Immunohistochemistry allows in situ detection of cell and extracellular components through specific antibodies. The objective was to compare the immunohistochemical expression patterns of the S-100, HMB-45 and MART-1 proteins for differential diagnosis of malignant melanoma and melanocytic nevus in human skin biopsies. Thirty-nine biopsies of human tissue were used. They were divided into two groups: 19 in malignant melanoma and 20 in melanocytic nevi. Next, the samples were fixed with paraformaldehyde and processed following the protocol for inclusion. Then, immunohistochemical staining was performed. Finally, the histological and qualitative analysis of the samples was carried out. S-100, HMB-45, and MART-1 markers showed positive immunoreaction in melanoma biopsies. HMB-45 marker was generally present with weaker expression than S-100 and MART-1 in melanocytic nevus biopsies. No expression pattern was observed which specifically associates one or more markers with some types of histopathological diagnosis. Immunohistochemistry is fundamental in differential diagnosis of melanomas and melanocytic nevi. However, there is no antibody or set of antibodies which allows unequivocal diagnosis between melanoma and nevus. It is therefore necessary to analyze with care the expression pattern and location of the lesion using standard morphological characteristics.

Progesterone receptors are expressed in the reproductive organs of adult sheep, where they regulate morphofunctional and reproductive development. However, various studies have shown the presence of these receptors in the uterus of prepubertal females. It is not clear what role these receptors have at this level of development in uterine tissue. Therefore, it is relevant as a first step in the investigation, to determine the expression and histological distribution of the progesterone receptor in prepubertal sheep in order to determine possible functions at this level of reproductive development. Immunohistochemical analysis allows visualizing the specific presence of a protein in the cellular and histological context, however, the results displayed through digital images are qualitative data and subject to the observer's criteria. In this work, a quantitative analysis method of immunohistochemical expression of the progesterone receptor in ovine endometrium is presented, using digital analysis of images, by means of integrated optical density of digital photographs of histological sections processed with immunohistochemical methods. The results show the possibility of quantitatively evaluating the expression of progesterone receptors in the endometrial stroma and prepubertal endometrial glands by applying the integrated optical density analysis of digital images.