Dr. James Manos (MD)
July 24, 2018
Sex, Gender, and Disorders
(the terminology was confusing ever for me, although I am familiar with medical issues)
The XY sex-determination system characterizes humans, most other mammals, some insects such as Drosophila (fruit fly), and some plants such as Ginkgo (such as Ginkgo biloba, a famous memory booster herb). In this system, the sex of an individual is determined by a pair of sex chromosomes, also called gonosomes. A chromosome is a packaged and organized structure containing most of the DNA of a living organism. DNA is the abbreviation of deoxyribonucleic acid; chemically, it is a nucleic acid. DNA is a molecule that carries most of the genetic instructions used in developing, functioning, and reproducing all known living organisms and many viruses. Males have two distinct sex chromosomes (XY) and are of heterogametic sex, while females have two of the same kind of sex chromosomes (XX) and are of homogametic sex.
Colloquially, sex and gender are often used interchangeably! However, these terms are not precisely the same. The distinction between sex and gender differentiates sex from gender Sex refers to the anatomy of a person’s reproductive system and the secondary sexual characteristics. In contrast, gender relates to either social roles based on the sex of the person (gender role) or personal identification of one's own gender based on an internal awareness (gender identity). Gender roles and identity may not coincide with the individual's sex. A case in which a person's assigned sex and gender do not align is a transgender person (mentioned below). Among scientists, the term ‘sex differences,’ as compared to ‘gender differences,’ is typically applied to evolved sexually dimorphic traits.
Genitalia, gonads & gametes
The Latin term ''genitalia,'' also known as ''genitals,'' refers to the externally visible sex organs, known as primary genitalia or external genitalia. In male mammals, these are the penis and the scrotum, while in female mammals, these are the clitoris and the vulva. The hidden, not visible, sex organs are called secondary genitalia or internal genitalia. The most important are the gonads, a pair of sex organs, specifically the testes in male mammals and the ovaries in female mammals. Gonads are the real sex organs, generating reproductive gametes, sperm in males, and ova (eggs) in females, containing inheritable DNA in the XY male sex chromosomes and XX female sex chromosomes. There are some rare genetic exceptions related to sex chromosomes, such as the Turner syndrome in females with XO sex chromosomes and the Klinefelter syndrome in males with XXY sex chromosomes.
Gonads additionally produce most of the primary hormones that affect sexual development and regulate other sexual organs and sexually differentiated behaviors. These sex hormones are androgens, such as testosterone, in males and estrogens (estradiol, estrone, and estriol, with estradiol being the most potent and prevalent) and progesterone in females. A gamete is a cell that fuses with another cell during fertilization (conception) in organisms that sexually reproduce. Everyone produces only one type of gametes in species that produce two morphologically distinct gametes. Therefore, females produce the larger class of gamete called an ovum, known colloquially as an ‘egg,’ while male produces the smaller called sperm.
About secondary sexual characteristics
While humans are born with apparent primary sex characteristics directly concerned with reproduction distinguishing males from females, such as the penis in men and the vagina in women. On the other hand, secondary sexual characteristics appear at puberty, such as pubic hair, breast development in females, and beards in males.
In men, secondary sexual characteristics include pronounced body hair characteristics (body hair, usually coarse; beard; facial hair; chest, axilla, abdominal, pubic area hair); heavier musculature than women; angular features (such as the square jaw, triangular mid-region; something like Sylvester Stallone); narrow hips; muscular pectorals (chest muscles); overall, less fat tissue; deeper voice; larynx (windpipe) enlargement (‘Adam’s apple’); broadening of shoulders and chest (shoulder span is wider than hip span), acne (that, when excessive, needs treatment to prevent scars), higher waist-to-hip ratio, and penis enlargement. I think the last change is the most striking and apparent!
In women, secondary sexual characteristics include less pronounced body hair characteristics (mostly in the pubic region, hair is usually finer); lighter musculature; rounded features (i.e., softer facial features, hourglass mid-region); wider pelvis (for childbearing); more pronounced breasts with more fatty tissue; overall, more fat tissue; and higher-pitched voice.
