For all women, breasts are a very important and very visible aspect of their "womanhood". It is also probably fair to say that the female breast is regarded by men and women as a key aspect of feminine beauty - both in our modern society and historically.
The development of breasts gives the male-to-female transsexual woman a tremendous confidence boost, and powerfully identifies her as a female to others. It is also impossible to ignore that the fact that breasts are immensely strong sexual symbols, and secondary sexual organs whose presence can be enjoyed by both the owner and their partner. Unlike a vagina, breasts can be easily and acceptably be publicly displayed in either part (cleavage) or full (e.g. topless sun bathing), or prominently implied underneath a skimpy top. Bra's and [usually] breast forms/padding are essential early purchases for every transsexual woman.
While ultimately many transsexual women will have breast implants, the first step is always female hormone treatment, using oestrogen and anti-androgens to enable the growth of breasts to their maximum natural size - although this is somewhat less than that of close female relatives. Breast growth can often be enhanced by use of appropriate progesterone, causing a more natural breast shape to form with lactating and ducting tissue as well as the fatty tissue laid down by oestrogen treatment. If the woman starts treatment already past puberty, the resulting breast development can range from respectable to very disappointing - although even in the latter case it should be noted that modern bra's, "push-ups" and breast enhancers can still do wonders appearance wise. But the final breast development may still be regarded as unsatisfactory, particularly in older patients, in which case implants may be desired.
Above, the male breast, and below the female breast
Breast Development in the Genetic Woman
At birth the rudiments of the functional mammary gland are in place for both boys and girls: the nipple and areola are formed along with a rudimentary system of mammary ducts extending into a small fat pad on the chest wall. The mammary gland remains a rudimentary system of small ducts until puberty when in a genetic woman the advent of oestrogen secretion by the ovaries brings about the first stage of the four stages of mammary development: mammogenesis. Only the breasts of child bearing women go through the next two stages - lactogenesis and lactation. Finally, the breasts of all post-menopausal women go through involution, although hormone replacement therapy can affect this.
Mammogenesis commences at puberty with the onset of oestrogen secretion by the ovaries, usually between the ages of 10 and 12 in a genetic girl. Oestrogen (often spelt 'Estrogen' in American English) stimulates breast growth by acting causing enlargement of the mammary fat pad, one of the most oestrogen-sensitive tissues in the human body, as well as lengthening and branching of the mammary ducts. The development occurs according to well-defined milestones called Tanner stages:
The levels of oestrogen required to cause breast development are surprisingly low - until stage IV, the growth of the breast in a girl takes place with oestrogen levels similar to an adult male. That is why about 40% of male children also initiate "Tanner I" type mammary development during their puberty due to the tendency of their testis to secrete significant quantities of oestrogens in early phases of its development. However, as testosterone secretion increases the breast development ceases and very few boys reach the Tanner II stage.
It takes approximately two to three years for a girl to achieve the majority of her breast growth. Stage V is aligned with the onset of the menstrual cycle - which results in the production of progesterone for the first time. The presence of progesterone stimulates the partial development of mammary alveoli, so that by the age of 20 the mammary gland in the woman who has not been pregnant consists of a fat pad through which pass 10 to 15 long branching ducts, terminating in grape-like bunches of mammary alveoli. In the absence of pregnancy the gland maintains this structure until menopause. It's worth noting that these ducts are very small and contribute little to breast size.
In Europe and the USA more than half of adult genetic women are a B to C bra cup, and relatively few (<25%) women are naturally a D cup or greater. But the figures vary widely from study to study, e.g. Triumph's European Bra Size Survey from 2007 famously found that 57% of UK women were D cup or more - a highly improbable finding which was widely reported in the UK media.
Mammogenesis is completed during pregnancy, with the gland becoming able to secrete milk sometime after mid-pregnancy. Pregnancy is often considered to be the period of most extensive mammary growth. Indeed extensive lobular and alveolar development occurs only during pregnancy. During pregnancy, it is not unusual for a woman's breast size to temporarily increase by a full cup size.
Lactogenesis (referred to as the time when the milk "comes in") starts about 40 hours after birth of a baby and is largely complete within five days. When nursing ceased the breast undergoes partial involution, losing most of its milk producing cells and structures. Many women have slightly smaller breasts after pregnancy and nursing because they have less fatty tissue and once the breast is no longer swollen with milk it can sag in an unsightly manner.
