FEATURES OF PRENATAL MORPHOGENESIS AND PECULARITIES OF THE UTRICULUS PROSTATICUS FETAL ANATOMY
Authors: Khmara Tatiana V. , Vlasova Olena V. , Bilyk Yaroslav O. , Kryvchanska Mariana I. , Vlasova Kateryna V. , Stravskyy Yaroslav S. , Fedoniuk Larysa Ya. 
Published: May 2023

Aim: To determine the peculiarities of the structural organization of the utriculus prostaticus (UP) in pre-fetuses and fetuses.
Materials and methods: The study of macroscopic features and microscopic peculiarities of the prostate gland and the prostatic part of the urethra was carried out on 46 sections of human pre-fetuses and fetuses aged from 9 weeks to birth (31,0-375,0 mm PCL). The work uses the method of microscopic study of serial histological and topographic-anatomical specimens of the prostate gland, as well as the method of the thin preparation of the prostate part of the urethra in fetuses of different ages and morphometry.
Results: In 58,0-66,0 mm PCL fetuses the paramesonephric ducts are reduced, except of their connected caudal part, which is a morphological substrate for the development of the UP. At 72,0-79,0 mm PCL fetuses, cavity is replaced by cellular mass. At the 85,0-120,0 mm PCL fetuses, the UP connects with the lumen of the urethra. The cavity of the UP intensivelly proliferates with cells. In fetuses of 125,0-135,0 mm PCL is presente dense arrangement of glandular elements, which are surrounded by fibrous-muscular membrane. In fetuses of 150,0-160,0 mm PCL, in the caudal direction, the cavity of the UP gradually narrows, it forms invaginations, especially in the middle and lower parts, or is divided into separate, interconnected chambers. In fetuses of 170,0-185,0 mm PCL, UP has elongated-oval or rounded-oval shape. In the caudal direction, the UP is directed ventral to the colliculus seminalis and is located slightly anterior and superior to the ejaculatory ducts. In 8-month-old fetuses, the lumen of the UP is lined with a pseudostratified cubical epithelium, outside of which there is a tunica muscularis. Ejaculatory ducts lined with a two-layer cuboidal epithelium are placed on both sides of the UP. A 270,0 mm PCL fetus has no UP at the apex of the colliculus seminalis. In fetuses 315,0-335,0 mm PCL, the process of cavity formation spreads to new areas of glandular formations of the prostate gland and their final branches. Most of the glandular formations open into the prostatic part of the urethra directly below the UP and the distal parts of the ejaculatory ducts. Microscopic examination of frontal sections of the prostate gland of a fetus with a 360,0 mm PCL revealed a septum in the UP which divides the cavity of the UP into the right and left halves of a round-oval shape.
Conclusions: The formation of utriculus prostaticus occurs from the paramesonephric ducts in the 11th week of fetal development. At the beginning of the 4th month of intrauterine development, it gradually decreases in size. From the middle of the 5th month of prenatal development, the utriculus prostaticus lengthens, and starting from the fetus of 7 months, both its length and width increase. At the end of the fetal period, the utriculus prostaticus acquires a round-oval shape, its length increases from 0,5 to 4,3 mm during prenatal ontogeny.