microscopic methods and availability of various mouse models allowed the research group of Marja Mikkola from HiLIFE Institute of Biotechnology, University of Helsinki to address this question. This is the first time when live tissue imaging has been used to visualise the emergence of the mammary gland.

Mammary gland is the class-defining organ of mammals, yet we know surprisingly little how its development commences. In their recent study published in Journal of Cell Biology, the research group of Marja Mikkola used time-lapse imaging to show that the growth of the mammary bud is primarily fueled by migration of cells to the bud. In contrast, although increase in cellular size and cell proliferation contribute to this process, the role of these mechanisms remains minor.

"Interestingly, mammary bud cells, unlike most of other skin derivatives such as hair follicle and tooth bud, do not divide for several days, indicating that this might be a unique feature of early mammary gland development" says graduate student Ewelina Trela, the lead author of the study. "However, we do not yet know why this happens", she continues.

Mammary buds use a previously undescribed mechanism for invagination

Tissue invagination, or tissue folding inwards into the underlying stroma, is a fundamental mechanism that occurs to generate the architecture of many organs. In the same piece of work, the authors describe a novel mechanism for tissue invagination.

"Using confocal fluorescence microscopy, we found thin and elongated epidermal keratinocytes surrounding mammary bud in a rim like fashion: their appearance and disappearance coincided with the invagination process suggesting that these cells, named ring cells, could be functionally important" details principal investigator Marja Mikkola.

Next, the Mikkola group teamed up with the group of Sara Wickström at HiLIFE and Faculty of Medicine, University of Helsinki to establish live imaging of the forming mammary bud, which confirmed that ring cells move circumferentially around the mammary bud.

The study also revealed that the ring cells exert contractile force through the actomyosin network, via non-muscle myosin IIA (NMIIA). The functionality of ring cells was impaired in NMIIA deficient mice leading to compromised mammary bud shape. Whether other developing organs utilize a similar cellular mechanism for invagination remains an open question.

Reference: Trela E, Lan Q, Myllymäki S-M, et al. Cell influx and contractile actomyosin force drive mammary bud growth and invagination. J Cell Biol. 2021;220(e202008062). doi: 10.1083/jcb.202008062

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.