Neural induction of taste buds

Bilateral innervation allows more than 80% of the 610 vallate taste buds to survive removal of one IXth nerve in adult rats. Removal of both IXth nerves in neonatal or adult rats results in the absence of taste buds. In studying development, we found that removing or crushing one IXth nerve in three-day-old neonates profoundly decreased the number of vallate taste buds that subsequently developed. Specifically, after removal of one IXth nerve at 3 days, only 228 taste buds formed, compared with 496 taste buds that one nerve would maintain in adults. Thus, during normal development, the right and left IXth nerves interact synergistically, as at least 150 more taste buds develop than predicted by the sum of the independent action of each IXth nerve. This suggests that vallate taste buds are induced by the IXth nerve. A second example of synergism, representing evidence for the neural induction of taste buds, came from experiments in which we crushed the left IXth nerve 3 days after birth and found that these regenerated IXth nerve axons induced 4 times as many taste buds in the presence of the normal right IXth nerve (118 taste buds) as in its early absence (30 taste buds). We conclude that taste buds are neurally induced and that axons of the IXth nerve interact synergistically in inducing them, rather than competing for targets. We propose that in development innervated progenitor cells form stem cells which lead to taste bud cells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50036/1/902600206_ftp.pd

Do prolactin and its receptor play a role in alopecia areata?

Context: Studying the link between prolactin and autoimmunity has gained much ground over the past years. Its role played in alopecia areata (AA) is not clear yet, as previous reports yielded controversial results. Aims: This study aimed to measure the serum level of prolactin and to detect the expression of its receptor in AA, in an attempt to highlight its possible role in the pathogenesis of this disease. Subjects and Methods: A case-control study of 30 AA patients and 20 controls from outpatient clinic were undertaken. Every patient was subjected to history taking and clinical examination to determine the severity of alopecia tool (SALT) score. Blood samples were taken from patients and controls to determine the serum prolactin level. Scalp biopsies were obtained from the lesional skin of patients and normal skin of controls for assessment of the prolactin receptor. Statistical Analysis: Depending upon the type of data, t-test, analysis of variance test, Chi-square, receiver operator characteristic curve were undertaken. Results: On comparing the serum prolactin level between patients and controls, no significant difference was found, while the mean tissue level of prolactin receptor was significantly higher in patients than in controls. In patients, a significant positive correlation was found between the prolactin receptor and the SALT score. Conclusions: Prolactin plays a role in AA, and this role is probably through the prolactin receptors rather than the serum prolactin level