FSP1/S100A4-Expressing Stem/Progenitor Cells Are Essential for Temporomandibular Joint Growth and Homeostasis.

The temporomandibular joint (TMJ) is one of the most used joints in the body. Defects and wear in the cartilage of the joint, condyle, and fibrocartilage disc lie at the heart of many common TMJ disorders. During postnatal development, the condyle acts as a growth center for the mandible, with cells moving as a conveyor belt away from the top of the condyle as they differentiate.

Cochlea development shapes bat sensory system evolution.

Sensory organs must develop alongside the skull within which they are largely encased, and this relationship can manifest as the skull constraining the organs, organs constraining the skull, or organs constraining one another in relative size. How this interplay between sensory organs and the developing skull plays out during the evolution of sensory diversity; however, remains unknown. Here, we examine the developmental sequence of the cochlea, the organ responsible for hearing and echolocation, in species with distinct diet and echolocation types within the ecologically diverse bat super-family Noctilionoidea.

Bat teeth illuminate the diversification of mammalian tooth classes.

Tooth classes are an innovation that has contributed to the evolutionary success of mammals. However, our understanding of the mechanisms by which tooth classes diversified remain limited. We use the evolutionary radiation of noctilionoid bats to show how the tooth developmental program evolved during the adaptation to new diet types.

Insights into the formation and diversification of a novel chiropteran wing membrane from embryonic development.

Background: Through the evolution of novel wing structures, bats (Order Chiroptera) became the only mammalian group to achieve powered flight. This achievement preceded the massive adaptive radiation of bats into diverse ecological niches. We investigate some of the developmental processes that underlie the origin and subsequent diversification of one of the novel membranes of the bat wing: the plagiopatagium, which connects the fore- and hind limb in all bat species.

Wnt signaling from Gli1-expressing apical stem/progenitor cells is essential for the coordination of tooth root development.

Stem cell regulation plays a crucial role during development and homeostasis. Here, an essential source of Wnts from Gli1 stem/progenitor cells was identified in the murine molar. Loss of Wnt production in Gli1 apical stem/progenitor cells led to loss of Axin2 at the root apex, mis-regulation of SOX9, loss of BMP and Hh signaling, and truncation of root development.