Gender is the range of characteristics differentiating masculinity from femininity, including biological sex (i.e., the state of being male, female, or intersex), sex-based social structures (including gender roles and other social roles), and gender identity.
The distinction between biological sex & gender as a role
In 1955, the sexologist John Money introduced the terminological distinction between biological sex and gender as a role. Money's meaning of the word ‘gender’ did not become widespread until the 1970s when feminist theory embraced the concept of a distinction between biological sex and the social construct of gender. However, even today, the terms ‘gender’ and ‘sex’ are often used interchangeably.
Gender role
The term 'gender role' was first coined by the sexologist John Money in 1955 during his study of intersex individuals. A gender role is a set of societal norms that determine which type of behavior is considered acceptable, appropriate, or desirable for an individual based on their actual or perceived sex and the personal conception and expectation of femininity and masculinity. The gendered expectations may vary substantially among cultures.
Gender identity
Gender identity is our personal experience and sense of gender, referring to being a man or a woman. Notably, some individuals do not identify themselves with some, most, or all of the aspects of gender that are assigned to their biological sex. In most Western societies, there is a gender binary, meaning a social differentiation related to the ideals of masculinity and femininity in all aspects of sex and gender: biological sex, gender identity, and gender expression.
Some societies have 3rd gender categories that can be used by individuals uncomfortable with their gender associated with their sex. Gender identity is usually formed by age three and is unlikely to change after that milestone. The formation of gender identity usually concludes between the ages of four and six. Gender identity is affected by social factors as well as individual perceptions and preferences.
Consequently, a three-year-old infant can self-identify as a boy or a girl, even without fully understanding the implications of gender completely! Studies suggest that children develop gender identity in three distinct stages: The first stage involves toddlers and preschool children affected by socialized aspects of gender. The second stage, around the ages of 5–7 years, is a consolidation phase in which identity becomes rigid. After this peak of rigidity follows the third stage in which fluidity returns and socially defined gender roles play a less critical role.
Sex assignment
Sex assignment, also known as gender assignment, is the discernment of the sex at the birth of a baby. The act of sex assignment is considered an observation or recognition. In most births, a medical professional (a physician, obstetrician, or pediatrician; a midwife or a nurse), or a relative, inspect the genitalia (genitals) visually when the baby is delivered, determining, without the expectation of ambiguity, the baby's gender: male or female. Sex assignment may also be done before birth with the help of ultrasonography.
In most cases, the gender of rearing of the child matches the assigned gender affecting the future expectation of gender identity. However, in some cases, the assigned sex based on observation may be incorrect, as in the example of transgender or intersex individuals in whom gender identity is not consistent with the assigned sex or sex of rearing! In some cases, termed ''intersex,'' the internal anatomy may not be compatible with the sex assignment based on observation of external anatomy.
Sexual orientation
Sexual orientation is an enduring pattern of romantic or sexual attraction, or a combination of these, to persons of the opposite sex or gender, the same sex or gender, or to both genders and more than one gender (see above for the difference between sex & gender). According to the American Psychological Association, sexual orientation is related to an individual's sense of identity based on romantic or sexual attractions, associated behaviors, and social interaction with others who share those attractions.
These attractions related to sexual identity are generally classified as heterosexuality, homosexuality, bisexuality, and asexuality (= the lack of sexual attraction to others). Additionally, some may label themselves as ''pansexual'' or ''polysexual.''
Sexual preference
The term sexual preference overlaps with sexual orientation and may contain a voluntary choice, although the scientific consensus is that sexual orientation is not a choice. However, sexual preference and sexual orientation are distinguished in psychological research. For instance, an individual who self-identifies as bisexual may sexually prefer one sex over another.
Medical diseases that affect gender identification
Medical diseases that affect gender identification include virilization, intersex or ambiguous genitalia, gynandromorphs, true hermaphroditism and pseudohermaphroditism, and gonadal dysgenesis. They also include medical disorders that involve intersex anatomies, such as inherited (gene-related) conditions and endocrinological diseases that may also be inherited or may be acquired.
