Urogenital Research Unit, State University, Rio de Janeiro, Brazil.
Histol Histopathol. 2012 Aug;27(8):1041-5. doi: 10.14670/HH-27.1041.
Foreskin development begins at twelfth gestational week through a circular invagination of the ectoderm in the glandular periphery that grows ventrally and totally involves the glans around the twentieth gestational week. Studies of foreskin formation chronology and its histological constituents in human fetuses are rare. The objective of this study is to analyze foreskin development during the second trimester of the human fetal period.
We studied twelve well-preserved human fetuses between thirteen and nineteen weeks post conception (WPC), according to the foot length criterion. The fetuses' weight ranged from 70 to 340 g and the crown-rump length from 11 to 18.5 cm. Their penises were formalin-fixed, paraffin-embedded and cut into 5 micrometers sections. Hematoxylin and eosin, Van Gieson solution, Gomori trichrome and Weigert staining were used.
The glans was partially covered by the foreskin in the fetus at 13 WPC and almost completely covered by the foreskin in fetuses at 16 WPC and 17 WPC. The complete foreskin was formed only in the fetuses at 18 and 19 WPC, in which the foreskin totally covered the glans. In all the fetuses studied we observed the presence of preputial lamella and a large amount of mesenchymal tissue between the foreskin and glans.
The chronology of foreskin formation in the second gestational trimester is well documented in our article. It is a fast process that lasts around five weeks and is coordinated with penile urethra formation.
包皮的发育始于第 12 孕周，通过外胚层在腺体周围的环形内陷开始，向腹侧生长，并在第 20 孕周完全覆盖龟头。研究人类胎儿包皮形成的时间进程及其组织学成分较为罕见。本研究的目的是分析人类胎儿妊娠中期包皮的发育情况。
我们根据足长标准研究了 12 例保存良好的 13-19 孕周妊娠（WPC）的人类胎儿。胎儿体重为 70-340g，头臀长为 11-18.5cm。他们的阴茎经福尔马林固定、石蜡包埋并切成 5 微米的切片。使用了苏木精和伊红、Van Gieson 溶液、Gomori 三色和 Weigert 染色。
13WPC 时胎儿的龟头部分被包皮覆盖，16WPC 和 17WPC 时几乎完全被包皮覆盖。只有在 18 和 19WPC 的胎儿中形成了完整的包皮，此时包皮完全覆盖了龟头。在所有研究的胎儿中，我们观察到存在包皮内板和大量位于包皮和龟头之间的间充质组织。
我们的文章详细记录了妊娠中期包皮形成的时间进程。这是一个快速的过程，大约持续 5 周，与阴茎尿道的形成相协调。
