Biology Commons^™

The Effects Of Photoperiod And Melatonin Injections On The Reproductive System Of Pinealectomized Male Mice Mus Musculus, Icr Strain, John Earnest Constantine

Master's Theses

One hundred two male mice , Mus musculus, ICR strain, age four weeks, were obtained. Fifty-one mice were pinealectomized and 51 were sham operated. The animals were divided into three photoperiod groups: 1.5L:22.5D, 14L:10D, 24L; 0D. The mice were subcutaneously injected daily with 10 ug melatonin or control solution from post-operative day J to post-operative day 60, On post-operative day 60 representatives of each photo­ period-surgery-injection regimen were paired with females. The remaining animals were killed and several organs were removed and weighed, Melatonin injections were progonadal in pinealectomized mice and inhibitory in sham mice in several instances. Histological examination …

The Effects Of Photoperiod And Melatonin Injections On The Reproductive System Of Male Mice, Mus Musculus, Icr Strain, Margaret Ann Shugart

Master's Theses

The reproductive effects of long (24L:OD), natural (14L:lOD), and short (1L:23D) photoperiods were studied in the male mouse, Mus musculus, ICR strain. One third of the mice in each photoperiodic regimen were sacrificed after 45 days. Half of the remaining mice in each regimen received daily melatonin (5-methoxy-N-acetyl tryptamine) injections for 45 additional days. Body weights, testicular and accessory sex organ weights were measured and microscopic examinations of the testes were made. Plasma testosterone levels were determined using radioimmunoassay. Other organ (pituitary, kidney, adrenal, thymus, thyroid) weights were also obtained.

An Ultrastructural Study Of Intramuscular Melanocytes In Pet/Wmr Mice, Charles August Gomer

Master's Theses

An examination of the lateral head of the gastrocnemius of the PET/Wn!.r mouse was made with an electron microscope. Cells of the perimysium and endomysium were described and the relationship of these cells to muscle cells was characterized. The relationship between melanocytes and muscle cells found in this strain was the major focus. Melanocytes were seen to be present in the perimysium and endomysium with the greatest concentration in the endomysium. Melanocytes of the perimysium appeared segregated from the adjacent tissue by fibroblasts,which surround ed the melanocytes with their cytoplasmic processes, a well as by collagen fibers. Melanocytes of the …

The Effects Of Prolonged Ultraviolet Irradiation On The Pigment System Of Pet/Wmr Mouse Epidermis, Penny Suzanne Nair

Master's Theses

Repeated exposure to ultraviolet radiation brings about an increase in the DOPA-positive melanocyte population of the human. However, there is an age-dependent decline in the melanocyte population regardless of UV irradiation. In the rhesus monkey, a drop in the DOPA-positive epidermal melanocyte population has been observed after prolonged UV irradiation. The population of DOPApositive epidermal melanocytes in PET/Wmr mice reaches a peak during the first post-natal week after which the number of cells declines, fading almost completely within 3 weeks. Their occurrence in adult mice is rare. With UV irradiation (300 nm) the melanocyte population of newborn and adult PET …

The Effects Of Topical Nitrogen Mustard On The Pigment System In Pet/Wmr Mouse Epidermis, Ronald Lee Salisbury

Master's Theses

Miniature melanocytes have been observed scattered among the typical melanocytes in the skin of the PET/Wmr mouse strain, They are weakly DOPA reactive and their cell bodies and nuclei are one quarter the size of those in typical melanocytes, Both populations reach a peak during the first postnatal week and then gradually disappear within the following three weeks. The miniatures appear very early and are among the last cells to disappear. During the first postnatal week, their population remains relatively constant against a radically changing population of typical melanocytes. That they may represent a stage in the development of typical …

The Effects Of Ultraviolet Irradiation On The Pigment Cells Of The Pet/Wmr Mouse Epidermis, Vaughan Henry Howard Jr.

Master's Theses

Epidermal melanocytes in mammals are known to occur in a variety of shapes, sizes, and colors. The basic melanocyte morphology is dependent upon genetics, but there are a number of environmental factors that can cause modification.

In the epidermis of PET/\vrnr mice, the population of rnelanocytes reaches a peak and begins to decline during the first post-natal week, and has disappeared within four weeks. Dispersed among the large, highly DOPA-reactive melanocytes are miniature melanocytes. These miniature melanocytes are weakly DOPA-reactive and appear early in the post-natal period. The miniature melanocyte population is relatively constant and these miniature cells are among …

The Induced Differentiation Of Mouse Ectoderm To Epidermis By Growth On Freeze-Thawed Dermis, Albert Joseph Banes

Master's Theses

Previous investigators have grown or maintained adult or embryonic skin in tissue culture and on the chorioallantoic membrane (CAM) of chickens. These studies have revealed two important factors involved in culturing skin: (1) the presence of an inducer which originates in the dermis and affects the phenotype of epithelial cells; and (2) the influence of the physical surface of the substrate on which epidermis is cultured.

The current investigation presents evidence that ectoderm from the limb buds of 10 to 12 day-old mouse embryos can form an epidermis when combined with dermis killed by alternate freezing and thawing, and cultured …

Refractoriness Of Pet Mouse Integument To The Nerve Growth Factor, Walter Hollified Dorman

Master's Theses

This paper deals with the refractoriness of PET mouse integument to the subcutaneous administration of nerve growth factor. Newborn mice were injected once daily with NGF through ten injections. Gross and histological examination showed that the skin of the experimental animals was completely unresponsive to this agent. No alterations in the hair growth cycle or pattern were observed.

A Comparative Study Of The Sulfhydryl Groups In The Gastrocnemius Of The Normal And X-Irradiated Pet Mouse, Robert Edward Shervette

Master's Theses

It has been recognized that hyperpigmentation of the skin is the result of eliminating the. -SH inhibition when treatment is by x-irraidiation. The results of a. study by fieams and Schaeffer indicate : a progressive increase of melanocytes in the skin with an increasing dosage of x-irradiation. However, it was also noted that the effect of x-irradiatin on the gastrocnemius of the PET mouse resulted in a decrease in the number of intramuscular melanocytes. The present study was designed to determine whether the changes in the x-irradiated muscle is related to possible changes in -SH concentration.The technique employed is a …

The Effects Of A Nerve Growth-Promoting Protein On The Integument Of Pet Mice, Craig Bauman Satterlee

Master's Theses

A factor which specifically stimulates the growth of sensory and sympathetic nerve cells has been under investigation for a number of years. This factor, originally isolated in 1951, from mouse sarcomas 37 and 180, was named the "nerve growth factor". Its action was first shown in vivo by inoculating the sarcoma into chick embryos and subsequently in vitro by culturing chick ganglia and mouse sarcoma together. In the years immediately following the initial discovery, much more potent sources of NGF were found in the salivary glands and salivary secretions of a variety of species. These include rattle snake venom, and …