RESEARCH ARTICLE Morphology and topography of internal reproductive organs in the female cat during prenatal and postnatal development: Scanning electron microscope and three-dimensional reconstruction study Ewelina Prozorowska | Hanna Jackowiak | Kinga Skieresz-Szewczyk Department of Histology and Embryology, Pozna n University of Life Sciences, Pozna n, Poland Correspondence Ewelina Prozorowska, Department of Histology and Embryology, Pozna n University of Life Sciences, Wojska Polskiego 71C, PL 60-625 Pozna n, Poland. Email: eprozor@up.poznan.pl Funding information Grand of the Young Researcher Program of the Faculty of Veterinary Medicine and Animal Science Poznan University of Life Sciences, Grant/Award Number: 507.511.18; Polish Ministry of Science and Higher Education, Grant/Award Number: 507.511.18 Abstract The study describes the morphology and topography of internal reproductive organs in the domestic cat from the early prenatal period to maturity, using macroscopic and scanning electron microscope (SEM) observations with three-dimensional (3D) reconstructions. Fifty- seven female cat fetuses aged between the 27th and 63rd day postconception (p.c.), two newborn cats, three juveniles (3-month-old) cats, and three mature (12-month-old) cats were used in the study. The age of fetuses was determined on the basis of the growth curve for the domestic cat. The rudiments of cat ovaries develop on the ventral surface of the mesonephroi and within 30 days p.c. move to the sides of the abdominal cavity, which is similar to the position of the ovaries in the adult cat. The mesonephroi regress at about the 50th day p.c., when the residual mesonephric ducts are still found in the lower part of the body of the uterus. The paramesonephric ducts develop on the lateral surface of the mesonephroi and by the 45th day p.c., differentiate into the uterine tubes and the uterus. The arrangement of the paramesonephric ducts in the abdominal cavity changes from the U- to the V-shaped system. The final topography of the uterine tubes is established between the 54th and 60th day p.c., as the uterine tubes become convoluted. Before the 54th day p.c., the uterine horns undergo rapid elongation and convolution, forming the W- shaped system. By the third month of postnatal life, the uterine horns become straight, as in the adult cat. KEYWORDS ovary, paramesonephric ducts, prenatal development, uterine tube, uterus 1 | INTRODUCTION Development of the female internal reproductive organs is a complex and multistage process starting with the formation of an undifferen- tiated mesodermal anlage in the embryonic period and ending with the development of fully functional organs in the postnatal period. The gonadal ridges, as rudiments of the ovaries, develop on the ven- tromedial surface of the mesonephroi and protrude to the abdominal cavity. During the prenatal development, the ovaries descent and take the species-specific position in the pelvic cavity (human) or in the abdominal cavity (carnivores, rodents, ruminants, the horse, and the pig; Clement, 1987; Dyce, Sack, & Wensing, 2010; Hyttel, Sinowatz, & Vejlsted, 2010; König & Liebich, 2006; McGeady, Quinn, FitzPatrick, & Ryan, 2006; Rüsse & Sinowatz, 1991). During the early embryogenesis of the urogenital system of verte- brates, two pairs of ducts develop: the mesonephric ducts (Wolffian ducts) and the paramesonephric ducts (Müllerian ducts; Hyttel et al., 2010; Sajjad, 2010). The development of the female-specific parame- sonephric ducts described, among others, in mice, ewe, cattle, swine, cat, mare, and human (Hashimoto, 2003; Hyttel et al., 2010; Inomata et al., 2009; Inomata, Eguchi, & Nakamura, 1989; Patten, 1948; Rob- boy, Kurita, Baskin, & Cunha, 2017; Sajjad, 2010; Spencer, Dunlap, & Received: 6 April 2018 Revised: 17 August 2018 Accepted: 25 August 2018 DOI: 10.1002/jmor.20895 1764 © 2018 Wiley Periodicals, Inc. wileyonlinelibrary.com/journal/jmor Journal of Morphology. 2018;279:1764–1775.