It is essential to have in mind that the final body appearance (called phenotype) does not always comply with what is written in the genes and their DNA sequence. Consequently, sometimes there is a discrepancy between genetic (or chromosomal) and phenotypic (or physical appearance) sex. Additional factors may influence sexual differentiation. For instance, the Intersex Society of North America challenges the XY sex-determination system’s assumption that chromosomal sex determines a person's ''original'' biological sex.
Virilization in medicine is the biological development of sex differences, changes that make a male body different from a female. Most of the variations of virilization are produced by hormones called androgens. Virilization occurs in three conditions: prenatal sexual differentiation, the postnatal changes of normal male puberty, and the excessive androgen effects in males or females.
Feminization in medicine is the development of an organism with physical characteristics unique to females and may represent a standard development process contributing to sexual differentiation. In animals and humans, when feminization occurs in a male or at an inappropriate developmental age, it is often because of an acquired endocrinological disorder or a genetic, congenital (inherited) chromosomal disorder. An example of abnormal feminization is gynecomastia (= the inappropriate development of breasts unrelated to fat tissue in obese people called pseudo-gynecomastia) which may result from elevated levels of female hormones such as estrogens. Another cause of feminization is a deficiency or blockage of virilizing hormones (androgens).
''Intersex,'' in humans and other animals, is a variation in sex characteristics, including chromosomes, gonads, or genitals (described above), that does not allow an individual to be distinctly identified as a male or a female. Such variation may involve genital ambiguity and combinations of chromosomal genotype and sexual phenotype other than XY (male) and XX (female). Intersex infants and children, such as those with ambiguous external (outer) genitalia, may be treated surgically and/or hormonally to achieve more socially acceptable sex characteristics (always when the individual feels uncomfortable with this condition). However, there is a controversy regarding this issue and the favorable outcome of the ''correction.''
Research in the late 20th century indicates that diverse intersex bodies are normal, relatively scarce forms of human biology. Intersex people have various gender identities; most identify as male or female, while some may recognize them as neither exclusively male nor solely female. Noteworthy, some intersex individuals may be raised as a male or a female but may identify with another gender later in life!
Ambiguous genitalia (genitals) appear as a large clitoris or small penis. Because there is variation in the development of the sex organs, a child can be born with sexual anatomy typically female or feminine in appearance with a larger-than-average clitoris (called ''clitoral hypertrophy'') or typically male or masculine in appearance with a smaller-than-average penis (called ''micropenis'') that is urinary opening (called ''meatus'') open along the underside (called ''hypospadias''). Specifically, hypospadias refers to a birth defect of the urethra in the male where the urinary opening is not at the usual location on the head of the penis, but, in about 90 percent of cases, the opening (meatus) is on or near the head of the penis (glans), while on the remaining cases, the meatus is near or within the scrotum. Epispadias is another rare birth defect of the penis in which the urethra ends in an opening on the upper aspect (the ''dorsum'') of the penis.
Genitalia may be ambiguous, such as female genitals with a very large clitoris and partially fused labia or male genitals with a very small penis, completely open along the midline (hypospadias; see above), and empty scrotum. Fertility in these cases is variable. According to some scientists, the distinctions "male pseudohermaphrodite," "female pseudohermaphrodite," and especially the term "true hermaphrodite are obsolete and outdated terms of the 19th century, while others believe define the terms "male pseudohermaphrodite," and "female pseudohermaphrodite" the gender in terms of the histology (microscopic appearance) of the gonads (testes (some also call them ''testicles'') or ovaries).
Genitalia may be ambiguous, such as female genitals with a very large clitoris and partially fused labia or male genitals with a very small penis, completely open along the midline (hypospadias; see above), and empty scrotum. Fertility in these cases is variable. According to some scientists, the distinctions "male pseudohermaphrodite," "female pseudohermaphrodite," and especially the term "true hermaphrodite are obsolete and outdated terms of the 19th century, while others believe define the terms "male pseudohermaphrodite," and "female pseudohermaphrodite" the gender in terms of the histology (microscopic appearance) of the gonads (testes (some also call them ''testicles'') or ovaries).
