Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School


First Advisor

Nels H. Granholm


The objective of this study was to assess if· MSH induces in yellow (Ay/a) mice, a program of black melanin production that is identical in terms of melanosome structure and development to that of normal black (a/a) mice. Since there is a difference between melanosomes of the two genotypes, Ay/a and a/a, and MSH induces eumelanin production in phaeomelanin producing Ay/a melanocytes of the opportunity exists to narrow down and define the Ay/a effects on melanosomal parameters after MSH treatment. If there is any significant difference between Ay/a and a/a melanosomal parameters measured, these differences are due solely to the Ay allele. Ultrastructural differences also reflect differences in the biochemical processes associated with each melanosome type. In order to conduct quantitative electron microscopy on a/a and Ay/a MSH treated melanocytes, I measured the following melanosome parameters: length, width, vesiculo-globular (VG) body count, and melanosomal matrix organization. Length-to-width ratios and melanosomal areas were calculated from these raw data. Comparisons between these measurements showed the extent to which MSH can switch the phaeomelanin production of the Ay/a melanocyte into eumelanin synthesis of the a/a melanocyte.

Library of Congress Subject Headings

MSH (Hormone)


Mice as laboratory animals

Melanins -- Synthesis



Number of Pages



South Dakota State University