Development and growth of auricular cartilage and muscles: A study using human fetuses

Auricular growth potential of patients with concha-type microtia after auricular cartilage stretching surgery: A prospective study

BACKGROUNDS

For patients with concha-type microtia, surgical intervention and the degree of deformity may affect the growth rate of the auricular cartilage, which is different at different ages. This study aimed to explore the auricular growth potential of patients with concha-type microtia at different ages after auricular cartilage stretching surgery.

METHODS

A total of 66 patients with unilateral grade II and III concha-type microtia were involved in this prospective cohort study. All patients underwent auricular cartilage stretching surgery. Relevant data were collected before surgery, immediately after surgery, and at the last follow-up.

RESULTS

The perimeter, width, and length of auricle, between each follow-up, was statistically significant, which supported the effect of surgery and auricular development. For patients in the grade II group, no statistical significance was found in the difference in the perimeter, width, and length between the affected and normal auricle. For the patients in the grade III group, the difference in the relevant indexes of the affected auricle was significantly different from those of the normal auricle. Between subgroups divided according to their age, the growth potential of affected auricle with the same degree of deformity was statistically significant.

CONCLUSIONS

Growth potential of the affected auricle of the grade II group was consistent with that of the normal auricle, which was significantly higher than that of the grade III group. For patients at different ages, auricles grew faster before 3 years of age. Surgical intervention improved the auricular aesthetics and released the auricular growth potential. Thus, surgical intervention should be recommend as early as possible.

Characteristic findings in the human fetus vestibule: A human temporal bone study

OBJECTIVE

The "collapse," a highly flexed, dented, or caved membrane between the endo- and peri-lymph of the saccule and utricle in adults, is considered as a morphological aspect of Ménière's syndrome. Likewise, when mesh-like tissues in the perilymphatic space are damaged or lost, the endothelium loses mechanical support and causes nerve irritation. However, these morphologies were not examined in fetuses.

METHODS

By using histological sections from 25 human fetuses (crown-rump length[CRL] 82-372 mm; approximately 12-40 weeks), morphologies of the perilymphatic-endolymphatic border membrane and the mesh-like tissue around the endothelium were examined.

RESULTS

The highly flexed or caved membrane between the endo- and peri-lymphatic spaces was usually seen in the growing saccule and utricle of fetuses, especially at junctions between the utricle and ampulla at midterm. Likewise, the perilymphatic space around the saccule, utricle and semicircular ducts often lost the mesh-like tissues. The residual mesh-like tissue supported the veins, especially in the semicircular canal.

CONCLUSION

Within a cartilaginous or bony room showing a limited growth in size but containing increased perilymph, the growing endothelium appeared to become wavy. Owing to a difference in growth rates between the utricle and semicircular duct, the dentation tended to be more frequently seen at junctions than at free margins of the utricle. The difference in site and gestational age suggested that the deformity was not "pathological" but occurred due to unbalanced growth of the border membrane. Nevertheless, the possibility that the deformed membrane in fetuses was an artifact caused by delayed fixation is not deniable.

Neural crest cells give rise to non-myogenic mesenchymal tissue in the adult murid ear pinna

Despite being a major target of reconstructive surgery, development of the external ear pinna remains poorly studied. As a craniofacial organ highly accessible to manipulation and highly conserved among mammals, the ear pinna represents a valuable model for the study of appendage development and wound healing in the craniofacial complex. Here we provide a cellular characterization of late gestational and postnatal ear pinna development in Mus musculus and Acomys cahirinus and demonstrate that ear pinna development is largely conserved between these species. Using Wnt1-cre;ROSAmT/mG mice we find that connective tissue fibroblasts, elastic cartilage, dermal papilla cells, dermal sheath cells, vasculature, and adipocytes in the adult pinna are derived from cranial crest. In contrast, we find that skeletal muscle and hair follicles are not derived from neural crest cells. Cellular analysis using the naturally occurring short ear mouse mutant shows that elastic cartilage does not develop properly in distal pinna due to impaired chondroprogenitor proliferation. Interestingly, while chondroprogenitors develop in a mostly continuous sheet, the boundaries of cartilage loss in the short ear mutant strongly correlate with locations of vasculature-conveying foramen. Concomitant with loss of elastic cartilage we report increased numbers of adipocytes, but this seems to be a state acquired in adulthood rather than a developmental abnormality. In addition, chondrogenesis remains impaired in the adult mid-distal ear pinna of these mutants. Together these data establish a developmental basis for the study of the ear pinna with intriguing insights into the development of elastic cartilage.

Auricular cartilage configuration: A histological study using late-stage human fetuses and adult cadavers

The auricular cartilage is considered to develop from a funnel-like arrangement of six embryonic hillocks. However, there is little information as to when and how the initial cartilage plate differentiates into the major three hollows or caves: the concha, the scapha and the triangular fossa. We examined semiserial histological sections from 42 human fetuses as well as from seven cadavers of elderly individuals. Tangential sections from adults suggested that three ring-like cartilages were combined to provide a single auricular cartilage and that the external auditory meatus was attached to the lowest ring or concha. All of the fetuses studied carried the three major hollows delineated by skin folds. These skin folds often contained a cartilage loop as a core in place of a thickening or tubercle. Conversely, some of the skin folds corresponded to a highly wavy cartilage plate without looping. According to whether the cartilage loop was present or absent in horizontal sections from 35 fetuses, we classified the cartilage morphology into four patterns, the most frequent of which was absence of the triangular fossa loop (27 fetuses), followed by absence of the scapha loop (11 fetuses). Each pattern was evenly distributed among small and large fetuses. This suggested that some form of cartilage correction or reconstruction was likely to occur after birth, especially at the triangular fossa and/or scapha. Infants appear to show significant region-specific variation in the postnatal growth of the auricular cartilages, especially at the triangular fossa and/or scapha.