Background: First described by Carl Toldt in the late 19th century, the mesorectum has since been a topic of anatomical and surgical debate. Its clinical importance was redefined by Heald’s introduction of Total Mesorectal Excision (TME), nowadays the golden standard in oncologic rectal surgery. This study aims to elucidate the embryological development and adult anatomy of the mesorectum and the mesorectal fascia, with a focus on clinically significant relations, particularly the peritoneum, and components of the hypogastric plexuses. Methods: We performed anatomical dissections on four 12–15-week-old human fetuses and eight formalin-fixed adult cadavers. In addition, a transverse pelvic section was examined to assess the spatial organization of mesorectal and fascial structures. Results: Our findings confirm the presence of a dorsal mesentery at the rectal level during fetal development, illustrating its transformation into the adult mesorectum. We identified the mesorectal contents in the fetus and examined the course and relations of the superior rectal vessels, hypogastric nerves, and pelvic splanchnic nerves, in both fetal and adult specimens. Conclusions: The observed fetal and adult configurations provide a continuous morphological description of the mesorectum and its compartmental organization within the pelvis. This study enhances the understanding of the mesorectum’s embryology, structure, and vital surgical landmarks. By delineating the so-called ‘Holy plane’ of Heald (the natural avascular plane between the mesorectal and presacral fasciae used during total mesorectal excision) and the delicate connective fibers known surgically as ‘angel’s hair’, which become visible when this plane is correctly entered, rectal and presacral fasciae, and neurovascular elements, provides a comprehensive anatomical framework that may inform surgical plane identification and support future clinical investigations into nerve-sparing rectal surgery.

Background: The concept of mesopancreas is frequently discussed in the surgical literature as the neural pathway for metastatic spread in pancreatic head cancer. It generally refers to a retro-pancreatic plane that should be resected to reduce the incidence of regional metastases. However, this concept remains poorly defined, both embryologically and anatomically. Our objective was to establish a clear embryological and anatomical definition of the mesopancreas, making anatomical data more applicable in surgical practice. Methods: We examined seven cadavers (5 males, 2 females, aged 62–71) with no medical or surgical history, preserved in 9% formalin at Carol Davila University’s Anatomy Department. Regional dissections were performed in successive planes, highlighting the celiac ganglia and the associated network of neural connections that comprise the mesopancreas. Results: Our study defines the “mesopancreas” as remnants of primordial mesenteries that coalesced into the Treitz fascia. We identified its functional components as nerve fibers linking the celiac ganglia and superior mesenteric plexus to the pancreas, along with vascular structures, lymphatics, and connective and adipose tissue. These components likely contribute to regional metastasis in pancreatic head cancer. While resection of the mesopancreas could help prevent metastasis, its complex anatomy and proximity to major vessels pose significant surgical challenges. Conclusions: Based on our findings, we propose a plausible definition for the term “mesopancreas”. It encompasses the structures that originated as part of the primordial mesenteries, which subsequently coalesced, resulting in the formation of the Treitz fascia. In essence, the mesopancreas is the functional content of a former mesentery.

Background/Objectives: The genital tubercle develops in the fourth week from mesenchymal cells in the lateral edges of the embryo. In females the genital tubercle develops into the clitoris while in males it participates in forming the penis. The aim of this study was to perform a macroscopic as well as an ultrasonographic assessment of the genital tubercle and its gender-dependent derivates, presenting a parallel comparative evaluation between the two. Methods: We performed a morphological assessment of the genital tubercle through micro-dissection of 141 embryos and fetuses with gestational ages between 5 and 14 weeks, in the Department of Anatomy of “Carol Davila” University of Medicine and Pharmacy. An ultrasound imaging study of the genital tubercle using 3-dimensional ultrasonography (3DUS) was also performed in the Department of Obstetrics and Gynecology of University Emergency Hospital of Bucharest. The morphology of the genital tubercle was analyzed by ultrasound scanning of 119 embryos and fetuses with gestational ages between 5 and 14 weeks. The age of all the embryos was determined by measuring the crown–rump length. Results: The dimensions and especially the direction of the genital tubercle were evaluated and compared in order to establish whether sex determination is possible as early as 7–8 weeks of gestation. The genital tubercle orientates cranially in males and caudally in females as early as 6 weeks of gestation, during the bi-potential phase. Conclusions: The orientation of the genital tubercle plays an essential role in establishing the sex of the fetus, regardless of its size.