The structure in the male body that corresponds to the uterus in the female body is understood through comparative anatomy and embryological development. Every major reproductive structure in the adult male and female can be traced back to a common, undifferentiated structure in the early embryo. This concept, known as homology, means that organs like the uterus and its male counterpart share a single developmental origin despite their different functions and appearances. This shared biological blueprint explains how all sex organs differentiate into their respective forms.
The Shared Blueprint of Reproductive Development
Early in development, the human embryo possesses two sets of internal reproductive ducts: the paramesonephric (Müllerian) ducts and the mesonephric (Wolffian) ducts. The Müllerian ducts contain the instructions to form the female internal reproductive tract, while the Wolffian ducts hold the instructions for the male tract.
The ultimate path of these ducts is determined by genetic signals and hormones produced by the developing gonads, which are initially bipotential. In individuals with an XY chromosome pair, the presence of the SRY gene on the Y chromosome triggers the bipotential gonads to develop into testes. These developing testes then begin to secrete two substances that determine the fate of the two duct systems.
One substance is Anti-Müllerian Hormone (AMH), secreted by the Sertoli cells within the testes. AMH actively suppresses and causes the regression of the Müllerian ducts, preventing the formation of female internal structures. Concurrently, the fetal Leydig cells produce testosterone, which stabilizes and promotes the differentiation of the Wolffian ducts into the epididymis, vas deferens, and seminal vesicles.
In the absence of the SRY gene and the hormones it triggers, the Müllerian ducts proceed to develop into the fallopian tubes, uterus, cervix, and the upper portion of the vagina. Without the stabilizing effect of testosterone, the Wolffian ducts naturally degenerate. Therefore, in a male embryo, the entire Müllerian duct system is meant to regress, leaving only a small, vestigial remnant.
The Direct Homologue: What Replaces the Uterus
The female uterus, along with the fallopian tubes, cervix, and upper vagina, forms from the fused lower portions of the Müllerian ducts. In the male, the action of Anti-Müllerian Hormone causes almost all of this duct system to disappear. However, the very caudal end of the Müllerian ducts does not completely vanish and persists as a small, non-functional structure.
This remnant is called the prostatic utricle, which is the direct anatomical homologue of the uterus and upper vagina. The prostatic utricle is a tiny, blind-ending pouch located in the posterior wall of the prostatic urethra. It opens via a small slit-like orifice situated on a bump known as the seminal colliculus.
Typically measuring only about one centimeter in length, the prostatic utricle projects upward and backward into the substance of the prostate gland. Its structure is considered vestigial, meaning it has lost its original function through evolution. The prostatic utricle serves no known reproductive purpose in the adult male.
Its presence is a clear physical marker of the shared developmental pathway between the sexes. Though it usually remains small and asymptomatic, a significantly enlarged prostatic utricle is sometimes noted in association with other congenital conditions, such as hypospadias.
Comparing Other Key Reproductive Organs
The concept of homologous structures extends beyond the uterus and its remnant to nearly all other reproductive organs, both internal and external. The ovaries in females and the testes in males are homologous, as both develop from the same bipotential primitive gonads. Both organs share the primary function of producing sex hormones and gametes—eggs and sperm, respectively.
Similarly, the external genitalia develop from common embryonic tissue known as the genital tubercle and labioscrotal folds. The genital tubercle differentiates into the clitoris in females and the penis in males. The tissue that forms the labia majora in females is homologous to the scrotum in males.
Furthermore, the labia minora in females are considered homologous to the ventral penile skin and the penile raphe, which is the seam-like ridge running along the underside of the penis. Glandular structures also have counterparts. The bulbourethral glands in the male are homologous to the greater vestibular glands (Bartholin’s glands) in the female, with both secreting lubricating fluid. These comparisons illustrate that sexual differences stem from how a single, shared blueprint develops in one of two distinct ways.