Figure 1-1. Diagram of a longitudinal section of a hair. The four main hair types drawn to scale.
Figure 1-2. The early stages in the development of the hair follicle and hair.
Figure 2-1. Schematic representation of phenotypic variability of coat-color patterns among Avy/am and am/am mice in Wolff's VYm stock.
Figure 2-2. Melanin granules in a melanocyte from the hair follicle of a yellow mouse (C57BL/6 Ay).
Figure 2-3. Eumelanosomes and phaeomelanosomes occurring within the same hair bulb melanocytes of a 3-day-old agouti mouse.
Figure 2-4. Metabolic pathway of eumelanin and phaeomelanin biosynthesis.
Figure 2-5. Recessive yellow ( e/e) mouse which had been partially plucked, and 5 days later had received a series of 10 daily injections of MSH; lethal yellow ( Ay) mouse similarly treated; Ay mouse which had been plucked but which received medium rather than MSH; Ay mouse similarly treated but which received MSH only on days 8 and 9 after plucking.
Figure 2-6. Histological section of the dorsal skin from an Ay mouse that had received a single innoculation of MSH 8 days after plucking.
Figure 3-1. A typical brown ( a/a;b/b) melanin granule at maturity. (b) Mature black melanin granules in both longitudinal section and cross-section.
Figure 3-2. Adult light ( a/a;Blt/Blt) and dark ( a/a;Blt/b) mice.
Figure 3-3. Whole mount preparations of pigmented hairs from Blt genotypes.
Figure 3-4. Mid-region of a light ( a/a;Blt/Blt) hair follicle (13th day of hair growth cycle).
Figure 3-5. Hair bulbs of a light ( a/a;Blt/Blt) mouse (13th day of hair growth cycle).
Figure 3-6. Hair bulb of a dark ( a/a;Blt/b) mouse (13th day of hair growth cycle).
Figure 3-7. Hair bulb of a light ( a/a;Blt/Blt) mouse (10th day of hair growth cycle).
Figure 3-8. Hair bulb of a light ( a/a;Blt/Blt) mouse (6th day of hair growth cycle).
Figure 3-9. Whole mount preparations of light ( a/a;Blt/Blt) melanocytes in the epidermis of the ear pinna, sole of the foot and tail.
Figure 3-10. Hair bulbs (7th day of hair growth) from the white spotted areas of varitint-waddler ( Va/+), belted ( bt/bt), splotch ( Sp/+), and piebald ( s/s) mice.
Figure 3-11. Hair bulbs (seventh day of hair growth) from white ( Miwh/Miwh) and viable dominant spotting ( Wv/Wv) mice.
Figure 3-12. Hair bulbs from an albino mouse (7th day of hair growth) and a pink-eyed chinchilla ( Aw/Aw;cch/cch;p/p) mouse (7th day of hair growth).
Figure 3-13. Hair bulbs that developed in (a) a graft of intact somites plus neural tube taken from 10.5-day-old albino ( c/c) embryo. (b) A graft from the limb bud of a 10 to 10.5-day-old albino ( c/c) embryo. (c) A neural crest-free limb bud graft from a 10.5-day-old potentially pigmented ( a/a;b/b;d/d) embryo. (d) A graft from the limb bud of a 12.5-day-old albino ( c/c) embryo.
Figure 3-14. Melanin granules in the retina of a 15-day-old albino mouse.
Figure 3-15. Three stages in the development of the black retinal granules prepared from 20-day-old embryos.
Figure 3-16. Schematic diagram of speculative sequence of melanin formation as viewed by M.A. Lutzner and C.T. Lowrie ( 1972).
Figure 4-1. Whole mount preparations of pigmented hairs. (a) Hair from an intense black ( a/a) mouse. (b) Hair from a dilute black ( a/a;d/d) mouse. (c) Another hair from a dilute black animal but in this case showing a region containing an unusually large clump of melanin. (d) Hair from a pink-eyed leaden ( a/a;p/p;ln/ln) mouse.
Figure 4-2. (a) Hair bulb from a 5-day-old intense black ( a/a) mouse. (b) Hair bulb from an adult leaden ( a/a;ln/ln) mouse (12th day of hair growth cycle). (c) Hair follicle from a 5-day-old dilute ( a/a;b/b;d/d) mouse. (d) Hair bulb from another 5-day-old dilute ( a/a;d/d;p/p) mouse.
Figure 4-3. (a) Melanocyte from the harderian gland of a 10-day-old a/a mouse. (b) Melanocyte from the harderian gland of a 4-day-old a/a;b/b mouse. (c) Melanocyte from the harderian gland of a 4-day-old a/a;d/d mouse. (d) Three melanocytes from the harderian gland of a 6-day-old a/a;b/b;d/d mouse. (e) Nucleofugal melanocytes imbedded in the connective tissue capsule of the harderian gland of a 10-day-old a/a mouse. (f) Nucleopetal melanocytes imbedded in the connective tissue capsule of the harderian gland of a 4-day-old Ay/a;d/d mouse.
Figure 4-4. A typical nucleopetal melanocyte from the harderian gland of a leaden ( a/a;b/b;ln/ln) mouse. (b) A typical nucleofugal melanocyte from the harderian gland of a nonagouti ( a/a) mouse.
