Sexual differentiation: male or female?

January 13th, 2018

-What happens in the embryo:

The sexual differentiation in the human embryo, is in itself the differentiation in the masculine sense, since the sex by default is the feminine; this means that in order for the masculine embryo to develop, it must deviate from that natural path that would lead the embryo to differentiate in the feminine sense.
This is achieved from the product of a gene, the SRY gene, which is found on the Y chromosome, of males.
Among its most important actions, stimulates the persistence of the primary sexual cords, which is synonymous with the transformation of the undifferentiated gonad into the testicle, since if these were to atrophy, they would be replaced by the secondary sexual cords, characteristic of the ovary.
Once the gonad of the embryo has differentiated into a testicle, we can find in it the cells of Sértoli and those of Leydig, each one with important functions in this mechanism of differentiation in the masculine sense:
The Sértoli cells produce anti-Müllerian hormone (AMH) which induces the involution of the Müllerian duct (Muller 1832). Leydig cells synthesize androgens (testosterone) which have a double function in this mechanism:
on the one hand they stimulate the persistence and development of the Wolff ducts (Caspar Wolff, 1820) and on the other hand they masculinize the external genitalia.
In the female embryo, in the ovary, we do not find either of these two cell types, therefore there will be not antimüllerian hormone, therefore the Müller duct does not atrophy and in the absence of androgens, the Wolff duct disappears (due to lack of testosterone).
In this way, the external genitalia will evolve in the female sense.
It is surprising how many disorders and pathologies there are, because of these complex cascades that exist for the generation of hormones, such as Morris syndrome or male pseudohermaphroditism.
Since it is a disease where the affected individual has a genotype and phenotype (inherited characteristics and external appearance) of different sexes, it would be like the case of a congenital transgender, in the figurative sense, by natural causes, without any external agent intervening.

-Morris syndrome:

This syndrome is defined as a physical abnormality, in which a person has the genetics of one sex (male) and the genitals of another (female). This is also known as (SIA): syndrome of insensitivity to androgens (testosterone), by absence of receptors.
The abnormality is due to the fact that men are resistant to male hormones, that is, androgens (testosterone among them).
This causes the development not only of the genital organs of the other sex, but also the aspect will be that of a woman and not realize anyone, that there is a pathology, until adolescence, in which menstruation will not appear. Therefore the sexual assignment, will be of woman, from birth.
They will present female features, female sexual organs or similar, testosterone with levels similar to those of men, but due to the pathology androgens can not act normally.
Morris syndrome (described in 1953) is a rare disease (described as testicular feminization syndrome), affecting only 1 in 40,000 babies born.
However, because only a few cases are known, it is possible that the prevalence is even higher and it is considered to be the third cause of amenorrhea in puberty.
In the severe form, the genitals are female but can sometimes present problems such as a smaller size of the vagina, and no connection to another organ, with hypoplasia of the lips.
Most have testicles, but these did not descend and remain in the abdomen.These are usually removed when the diagnosis is made to avoid the development of cancer in the future.
Affected people have no (or very little) underarm or pubic hair. At puberty, there is no menstruation, since they are genetically male. Affected individuals are infertile, since neither the ovaries nor the uterus have developed.
Causes of Morris syndrome:
The disease is inherited, where there is a mutation in a gene, called AR, which is on the X chromosome, as men have only one X chromosome, it is easier to develop the disease, while women can carry the gene mutation, and transmit it to a child.
What causes the problem is the absence of receptors, which are the AR proteins (androgen receptors), which does not allow them to act in conjunction with testosterone for the formation or development of men; which means that the person is resistant to testosterone.
To explain the process in a much simpler way, it should be taken into account that women have the XX chromosomes, while men have the XY.
Its main difference is that men produce testosterone and this hormone is in charge of the development of the male individual.
When the body has an absence of it, (in this case there is one, generated by the embryo itself but it is as if there were none, since in the absence of receptors, it is transformed into estrogen), then the individual develops as a woman externally although inside he continues to be a man, in his genes.
Diagnosis of Morris syndrome:
The diagnosis is not usually made in the individual’s childhood stage, since at that time there are still no symptoms that indicate that the individual suffers from this disease.
It is in the stage of the puberty when the problem is evident, where the doctors will be able to make different tests to diagnose the person:
A chromosomal study can confirm the existence of the 46 XY karyotype, characteristic of people who have the syndrome.
Since the vagina is usually blind and smaller, with the help of a gynecological ultrasound scan the absence of a uterus and ovaries could be observed.
People affected with the syndrome receive three treatments: dilation therapy, gonadectomy and psychological therapy that will help the patient feel comfortable with his body, as it should be and avoid absurd complexes.
In the puberty, the feminine sexual characters are developed, reaching a total appearance of woman, by the action of the estradiol, that is generated from the testosterone, that is transformed by the action of an enzyme called aromatasa.

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