SUMMARY :
Human cloacal division is not yet well understood by most of the embryologists. It is a very important step of the embryological caudal pole differentiation which is composed of successive events with morphological profit and loss.
This sequential development depends on a genetic code which will be kept inside the "unconscious" mind of the embryo, the f¦tus then the newborn.
If a defective link of this sequential chain happens, malformation will appear. Cloacal division creates the bladder with urethra, the anal canal, and genital apparatus.
The mesenchymal tissue which surrounds each structure, condense, and differentiate to elaborate sphincteric structures composed of striated and smooth muscular cells.
This is the starting point of the development of the deep and superficial pelvic floor.
Differentiation of the embryological cephalic pole happens at the same time. At the beginning of the first month of gestation, mouth opens before anus and urethra.
This precise point of organogenesis could explain some urinary, sexual and rectal troubles developed in adult probably connected with a problem of identity during childhood.
Devroede referred an observation of a 35 year old woman who suffered from urinary troubles (repeated urinary retention) with constipation in relation with anismus and dyspareunia related to sexual abuse in childhood (1,2). According to her declaration the process later became to be asymptotic. Her father ordered her to shut up and then he violates her by perineal way.
The author refers a similar observation: a 35 year old woman, without special history, consulted for an urinary incontinence appeared after the delivery of two big children of 5 and 4 kg. She suffered from constipation and vaginismus. Vaginal lips remain closed and vaginal cavity dry, and the urethra and urinary bladder at the contrary. An interview uncovered that she has conflicts with her father since the age of three years. He grabbed a puppet from her arms, she fought against him and finally closed into herself. This comportment persisted until her teens. Later she refrained to fulfil her father¹s dream to become to be a nurse and when she chose a man who did not suit the family, he humiliated her. After talking, she realizes her own history, her own obedience; she somatized when her father had tell her to shut up.
She cried a lot and later, after a joke, she coughed, and the author asked her at this moment: do you still "cry" in your knickers? she answered no. She was dry.
Both those observations show the fact that it is necessary to consider the perineum as an unit and not to divide it into three anatomical different parts: urinary, anorectal and gynaecological. The pediatric surgeon has an advantage to preserve this entity.
The perineum is a functional unity. The dependability of the human body is bigger than the speech. The body functions itself before a speaking. The body language is the most archaic of all human expressions (1,2).
Regarding on embryology, in other words, at the very beginning of all things, it is impossible to find an explanation if there is not any cloacal thinking.
The embryology is a field often forgotten by the majority of physicians. Tought very soon during medical studies, its utility is later well reduced. However, a better approach in its teaching should make it for students more attractive, because it gives explanation of the origin of a malformation, but only under the condition of a well understanding of the normal development.
Based on more than 15 years long personal experiences upon human embryos and fetuses, the author can understand the differentiation of the caudal pole of the embryo, which assumes the development of the urinary bladder, urethra, rectum, and anal canal, as well as the perineum (3,4,5).
The cloacal division remains the most important period of the development of the embryo¹s caudal pole. Yet poorly understood, it originates succession of morphologic, well précised changes which result in the division of close one cavity into two ones. Share anterior the urogenital sinus which gives origin to the urinary bladder and posterior portion which develops into rectum and anal canal. The mechanism of this division remains discussed, however it is sure that the mesoblast partially participates upon it. In fact, a very important caudal mesenchymal condensation behind the terminal portion of the digestive tube supports the development of the caudal component of the human embryo, the tail of the embryo. This growth assumes not only medulla tract but also vertebral, vascular (median sacral artery) and digestive tissue. The cloaca develops a cranial appendix, well illustrated on modelling embryological reconstructions at the end of the first month (Figure 1).
A first energetic movement does exist, visible also on pig and rat¹s embryos which looks like a posterior flow moving from up to down.
In some species (amphibian, urodeles, birds), the cloaca persists; urine and stools mixed together into the same reservoir, which uses also for reproduction.
Human embryo has at the end of the first month, a similar tail as an animal, but progressively and quickly, this tail disappears. This is the caudal regression. After this period of construction, a period of destruction takes place, with the amputation of what had been formed, artery (median sacral artery), mesoblastic tissue, spinal cord, coccygeal and sacral vertebras, and cranial cloacal appendix. There is an ascending movement from down to up which does not exist in animal. The caudal regression allows the cloacal division and the development of the perineum (Figure 2).