True hermaphroditism is defined as the appearance of both testicular and ovarian tissue. This is not only observed in humans but also in other species. For instance, in 2003, researchers at UCLA University published a study referring to a lateral gynandromorphic Zebra finch (a bird that lives in Australia, Indonesia, and East Timor), which had a testicle on the right and an ovary on the left. Its entire body was split between female and male, with hormones from both gonads running through the blood. This is a very rare example of ''mosaicism'' (= the presence of two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg) or ''chimerism'' (chimera is a single organism composed of genetically distinct cells; this can result in male and female organs, two blood types, or subtle variations in form).
Importantly, there are no documented cases in which both types of gonadal tissue function. Encountered karyotypes (= the number and appearance of chromosomes in the nucleus of a eukaryotic cell, i.e., a cell that contains a nucleus and other organelles enclosed within membranes) include 47XXY, 46XX/46XY, or 46XX/47XXY, and various degrees of mosaicism including an unusual case of an XY predominant (96 percent) mosaic giving birth. Although many, if not most, medical textbooks mention that true hermaphroditism in humans does not exist, in fact, this condition is infrequent, but it does exist. For example, a search in the PubMed medical database reveals some cases, such as the one published on http://www.ncbi.nlm.nih.gov/pubmed/25295140
Pseudohermaphroditism is the condition in which an organism is born with primary sex characteristics of one sex but develops secondary sex characteristics that are different from what would be expected based on the gonadal tissue (ovary or testis). Sometimes, the external sex organs appear intermediate between a typical clitoris and penis. In contrast, in other cases, the external sex organs have an appearance that would be expected to be seen with the "opposite" gonadal tissue. For this reason, pseudohermaphroditism is sometimes not identified until puberty or even until adulthood. The term "male pseudohermaphroditism" is used when a testicle is present, and the term "female pseudohermaphroditism" is used when an ovary is present.
Associated medical conditions in males include 5-alpha-reductase deficiency. An ''ovotestis'' is a gonad (a reproductive gland) with both testicular and ovarian aspects. In humans, ovotestes are an anatomical abnormality associated with ''gonadal dysgenesis.'' There are various forms of ovotestes, such as having two ovotestes or one ovary and one ovotestis, often in the way of streak gonads. The phenotype (= the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment) is not determinable from the ovotestes. In some cases, regarding genital development, the appearance is "fairly typically female," while in others, it is "fairly typically male," or it may be "fairly in-between.
Gonadal dysgenesis is any congenital (= a condition existing at or before birth, regardless of cause) developmental disorder of the reproductive system characterized by a progressive loss of germ cells (= any cell that gives rise to the gametes, i.e., sperm and ovum in humans, of an organism that reproduces sexually) on the developing gonads (reproductive glands) of an embryo (fetus). This loss leads to extremely hypoplastic (underdeveloped) and dysfunctioning gonads, mainly composed of fibrous tissue called ''streak gonads.'' An example of this defection is a form of aplasia (= defective development or congenital absence of an organ or tissue) in which the ovary is replaced by functionless tissue.
The accompanying hormonal failure also prevents the development of secondary sex characteristics (described above) in either sex, resulting in a sexually infantile female appearance and infertility. An example of gonadal dysgenesis is Turner’s syndrome (XO) in females that are typical of short stature and have specific facial and body features (such as a short and webbed neck, low-set ears, low hairline at the back of the neck, short stature, and swollen hands and feet) and are infertile.
According to the ‘Intersex Society of North America,’ examples of medical disorders that sometimes involve intersex anatomy (although these conditions are not always intersex) are the following:
• 5 – alpha-reductase deficiency
• Androgen insensitivity syndrome
• Aphallia (absence of penis)
• Clitoromegaly (clitoris enlargement)
• Congenital adrenal hyperplasia
• Gonadal dysgenesis (partial & complete)
• Hypospadias (described above)
• Klinefelter syndrome (47, XXY)
• Micropenis (small penis < 8 cm)
• Mosaicism (described above) involving sex chromosomes
• Ovotestes (described above)
• Partial androgen insensitivity syndrome
• Progestin-induced virilization
• Swyer syndrome
• Non – Klinefelter XXY
• 17 – beta-hydroxysteroid dehydrogenase deficiency
• Cryptorchidism (the testicle or both testes have not descended to the scrotum but remain in the abdominal area)
For an extended list of the disorders affecting sexual development, you may visit:
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