Innovolution completes after menopause, when many women move to a smaller bra size.
Development in the Transsexual Woman
Although often only partially developed, the breast structure of a transsexual "XY" woman is basically the same as a genetically "XX" woman after the first phase of mammogenesis, indeed transsexuals with well-developed breasts are quite able to nurse given the right stimuli.
It's important to note that all the common information and rules about the female breast (including the need for regular breast self-examination and mammogram's) apply just as much to transsexual women taking oestrogen as they do to genetic women.
Externally, breast growth and development is medically defined by "Tanner's Five Stages":
After female hormones are commenced the breast slowly evolves and gradually increases in size, often with periods of growth and periods of apparent standstill. In the initial phase of hormone therapy subareolar nodules - which can be painful - are common. Both oestrogen and progesterone should be taken, it's thought that oestrogen stimulates cell mitosis and growth of the ductal system, while growth, development and differentiation of the glandular tissue (called lobules or alveoli) seems to be dependent on progesterone, and breast fat accretion seems to require both.
It's perhaps worth emphasising here that the results of female hormone treatment eventually become obvious to everyone, whether called breasts or "man boobs". Indeed breast growth is often a severe embarrassment for the pre-transition woman on hormones - ranging from in bed with a partner, running, or a visit to the beach.
Taking hormones hoping to somehow become a closet page 3 girl - but without any one at work or even the wife noticing - is simply not realistic. Breast growth is irreversible without reduction surgery, stop taking the hormones and the breast growth that has been stimulated will still be around ten years later, it does not melt away.
Assuming that hormones is the right route, patience is essential, it will take at least two years to achieve full growth and some imperceptible changes will continue for the rest of your life - as trying on a very old bra will reveal.
Dissatisfied girls rushing to seek breast implants after one year may then experience complications and misshaped breasts when another spurt of breast tissue growth sets in - as is quite common after SRS or an orchiectomy. It should also be expected that the breasts will grow unevenly, e.g. the right may become much fuller that the left. In the long-term the differences will mostly even out, but even in mature genetic women there is often a quite visible difference in size and shape between the left and right breasts when a study is made of them.
All transsexual women like to 'round up' the breast development they achieve from hormones, and other more uncertain methods.
The final amount of breast development obtained by a transsexual woman on hormone treatment is undoubtedly very variable and depends on a numbers of factors.
One thing no MTF can do anything about is the fact that their body has since the foetus stage been exposed to larger amounts of testosterone hormones than a girl. The cumulative effect on the body is very significant - the most obvious early differentiation is a penis rather than a vagina, but there does seem to be a significant impact on potential breast growth as well. Women suffering from AIS (i.e. genetically XY male, but unaffected by androgens) tend to be at least as as "well endowed" bust wise as their female relatives, so a constant of drizzle of testosterone from the womb onwards seems to have an irreversible effect in breast development even pre-puberty.
Genetics also plays a very significant role - some people are genetically predisposed to have copious amounts of fat cells in therefore large breasts, others practically none. Thus amply endowed sisters are a promising sign that development will be good, while flat chested sisters are a serious worry!
Next, breast growth seems to be very age dependent - the younger a person and the more recent puberty (which normally ends between 18 and 20), the better the development will be. The limited available evidence (clearly there is a need for medical studies, but so far none seem to have been conducted) indicates that maximum breast development will be achieved by starting female hormone treatment just before the on-set of male puberty. In terms of breast volume, the final result is likely to be only slightly less than the girls mother and sisters.
Other smaller factors come into play in determining the size of a woman's breasts, including nutrition, exercise, health, and weight. For example, if a woman's body weight falls below its optimum then her breasts can shrink dramatically as the fat cells in them are burnt up (or in the case of a skinny transwoman are perhaps never deposited), while if her weight is above optimum then the apparent or relative size of her breasts may diminish as they are swallowed by the surrounding "padding".
An unscientific review of seven transgirls who started taking oestrogen in their teens shows that they all reached a good A cup or reasonable B cup, i.e. only slightly smaller than genetic women. Unfortunately the overall appearance of their breasts is often hampered by the girls having a larger than average (for a woman) chest cage.