A second evolution occurs, observed also in animal, concomitant with this caudal amputation. It is the development of the anterior genital tubercle which gives origin to the penis in males, clitoris in females, anterior horizontal urethra; at the contrary, posterior vertical urethra depending on urogenital sinus exists in both sexes (Figure 3).
The movement performed first from the anterior growth from down to up, and then by the amputation of embryological caudal part occurred a phenomenon of sharing, which participates of the cloacal division (6).
If caudal regression is too important or too fast, an amputation of the sacrum and a recto-urinary fistula is resulting. The importance of this anorectal malformation depends on the intensity of this movement. If caudal regression is incomplete or insufficient, the tail persists, and it is called the sirenomelia (the mermaid syndrome).
Two remaining cavities open outside. The anal membrane opens passively by cellular destruction of its components, a passive and non-explosive mechanism, which later allows the meconium flow. Levels of the digestive enzymes in amniotic liquid prove this opening between the 2nd and 3rd months.
The urethral membrane opens about this stage, allowing the passage of the very first fetal urine, which can be analyzed by amniocentesis.
The par-mesonephotic ducts come together to create vagina, which opens into urogenital sinus. The mesonephrotic ducts in male give origin to the deferent canal while the par-mesonephotic disappears. It exists an anatomical lost as well as conservation of the other area: growth evolution from up to down (Figure 4).
The mesoblastic tissue condenses around the anal canal and the urethra to give the sphincter apparatus which is present since the end of the second month of pregnancy; striated muscle cells differentiate during the fetal period, smooth muscle cells differentiate later after birth, before two years. The deep perineum takes place at the end of the second month of gestation.
Studying evolution during cloacal division, three energetic evolutions are noticed. First, from up to down at the beginning of the development and later two others ascending (caudal amputation) and descending anterior prolifer a whose fulfil the division. This mechanism can be compared with the pendulum.
This morphological transformation corresponds with opening of the pharyngeal membrane, opening of the mouth, which precedes opening of the anal membrane. In fact, the mouth opens before the anus and the urethra. Only after opening of those orifices into amniotic cavity the sphincter apparatus develops.
The length of the fetal vagina is important, and the anatomical relations with urethra are very narrow (7).
The muscles around the vulva are elaborated since the third trimester of pregnancy. It is a descending evolution, which follows the development of the urethra. It is possible that the embryo keeps in mind this transformation which leads to the existence of the human being with its identity.
The downhill evolutions assume the formation of the urethra and later miction, creation of the anal canal and defecation which does not exist during the pregnancy, and consequently genital functions with the menstruation after puberty and finally pregnancy with delivery. Those three evolutions are fundamental and quasi physiologic. After cloacal division becomes the elimination of urine, stools. The uphill movement observed during caudal regression is reflected in coitus, as well in the man as in the animal. An animal makes it for reproduction, man with the same goal but also for his own pleasure, under the condition that both partners agree with the act. It is a common pleasure, acceptation, and a realized desire.
If desire is different, not shared, there is affection; the representation of the perineum is affected. The perineum will be attacked, not willingly; in this case, it is the perineum of the sexual abuse with perineal affectation.
In this evolution named "the caudal regression", there is an idea of reproduction, but above all of pleasure, identity, identification to somebody else by act and speech in the communion of the body with soul. It is verbal acceptation with body expression.
In the case of sexual assault or incest, there is aggression. Penetrating person acts as an animal, looking only for first function of the reproduction that can be realized immediately even against verbal refuse. Even after submission or false acceptation, abused person loses some portion of himself, part of his/her body passes away, and closes. It is worse than during violation; there is almost always verbal injunction, threats or announced ill treatment. "If you open your mouth, I shall close it".
The cloacal thinking is an unconscious protecting action, human in the most intimate part of a body. In fact it is a return from childhood or adultery to an embryological origins.
Thanks to the speech, the child learns to be proper, will understand his physiology. However, the speech can also perturb. He will always remember this stage of cloacal division, when embryo mouth opens. He will conserve in his own mind his own fetal miction and stools evacuation. Enuresis with encopresia could be a prolongation of the fetal period (8).
Human being never forgets this stage and remembers all modifications which are genetically programmed, but as well as it will discover the speech control, which provides the control of his sphincters. It is the existential stage, the stopover point of the differentiation; it is the reciprocal apprenticeship, to give for receiving. It is the apprenticeship of the life.