The sensory innervation of the human nipple

Prognostic Evaluation of Piezo2 Channels in Mammary Gland Carcinoma

In the last decade, a group of Ca2+ channels called Piezo were discovered, demonstrating a decisive role in the cellular response to mechanical stimuli and being essential in the biological behavior of cells regarding the extracellular compartment. Several investigations have suggested a potential role in carcinogenesis, with a tumor suppressor role in some cases but increased expression in several high-grade neoplasms. Regarding Piezo2 expression in mammary gland neoplasms, a protective role for Piezo2 was initially suggested, but a subsequent study demonstrated a relationship between Piezo2 expression and the highly aggressive triple-negative phenotype of breast carcinoma. A cohort of 125 patients with clinical follow-up was chosen to study Piezo2 expression and clarify its clinical implications using the same immunohistochemical evaluation performed for other breast carcinoma parameters. Fisher's exact test was chosen to identify potential relationships between the different variables. A significant association was found with the Ki67 proliferation index, but not with mitoses. The tendency of most proliferative tumors was to have an increased score for Piezo2. A similar association was found between Piezo2 expression and perineural invasion.

Mentalis nerve branches supplying the lower lip revisited: a study of human fetuses and donated elderly cadavers

PURPOSE

Little information is known about the mentalis nerve course from the lower lip approximation margin (free margin) to the upper lip. Likewise, no difference in nerve distribution has been observed between the cutaneous and mucosal parts of the lip. Therefore, this study reexamined mentalis nerve morphology.

METHODS

For macroscopic observations, three fresh cadavers were dissected (one male and two females; aged 78-93). We also evaluated histological sections obtained from five donated elderly cadavers (two males and three females, aged 82-96 years) and 15 human fetuses (11-40 weeks or crown-rump length 80-372 mm). Immunohistochemical analysis for S100 protein and tyrosine hydroxylase was performed.

RESULTS

In both fetuses and adult cadavers, one to three nerve branches ran upward in the submucosal tissue from the mental foramen. Near the free margin of the lip, some branches passed through the orbicularis oris muscle layer toward the lip skin, whereas others followed a reversed J-shaped course along the free margin. Nerve twigs ran in parallel beneath the mucosa, whereas wavy nerve twigs attached to the basal lamina of the lip epidermis. The difference in nerve endings abruptly occurred at the skin-mucosal junction. Tyrosine hydroxylase-positive sympathetic nerve twigs surrounded arteries and formed a branch composed of S100-negative unmyelinated fibers.

CONCLUSION

The lower lip skin was innervated by a perforating branch passing through the orbicularis oris muscle, that was different from the lip mucosa. A sudden change in the nerve ending configuration at the mucocutaneous junction seemed to develop postnatally.

An Evolving Landscape: Return of Breast Sensation After Mastectomy Varies by Anatomic Region and Reconstructive Method

PURPOSE

Loss of breast sensation after mastectomy has been well documented. Postoperative reinnervation of the breast is influenced by factors including reconstructive technique, patient comorbidities, and adjuvant treatment. However, little attention has been paid to the differences in sensation across regions of the breast and the impact of reconstructive method on these regional differences over time.

METHODS

Patients undergoing nipple-sparing mastectomy with immediate autologous or alloplastic reconstruction were prospectively followed. Neurosensory testing was performed in 9 breast regions using a pressure-specified sensory device. Patients were stratified by reconstructive technique, and regional sensation was compared at different preoperative and postoperative time points using Student t tests.

RESULTS

One hundred ninety-two patients were included; 106 underwent autologous reconstruction via neurotized deep inferior epigastric artery perforator flap, and 86 underwent 2-stage alloplastic reconstruction. Preoperative sensation thresholds did not differ between reconstructive cohorts in any region and averaged 18.1 g/mm2. In the first year after mastectomy, decreased sensation was most pronounced in the inner breast regions and at the nipple areolar complex (NAC) in both reconstructive cohorts. At 4 years postoperatively, sensation increased the most at the NAC in the alloplastic cohort (34.0 g/mm2 decrease) and at the outer lateral region in the autologous cohort (30.4 g/mm2 threshold decrease). The autologous cohort experienced improved sensation compared with the alloplastic cohort in 5 of 9 regions at 1 year postoperatively, and in 7 of 9 regions at 4 years postoperatively; notably, only sensation at the outer superior and outer medial regions did not differ significantly between cohorts at 4 years postoperatively.

CONCLUSIONS

Although patients undergoing breast reconstruction experience increased breast sensation over time, the return of sensation is influenced by type of reconstruction and anatomic region. Regions closer to and at the NAC experience the greatest loss of sensation after mastectomy, although the NAC itself undergoes the most sensation recovery of any breast region in those with alloplastic reconstruction.Autologous reconstruction via a neurotized deep inferior epigastric artery perforator flap results in increased return of sensation compared with alloplastic reconstruction, particularly in the inferior and lateral quadrants of the breast.

Mammary homeostasis in the mother-offspring dyad

Homeostasis during lactation is a special case in which the unit for regulation is a dyad comprising the mother and her currently nursing offspring (the mother-offspring dyad). This arrangement is not a trivial. A litter of mice can have a mass greater than the mother and nutrient demands that far exceed her. Homeostasis for milk secretion, appetite, and calcium metabolism must come under integrated control, responding seamlessly to the needs of the mother and the offspring. Serotonin (5-HT) is a primary local regulator of mammary homeostasis. 5-HT synthesis in the mammary epithelium is high during lactation and increases during milk stasis. Two important functions are attributed to the 5-HT system. Firstly, when alveolar spaces are filled with milk 5-HT inhibits milk secretion and opens tight junctions. This feedback induces early phases of involution. Secondly, 5-HT induces synthesis and secretion of parathyroid hormone-related peptide (PTHrP).