When puberty ends (around age 18) a "switch" in the body seems to turn off and the likely amount of breast development rapidly falls away in an elongated 'reverse S-curve' to a much lower level. Thus whilst a 12 year old boy-to-girl will typically end up with well-developed breasts not that much smaller to his sisters and mother, and the same person starting hormone therapy as a 20 year-old will still have reasonable results, but as a 30 year-old she will have far less satisfactory results, and this will be only slightly better than a 40 year-old who in turn will be barely better off than a 50 plus year-old. The claims often made by many middle aged transwomen to have developed C or D cup breasts after a year on hormones need to be treated very sceptically.
Whilst most girls who start hormone treatment while in their teens seem to eventually develop "B cup" Tanner IV or V type breasts, even this is still by no means certain. For example the model Caroline Cossey started hormones at age 17 but owes most of her famous 36C chest to implants two years later, and Caroline is far from unique. Other young (age 16 to 18) transsexuals report having very little breast growth even after a year or two on hormones - although in these circumstances there must be a suspicion that a change of hormone regimen would have helped them. Certainly many young transsexuals are dissatisfied with their breast growth as they compare themselves with other girls, and begin to compete for boyfriends.
Conversely, while most of those women starting hormones when already in their mature years will achieve only slight Tanner II or III "AA cup" breast buds, a few will get adequate, even ample, breast development.
There is undoubtedly often a degree of wishful thinking and 'rounding up' in the bra sizes claimed by transsexual women. Realistically, most adult transsexual women starting hormone treatment over the age of 20 will be very lucky if they eventually genuinely fill a "B cup" bra from hormone use alone, and those over 30 an "A cup". However, if letters are important it should be remembered that despite a perception created by television and the press, the average cup size of genetic women is actually only "B".
One odd problem that transsexual women face is that their areala - the coloured skin surrounding the nipple - rarely expands in accordance with 'normal' female breast growth. The areolae of a man averages about 25 mm (1 inch) in diameter, but few woman are under 30 mm and 50 mm is common, and the areola of women who have large breasts or who are lactating may be over 100 mm (4 inch) in diameter. Unfortunately even well-endowed transsexual women tend to have male type arealoe - this seems to be a genetic limitation as AIS women (who are also genetically XY) face a similar problem despite otherwise above average breast development.
As a tubular breast consists primarily of just fatty tissue, milk production and breast feeding can be problematic - although of course this is rarely relevant for transsexual women. The use of a "cocktail" of hormones that includes both oestrogen and progesterone may help reduce hypoplasticy.
In older transwomen, their small breasts are also likely to be spaced widely, and one breast is often noticeably larger than the other. These problems make it difficult to monitor the degree of breast development in mature transsexual women using the Tanner scale.
It clearly shows that the breasts of male-to-female transsexual women are considerably smaller than genetic XX women. To make matters worse, the width of the average transsexual woman's thorax is greater than that of the average female thorax, and so the breast development is proportional to the chest size even less than the figures indicate. Consequently, the overall effect and appearance of their hormone-only induced breasts is judged unsatisfactory by some 50-60% of MTF transsexual women, and the vast majority of these seek augmentation mammaplasty (breast implants).
Another characteristic of the breasts of MTF transsexual women compared with genetic women is the smaller average diameter of their areola, even if the breasts themselves are actually quite generous in size. Only starting hormone treatment at a young age seems to avoid this tendency. Also, because the breasts of transsexual woman rarely reach full Tanner V size and maturity, their nipples often appear very prominent - although few women object to this too much!
The advent of the first, very expensive, female hormone treatments in the 1950's was a massive advance for transsexual women seeking 'natural' breasts. Since then there have been improvements in potency, delivery and cost - but no fundamental progress in the likely final result. This may soon change with stem cell injections becoming a possibility in the next few years. Named Celution, the procedure involves injecting a stem cells into the breast tissue.
Fat is taken through liposuction from the woman's belly or bottom. The stem cells are filtered out from the extract and then put into a cartridge for injection into her breasts maybe an hour later under local anaesthetic. While the initial change is small, it is claimed that the breasts will gradually 'inflate' over a six-month period and the eventual result will be an increase in two cup sizes (e.g. a B- cup to a D). For many transsexuals this technique could represent a wonderful alternative to breast augmentation.
Please contact me if you have any comments.
Below are pictures sent to me by transgender women of their hormone induced breast development (i.e. with no implants). They seem to confirm that breast development in XY transwomen is much less than that in most natal XX women.
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Copyright (c) 2015, Annie Richards