Descent of mesonephric duct to the final position of the vas deferens in human embryo and fetus

Congenital absence of vas deferens: Anatomical and embryological inputs from a series of autopsies reported in Europe throughout the 18th and 19th century

Congenital absence of the vas deferens (CAVD) is a syndrome with a heterogeneous presentation: bilateral (CBAVD) or unilateral (CUAVD), complete or partial and associated or not with other anomalies of the male urogenital system. A turning point came in 1968 when CBAVD was associated with cystic fibrosis and its CFTR gene mutations. Genetic studies then revealed that a minority of CBAVD but a majority of CUAVD are CFTR-independent. In the literature, reference is classically made to two sources from the 18th and 19th century: Hunter and Reverdin. This scarcity prompted us to look for additional observations of CAVD. By a meticulous bibliographical search, we identified a corpus of 10 European observations (8 CUAVD and 2 CBAVD) some of them richly illustrated. They were collected between 1755 and 1876 throughout adult men autopsies. We also provided their primary and unambiguous sources. Analysis of the reported data revealed some interesting facts: both CBAVD cases were unlikely linked to cystic fibrosis and half of CUAVD cases were associated with an ipsilateral kidney absence, suggesting a CFTR-independent pathophysiology. Moreover, the anatomical details of the anomalies raise interesting embryological questions we have tried to address in the light of current data. This work made it possible to identify new historical sources dealing with male genital tract pathologies. It sheds light on the origins of andrology and opens up interesting prospects for research and education in the field.

Genetics of the congenital absence of the vas deferens

Congenital absence of the vas deferens (CAVD) may have various clinical presentations depending on whether it is bilateral (CBAVD) or unilateral (CUAVD), complete or partial, and associated or not with other abnormalities of the male urogenital tract. CBAVD is usually discovered in adult men either during the systematic assessment of cystic fibrosis or other CFTR-related conditions, or during the exploration of isolated infertility with obstructive azoospermia. The prevalence of CAVDs in men is reported to be approximately 0.1%. However, this figure is probably underestimated, because unilateral forms of CAVD in asymptomatic fertile men are not usually diagnosed. The diagnosis of CAVDs is based on clinical, ultrasound, and sperm examinations. The majority of subjects with CAVD carry at least one cystic fibrosis-causing mutation that warrants CFTR testing and in case of a positive result, genetic counseling prior to conception. Approximately 2% of the cases of CAVD are hemizygous for a loss-of-function mutation in the ADGRG2 gene that may cause a familial form of X-linked infertility. However, despite this recent finding, 10–20% of CBAVDs and 60–70% of CUAVDs remain without a genetic diagnosis. An important proportion of these unexplained CAVDs coexist with a solitary kidney suggesting an early organogenesis disorder (Wolffian duct), unlike CAVDs related to CFTR or ADGRG2 mutations, which might be the result of progressive degeneration that begins later in fetal life and probably continues after birth. How the dysfunction of CFTR, ADGRG2, or other genes such as SLC29A3 leads to this involution is the subject of various pathophysiological hypotheses that are discussed in this review.

Sex differences in lower urinary tract biology and physiology

Females and males differ significantly in gross anatomy and physiology of the lower urinary tract, and these differences are commonly discussed in the medical and scientific literature. However, less attention is dedicated to investigating the varied development, function, and biology between females and males on a cellular level. Recognizing that cell biology is not uniform, especially in the lower urinary tract of females and males, is crucial for providing context and relevance for diverse fields of biomedical investigation. This review serves to characterize the current understanding of biological sex differences between female and male lower urinary tracts, while identifying areas for future research. First, the differences in overall cell populations are discussed in the detrusor smooth muscle, urothelium, and trigone. Second, the urethra is discussed, including anatomic discussions of the female and male urethra followed by discussions of cellular differences in the urothelial and muscular layers. The pelvic floor is then reviewed, followed by an examination of the sex differences in hormonal regulation, the urinary tract microbiome, and the reticuloendothelial system. Understanding the complex and dynamic development, anatomy, and physiology of the lower urinary tract should be contextualized by the sex differences described in this review.