Morphological analysis of the human sperm tail during the early post-fertilization stage.

After fertilization, the human sperm tail lost its fibrous sheath at the pronuclear stage to become coiled and then attached to one of the first mitotic spindle poles. The tip of the sperm tail was branched and its degree did not change from the pronuclear stage to the second mitosis.

Staphylococcus cohnii is a potentially biotherapeutic skin commensal alleviating skin inflammation.

Host-microbe interactions orchestrate skin homeostasis, the dysregulation of which has been implicated in chronic inflammatory conditions such as atopic dermatitis and psoriasis. Here, we show that Staphylococcus cohnii is a skin commensal capable of beneficially inhibiting skin inflammation. We find that Tmem79 mice spontaneously develop interleukin-17 (IL-17)-producing T-cell-driven skin inflammation.

Ultrastructural and histochemical evaluation of appositional mineralization of circumpulpal dentin at the crown- and root-analog portions of rat incisors.

Mineralization of circumpulpal dentin has been interpreted in such a way that predentin matrix is abruptly converted to almost fully mineralized dentin at the mineralization front. A group of investigators pointed out the existence of intermediary layer along the mineralization front of rat incisor dentin and claimed that dentin mineralization is a rather transient process. Owing to a paucity of information, however, the entity of transient mineralization of dentin has remained elusive.

Introduction of a three-dimensional and layered (TDL) culture, a novel primary co-culture method for ameloblasts and pulp-derived cells.

The enamel organ engaged in enamel matrix formation in tooth germs comprises four different cell types: the ameloblasts, the cells of the stratum intermedium, stellate reticulum, and the outer enamel epithelium, each characterized by distinct structural features. In ordinary primary cultures of tooth-derived cells, these cells generally become flat in profile and hardly regain their original profiles comparable to those in vivo, even under conditions that can induce the expression of functional markers from these cells. To overcome this limitation inherent to the cell culture of tooth-derived cells, we introduced a novel co-culture method, a "three-dimensional and layered (TDL) culture", a three-dimensional (3D) culture of dental pulp-derived cells dispersed in type I collagen gel combined with a layered culture of enamel epithelial cells seeded on top of the gel to establish thereby a culture condition where the functional tooth-derived cells regain their original structures and spatial arrangements.

Development and terminal differentiation of pulp and periodontal nerve elements in subcutaneous transplants of molar tooth germs and incisors of the rat.

Ectopic tooth transplants are known to receive rich innervation of local neurons, but the precise location and structural features of neurites in the pulp and periodontal ligament (PDL) of such transplants are unclear. In this experiment, the molar tooth germs of rat embryos and incisors of young rats were subcutaneously transplanted into the dorsal regions of rats and processed, at various time intervals, for immunohistochemical demonstration of neural elements. Teeth with periodontal tissue elements developed in most of the molar transplants in 6 or 8 wk and received rich innervation, including some autonomic fibres, in the pulp.