Hemipenis
As hemipenis ( . AltGr ἥμι hemi "half"; plural Hemipenes ) refers to the male reproductive organ in the Schuppenkriechtieren . At the side of the cloaca there is a paired, fold-out pocket, each with a hemipenis that is often spiky due to thorn-like ossification of the skin. Other reptiles such as turtles , bridge lizards and crocodiles do not have these paired mating organs, which is why they are classified as autapomorphism of the scalp reptiles .
morphology
The hemipenis is an invagination in the cloacal wall on both sides of the tail root, which is everted for copulation. Depending on the species, the hemipenis is piston-shaped to very deeply forked, depending on the structure of the cloaca of the female. Sometimes there are complex fold structures called calyces and paryphasms. The calyces are small and unicellular, whereas the paryphasms are permanent and often very large. There are also spines that are partially horny or even calcified in the snakes. On the inside of the hemipenis there is a groove, the sulcus spermaticus , in which the sperm are directed into the female cloaca during copulation .
A special feature of the hemipenis Warane is that he will end up with the Hemibaculum (analogous to the penis bone some mammals) has an ossified structure. The benefit of this ossification has not been clarified; it is assumed that these structures will have an as yet undefined advantage in biological fitness .
Function and use in copulation
Since males of Squamata during copulation not such as mammals ascend completely to the female, but nestle side, only the hemipenis is always used during copulation, which lies on the side facing the female side. Even if one of the two hemipenes is lost, the animal is still capable of copulation.
The protuberance takes place in two phases: the hemipenis is everted by means of muscles and inserted into the female's cloaca, then the hemipenis is filled with blood and lymph and further everted and strengthened until it is plump. During ejaculation, the sperm runs through the sperm groove on the inside of the hemipenis into the female cloaca. After copulation, a pulling back muscle that extends far into the tail pulls the hemipenis back into the base of the tail and thus into the resting position. In species capable of autotomy, the muscle extends to the first caudal vertebra with an autotomy suture, since otherwise the animal would be incapable of copulation after shedding its tail and there would be a risk of a hemipenis prolapse (see below).
Hemipenis disorders
One of the most common diseases of the hemipenis is the so-called hemipenis prolapse. In such an incident, the hemipenis is everted without any connection to copulation and can not be drawn in due to a constriction through the cloacal opening. There is a risk of dehydration and necrosis of the organ. The treatment attempts to move the hemipenis back; if this measure fails, the hemipenis is usually amputated. The animal's ability to mate is retained by the other hemipenis. The cause of this condition can be the result of an inflammatory process or an injury. In snakes , a hemipenis prolapse often occurs when a male tries to mate, the partner flees and the male animal pulls behind him on the sexual organ. The hemipenis cannot be pulled back through stretching, twisting or similar damage and it dries up.
In addition to the prolapse of the hemipenis, the clogging of the skin pockets in which the organs are located by exfoliated epithelial cells is described. This plug can interfere with normal sexual function. Treatment consists of manual removal of the plug.
Remnants of previous moults often appear on the hemipenes (hemipenis exuvia ). The sloughed skin tears off at the cloacal ring and the old skin covering of the hemipenis is not stripped off, so that several layers of skin can appear.
Hemiclitoris
Females of the scalloped reptiles have homologous structures in the form of the so-called hemiclitoris . These correspond completely to the Hemipenes in structure, including the sperm groove as well as the Hemibaculus in the monitor lizards, but are usually much smaller than these, in some species the Hemiclitores can, however, assume similar dimensions as their male counterparts. Almost nothing is known about the function of these organs, and they are not used during copulation.
Sex determination by probing the hemipenis
Since reptiles often have no clear external sexual characteristics, probing the sexual organs is one of the most common sex determination methods in scale crawls. The cloaca of the specimens is examined with a probe. If the probe penetrates deeply (in snakes, for example, about seven rows of scales), it is a male, if the penetration depth is shallow (in snakes about three scales), it is a female. However, with this method there is a chance of falsifying the results: on the one hand, the male's hemipenis can become tense or have a sperm plug, which means that the animal is mistaken for a female, on the other hand, the tissue of females can be pierced, thus becoming a male held.
Hemipenes in taxonomy
In addition to their role as a characteristic feature of the scalloped reptiles, the Hemipenes play an important role in the description and differentiation of the species. By their species-specific form they can be clearly assigned to certain species and accordingly as determining characteristic use. For this reason, in the case of museum and collection specimens, the hemipenes are everted out before preparation.
swell
- ↑ PH Beynon, MPC Lawton, JE Cooper (Ed.): Compendium of Reptile Diseases. Attitude - diagnostics - therapy. Schlütersche, Hannover 1997, ISBN 3-87706-469-8 , p. 130.
- ↑ Petra Kölle: Snakes. Kosmos Verlag, Stuttgart 2004, ISBN 3-440-09377-8 .
literature
- Wolfgang Böhme : Squamata, scale reptiles. In: Wilfried Westheide , Reinhard Rieger (Ed.): Special Zoology. Part 2: vertebrates or skulls. Spektrum Akademischer Verlag et al., Heidelberg et al. 2004, ISBN 3-8274-0900-4 , pp. 354-357.
- Harald Jes: Lizards. Gräfe and Unzer Verlag, Munich 1999, ISBN 3-7742-3709-3 , p. 57, note: Popular science; served mainly as a source for the diseases.
