Structure-Function Study of the Lab Opossum Prostate

The mammalian prostate gland secretes fluids that, along with sperm from the testes and fluids from other glands, comprise semen. While the structure and function of the prostate is well known in eutherians, the anatomy of the prostate gland in metatherian (marsupial) mammals is poorly studied. My goal is to contribute to the knowledge regarding prostate anatomy as a way of understanding the evolution of internal fertilization as an effective reproductive strategy by exploring the homologous and analogous aspects of this organ in metatherians versus eutherians. Through dissections of male laboratory opossums and rats (M. domestica and R. norvegicus), I collected data on their gross prostate anatomy. The rat prostate consists of three lobes, dorsal, lateral, and ventral arranged around the base of a short urethra. The opossum prostate consists of three regions, S1, S2, and S3 that wrap around a much longer urethra. Using histological analysis, I compared their microanatomy to establish homologies when possible. I used immunochemistry to localize the three proteins that are produced in the three different lobes of the rat prostate. Detecting the presence similarly in distinct sections of the opossum prostate would provide insight into the functional homology of this organ as well as provide evidence that prostate genes are conserved in both species. I found that while the pattern of immunostaining for each protein differed between S1, S2, and S3, the staining was not as localized as the lobes of the rat prostate. This suggests that the way in which the sections of the opossum prostate function differ from the lobes of the rat prostate despite the conservation of genes