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Please address the matters covered in the embedded file. > The "human anus" article has an image of a human female's anus and perineum that probably were damaged by some kind of major trauma. Biological human females should lack an obvious perineal raphe (seamlike union/ridge) in the anogenital region between the anus and the vagina, because the bulbospongiosus muscle is separated in them; embryologically it does not promote formation of a persistent, externally-visible midline raphe as it may in biological males [References: Anatomy & Trauma]. Furthermore, the "perineal raphe" article suggests otherwise (involving urogenital folds) with no support from any cited source. I'm still not happy with that wording, so expect it to change soon. I strongly dislike referencing old posts of mine on 4chan any longer (chiefly due to treatment similar to what I'm experiencing here on lainchan), but since this thread probably will disappear soon anyway... Here's an old post of mine explaining why I'm still working on the wording: 4chan /gif/thread/9574800 Wed 16 Nov 2016 07:05:11 No.9608234 (Quoting post 9592531) > It's the perineal raphe I doubt that; the narrow, raised band along her perineal midline doesn't appear to extend along the entire length of her perineum (from her anus to her vagina) for one thing, as an observable perineal raphe probably would. It may instead be scar tissue (such as an anal skin tag, e.g. from an episiotomy, some other surgical procedure, or sexual trauma) or some sort of abnormality. In men, the perineal raphe would be one explanation for significantly raised, observable tissue along the midline of the perineum, but women don't seem to have that normally. While the perineal raphe does seem to be an anatomical reference point for both sexes, "the raphe is not evident in females" according to one Japanese source.

> Biological human females should lack an obvious perineal raphe (seamlike union/ridge) in the anogenital region between the anus and the vagina, because the bulbospongiosus muscle is separated in them; embryologically it does not promote formation of a persistent, externally-visible midline raphe "To investigate intergender differences in muscle cleavage and joining during development of the external anal sphincter (EAS), we examined semiserial sections of 16 fetuses between 15 and 30 weeks of gestation (6 males and 10 females). The subcutaneous part of the EAS (EASsc) developed along the male perineal raphe and extended posteriorly. Thus, the male EAS was characterized by anterior protrusion of the subcutaneous muscle, in contrast to the almost circular female EAS. In both genders, the bulbospongiosus anlage (or the levator ani anlage) issued muscle fibers to form the superficial (or deep) part of the EAS. The EASsc communicated with the superficial part in males, whereas the female bulbospongiosus tended to communicate with the levator ani rather than the EAS. In both genders, the longitudinal muscle bundle(s) of the anorectum contributed to perineal body formation. However, the male perineal body also had a thick fascia between the rhabdosphincter and the levator. The bulbospongiosus seems to play a critical role in forming the EAS. A strict intergender difference in subcutaneous muscle development is evident along the perineal raphe, as the raphe is not evident in females. These results help to explain variations in the EAS, including anal malformations." "Development of the external anal sphincter with special reference to intergender difference: observations of mid-term fetuses (15-30 weeks of gestation)." Okajimas Folia Anatomica Japonica. 2010 Aug; 87(2): 49-58. PMID 20882767. doi:10.2535/ofaj.87.49. "The raphe of the human penis and scrotum is considered to develop secondarily after disappearance of the initial midline seam by fusion of the bilateral genital folds. However, the fetal development was still obscure. We examined histological sections of 30 fetuses (17 males and 13 females) at 10–15 weeks. In male fetuses, the scrotum was not yet clearly identified because of no descent of testis. The perineal raphe was thin and wavy at 10 weeks, and it was continuous with and took a direction same as the inferior wall of the closed penile urethra after physiological hypospadias. Depending on growth of the bulbospongiosus muscle and corpus spongiosus penis, the midline intermuscular septum obtained a connection to the subcutaneous wavy raphe and made the latter thick and straight at 12–15 weeks. Notably, the perineal raphe extended posteriorly to attach to the external anal sphincter. In female fetuses, an epithelial fusion occurred along a short distance at the posterior end of the vestibule. However, in front of the external anal sphincter, a large midline mesenchymal tissue from the urorectal septum did not contain a raphe-like structure. Moreover, since the bilateral bulbospongiosus muscles were separated widely by the vestibule, they did not provide a midline septum. Fetal development of the perineal raphe was accelerated by reinforcement from the muscular septum. In contrast, without such a muscular support, the female raphe could not maintain its growth even if the seed appeared at the posterior end of the vestibule." "Perineal raphe with special reference to its extension to the anus: a histological study using human fetuses." Anatomy & Cell Biology. 2016 Jun; 49(2): 116-124. PMC4927426. doi:10.5115/acb.2016.49.2.116.

> Furthermore, the "perineal raphe" article suggests otherwise (involving urogenital folds) with no support from any cited source. "COMPARISON BETWEEN MALES AND FEMALES "The main difference between the male and the female is the absence of the development of the external urethra in the female (to be precise, only the urethra in the glans is missing) due to the nonfusion of the urogenital folds; however, the structures that form the external urethra in the male are present in the female and correspond to the vestibule of the vagina and the internal surface of the labia minora (Testut and Latarjet, 1972; Standring, 2008; Puppo, 2011a)." "Anatomy and physiology of the clitoris, vestibular bulbs, and labia minora with a review of the female orgasm and the prevention of female sexual dysfunction." Clinical Anatomy. 2013 Jan; 26(1): 134-52. doi:10.1002/ca.22177. (PMID 23169570) Epub 2012 Nov 21. "As a result of their similar embryological origins, the clitoris and the penis are homologous in much of their anatomy. The dominant difference between the two organs is the lack of fusion of the urogenital folds, so the urethra does not pass down the body of the clitoral glans (Puppo, 2011). Furthermore, the body of the glans clitoris is surrounded by a fibrous tunica albuginea (Toesca et al., 1996; Shih et al., 2013), which is absent from the glans penis." "Anatomy of the clitoris and the female sexual response." Clinical Anatomy. 2015 Apr; 28(3): 376-84. doi:10.1002/ca.22524. (PMID 25727497) > While the perineal raphe does seem to be an anatomical reference point for both sexes, "the raphe is not evident in females" according to one Japanese source. "We present a case where a baby girl was born with failure of fusion of the perineal raphe. To our knowledge, there has been limited reports of this form of congenital abnormality in the literature and is referred to as "perineal groove." The incidence of perineal groove is unclear but it is considered to be rare. This case reviews the embryological origin of this congenital abnormality." "Perineal groove: A rare congenital abnormality of failure of fusion of the perineal raphe and discussion of its embryological origin." Clinical Anatomy. 2009 Oct; 22(7): 823-5. PMID 19753644. doi:10.1002/ca.20855.

> While the perineal raphe does seem to be an anatomical reference point for both sexes, "the raphe is not evident in females" according to one Japanese source. Work-in-progress explanation: When the outermost cutaneous (skin) layer fails to join together embryologically, that's considered failed fusion, resulting in something like perineal groove. Repairing that might leave an evident indication, which someone might call "a prominent perineal raphe" (as in Wikipedia's "human anus" article). Of course, as I noted that could instead be a result of surgical or other trauma (and perhaps subsequent healing e.g. with stitches). Possibilities include an episiotomy, complete anal sphincter complex disruption ("a laceration at the anal mucosa, extending through the entire thickness of the anal sphincter complex into the vagina"), etc. In normal cases there is no obvious seam in biological females. In biological males on the other hand there may be an obvious, raised seam due to more fusion happening embryologically at least with the bulbospongiosus and urogenital folds.