Induction of melanogenesis in the epidermal melanoblasts of newborn mouse skin by MSH

Development ◽  
1977 ◽  
Vol 37 (1) ◽  
pp. 79-90
Author(s):  
Tomohisa Hirobe ◽  
Takuji Takeuchi
Keyword(s):  
Microscopic Observation ◽  
Mouse Skin ◽  
Electron Microscopic Observation ◽  
Newborn Mouse ◽  
Electron Microscopic ◽  
Newborn Mice

The number of melanocytes positive to the dopa reaction in the epidermis was shown to increase after newborn mice were injected with α-MSH or DBc-AMP. The agents seemed to induce the initiation of melanogenesis in the pre-existing melanoblasts. Electron-microscopic observation also demonstrated that α-MSH induced not only maturation of melanosomes but also the formation of melanosomes.

Stimulation of dendritogenesis in the epidermal melanocytes of newborn mice by melanocyte-stimulating hormone

1978 ◽  
Vol 33 (1) ◽  
pp. 371-383
Author(s):  
T. Hirobe
Keyword(s):  
Microscopic Observation ◽  
Actinomycin D ◽  
De Novo ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Newborn Mice ◽  
Melanocyte Stimulating Hormone ◽  
Total Length ◽  
Skin Explants ◽  
Stimulation Of

The number of dendrites and the total length of dendrites in the epidermal melanocytes positive for the dopa reaction were shown to increase when newborn mice were injected with alpha-MSH or DBc-AMP. Moreover, both indices of the degree of dendritogenesis increased when skin explants of newborn mice were cultured in medium containing alpha-MSH or DBc-AMP. Electron-microscopic observation showed that the number of melanosomes was also increased by alpha-MSH treatment. Many mature melanosomes were observed in the dendrites of the epidermal melanocytes of alpha-MSH-injected mice. Highly dendritic melanocytes seem to be the cells stimulated by MSH to form melanosomes and translocate them to dendrites. Dendritogenesis stimulated by the hormone was suppressed by actinomycin D or cycloheximide, suggesting that the dendritogenesis in the epidermal melanocytes requires de novo transcription and translation.

Changes of organelles associated with the differentiation of epidermal melanocytes in the mouse

Development ◽  
1978 ◽  
Vol 43 (1) ◽  
pp. 107-121
Author(s):  
Tomohisa Hirobe ◽  
Takuji Takeuchi
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Mouse Skin ◽  
Newborn Mouse ◽  
Electron Microscopic ◽  
Induced Differentiation ◽  
Newborn Mice ◽  
Old Mice

Electron microscopic observations on normally differentiating and α-MSH (melanocytestimulating hormone)-treated epidermal melanocytes of newborn mouse skin were carried out. The process of melanocyte differentiation from premelanosome-containing melanoblasts was investigated in detail with respect to melanosomes as markers. Melanoblasts containing unmelanized premelanosomes gradually decreased in number after birth, while the number of melanocytes rapidly increased. The epidermis of α-MSH-treated 3-day-old mice and normal 6-day-old mice contained melanocytes with numerous fully melanized melanosomes, and with no or only a few melanoblasts. Changes in other organelles in differentiating melanocytes were also noticeable. Golgi apparatus and RER (rough endoplasmic reticulum) decreased in number during the normal or α-MSH-induced differentiation of the epidermal melanocytes, though the number of mitochondria showed no notable change. The number of SER (smooth endoplasmic reticulum) per cell did not change in the cells of newborn mice, while in α-MSH-treated cells the number increased significantly. These results led us to an assumption that Golgi apparatus or RER transforms into other forms of organelles including melanosomes and SER during the differentiation of melanocytes.

Electron Microscopic Observation of the Longitudinal Organization of Poly (p-Phenylene Terephthalamide) Fibers

1982 ◽  
Vol 40 ◽  
pp. 680-681
Author(s):  
Li Li-Sheng ◽  
L.F. Allard ◽  
W.C. Bigelow
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Microscopic Observation ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Aromatic Polyamides ◽  
Radial Arrangement ◽  
Scanning Electron ◽  
Better Than

The aromatic polyamides form a class of fibers having mechanical properties which are much better than those of aliphatic polyamides. Currently, the accepted morphology of these fibers as proposed by M.G. Dobb, et al. is a radial arrangement of pleated sheets, with the plane of the pleats parallel to the axis of the fiber. We have recently obtained evidence which supports a different morphology of this type of fiber, using ultramicrotomy and ion-thinning techniques to prepare specimens for transmission and scanning electron microscopy.

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