Figure 4-5. (a) Melanocytes recovered from a graft of a/a;D/D 12-day-old embryonic skin to the eye of an a/a;b/b;d/d;p/p host. (b) Nucleopetal melanocytes recovered from a graft of a/a;b/b;ln/ln 10-day-old embryonic dorsal tissue to the eye of a nonleaden albino host. (c) Melanocytes recovered from a graft of a/a;b/b;d/d 12-day-old embryonic dorsal tissue to the eye of a nondilute abino host.
Figure 4-6. Pigment granules in awl hairs of six different genotypes.
Figure 4-7. Stages in the development of a/a;p/p melanin granules.
Figure 4-8. Fresh, squash preparation of the retina and choroid from a 14-day-old nonagouti ( a/a) mouse.
Figure 6-1. (a) Cleared whole mount of a beige ( a/a;bgslt/bgslt) hair showing medullary and cortical pigment. (b) Cleared whole mount of a beige ruby-eye ( a/a;bg/bg;ru/ru) hair. (c) Region of a hair from a C57BL/6 ( a/a;+/+) mouse showing small, ovoid granules. (d) A similar region from a C57BL/6- bgJ/bgJ mouse showing large, irregular melanin granules.
Figure 6-2. (a) From the eye of a C57BL/6J (+/+) mouse showing that normal, small ovoid granules are present in the choroid and round and rod-shaped granules occur in the retina. (b) A similar region from the eye of a C57BL/6- bgJ/bgJ animal in which large, irregular melanin granules are present in both the choroid and retina.
Figure 6-3. Melanin granules of beige mice as viewed with the electron microscope. (a) Giant melanosome from the retina of a brown beige ( a/a;b/b;bgJ/bgJ) adult. (b) Giant granules from the choroid of a brown beige adult. (c) Mature choroidal granule from an adult beige ( a/a;bgJ/bgJ) mouse which is melanized in all areas.
Figure 7-1. Diagram of the experimental procedures involved in producing allophenic mice.
Figure 7-2. These 14 B10CBAF1 (C/C) <--> SJL ( c/c) allophenics demonstrate the variation that can occur between animals of the same genotype.
Figure 7-3. The striped patterns which occur in these three C/C <--> c/c allophenics are the same as those which occur when the two pigmented genotypes are employed except that, on the average, half the bands are white.
Figure 7-4. Patterns realized in allophenic animals as a consequence of independently originating melanoblast and hair follicle clones.
Figure 7-5. A pun/pun mouse which, as a result of spontaneous somatic reversion to wild type, possess two populations of melanoblasts.
Figure 7-6. (a) A/A <--> a/a allophenic showing a typical hair-follicle clonal pattern and (b) viable yellow ( Avy/a) single-genotype mouse displaying the same pattern.
Figure 7-7. (a) Miwh/Miwh <--> +/+ allophenic and (b) Miwh/+ single-genotype animal showing the same spotting pattern.
Figure 8-1. A diagrammatic representation of X-inactivation as applied to coat-color mosaicism in the mouse.
Figure 8-2. Diagrams showing dorsal and ventral sides of two typical dappled-2 females.
Figure 8-3. A young brindled ( Mobr) male.
Figure 8-4. Brindled hairs. (a) Awl from a Mobr/+ female (19 days), (b) awl from Mobr male (littermate, 12 days), (c-f) other hairs from the same animal at lower magnification (all completely devoid of pigment in the segments shown).
Figure 8-5. Variation in the degree of expression of brindles ( Mobr) in heterozygotes.
Figure 8-6. Brindled ( Mobr/+) female, 19 days.
Figure 9-1. A diagram of the 14 primary areas proposed by Schaible (see text).
Figure 9-2. A typical piebald lethal ( sl/sl) mouse.
Figure 9-3. A typical piebald mouse ( a/a;s/s) of the stock employed by Mayer in his studies.
Figure 9-4. A 3-week-old lethal spotting ( ls/ls) mouse displaying spotting typical of this mutant.
Figure 9-5. Belted ( bt/bt) mouse illustrating the "belt" across the back posterior to the midline.
Figure 10-1. Mouse homozygous for viable dominant spotting ( Wv).
Figure 10-2. Dorsal and ventral views of Wf/Wf (left), Wf/+ (middle), and +/+ (right) mice.
Figure 10-3. Dorsal and ventral views of three patch ( Ph/+) mice.
Figure 10-4. Typical spotting patterns of (a) Ph/+ alone and in combination with (b) Rw/+, (c) Sld/+, and (d) Wx/+.
Figure 10-5. Typical a/a;Ph +/+ Wv mouse.
Figure 10-6. Typical spotting patterns of (a) Phe/+ alone and in combination with (b) Wv/+ and (c) Rw/+.
Figure 10-7. Dorsal and ventral views of three rump-white ( Rw/+) mice.
Figure 10-8. Typical spotting patterns of (a) rw/+ alone and in combination with (b) Wv, (c) bt/bt, (d) Sld/+, and (e) Sp/+.
Figure 10-9. Dorsal and ventral views of three Rw +/+ Wv mice.
Figure 11-1. Dorsal and ventral views of littermate 6-week old (a) W/+;f/f, (b) W/+;f/+, (c) +/+;f/f and (d) +/+;f/+ genotypes.
Figure 11-2. Varitint-waddler ( Va/+) heterozygote.
Figure 11-3. Dorsal and ventral views of (a) +/+, (b) VaJ/+, (c) Va/+, and (d) VaJ/VaJ mice.
Figure 12-1. [2-14C] Tyrosine incorporation in skin slices of 5-day-old mice differing at the microphthalmia locus. Means, standard errors, and the number of determinations are shown for each genotype.