References: Hair growth and hair loss
J Hirnforsch. 1997;38(3):341-51.
Structure of glycogen particles in organ of Corti's outer hair cells in three rodent species.
Beneyto M, Sala JC, Sala ML, Merchan JA, Prieto JJ.
Department of Histology, University Miguel Hernandez, San Juan, Spain.
Organ of Corti's outer hair cells are one of the few cell types in mammals to contain large cytoplasmic glycogen stores, and the only one in the adult auditory receptor. Previous reports on the structure and distribution of glycogen in the adult organ of Corti were mainly based on light microscopy histo- and cytochemical methods, and the scare EM studies on the topic relied on techniques which were not sensitive or specific enough. Furthermore, it has been reported that glycogen particles are not present in outer hair cells of all species. A first goal of the present study was to describe the ultrastructure of glycogen stores in organ of Corti's outer hair cells in Guinea pig, rat, and mouse, using the periodic acid-thiocarbohydrazide-silver proteinate method. In addition, differences in the subcellular and cochleotopic distribution of this substance were analyzed. In the adult organ of Corti only the outer hair cells contain glycogen stores. Present throughout their cytoplasm, these deposits appear either as single beta particles, or as aggregates of these, forming alpha particles. Though most alpha particles are round, some appear long and conspicuously straight in longitudinal sections of those cells near the apex of the cochlea, and they seem to be apposed to some filamentous structure. On the other hand, when the cells are sectioned transversely the larger aggregates of glycogen particles follow a curved course. Since outer hair cells of the apical region of the cochlea contain a bundle of contractile microfilaments, our results suggest that glycogen is associated with the contractile apparatus of these cells. This hypothesis is in good accordance with previous experimental data which suggest that glycogen is used as energy source for the contractile movements of outer hair cells.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9350505&dopt=Abstract
Exp Anim. 1997 Oct;46(4):319-22.
Study on histamine related enzyme activities during murine hair cycle.
Hamada K, Suzuki K.
Kanebo Cosmetics Laboratory, Kanebo Ltd., Kanagawa, Japan.
The beginning of each anagen phase of the hair growth cycle appears to partially repeat the stages in the initial development of the hair cycle, but the regulatory mechanism of the hair cycle is unclear. We have investigated the levels of histamine related enzyme activities in the third hair cycle period of C3H mouse after depilation. The level of histidine decarboxylase activity increased just after depilation treatment and returned to the normal level within two weeks: this change was relevant to histamine content as we have previously reported. This result suggests that the histamine synthesising enzyme, histidine decarboxylase, activity may be involved in the distinctive process of hair re-growth, in particular, the initiation of the anagen phase.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9353643&dopt=Abstract
Lab Invest. 1997 Oct;77(4):319-32.
Activated skin mast cells are involved in murine hair follicle regression (catagen).
Maurer M, Fischer E, Handjiski B, von Stebut E, Algermissen B, Bavandi A, Paus R.
Department of Dermatology, Charite, Humboldt-Universitat zu Berlin, Germany.
Increasing evidence supports a role for mast cells (MC) in the control of tissue remodeling. Using the cyclic growth and regression activity of the murine hair follicle (HF) as a model, we have previously demonstrated that MC are involved in regulating the HF transformation from resting (telogen) to active hair growth (anagen). In the present study, we investigated the potential role of skin MC in spontaneous HF regression (catagen), a rapid and highly controlled process of organ involution characterized by massive epithelial cell apoptosis. By histochemistry, immunohistochemistry, and electron microscopy, we first assessed the number, location, and granulation status of perifollicular MC during the anagen-catagen-telogen transformation of back skin HF. Spontaneous catagen induction was associated with a dramatic reduction of dermal MC numbers, preceded by an increase in the percentage of degranulated MC. In vivo, the MC-secretagogues substance P and adrenocorticotropic hormone induced premature and dystrophic catagen development in anagen HF, whereas inhibitors of MC degranulation retarded normal catagen development. Comparing HF cycling in MC-deficient WBB6F1-KitW/KitWv and congenic normal (+/+) mice, catagen development was retarded in the virtual absence of MC. These data support the notion that MC function as hair cycle regulators and are involved in the control of HF regression. The mouse model employed here offers an excellent tool for dissecting the physiologic role of MC as "central switchboards of tissue remodeling" in developmentally regulated systems, specifically in organ involution processes.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9354767&dopt=Abstract
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