PMC

Differences in the placement of the urethral meatus (UM; ventral cleft) in a WT, αERKO, DES-treated mouse penis, and juvenile human penis with mild hypospadias. A) Sagittal cross section of the adult mouse penis (P57) with the external prepuce removed. The UM is directly underneath the MUMP (M), and the os penis (O) is more proximal than the UM. B–D) Transverse sections of adult mouse penises. In the WT mouse penis (P90), the UM (arrowhead) is present in the distal section (top panel) as a ventral cleft extending from the urethra (U) beneath the MUMP. In the more proximal section (bottom panel) showing the most distal tip of the os penis, the urethra is tubularized and internal to the penis (B). In a DES-treated adult penis (P57), the UM (black arrowhead) is present in the proximal section and thus opens more proximally than in the WT penis (C). An identical phenotype can also be seen in the αERKO penis with an open ventral cleft in proximal penis sections (P46) (D). E) Juvenile human penis with mild hypospadias, with the white arrow indicating the location of the UM. Scale bar, 500 µm.

Three-dimensional reconstruction of the prepuce and penis of an adult broad-footed mole (Scapanus latimanus) with transverse sections depicting morphology at different locations within the penis. Three-dimensional reconstruction (A) the prepuce is semi-transparent with the penis opaque orange demonstrating the shape and the position of penis relative to the prepuce. The mole penis at rest is an “internal” organ housed within the preputial space (lighter purple region bordered by white dotted lines). Three white lines are labeled denoting the length of the external prepuce, the length of the penis and the length the penis/prepuce overlap. Three dimensional reconstruction (B) the prepuce and penis are rendered semi-transparent to show the internal morphology of the penis. The perineal appendage (prepuce) merges with the body surface (green asterisks). Red arrowheads denote the reflection of the inner preputial epithelium onto the surface of the penis. The distal end of the urethra (green) is the urethral meatus where urine/semen exits from the penis. Three transverse section images (C–E) depict the internal morphology of the penis from proximal to distal at differing morphological points. CC=Corpus Cavernosum, PS=Preputial Space, UR= Urethra. Note the morphometric measures mentioned in the text.

An obese 87-year-old man’s adult acquired buried penis cannot be observed; however, a yellow arrow shows where his hidden uncircumcised penis was located (a). The distal portion of his penis was able to be demonstrated after pressure had been applied to the suprapubic fat (escutcheon); the black arrows demarcate his proximal penis (b).   

Mating and morphology of the penis in Chromodoris reticulata. (a,b) Two individuals reciprocally insert their penis into the partner's vagina. (c,d) Autotomized penes after copulation; the tip of the penis is swollen. A mass of sperm (sp) is attached to the thorny penis in (d). (e) Surface of the penis is equipped with innumerable backward-pointed spines. (f) Sperm are entangled in the spines. Autotomized penis stained with haematoxylin after being air-dried on a glass slide. Arrows show the direction of penis insertion.