The goal of this report is (a) to provide the first detailed description of mouse clitoral development, and (b) to compare mouse and human clitoral development. For this purpose, external genitalia of female mice were examined by wholemount microscopy, histology and immunohistochemistry from 14 days of gestation to 10 days postnatal. Human clitoral development was examined by these techniques as well as by scanning electron microscopy and optical projection tomography from 8 to 19 weeks of gestation. The adult mouse clitoris is an internal organ defined by a U-shaped clitoral lamina whose development is associated with the prenatal medial and distal growth of the

female preputial swellings along the sides of the genital tubercle to form the circumferential preputial lamina. Regression of the ventral aspect of the preputial lamina leads to formation of the U-shaped clitoral lamina recognized as early as 17 days of gestation. While the adult U-shaped mouse clitoral lamina is closely associated with the vagina, and it appears to be completely non-responsive to estrogen as opposed to the highly estrogen-responsive vaginal epithelium. The prominent perineal appendage in adult females is prepuce, formed via fusion of the embryonic preputial swellings and is not the clitoris.

The human clitoris is in many respects a smaller anatomic version of the human penis having all of the external and internal elements except the urethra. The human clitoris (like the human penis) is derived from the genital tubercle with the clitoral glans projecting into the vaginal vestibule. Adult morphology and developmental processes are virtually non-comparable in the mouse and human clitoris.

本报告的目标是（a）提供小鼠阴蒂发育的第一个详细描述，以及（b）比较小鼠和人类阴蒂发育。为此目的，从妊娠14天到产后10天，通过整体显微镜，组织学和免疫组织化学检查雌性小鼠的外生殖器。通过这些技术以及妊娠8至19周的扫描电子显微镜和光学投影断层扫描技术检查了人类的阴蒂发育。成年小鼠的阴蒂是由U形的阴蒂椎板定义的内部器官，其发育与胎儿的产前内侧和远端生长有关。

沿生殖器结节的两侧有女性的包膜红肿，形成圆周的包膜层。包皮层的腹侧退缩导致形成U形的阴蒂层板，最早在妊娠17天时就已形成。尽管成年U型小鼠的阴蒂薄层与阴道紧密相关，但与高度雌激素反应性的阴道上皮相反，它似乎对雌激素完全无反应。成年雌性的会阴部突出物是包皮过长的，是通过融合胚胎的包皮隆起形成的，不是阴蒂。

人体阴蒂在许多方面是人体阴茎的较小解剖版本，具有除尿道外的所有外部和内部元件。人的阴蒂（如人的阴茎）来源于生殖器结节，阴蒂龟头伸入阴道前庭。在小鼠和人类的阴蒂中，成人的形态和发育过程几乎是无法比拟的。